Archives of Nephrology ISSN: 2639-3573 Volume 2, Issue 2, 2019, PP: 16-28 Role of Molecules in Medical Laboratory Diagnosis Nnodim Johnkennedy*, Diala Tecla Ifesinachi, Ndunelo Chidiebere, Nwajiaku Victor, Nwanebu Chidimma Department of medical laboratory science, faculty of health science, Imo State University Owerri, Nigeria. [email protected] *Corresponding Author: Nnodim Johnkennedy, Department of medical laboratory science, Faculty of health science, Imo State University Owerri, Imo State, Nigeria.

Abstract Cell adhesion is a fascinating process. It plays a key role in many situations of biological and medical interest. It is probably the best cell function to be considered for biophysical modeling from the micrometer to the molecular level. Studying the biophysical aspects of cell adhesion leads to face many important problems of physics and physical chemistry as well as cell physiology. Perturbation of this process leads to the disruption of homeostasis and dysontogenesis. Perturbation of cell-cell adhesion can also be a cause of disease.

Introduction are constantly being lost from the outer surface and replaced from the basal layer of the Cell adhesion is the process by which cells interact multilayered such that all cells are renewed and attach to neighboring cells through specialized approximately once every 28 days depending on body molecules of the cell surface (Chothia and Jones, 2000). site. Other cells such as blood platelets must circulate This process can occur either through direct contact freely in the blood and thus must be non adhesive. between cell surfaces or indirect interaction, where cells attach to surrounding extracellular matrix_ a However, when wound occurs, they must become gel-like structure containing molecules released by adhesive rapidly to participate in hemostasis, that is, cells into spaces between them (Alberts et al., 2008). the coagulation of the blood that prevents bleeding. Cell adhesion is crucial for multicellular life. Not only This important cell adhesion is made possible by the does it allow cells to physically interact with each presence of Cell Adhesion Molecules (CAM). Cells other and their surroundings to form tissues, but cell express a wide variety of adhesion receptors which adhesion also allows cells to sense their environment may mediate cell-cell interactions, adhesion to the and respond accordingly. Therefore, cell adhesion extracellular matrix or both (Alberts et al., 2008). has important roles in immunity, cell migration and embryogenesis (Lessey, 2008). Also tissues have Cell adhesion molecules (CAMs) are proteins located the ability to carry out tasks no single cell could on the cell surface involved in binding with other cells accomplish in its own due to this cell communication. or with the extracellular matrix (ECM) in the process of Cell adhesion is also essential for infectious organisms, cell adhesion. In essence, cell adhesion molecules help such as bacteria or viruses, to cause diseases. cells stick to each other and to their surroundings. Cell adhesion is a crucial component in maintaining tissue Cell adhesion is not just a structural element that structure and function. Combined with cell junctions binds things together; it is also a highly dynamic and Extracellular Matrix, CAMs help hold animal cells process. For example, the cells of the epidermis, called together (Juliano, 2002). keratinocytes, have to be tightly bound together to provide the barrier properties of the skin that protect There are four major families of the CAMs namely: , Immunoglobulin (Ig) superfamily, and tear of everyday activities. However, epidermal and . humans against fluid loss, infection, and the wear Archives of Nephrology V2 . I2 . 2019 16 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis Immunoglobulins Superfamiliy. Such homophilic binding leads to selective adhesion between cells of cellEach adhesion of these are adhesion usually molecules attributable has to a defects different in the same type. function and recognizes different ligands. Defects in expression of CAMs. For example, nerve Cell Adhesion Molecules (N-CAMs) History are members of the Ig superfamily expressed on nerve cells, and homophilic binding between N-CAMs Recognition of the importance of cell adhesion grew contributes to the formation of selective associations steadily during the twentieth century as it promised between nerve cells during development (Park et al., 2010). that included cell biology, developmental biology, tumorigenesis,answers to fundamental immunology questions and neurobiology. in diverse fields Cadherins form homophilic attachment between themselves, which results in cells of a similar type Early tissue culture studies, initiated by Harrison in sticking together and can lead to selective cell 1907, showed convincingly that most tissues were not adhesion, allowing vertebrate cells to assemble into a syncytium but rather were comprised of individual organized tissues. Cadherins are essential for cell–cell cells. Thus, the presence of tissues required cell adhesion and cell signaling in multicellular animals adhesion. The integrity of tissues is also dependent (Chothia and Jones, 2000). on the adhesion, by CAMs, of cells to cells and cells to In heterophilic binding, a CAM on one cell will bind the Extracellular