Effect of pretreatment with interleukin-1 beta on inflammatory infiltrates and tissue damage after experimental endotoxic challenge

Effects of whole-body heat acclimation on cell injury and cytokine responses in peripheral blood mononuclear cells

To test the hypothesis that whole-body heat acclimation (HA) would increase peripheral blood mononuclear cells' (PBMC) tolerance to heat shock (HS) and/or alter the release of cytokines (IL-1β, IL-6, IL-10 and TNF-α) to bacterial lipopolysaccharide (LPS), we heat acclimated nine subjects by exercising them for 100 min in a hot environment for 10 days. The subjects' PBMC were separated and cultured on days 1 and 10 of HA pre- and post-exercise. Pre-exercise PBMC were allocated to three treatments: control (PRE, 37°C), HS (42.5°C for 2 h), or LPS (1 ng mL(-1) for 24 h). Post-exercise samples were incubated at 37°C. PBMC lactate dehydrogenase release increased (p < 0.05) after HS but it was not different (p > 0.05) between days 1 and 10 (0.100 ± 0.012 and 0.102 ± 0.16 abs., respectively). LPS treatment induced an increased (p < 0.05) release of cytokines but HA did not alter this response (p > 0.05). Pre-exercise intracellular heat shock protein 72 (Hsp72) was higher (p < 0.05) on day 10 compared to day 1 of HA (13 ± 5 and 8 ± 5 ng mL(-1), respectively). HS treatment caused a greater increase (p < 0.05) in Hsp72 than the exercise sessions on HA days 1 and 10. In addition, after HA, the Hsp72 response to HS was reduced (day 1, 129 ± 46; day 10, 80 ± 32 ng mL(-1), p < 0.05). In conclusion, HA increases PBMC Hsp72 but it does not reduce cellular damage to HS or alter cytokine response to LPS. We speculate that the stress applied during HA is not sufficient to modify the PBMC response.

Nonspecific phosphodiesterase inhibition attenuates liver injury in acute endotoxemia

BACKGROUND

Endotoxemia is accompanied by pro-inflammatory cytokine production, generation of reactive oxygen species, and end-organ injury. Pentoxifylline (PTX), a methylxanthine derivative and phosphodiesterase inhibitor, is known for its anti-inflammatory properties, including down-regulation of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha synthesis. Its effects on liver function and hepatic histology following acute endotoxemia have not been investigated fully. We hypothesized that PTX would preserve liver architecture and function after intravenous lipopolysaccharide (LPS) injection.

METHODS

Anesthetized Sprague-Dawley rats received an i.v. bolus injection of LPS (5 mg/kg), LPS + PTX (25 mg/kg), or saline (sham). Plasma concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), TNF-alpha, IL-6, and nitrite were measured at different time points after LPS injection. Liver injury was graded according to a scoring system in a blinded fashion from 0 (normal) to 4 (severe) for hepatocellular necrosis, hemorrhage, and parenchymal and sinusoidal inflammatory infiltrates. Neutrophil infiltration was measured by counting myeloperoxidase (MPO)-positive stained cells. Nuclear factor (NF)-kappaB p-65 was measured by counting positive stained nuclei of hepatocytes and Kupffer cells (KC). Inducible nitric oxide synthase (iNOS) was evaluated by positively stained KC. Data are presented as mean +/- SEM. Analysis of variance with p < 0.05 was considered statistically significant.

RESULTS

Animals treated with PTX showed a significant reduction in liver injury score and neutrophil infiltration. Treatment with PTX significantly decreased TNF-alpha, IL-6, and the concentrations of AST and ALT when compared to LPS alone. In addition, a significant decrease in NF-kappaB-positive staining in hepatocytes and KC, as well as in KC iNOS immunostaining was observed in PTX-treated animals compared to the LPS group.

CONCLUSIONS

Pentoxifylline downregulates the inflammatory response significantly and decreases liver injury in acute endotoxemia.