Estudio de los factores que determinan la variabilidad en la respuesta inflamatoria que se produce en pacientes cirróticos en respuesta a fenómenos de traslocación bacteriana molecular

Resumen

Background Spontaneous bacterial peritonitis is a deadly complication in patients with advanced cirrhosis, and the pathogenic mechanism involved is considered to be bacterial translocation (BT) from the intestinal lumen. The inflammatory reaction induced by the infection may be related to development of complications such as renal insufficiency and death. We have previously demonstrated the presence of bacterial DNA (bactDNA) as surrogated marker of BT in roughly 35% of patients with cirrhosis and ascitic fluid (AF) and showed that it is associated to a marked innate immune response (elevated levels of TNF-alpha, IFN-gamma, IL-12 and nitric oxide (NO)), that reaches similar levels to that observed in patients with fully established SBP. However, the degree of the inflammatory response varies among patients. Aim To assess the relevance of different factors that may be involved in the modulation of the intensity of immune response in patients with cirrhosis and ascites presence of bactDNA by studying: i) The clinical and analytical characteristics of the patients ii) The serum levels of BactDNA Lipopolysaccharide (LPS) Inflammatory cytokine levels (TNF-alpha, INF-gamma and IL-12) and Nitric oxide Methods Prospective study in blood and AF of 77 patients with cirrhosis consecutively included. Identification of bacterial-DNA was evaluated by 16SrRNA gene PCR followed by nucleotide sequencing and by species-specific PCR. Concentration of amplified bacterial-DNA, LPS, TNF-alpha, INF-gamma, IL-12 and NO in serum was evaluated. ANOVA and ANCOVA analyses were performed. Results No episodes of multiple bacterial translocation were detected. Serum TNF-alpha, INF-gamma, IL-12 and NOx levels showed a significant correlation with their respective values in ascitic fluid (r=0.62; p=0.001), (r=0.84; p=0.001), (r= 0.69; p=0.001) and (r=0.90; p=0.000), respectively. Serum TNF-alpha levels significantly correlated with bacterial-DNA concentration (r=0.87; p=0.001), LPS (r=0.28; p=0.016) and blood WBC (r=-0.27; p=0.02). Serum TNF-alpha levels were significantly different between gram-negative and gram-positive groups (504±120 vs 399±88 pg/mL, p<0.05). The best-fitting, significant ANCOVA model included bacterial-DNA concentration, LPS and the interaction of both variables. Serum INF-gamma levels significantly correlated with Mean blood pressure (r=0.39; p=0.02), blood WBC (r=-0.34; p=0.03) and blood PMNLs (r=-0.31; p=0.003) but not with bacterial-DNA concentration (r=0.18; p=0.12) and LPS (r=0.18; p=0.12). INF-gamma levels were not significantly different either between gram-negative and gram-positive groups or when individual bacterial-species were compared. IL-12 levels were significantly different either between gram-negative (553±19 pg/ml) and gram-positive groups (653±32 pg/ml) (p=0.012) or when individual bacterial-species were compared; S. aureus (707±94), E. coli (583±125) (p<0.05). Serum IL-12 levels significantly correlated with LPS (r=-0.24; p=0.04) and prior encephalopathy episodes (672±173; p=0.04) but not with bacterial-DNA concentration (r=-0.10; p=0.39). Serum NOx levels significantly correlated with bacterial-DNA concentration (r=0.76; p=0.001), LPS (r=0.25; p=0.03), blood WBC (r=-0.27; p=0.04) and LA PMNLs (r=-0.27; p=0.03). NOx levels were not significantly different either between gram-negative and gram-positive groups or when individual bacterial-species were compared. Conclusions Bacterial-DNA presence in patients with cirrhosis and ascites is due to single-species translocation. Bacterial-DNA concentration is the most influencing variable associated with serum cytokine and NO response.