Matrix. Studies of tissue dissociation and reassociation in invertebrates also pointed to matrix as seen in Integrins and Selectins. the importance of adhesion. In 1900, Herbst showed with different CAMs on another cell or the extracellular that sea urchin blastomeres fall apart when calcium In multicellular organisms, bindings between CAMs is removed and then reassociate in normal seawater allow cells to adhere to one another and creates to form embryo-like structures. Soon after, Wilson structures called cell junctions. observed that sponges could similarly be dissociated Classification of the Cell Adhesion into single cells and then reassociate to form a small Molecules These four families of the Cell Adhesion Molecules are differentiatedIn 1975, Gerald sponge Maurice (Lewis, 1999). Edelman discovered categorized based on their Calcium dependence. substances called cell adhesion molecules (CAMs), Integrins and the Ig-superfamily CAMs do not depend which “glue” cells together to form tissues. Edelman on Ca 2+ while cadherins and selectins depend on Ca found that, as the brain develops, CAMs bind neurons 2+ (Alberts et al., 2008) together to form the brain’s basic circuitry. His work led to the construction of a general theory of brain Integrins development and function called neuronal group Integrins are large, membrane-spanning, hetero- selection. dimeric proteins (as they consist of an alpha and Structure and Interaction of Cell Adhesion beta subunit) that are essential for a metazoan Molecules existence. All members of the family are transmembrane proteins found in all animal cells CAMs are typically transmembrane receptors and are that bind to extracellular matrix ligands, cell-surface composed of three conserved domains: an intracellular ligands, and soluble ligands, thus they facilitate Cell- domain that interacts with the cytoskeleton, a ECM Adhesion (Humphries, 2000). Even simple transmembrane domain, and an extracellular domain animals like sponges have these proteins. Integrins (Chothia and Jones, 2000). are among the major classes of receptors within the Extracellular matrix. Integrins provide essential links between the extracellular environment and the ways which could be hemophilic or heterophilic intracellular signaling pathways, which can play roles protein-proteinThese proteins interactions can interact or protein-carbohydrate in several different interactions. survival, and transcription. The presence of Integrins In Homophilic interactions, CAMs bind with the in cell behaviors such as apoptosis, differentiation, same CAMs on another cell as seen in Cadherins and cell surface (Alberts et al., 2008). allows rapid and flexible responses to events at the 17 Archives of Nephrology V2 . I2 . 2019 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis Structure of the Integrins this inserted domain also have an A-domain in their ligand binding site, but this A-domain is found on the Integrins are obligate heterodimers, meaning that together by disulphide bond. β-In bothsubunit cases, (Humphries, the A-domains 2000). carry up to three divalent they have two subunits: α (alpha) and β (beta) linked cation binding sites. One is permanently occupied in There are currently 18 alpha subunits and 8 beta physiological concentrations of divalent cations, and carries either a calcium or magnesium ion, the principal subunits, which combine differently to make up 24 divalent cations in blood at median concentrations of alphadifferent and betareceptors subunits with accounts different for binding the wide properties variety two sites become occupied by cations when ligands ofand integrins different observed tissue throughout distribution. the animal Variation kingdom. in the bind—at1.4 mM (calcium) least for and those 0.8 mM ligands (magnesium). involving The an acidicother amino acid in their interaction sites. An acidic amino kinds of integrins. Within each of the alpha and acid features in the integrin-interaction site of many betaFor example, subunits humans there is alone a large have extracellular over 20 different domain, ECM proteins, for example as part of the amino acid a transmembrane domain and a short cytoplasmic sequence Arginine-Glycine-Aspartic acid (Giancotti domain. and Ruoslanti, 2010). Integrin subunits span the cell membrane and have Functions of the Integrins Integrins have two main functions:- cytoplasmicshort cytoplasmic domain domains of 1,088 ofamino 40–70 acids, amino one of acids. the I. Attachment of cell to the ECM and Cell largestThe exception of any membrane is the beta-4 protein subunit, (Humphries, which 2000). has a Migration Outside the cell membrane, the alpha and beta chains II. Signal transduction from the ECM to the cell lie close together along a length of about 23 nm; the However, they are also involved in a wide range of other binding region for the ECM. They have been compared biological activities, including immune patrolling, and tofinal lobster 5 nm claws, N-termini although of each they chaindon’t formsactually a “pinch” ligand- binding to cells by certain viruses, such as adenovirus, their ligand, they chemically interact with it at the echovirus, hantavirus, and foot-and-mouth disease insides of the “tips” of their “pinchers”. viruses. The molecular mass of the integrin subunits can vary Attachment