Relationship of Fibronectin to C-Reactive Protein, Ceruloplasmin, Alpha-1 Antitrypsin, and Transferrin in Septicemic Children

J. Clin. Biochem. Nutr., 22, 177-181, 1997

Nermin GULER,1,*Ulker ONES,1Nihal SALMAYENLI,2 Isik YALCIN,1Ahmet SIVAS,2and Nuran SALMAN1

1Department of Pediatrics and Department of Biochemistry, Istanbul University, Faculty of Medicine, Capa, Istanbul, Turkey

(Received December 2, 1996)

Summary We investigated the relationship between plasma levels of

fibronectin and other acute-phase reactant proteins such as C-reactive

protein, alpha-1 antitrypsin, ceruloplasmin, and transferrin in children with severe septicemia. The study included 33 septicemic patients and 10

normal children. Mean plasma fibronectin level was significantly lower in

patients on admission (204.7±57.3 mg/dl), and was higher after recovery (349.3±89 mg/dl), than in normal children (300.2•}65 mg/dl). No significant difference was found between the mean plasma fibronectin levels

of patients with and without meningitis. After the recovery, fibronectin

correlated positively with age. No correlation was found between plasma fibronectin and C-reactive protein, transferrin, ceruloplasmin, or alpha-1

antitrypsin levels at any stage of the disease. We concluded that fibronec-

tin has no modulating effect on acute-phase responses of these proteins in severe septicemia.

Key Words: fibronectin, septicemia, acute-phase reactants

Fibronectin is an important opsonic glycoprotein present on most cell surfaces and in extracellular fluids. The protein interacts with a number of macro- molecules on cell surfaces, and plays an important role in opsonic functions. Fibronectin is synthesized by a variety of cells, including epithelial cells, endo- thelial cells, fibroblasts, platelets, neutrophils, macrophages, and hepatocytes. The liver is the main source of circulating fibronectin [1-3]. The plasma fibronectin level is depleted in patients with sepsis, trauma, burns, or shock, and this reduction is associated with reticuloendothelial system dysfunc-

* To whom correspondence should be addressed .

177 178 N, GULER et al. tion [4, 5]. Studies have shown that lowered fibronectin concentrations decrease resistance to sepsis and that fibronectin levels decrease further secondary to sepsis itself [6]. The interaction of fibronectin with reticuloendothelial system dysfunction during acute bacterial sepsis is not fully understood. The purpose of the present prospective study was to investigate the relationship between plasma levels of fibronectin and some other acute-phase reactant proteins such as C-reactive protein, alpha-1 antitrypsin, ceruloplasmin, and transferrin in children with severe septicemia.

MATERIALSAND METHODS

This study included 33 children (13 females and 20 males) at the age of 3-72 months (median: 24 months) when they were referred to Istanbul Medical Faculty, Department of Pediatrics, because of severe septicemia. All children were evaluat- ed from the results of clinical examination, complete blood cell count, lumbar puncture for routine studies, and cultures. Septicemia was confirmed by positive blood cultures and/or by positive latex particle agglutination tests in blood. Microorganisms identified were Staphylococcus aureus in 5 (15.1%), Streptococcus pneumoniae in 3 (9%), Neisseria meningitidis in 20 (60.6%), and Klebsiella pneumoniae in 5 (15.1%) patients. Bacterial meningitis was confirmed in 18 (54.5%) of the patients. Patients with favorable outcome were selected for the study. Blood samples were obtained by venipuncture in a tube with citrate for fibronectin and without citrate for C-reactive protein, transferrin, ceruloplasmin, and alpha-1 antitrypsin determinations. The measurements were performed by use of radial immunodiffusion plates (Boehringwerke AG, Marburg, Germany). Simultaneous determinations of these parameters were performed in the blood obtained on the first day of admission and on the day of discharge from the hospital, the interval between the two ranging from 14 to 21 days. Control fibronectin values were obtained from 10 healthy children (median age: 21 months; range: 7-72 months). The distribution of the variables were compared with a standard normal distribution by the Kolmogorov-Smirnov test. Two-tailed t-tests were used to compare means. The correlations between variables that were normally distributed were tested with Pearson's linear correlation; and the ones that were not normally distributed, with Spearman's rank correlation.

RESULTS

At the initial stage of septicemia, the plasma fibronectin levels were 204.7+ 57.3 mg/dl (mean + SD) for patients and 300.2±65 mg/dl for normal children. Patients showed a significantly lower mean value than normal children (p<0.001). Twenty-five (75.7%) patients had fibronectin levels below the lower limit for

J. Clin. Biochem. Nutr. FIBRONECTIN AND ACUTE-PHASE REACTANTS 179

Table 1. Mean plasma levels of fibronectin, C-reactive protein, transferrin, ceruloplasmin, and alpha-1 antitrypsin at the initial stage and after recovery.

