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A Test of Connective Tissue State and Reactivity in Collagen Diseases

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A Test of Connective Tissue State and Reactivity in Collagen Diseases A TEST OF CONNECTIVE TISSUE STATE AND REACTIVITY IN COLLAGEN DISEASES Daniel M. Laskin, … , Norman R. Joseph, Victor E. Pollak J Clin Invest. 1961;40(12):2153-2161. https://doi.org/10.1172/JCI104441. Research Article Find the latest version: https://jci.me/104441/pdf A TEST OF CONNECTIVE TISSUE STATE AND REACTIVITY IN COLLAGEN DISEASES * By DANIEL M. LASKIN, MILTON B. ENGEL, NORMAN R. JOSEPH AND VICTOR E. POLLAK t (From the Colleges of Dentistry, Pharmacy and Medicine, University of Illinois, Chicago, Ill.) (Submitted for publication January 12, 1961; accepted August 17, 1961) In the group of conditions known as "collagen bears a net negative charge; this is distributed be- diseases" there are often morphological changes tween the two phases. The colloidal charge gov- in discrete areas of the connective tissue. For ex- erns the distribution of mobile cations and anions ample, fibrinoid degeneration of the collagen fibers through thermodynamic and electrostatic equilib- and changes in the ground substance may be seen rium and through the chemical binding of ions to in the subcutaneous nodules of rheumatoid arthri- the matrix. Electrolyte concentrations and water tis and in the skin lesions of lupus erythematosus. content in connective tissues are thus determined These lesions are not well understood. The more by the colloidal structure (1-5). generalized alterations in the connective tissue Collagen, glycoproteins and mucopolysaccha- are even more difficult to demonstrate and remain rides, including chondroitin sulfate and hyalu- poorly defined. Using an in vivo electrometric ronic acid, have been conceived to be constituents method, we have previously determined certain of a complex coacervate in the matrix of dermal physicochemical properties of normal mammalian connective tissue (12). The isoelectric point of connective tissue which are related to its ampho- the matrix ranges from about pH 2.2 to 2.5 de- teric colloidal structure (1-5). Since these prop- pending on its composition. The low isoelectric erties may be altered in pathological states, we point is a result of the acidic character of sub- have adapted this method to study some of the stances such as chondroitin sulfate and other mu- fundamental connective tissue changes in collagen copolysaccharides. The density of negative charge diseases of humans. of the colloidal matrix is related to the number of Based upon histochemical, physicochemical and titratable groups which bind hydrogen ions be- morphological studies, a unified concept of the tween pH 7.4 (physiological) and the isoelectric organization of the extracellular part of normal point (pH 2.2 to 2.5). This depends on the com- connective tissue has been developed (6-11 ). The postion of the matrix with respect to all the col- ground substance has been characterized physico- loidal components. That these form complex in- chemically as a two-phase system containing hetero- soluble aggregates may be inferred from the diffi- geneous (soluble and insoluble) colloids, electro- culties usually encountered in attempts to isolate lytes and water. A water-rich phase containing the colloidal components in pure form. the soluble components is considered to be in When the enzyme hyaluronidase is injected into equilibrium with a colloid-rich phase. The exist- the dermis, hyaluronic acid and some of the chon- ence of these phases at a submicroscopic level has droitin sulfate are disaggregated. This leads to been demonstrated with the electron microscope. measurable changes in spreading properties and to The water-rich phase consists of vacuoles with a lowering of the negative charge density (13-16). diameters ranging from 600 to 1,200 Angstrom The effect may be explained by: 1) removal of units (7-10). These vacuoles are enclosed by a negatively charged components, such as hyaluronic much denser colloid-rich phase. Under physio- acid and chondroitin sulfate A, accompanied by 2) logical conditions the amphoteric colloidal matrix redistribution of water and electrolytes within the region of spreading. By the action of the en- * This work was supported in part by a grant from the Graduate Research Board, University of Illinois. zyme, the normal balance between soluble and in- t Established Investigator, American Heart Association, soluble colloidal components is disturbed, and the supported by the Illinois Heart Association. remaining insoluble colloids are characterized by- 2153 2154 LASKIN, ENGEL, JOSEPH AND POLLAK a low density of negative charge. In animal ex- where 1.52 is the ratio of the ionic conductance of periments, the effect of hyaluronidase applied chloride to that of sodium (5, 17). The density subcutaneously is to lower the negative colloidal