of Cell to the ECM and Cell Migration from 90 kDa to 160 kDa. Beta subunits have four Integrins couple the ECM outside a cell, to the cysteine-rich repeated sequences. Both alpha and beta subunits bind several divalent cations. The role the cell. Which ligand in the ECM the integrin can bind of divalent cations in the alpha subunit is unknown, cytoskeleton (in particular, the microfilaments) inside but may stabilize the folds of the protein. The cations the integrin is made of. Among the ligands of integrins in the beta subunits are more interesting: they are to is defined by which alpha (α) and beta (β) subunits directly involved in coordinating some of the ligands connection between the cell and the ECM may help that integrins bind (Giancotti and Ruoslanti, 2010). theare fibronectin,cell to endure vitronectin, pulling forces collagen, without and beinglaminin. ripped The Integrins can be categorized in multiple ways. For out of the ECM. The ability of a cell to create this kind of bond is also of vital importance in ontogeny. element (or “domain”) inserted toward the N-terminal; Cell attachment to the ECM is a basic requirement to theexample, alpha-A some domain α chains (so called have anbecause additional it has structural a similar build a multicellular organism (Juliano, 2002). structure to the A-domains found in the protein von Willebrand factor), it is also termed the alpha-I The attachment of the cell takes place through domain. Integrins carrying this domain either bind to formation of cell adhesion complexes, these adhesion complexes attach to the actin cytoskeleton. The integrins thus serve to link two networks across the collagens (e.g. integrins α-1 β-1, and α-2 β-1), or act plasma membrane: the extracellular ECM and the ofas cell-cellsuch integrins. adhesion Those molecules integrins (integrins that don’t of the carry β-2 family). This α-I domain is the binding site for ligands Archives of Nephrology V2 . I2 . 2019 intracellular actin filamentous system. Integrin α6β418 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis is an exception: it links to the keratin intermediate Depending on the integrin’s regulatory impact

2011). experience; filament system in epithelial cells (Frisch and Screaton, on specific receptor tyrosine kinases, the cell can One important function of integrins on cells in tissue celll growth culture is their role in cell migration. Cells adhere to a cell division • substrate through their integrins. During movement, cell survival the cell makes new attachments to the substrate at • its front and concurrently releases those at its rear. • apoptosis (programmed cell death) When released from the substrate, integrin molecules • cellular differentiation, and Some cell signaling occurs on a local level, such as are taken back into the cell by endocytosis; they • are transported through the cell to its front by the when cells interact with the surrounding extracellular endocytic cycle, where they are added back to the matrix or with their immediate neighbors. This type of surface. In this way they are cycled for reuse, enabling signaling is especially important to the structure and the cell to make fresh attachments at its leading front. It is not yet clear whether cell migration in tissue the cells within a tissue to share information about function of tissues. Various signaling molecules allow culture is an artifact of integrin processing, or whether internal and external conditions. This information such integrin-dependent cell migration also occurs in helps the cells arrange themselves, coordinate their living organisms (Jacquemet et al., 2013) functions, and even know when to grow and when to die. Signal Transduction It is worthy to also note that Integrins have an Signal transduction is the process by which a chemical important function in neuroregeneration after injury or physical signal is transmitted through a cell as a of the peripheral nervous system (PNS). series of molecular event, most commonly by protein phosphorylation catalyzed by protein kinases, which A prominent function of the integrins is also seen in the molecule GPIIbIIIa, an integrin on the surface ultimately results in a cellular response. Proteins of blood platelet (thrombocytes) responsible for responsible for detecting stimuli are generally termed receptors or sensors (Frisch and Screaton,2011). This molecule dramatically increases its binding Signal transduction by Integrins is bidirectional attachment to fibrin within a developing blood clot. meaning that they can transmit information both platelets with exposed collagens in the wound site. outside-in and inside-out (Hynes, 2012). Uponaffinity association for fibrin/fibrinogen of platelets with through collagen, association GPIIbIIIa of Integrins play an important role in cell signaling blood components (McGray et al., 2012). by modulating the cell signaling pathways of changes shape, allowing it to bind to fibrin and other transmembrane protein kinases such as Receptor Immunoglobulin Superfamily Tyrosine Kinases (RTK). Integrins can regulate the The immunoglobulin superfamily (IgSF) cell receptor tyrosine kinase signaling by recruiting adhesion molecules are large calcium-independent transmembrane glycoproteins that are involved in the recognition, binding, or adhesion processes of cells