Host -Fungal Interface in the Liver during Candida albicans Infection: Steatosis, Apoptosis Hepathocellular and Association with Fungal Infectivity

RENNA MS, CORREA SG, PARAJE MG, PORPORATTO C, RIERA CM, SOTOMAYOR CE

Montreal

Congreso; XII International Congress of Immunology and 4th Annual Conference of FOCIS.; 2004

International Union of Immunological Societies

RATIONALE: The liver is the first barrier controlling the hematogenous dissemination of C. albicans of intestinal origin, limiting the fungal growth and mounting an efficient inflammatory reaction that is crucial in the outcome of the infection, meanwhile the activation of pathogen virulence factors promote the tissue damage and the persistence in the host. Rats exposed simultaneosly to C. albicans infection and chronic varied stress show alterations in innate mmunity mediators associated with clear signs of hepatotoxicity. Here we characterize the steatosis associated to C. albicans infections, evaluate the occurrence of apoptosis in situ and assess fungal infectivity under normal and stress conditions. METHODS: Wistar rats were: untreated, stressed, C. albicans infected (Ca) (3x108 yeast) and infected-stressed (CaS). After 3 days, liver and serum were obtained. Hepatic injury was evaluated by specific lipid stain of liver sections, serum levels of hepatic enzymes (ALT and g-GT) and lipid peroxidation in liver homogenates. In situ apoptosis was assessed by DAPI and TUNEL reaction; the local expression of TNF-a mRNA was determined by RT-PCR. Fungal infectivity was evaluated by UFC and histological studies. The production of lipase (LIP) by C. albicans was checked in Egg-Yolk and SDA-Rb medium; later LIP was purified (Sph G-100) and analyzed by SDS-PAGE. RESULTS: Liver injury was more severe after stress exposure with micro and macro steatosis in acinar zone 1, increased levels of serum enzymes and higher lipid peroxidation (Ca vs CaS p<0,05). A novel and interestingly finding was the induction of apoptosis in situ during C. albicans infection (DAPI+ hepatocytes) and the increase of this phenomenon after stress exposures (TUNEL+ cell Ca vs CaS p<0,05). The expression of TNF-a mRNA was similar in both groups of infected animals. CaS groups also showed increased UFC and hyphal forms evidencing a major severity. Yeast and hyphae of C.albicans released a proteic fraction with LIP activity; the lipolitic activity was 75U and MW was 70 KD. CONCLUSION: In the scenario of the early liver response a complex interplay of fungal infectivity, proinflammatory mediators, and stress hormones promotes a major liver injury and anticipates a more severe evolution of this opportunistic infection.