Values are the mean ± SD (n = 33). *p <0.01; * *p <0.001. NS, not significant. normal children (mean± 1SD). No significant difference was found between the mean plasma fibronectin levels of patients with and without meningitis (214.11 ± 40.6 mg/dl and 193.6+72.5 mg/dl, respectively). Alpha-1 antitrypsin and ceruloplasmin levels correlated positively with age (r=0.41; p<0.05 and r = 0.46; p < 0.01, respectively). Alpha-1 antitrypsin levels also had correlation with C-reactive protein and ceruloplasmin levels (r=0.37; p<0.05 and r=0.35; p<0.05, respectively). Fibronectin, however, did not show significant correlation either with age or with any of these acute-phase reactants investigated in the acute stage of septicemia. After the recovery, the plasma fibronectin level (mean: 349.3 + 89 mg/dl) was higher in the septicemic patients than in the normal children, but this difference was not statistically significant. Sixteen (48.5%) patients had fibronectin values higher than normal. These increased levels also did not show any correlation with other acute-phase proteins. Plasma fibronectin correlated positively with the age of the patients. In this stage, plasma levels of C-reactive protein had positive correlation with ceruloplasmin levels (r=0.48; p<0.01). Mean plasma levels of fibronectin, C-reactive protein, transferrin, ceruloplasmin, and alpha-1 antitrypsin at the initial stage and after recovery are shown in Table 1. The differences between the two stages for fibronectin, C-reactive protein, transferrin, and alpha-1 antitrypsin levels were statistically significant (p<0.001) but the difference between ceruloplasmin levels was not. Positive correlations were found in C-reactive protein (r=0.59; p<0.001), ceruloplasmin (r=0.53; p<0.01) and transferrin (r=0.47; p<0.01) levels and no correlations were found in fibronectin and alpha-1 antitrypsin levels between the initial and recovery stages.

DISCUSSION

Fibronectin is a protein that participates in a variety of unrelated biologic processes within tissues. Data from experimental studies imply that fibronectin has a central role in the inflammatory response [3]. The mechanism by which fibronectin synthesis is regulated at the cellular level is unknown. This protein may augment phagocytosis, modulate adherence, and prepare the reticuloendothelial

Vol. 22, No. 3, 1997 180 N. GULER et al. system for clearance of complement- or antibody-coated material such as microorganisms and cellular debris. Plasma concentrations of fibronectin typically decrease during septic episodes in children and adults [5-7]. Probably, the reason for this is increased consumption of fibronectin secondary to reticuloendothelial system clearance of fibronectin-coated material. Fibronectin deficiency and resultant reticuloendothelial system impairment may have important effects on the ability of infants to clear bacterial infections [6]. Newborn infants have lower plasma fibronectin levels, which increase postnatally and reach adult values by approximately 2 months of age [8]. Patients included in this study were severely ill and had fibronectin values in the acute phase of sepsis significantly lower than those of normal children due to peripheral consumption. We couldn't find any correlation initially between the fibronectin level and that of some of acute-phase reactants such as C-reactive protein, transferrin, ceruloplasmin, and alpha-1 antitrypsin, which are proteins synthesized primarily in the liver. Acute starvation and calorie deprivation are important factors altering he- patic functions and contributing to the reticuloendothelial system depression in septic children [9]. This is associated with low plasma fibronectin concentrations [10]. Transferrin and ceruloplasmin are also known indices of nutritional status [11]. The absence of correlation between these proteins suggests that regulation of the synthesis and degradation must be different among these proteins. After the recovery from the clinical infection, the concentrations of fibronectin in plasma increased above normal levels, suggesting the increased produc- tion. Polin also had found high fibronectin levels after recovery from sepsis [12]. It is likely that bacterial sepsis has the capacity both to increase and to decrease plasma fibronectin levels. This increased levels also did not show any correlation with other acute-phase reactants investigated. Substitution therapy with intravenous fibronectin preparations has been used in septicemia, and encouraging results have been obtained. Its effects on host defenses are not clear yet. Further studies investigating fibronectin therapy and acute-phase reactants may provide useful information to determine the role of this protein in infections. In this study, our findings indicate that although plasma fibronectin is an important marker of septicemia, it hasn't any relation with C-reactive protein, ceruloplasmin, alpha-1 antitrypsin, and transferrin. We can conclude that fibronectin has no modulating effect on acute-phase responses to infection.

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