specific adaptors to the plasma membrane. For Shp2 to IGF1R, resulting in dephosphorylation of (Barclay, 2003). theexample, receptor. β1c integrinIn a reverse recruits direction, Gab1/Shp2 when and a presentsreceptor tyrosine kinase is activated, integrins co-localise at Molecules are categorized as members of this focal adhesion with the receptor tyrosine kinases and superfamily based on shared structural features with their associated signaling molecules. (Focal adhesions immunoglobulins (also known as ). They are large molecular complexes, which are generated all possess a domain known as an immunoglobulin following interaction of integrins with ECM, then their domain or fold. The purpose of immunoglobulins (antibodies) is to recognize and adhere to other actin complexes strengthen the focal adhesion molecules. interactionclustering). Clustering and initiate and activation the framework of the integrins/ for cell IgSF has over 765 members, and is one of the largest signaling through assembly of adhesomes (McGray et and most diverse families of proteins in the body al., 2012). (Barclay,2003). 19 Archives of Nephrology V2 . I2 . 2019 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis Members of the Ig superfamily include; with conserved cysteine residues, a transmembrane domain,several Ig-like and an intra-chain intracellular disulfide-bonded domain that interacts loops • VascularNeural Cell Cell Adhesion Adhesion Molecules Molecules (NCAM) (VCAM) with the cytoskeleton (Halaby and Mornon, 2015). Intercellular Adhesion Molecules (ICAM) • The Immunoglobulin Domains and nectin-like (Nec1)family. • Proteins of the IgSF possess a structural domain • known as an immunoglobulin (Ig) domain, this superfamily are found to be expressed in the Immunoglobulin (Ig) domain is the common feature mammalianOver 50 different nervous system. members The ofextracellular the immunoglobulin domain of immunoglobulin superfamily members. of IgSF CAMs typically mediate Homophilic cell adhesion, i.e., cell adhesion mediated by interactions Ig domains are named after the immunoglobulin between the same molecules in membranes of molecules. They contain about 70-110 amino acids and adjacent cells. are categorized according to their size and function. Ig-domains possess a characteristic Ig-fold , which They are commonly associated with roles in the has a sandwich-like structure formed by two sheets of opposing antiparallel beta strands stabilized by a protein IZUMO1, a member of the immunoglobulin immune system. Otherwise, the sperm-specific disulphide bridge - Interactions between hydrophobic membrane protein essential for sperm-egg fusion amino acids on the inner side of the sandwich and the (Juliano,superfamily, 2002). has also been identified as the only sperm cysteine residues in the B and F strands, stabilize Structure of the Immunoglobulin Superfamily thehighly Ig-fold. conserved One end disulfide of the Ig bonds domain formed has a between section Proteins which have a similar structure to called the complementarity determining region that

CAM has an extracellular domain, which contains ligands (Barclay, 2003). immunoglobulin are classified as IgSF. Each IgSF is important for the specificity of antibodies for their

Fig 1. Diagram representing structure of the Immunoglobulin Domain of the IgSF. Source: Halaby and Mornon, 2015. II. IgC1, IgC2 or Classification of the Immunoglobulin Superfamily III.I. IgIIgV, IgV

Classified based on the Immunoglobin domains. Most longer than IgC domains with 7 beta strands. Ig domains are either variable (IgV) or constant (IgC) IgV domains with have 9 beta strands are generally andArchives thus could of Nephrology be classified V2 as: . I2 . 2019 20 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis IgC1 and IgC2 through the membrane and the remaining bulk of the protein is extra-cellular (outside the cell). IgC2 are similar in size to IgC domains but resemble The external domain of a molecule - the part IgC domains are called IgC1 domains. that is on the outside of a cell - is made up of many IgV domains in the amino sequence. While standard repeats of the same protein chain. Classical cadherins IgI Other Ig domains exist that are called intermediate (I) for binding calcium. Calcium makes the chain rigid, domains (Halaby and Mornon, 2015). helpinghave five it cadherinto connect repeats. with a Eachchain repeat from another has a space cell Functions of the IGSF (Angst et al., 2011). IgSF CAMs play key role in the developing nervous Most cadherins adhere by homophilic interaction (i.e. system by regulating migration of neurons, growth and they bind to the same type of cadherin) but certain branching of axons and dendrites and establishment types (e.g. E-cadherin) also adhere by heterophilic of contacts between neurons (Maness and Schachner, interactions (i.e. they bind other type of cadherin). 