of negative colloidal charge, x, in equivalents (Eq) charge to less than half the initial level (14). The per kilogram water is related to r by the formula initial state, as indicated by the negative charge density, may be compared with a hyaluronidase- x = 0.15 (r - 1/r) [4] modified state produced during a standard time where r = (Na+)2 - (Clii The subscripts 1 interval. After the colloidal charge density be- (Na+) i (Clj)2' comes minimal the subsequent recovery curve, and 2 refer to the solution phase (0.15 M), and observed electrometrically, illustrates the func- the colloidal phase, respectively. Graphical meth- tional state of the connective tissue (14.16). ods have been described to estimate x, the col- The serial electrometric evaluation of colloidal loidal charge, from (ED'- ED) at any pH (5). charge offers a means of comparing normal and At pH 7.4 and 370 C, for values of x less than pathological tissues and the effects of various about 0.06 Eq per kg water, there is a simple treatments. linear relation: THEORETICAL Ed=--12.3 +206 x [5] At an equilibrium boundary between a charged where Ed denotes the difference (ED'- ED), and colloidal surface and an isotonic saline solution is termed the "dilution potential." On the basis of there is a difference of potential which depends this method, titration curves of numerous col- on the density of colloidal charge and on the com- loidal surfaces have been measured. These in- position of the applied electrolyte solution (5, 17, clude dermis, cartilage and epidermis in vivo, and 18). This is the normal Donnan potential, ED, wool surfaces in vitro (5, 17, 18). which is related to the Donnan ratio, r, by the formula: MATERIAL AND METHODS 2.303 RT The connective tissue function test was performed in ED =D 96,5009650 logiogO[r [1] 10 healthy persons and in 14 untreated patients with various connective tissue diseases. The age and sex where 2.303 is the conversion factor between com- distributions of the two groups are given in Table I. mon and natural logarithms, R is the gas constant The following pathological conditions were studied: in joules per degree, T is the absolute temperature, rheumatoid arthritis (3 cases), systemic lupus erythema- and 96,500 is the value of the Faraday constant in tosus (3 cases), and scleroderma (8 cases). In addi- coulombs. ED is not determined tion, the alteration in connective tissue was also investi- usually directly gated in 3 patients with Cushing's syndrome. A num- in tissues; it is measured indirectly by the po- ber of patients in each group was retested after periods tential at the surface after substitution of 0.015 M of treatment. NaCl at the boundary (5, 17). This yields a dis- Displaced Donnan potentials in dermal connective tis- placed Donnan potential, ED', related to the follow- sue were measured by a modification of the method previ- ing quantities: the Donnan the Donnan ously described for animal studies (5, 14-16). Details potential, of the method are as follows: a 25 gauge platinum needle ratio, the fractions of current transported by anions with a glass hub was inserted into the dermis on the and cations, and the density of negative colloidal anterior surface of the right forearm.' The reference x Thus charge, (5, 17, 18). 1 In human subjects the use of a platinum needle is preferable to surgical exposure of the dermis and direct ED' - ED = 96,500 (n,' - n2l) [2] application of the solutions. In experiments with rats and rabbits the dilution potential in the dermis has been where and n2' denote the fractions of current found to be about -2 mv after direct exposure of the n,' tissue to the dilute solution (5). The same result has carried respectively by cations and anions in the been found in a series of animals and humans using the colloidal phase. The difference is related to the platinum needle technique. In both series of experi- Donnan ratio, r, by the formula: ments the calculated value of x is about 0.050 Eq. Since the platinum needle is filled with saline solution, the metal is at constant potential. Contact with the solu- = nil-n2l r2 + 1.52 [3] tion is made by means of saturated KCl, and there is no TEST OF CONNECTIVE TISSUE REACTIVITY IN COLLAGEN DISEASES 2155 TABLE I Electrometric results in normal subjects and in patients with connective tissue diseases * Baseline dilution Minimum dilution Half-recovery Condition Male Female Age range potential (EdO) potential (E)t k time Yrs mv mv milt Normal 0.002 1 subjects 5 5 22-76 -1.9 i 0.7 - 7.9 i 0.8 +0.0006 156 i 40 Rheumatoid arthritis 0 3 40-47 -9.1 -12.3 0.0000 No recovery (-8.0 to -10.1) (-12.0 to -12.5) Lupus erythematosus 1 2 14-45 -4.9 -11.1 0.0000 No recovery -(4.4 to - 5.2) (- 9.9 to -11.8) Scleroderma 0 8 28-63 -9.6 4 0.8 -12.1 ± 0.4 0.0000 No recovery Cushing's syndrome 1 2 20-35 -5.7 -11.3 0.0047 65 (-5.5 to - 6.0) (-10.8 to -11.7) * Mean values (4+ standard deviations where stated).
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