Ascitic fluid regulates the local innate immune response of patients with cirrhosis

Abstract

Ascitic neutrophils from cirrhotic patients with spontaneous bacterial peritonitis (SBP) exhibit an impaired oxidative burst that could facilitate bacterial infection. However, the influence of the cell-free ascitic fluid of these patients on neutrophil function has not been investigated. To analyze this influence, we determined the ascitic levels of cytokines, resistin, and lactoferrin and their association with neutrophil function, disease severity score, and SBP resolution. We analyzed NETosis induction by microscopy and oxidative burst by the flow cytometry of healthy neutrophils cultured in ascitic fluid from cirrhotic patients with sterile ascites (SA) and with SBP before and after antibiotic treatment. Resistin, IL-6, IL-1 receptor antagonist, IL-1β, and lactoferrin levels were measured in ascitic fluids and supernatants of cultured neutrophils and PBMCs by ELISA. Upon stimulation, healthy neutrophils cultured in SBP ascitic fluid produced lower NETosis and oxidative burst than those cultured in SA. Ascitic resistin levels were negatively correlated with NETosis, oxidative burst, and ascitic glucose levels; and positively correlated with the model for end-stage liver disease score. After an E. coli or TNF-α stimulus, neutrophils were the major resistin producers. Resistin indirectly reduced the oxidative burst of neutrophils and directly reduced the inflammatory phenotype of monocytes and TNF-α production. Bacterial-induced resistin production can down-regulate the inflammatory response of macrophages and neutrophil function in ascitic fluid. Consequently, this down-regulation may jeopardize the elimination of bacteria that translocate to ascitic fluid in patients with cirrhosis.

Impaired neutrophil extracellular traps and inflammatory responses in the peritoneal fluid of patients with liver cirrhosis

“…The authors argue that the synthesis and secretion of high levels of IL‐10 and IL‐1Ra are synthesized to regulate the inflammatory process . Moreover, in the recent study of Nieto et al a positive correlation between resistin and IL‐1Ra levels and between IL‐1Ra and IL‐6 was observed, levels which coincides with our results, the authors propose that resistin indirectly downregulates neutrophil function through their interaction with macrophages. According to our and previous results, more research is required to elucidate the relationship between the variety of molecules and factors present at the local/systemic microenvironment, and the CAID.…”

“…These results are also similar to those reported by Nieto et al, who observed higher levels of IL‐6 in AF from patients with SBP compared with AF from patients with ASC, the IL‐6 was positively correlated with the percentage of neutrophils in AF. Furthermore, recently the same group have also reported that levels of resistin produced by neutrophils, positively correlates with IL‐6 levels, contributing to the impaired function of neutrophils . Suliman et al also observed higher levels of IL‐6 in both serum and AF from patients with SBP vs patients with ASC, in contrast to our results they also found elevated levels of TNF‐α in their patients, although it is noteworthy that they measured the cytokine concentrations by a different method (ie ELISA).…”

“…A recent study showed that elevated levels of resistin in AF of patients with SBP are related with decreased oxidative burst and NETosis in neutrophils from HC, this reinforces the previous hypothesis that the presence of inflammatory and anti‐inflammatory local factors in AF causes the dysfunction in neutrophils and other cells. This same factors (ie resistin) could act in systemic level explaining why we found a deeper failure in PB neutrophils in our SBP patients …”

“…This same factors (ie resistin) could act in systemic level explaining why we found a deeper failure in PB neutrophils in our SBP patients. 18 In addition, ROS production in neutrophils is dependent on the functional capacity of NADPH oxidase. ROS is not only essential for phagocytosis but is also crucial in the release of NETs.…”

“…11,19 In patients with SBP, the failure in the NADPH oxidase function could contribute to the impaired NETs formation and may be mediated by excessive secretion of molecules such as pro-and anti-inflammatory cytokines and resistin. 18,20 On the other hand, considering that platelets can recognize PAMPs through TLR4 and that activated platelets can interact with neutrophils and prompt them to release NETs in presence of bacterial or inflammatory stimuli, 15 and that patients with LC characteristically present thrombocytopenia, 6 this could be another mechanism involved in the reduced capacity to release extracellular traps from the neutrophils of patients. However, additional research is required to support this hypothesis.…”