2007). Cadherin association is sensitive to extracellular calcium hence their name, calcium adhering (Juliano, Immunoglobulin superfamily also play central roles 2002). The interactions can take place laterally on the in regulating adaptive and innate immune responses, same cell, called a cis interaction or between two cells, and are prime targets for the development of protein- called a trans interaction (Gumbiner, 2005). based therapeutics. The functionality of cadherins relies upon the Cadherins formation of two identical subunits, known as Cadherins are a class of cell adhesion molecules homodimers. The homodimeric cadherins create cell- that are dependent on Ca2+ ions for their function. cell adhesion with cadherins present in the membranes They are known as class-1 transmembrane 120 of other cells through changing conformation from cis kD glycoprotein that mediate cell-cell adhesion in -dimers to trans-dimers. Once the cell-cell adhesion animals. By regulating contact formation and stability, between cadherins present in the cell membranes of cadherins play a crucial role in tissue morphogenesis and homeostasis. Cadherins function in tissue can then be made when protein complexes, usually morphogenesis by controlling both cell-cell adhesion two different cells has formed, adherens junctions and cell signaling and holding the tissues together as cytoskeleton portion of the cadherin. It should be they form during embryonic development. notedcomposed that ofindividual α-, β-, and cadherin γ-catenins interactions , bind to are the weak. actin Cell-cell adhesion is mediated by extracellular The strength of cadherin-based adhesive junctions cadherin domains in the presence of calcium whereas comes from the clustering of multiple, weak cadherin- the intracellular cytoplasmic tail associates with cadherin interactions, thus, although cadherin- a large number of adaptor and signaling proteins, cadherin binding between the extracellular domains including linkers to the cytoskeletal network. Loss of is relatively weak, the conformational changes that are function of cadherins has also been linked to cancer, induced after binding imparts the individual cadherins and some researchers are investigating cadherins as with rigidity. This stabilizes the interaction and fosters drug targets (Angst et al., 2011). additional lateral cis interactions with other cadherins and generates tighter adhesions. Increased clustering Cadherin Structure of cadherins at sites of cell-cell contact correlate with Cadherins are named for calcium dependent increased stability and maturation of actin-based adhesion. Cadherins are synthesized as polypeptides structures such as dendritic spines (Beavon, 2011). Types of Cadherins to become the proteins which mediate cell-cell adhesionand undergo and many recognition. post-translational These polypeptides modifications are There are about one hundred types of cadherins in approximately 720-750 amino acids long. Each vertebrates, and they fall into four groups; Classical, cadherin has a small cytoplasmic component, a desmosomal, , and unconventional. transmembrane component- piece that penetrates The classical cadherins can also be further sub-divided 21 Archives of Nephrology V2 . I2 . 2019 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis in to several categories based on their location and be related to an ancestral cadherin. Their extracellular function (Hulpiau, 2009). Invertebrates contain fewer than 20 types of cadherins. distinguishing them from classical cadherins. The intracellulardomains have domains more than of five the repeated protocadherins cadherin are motifs, also Classical Cadherins The classical cadherins are the most common variable, with a variety of functions in the nervous family members. The Cadherins are transmembrane different from their classical cousins. They are highly proteins, and the N and C terminal of the cadherins are formation of synapses. present in the extracellular and intracellular domain system, including neuronal differentiation and the Unconventional/Ungrouped Cadherins of a cell, respectively. Classical cadherins consist of Ungrouped cadherins are a large group of cadherins (Hulpiau, 2009). that are not otherwise categorized into the previous five cadherin domains which are termed EC1-EC5 The classical cadherins can also be further sub-divided and many others (Hulpiau, 2009). into several categories based on their location and three groups. They include VE-cadherin, R-cadherin, function, namely: Function of the Cadhedrins i) E-Cadherin (Epithelial): This cadherin is present Cadherins’ Special Role in Cancer in epithelial cells, hence the name ‘E-Cadherin. E-cadherin, a member of the cadherin family, has a Defects in E-Cadherin adhesion have been associated very important role in organizing the epithelium. with several diseases, such as cancer, Listeriosis, Most cancers arise from epithelial tissue, and in Candidiasis, Bacteroides infection. those cancers, cell adhesion mediated by E-cadherin ii) N-Cadherin (Neural): This cadherin is present in is lost at the same time that a tumor progresses toward malignancy. Some studies have focused on N-Cadherin. Defects in N-Cadherin are associated with restoring E-cadherin’s function in the epithelium as a cancerneurons, (skin, fibroblasts, prostate, and pancreaticmuscle cells, and hence gastric) the name, and Candidiasis. mechanismSelect in for cancer therapy (Nguyen, 2014). iii) P-cadherin (placental): P-cadherins are found in Selectins are a group of cell adhesion glycoprotein that the placenta. play a key role in the initial immunological response. Desmosomal Cadherins the attachment and movement of white blood cells are intercellular cadherins that connect toIt isother a group cells of and cell to surface the lining molecules of blood that vessels influence (the important in forming a type of cellular junction called intermediate filaments and cardiac muscle. They are a . It includes: conditions.first adhesive It step is specialized during in capturing and leukocytes immune surveillance), e.g., in inflammatory diseases and (Dsg) and from the bloodstream to the blood vessel wall. The migration of leukocytes from the blood vessel into • Desmocollin (Dcg). •Dsc and Dsg are approximately 30% identical to each other in terms of amino acid sequence. endothelialinflamed tissue cell surface is the centralis mediated step inby theselectins process (Ley, of 2013).inflammation. The tethering of leukocytes to the Desmocollins are present in epidermis, hair follicle cell hile All selectins are single-chain transmembrane are present in simple and stratified glycoproteins that share similar properties to C-type epithelia,s, myocardium, myocardium, stratified hair follicle epithelia cells, and w the lectins due to a related amino terminus and calcium- outermost epidermis, among other tissues. dependent binding. The absence of selectins or their ligands has severe health consequences, with Proto-Cadherins recurrent bacterial infections and persistent disease Protocadherins are a large group of cadherin molecules occurring. Due to their essential role in leukocyte present in a wide range of species that are thought to recruitment, selectins are an attractive target for

Archives of Nephrology V2 . I2 . 2019 22 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis therapeutic intervention against diseases involving of leukocytes from the bloodstream, which causes numerous cardiovascular and autoimmune diseases theirinflammation, downstream selectins movement enable along the initial the endothelium attachment (McGrayexcessive et al inflammatory., 2012). response as found in via adhesive interactions referred to as leukocyte rolling (Ley, 2013). Structure of the Selectins. All three known members of the family (L-, E-, Role in Human Implantation and P-selectin) share a similar cassette structure: In the last decades, Selectin and it’s ligands have been found to play an essential role in the process of human . an N-terminal, calcium-dependent lectin domain, implantation (Liu et al., 2011). . an epidermal growth factor (EGF)-like domain, For a successful implantation process, the appropriate . a variable number of consensus repeat units (2, 6, arrival time, a viable blastocyst and a receptive and 9 for L-, E-, and P-selectin, respectively), endometrium are the three essential elements . a transmembrane domain (TM) and (Norwitz et al., 2010). . an intracellular cytoplasmic tail (cyto) Furthermore, the attachment at the embryo- (Chothia,2000). endometrium contact surface is the key step in starting a successful implantation process. From a Types of Selectins morphological point of view, there is a remarkable There are three types of selectins according to the cell resemblance between vascular leucocyte extravasation and attachment of the embryo to the endometrium. L-selectin expressed on the surface of the trophoblast typeL-selectin in which it(in was lymphocytes) first characterized: and L-selectin ligand expressed on the surface of • E-selectin (in endothelial cells) the endometrial epithelium play crucial roles in the adhesion of the blastocyst and endometrial epithelium. P-selectin (in platelets and endothelial cells) • After the trophoblast has successfully attached to the •L-selectin is the smallest of the vascular selectins, endometrial epithelium, there is now a diversion of expressed on all granulocytes and monocytes and on maternal blood to the placenta (Carter et al., 2015). most lymphocytes, can be found in most leukocytes. Relevance of Cell Adhesion Molecules in Medical Laboratory Diagnosis of platelets and in Weibel–Palade bodies of endothelial cells,P-selectin, and is the translocated largest selectin, to the cellis stored surface in of α-granules activated Cell adhesion molecules have been recognized to play a endothelial cells and platelets. E-selectin is not major role in a variety of physiological and pathological expressed under baseline conditions, except in skin phenomena and advances in the treatment of human diseases rely upon the understanding of the patho- cytokines (Chothia,2000). physiology of the disease process. microvessels, but is rapidly induced by inflammatory Roles of the Selectin. Role in Cancer Selectins have been implicated in several roles but Dysfunction of cell adhesion occurs during cancer they are especially important in the immune system metastasis. Loss of cell-cell adhesion in metastatic tumor cells allows them to escape their site of origin and also, they play very essential role in Human and spread through the circulatory system (Friedl, Implantationby helping white (Ley, blood2013). cell homing and trafficking 2003). Indeed, changes in the expression or function of cell adhesion molecules have been implicated in Role in Immune System all steps of tumor progression, including detachment of tumor cells from the primary site, intravasation immune system cells, T lymphocytes and platelets. into the blood stream, extravasation into distant TheSelectins absence are of required selectins for or the their trafficking ligands has of severeinnate target organs, and formation of the secondary lesions health consequences, with recurrent bacterial (Johnson, 1999). One example of CAMs deregulated infections and persistent disease occurring. During in cancer are cadherins, which are inactivated either 23 Archives of Nephrology V2 . I2 . 2019 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis by genetic mutations or by other oncogenic signaling In the treatment of this disease, although patients can molecules, allowing cancer cells to migrate and be more receive intensive antibiotherapy and even granulocyte invasive, endowing on the neoplastic cells an invasive transfusions from healthy donors, the only current and migratory phenotype. This contributes to cancer curative therapy is the hematopoietic stem cell invasion and metastasis. Alterations in the expression of E- Cadherin have been found in esophageal (Robert et al., 2012). carcinoma, gastric carcinoma, breast Cancer, bladder transplant. However, gene therapy is also effective As a Predictive Marker of Human Uterine carcinoma and head and neck carcinomas (Nguyen, Receptivity L-selectin ligand can be used clinically as a marker for 2014).Other CAMs, like selectins and integrins, can facilitate metastasis by mediating cell-cell interactions between migrating metastatic tumour cells in the circulatory implantationHuman blastocysts efficiency utilize (Lessey, L-selectin 2008). to initiate system with endothelial cells of other distant tissues. implantation by binding to endometrial ligands composed of oligosaccharide moieties on the surface Due to the link between CAMs and cancer metastasis, glycoproteins. The absence of these ligands could lead these molecules could be potential therapeutic targets to recurrent implantation failure (RIF). for cancer treatment (Chiang and Massagué, 2008). Altered expression of Selectins and their ligands Leukocyte Adhesion Deficiency -I (Lad-I) has been found to be associated with abnormal Disease pregnancies and infertility (Liu et al., 2011). This is a genetic disorder which causes the immune Patients with RIF (repeated lack of implantation after system to malfunction, resulting in a form of the transfer of embryos) tested for the presence of the L-selectin ligands by immunohistochemistry usually immunodeficiency. Patients with LAD-1 have an shows the absence, or much reduced presence of the isinherited encoded molecular by the ITGB2 defect gene that found causes on chromosome a deficiency of the β-2 integrin subunit, also called CD18, which plays a role in implantation, not only by its presence, butL-selectin also by ligand its degree as finding (Norwitz has etproved al., 2010). that L-selectin reduced21. This subunitor lost. Theis involved main function in the formation of these proteins of the β-2 is Screening for the absence of the ligand may help many tointegrins, allow neutrophils thus expression to make of thetheir β-2 way integrin out of subunitthe blood is patients with RIF to avoid undergoing repeated failed treatment cycles. ligands expressed by the endothelium, e.g. ICAM-1. In Pemphigus LAD-1stream patients,to the infected neutrophils tissues cannotby adhering extravasate to different and Pemphigus is an autoimmune blistering skin disease proliferate, leading to symptomatic infection, which as it results from autoantibodies targeting a person’s canfight spreadagainst unimpededbacteria in tissues. and cause The seriousbacteria injurycan then to own desmosomal cadherins which leads to epidermal important tissues (Robert et al., 2012). cells detaching from each other and causing skin blistering (Yeh et al., 2013). Starting from birth, people with leukocyte adhesion In pemphigus, keratinocytes in epidermis and mucous membranes lose cell-cell adhesion, a process called deficiency type 1 develop serious bacterial and fungal acantholysis. IgG autoantibodies are characteristically umbilicalinfections. cordOne of stump the first after signs birth. of leukocyte In newborns, adhesion the directed against desmogleins (desmoglein-1 and deficiency type 1 is a delay in the detachment of the desmoglein-3), which are part of the cadherin family of cell-cell adhesion molecules that are found in type-1,stump normally this separation falls off usually within occurs the first at twothree weeks weeks of desmosomes, which are the structures primarily life; but, in infants with leukocyte adhesion deficiency responsible for maintaining intercellular adhesion in or later. In addition, affected infants often have oral mucosa. due to a bacterial infection. These individuals do not stratified squamous epithelia, such as the skin and forminflammation abscesses of becausethe umbilical granulocytes cord stump cannot (omphalitis) migrate Circulating anti-Dsg antibodies are found in pemphigus to the sites of infection (Medkaikar et al., 2012).

Archives of Nephrology V2 . I2 . 2019 (Beavon,2014). 24 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis The primary treatment modality has been oral In addition, several immuno suppressants, corticosteroids (which are used as an anti- including azathioprine, cyclosporine, mizoribine, mycophenolate mofetil and cyclophosphamide, are used (Yeh et al., 2013). inflammatory agent because of their suppressive effects on the inflammatory and allergic responses).

Fig 2. Image of a palm infected with Pemphigus Source: Yeh et al.,2013

Role in Infection molecules. HIV has an adhesion molecule termed Pathogenic microorganisms, including bacteria, ofgp120 cell that junctions binds to to its enter ligand host CD4 cells, , which which is expressed is what happenson lymphocytes. when the Viruses hepatitis can C also virus target targets components occludins cells in order to infect and cause diseases and this is and claudins in tight junctions to enter liver cells viruses and protozoans, have to first adhere to host made possible by adhesion molecules. (Mateo et al .,2015). Protozoans express multiple adhesion molecules Anti-adhesion therapy can be used to prevent infection by targeting adhesion molecules either located on surfaces of their host cells. An example on the pathogen or on the host cell to alter their ofwith a different pathogenic specificities protozoan that is thebind malarial to carbohydrates parasite production. Apart from altering the production of (Plasmodium falciparum), which uses one adhesion adhesion molecules, competitive inhibitors that bind molecule called the circumsporozoite protein to bind to adhesion molecules to prevent binding between to liver cells, and another adhesion molecule called cells and pathogenic organisms, can also be used, the merozoite surface protein to bind red blood cells. acting as anti-adhesive agents (Ley, 2013). Pathogenic fungi use adhesion molecules present on its cell wall to attach, either through protein-protein Research or protein-carbohydrate interactions, to host cells Selectins are involved in projects to treat osteoporosis- a disease that occurs when bone-creating cells called also have adhesion molecules required for viral osteoblasts become too scarce. Osteoblasts develop or fibronectins in the extracellular matrix. Viruses from stem cells, and scientists hope to eventually be has a hemagglutinin on its surface that is required for able to treat osteoporosis by adding stem cells to a recognitionbinding to hostof the cells. sugar For sialic example, acid on host influenza cell surface virus patient’s bone marrow. 25 Archives of Nephrology V2 . I2 . 2019 Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis Researchers have developed a way to use selectins to After washing, the enzyme substrate is added, and direct stem cells introduced into the vascular system the activity of the microplate well-bound enzyme to the bone marrow. E-selectins are constitutively is measured by the colour development, which is expressed in the bone marrow, and researchers proportional to the amount of CAMs bound in the have shown that tagging stem cells with a certain initial step. glycoprotein causes these cells to migrate to the bone The immobilized and the enzyme-labeled marrow. Thus, selectins may someday be essential to a regenerative therapy for osteoporosis (Ley, 2013). target protein. Critical Illness Polyneuropathy antibody must recognize different epitopes of the Procedure In cases of elevated blood glucose levels, as in diabetes, also in sepsis, plasma cell adhesion molecules are a microplate. Standards and samples are pipetted higher than normal especially E-selectin resulting Antibody specific for CAMs is been pre-coated onto in greater microvascular permeability. The greater into the wells and any CAMs present is bound by the permeability leads to edema (swelling) of the skeletal immobilized antibody. endothelium (blood vessel linings), resulting in After removing any unbound substances by washing, skeletal muscle ischemia (restricted blood supply) and eventually necrosis (cell death). This underlying added to the wells. After washing, avidin conjugated pathology is the cause of the symptomatic disease, Horseradisha biotin-conjugated Peroxidase antibody (HRP) is specific added to for the CAMs wells. is Critical Illness Polyneuropathy (CIP) (Jia et al., 2001). Following a wash to remove any unbound avidin- Increased concentrations of adhesion molecules have enzyme reagent, a substrate solution is added to also been associated with multiple organ dysfunction, the wells and color develops in proportion to the disease severity, or death. amount of CAMs bound in the initial step. The color Laboratory Diagnosis of the Cell development is stopped and the intensity of the color Adhesion Molecules is measured. Blood level of soluble form of cell adhesion molecules Conclusion Cell adhesion molecules are critical to many normal Enzyme Linked ImmunoSorbent Assay (ELISA) physiological processes. Given their widespread can be effectively diagnosed in the laboratory using Technique. importance it is not surprising that cell adhesion Specimen types: Serum, Heparin Plasma molecules have also been implicated in many Specificity: This assay has high sensitivity and and wound healing, septic shock, cancer, and atherosclerosis.diverse pathological processes such as inflammation humanexcellent CAMs specificity and analogues for detection has being of human observed. CAMs. No Recently, an understanding of the role of cell adhesion significant cross-reactivity or interference between molecules in these processes has suggested their Assay Type: Sandwich use as either diagnostic or prognostic markers, or as Detection Range: potential targets for therapeutic intervention. This is sensitivity is very high. 0. 156 ng/ml -10 ng/ml. Thus, its Principle of the Assay: This assay employs the bestReferences exemplified in cancer quantitative sandwich enzyme immunoassay [1] K and Walter, P. (2008). 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Citation: Nnodim Johnkennedy, Diala Tecla Ifesinachi, Ndunelo Chidiebere, Nwajiaku Victor, Nwanebu Chidimma. Role of Cell Adhesion Molecules in Medical Laboratory Diagnosis. Archives of Nephrology. 2019; 2 (2): 16-28. Copyright: © 2019 Nnodim Johnkennedy, Diala Tecla Ifesinachi, Ndunelo Chidiebere, Nwajiaku Victor, Nwanebu Chidimma. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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