FK506 impairs neutrophil migration that results in increased polymicrobial sepsis susceptibility.

OBJECTIVE: This study aimed to investigate the effects of FK506 on experimental sepsis immunopathology. It investigated the effect of FK506 on leukocyte recruitment to the site of infection, systemic cytokine production, and organ injury in mice with sepsis. METHODS: Using a murine cecal ligation and puncture (CLP) peritonitis model, the experiments were performed with wild-type (WT) mice and mice deficient in the gene Nfat1 (Nfat1-/-) in the C57BL/6 background. Animals were treated with 2.0 mg/kg of FK506, subcutaneously, 1 h before the sepsis model, twice a day (12 h/12 h). The number of bacteria colony forming units (CFU) was manually counted. The number of neutrophils in the lungs was estimated by the myeloperoxidase (MPO) assay. The expression of CXCR2 in neutrophils was determined using flow cytometry analysis. The expression of inflammatory cytokines in macrophage was determined using ELISA. The direct effect of FK506 on CXCR2 internalization was evaluated using HEK-293T cells after CXCL2 stimulation by the BRET method. RESULTS: FK506 treatment potentiated the failure of neutrophil migration into the peritoneal cavity, resulting in bacteremia and an exacerbated systemic inflammatory response, which led to higher organ damage and mortality rates. Failed neutrophil migration was associated with elevated CXCL2 chemokine plasma levels and lower expression of the CXCR2 receptor on circulating neutrophils compared with non-treated CLP-induced septic mice. FK506 did not directly affect CXCL2-induced CXCR2 internalization by transfected HEK-293 cells or mice neutrophils, despite increasing CXCL2 release by LPS-treated macrophages. Finally, the CLP-induced response of Nfat1-/- mice was similar to those observed in the Nfat1+/+ genotype, suggesting that the FK506 effect is not dependent on the NFAT1 pathway. CONCLUSION: Our data indicate that the increased susceptibility to infection of FK506-treated mice is associated with failed neutrophil migration due to the reduced membrane availability of CXCR2 receptors in response to exacerbated levels of circulating CXCL2.

CXCL12 estimula fibroblastos pulmonares a produzir CCL3, CXCL2, LTB4 e LTC4 via p38, MEK1/2, PI-3K e JNK / CXCL12 stimulates pulmorary fibroblasts to produce CCL3, CXCL2, LTB4 and LTC4 via p38, MEK1/2, PI-3K and JNK

A quimiocina C-X-X motif ligand 12 (CXCL12) e seu receptor de quimiocina 4 (CXCR4) desenvolvem um papel crítico na inflamação das vias aéreas. No entanto, os efeitos da ativação da via CXCL12/CXCR4 sobre fibroblastos pulmonares ainda são desconhecidos. Neste estudo, investigamos o efeito da via CXCL12/CXCR4 sobre a quimiocina (C-C motif) ligante 3 (CCL3) e (C-X-C motif) ligante 2 (CXCL2) e sobre os mediadores lipídicos leucotrienos B4 (LTB4) e C4 (LTC4) por fibroblastos pulmonares e a sinalização intracelular envolvida neste processo. CXCL12 foi capaz de induzir a produção de CCL3, CXCL2, LTB4 e LTC4; a produção de CCL3 não é dependente da produção de CXCL2, mas a produção de CXCL2 é dependente da produção de CCL3. A produção de LTB4 pode ser parcialmente regulada por CXCL2 e CCL3 e a produção de LTC4 é dependente da produção de CCL3 e CXCL2. Fibroblastos pulmonares constitutivamente expressam CXCR4 e a estimulação com CXCL12 induz sua expressão. Análises de Western blot mostraram que CXCL12 aumenta a expressão proteica de CXCR4 e induz a fosforilação da S339 do CXCR4. A expressão gênica constitutiva e induzida de CXCR4 foram inibidas pelo anticorpo anti-CXCL2. No entanto, o anticorpo anti-CCL3 e o inibidor farmacológico MK886 foram capazes de diminuir a expressão gênica induzida de CXCR4. Os fibroblastos pulmonares foram pré-tratados com MK886, dexametasona (Dexa) e/ou loratadina (Lor). MK886 e Lor promoveram a diminuição da produção de LTC4 e LTB4, mas não a de CCL3 e CXCL2. Dexa diminuiu níveis de CCL3, CXCL2, LTB4 e LTC4, e quando associado com Lor esta diminuição foi mais eficaz. Identificamos que as vias de sinalização intracelular PI-3K e JNK estão envolvidas na produção CCL3; p38, MEK1 / 2, PI-3K e JNK estão envolvidas na produção de CXCL2 e as vias p38 e MEK1/2 estão envolvidas na produção de LTB4 por meio da ativação do eixo CXCL12/CXCR4 em fibroblastos pulmonares. CXCL12 induz o aumento de CCL3, CXCL2, LTB4 e LTC4 em fibroblastos pulmonares...

C-X-X motif ligand 12 (CXCL12) and its specific receptor Chemokine receptor 4 (CXCR4) play a critical role in airway inflammation. However, the effects of CXCL12/CXCR4 axis on pulmonary fibroblast activation are unknown. In this study, we investigated the effect of CXCL12/CXCR4 axis on chemokine (C-C motif) ligand 3 (CCL3), chemokine (C-X-C motif) ligand 2 (CXCL2), leukotrienes B4 (LTB4) and C4 (LTC4) production by pulmonary fibroblasts and the intracellular signaling involved in the process. CXCL12 induced CCL3, CXCL2, LTB4 and LTC4 production, and CCL3 production is not dependent on CXCL2; but CXCL2 production is dependent on CCL3 production. LTB4 production can be partially down-regulated by CXCL2 and CCL3 production and LTC4 production is dependent on CCL3 and CXCL2 production. Pulmonary fibroblasts constitutively expressed CXCR4, and CXCL12 stimulation up-regulated its expression. Western blot analysis showed that CXCL12 increased protein expression of CXCR4 and induced phosphorylation at S339 of CXCR4. Constitutive CXCR4 expression was decreased by anti-CCL3 antibody or MK 886. Inducible CXCR4 was inhibited by anti-CXCL2 antibody. Indeed pulmonary fibroblasts were pretreated with MK886, dexamethasone (Dexa) and loratadine (Lor). MK886 and loratadine was able to reduced LTB4 and LTC4 production but not CCL3 and CXCL2. Dexa decreased CCL3, CXCL2, LTB4 and LTC4 production, and when associated with Lor this decrease was more effective. We found that PI-3K and JNK intracellular signaling play a role in CCL3 production; p38, MEK1/2, PI-3K and JNK are involved in CXCL2 production and p38 and MEK1/2 pathways are involved in LTB4 production by CXCL12/CXCR4 axis activation in pulmonary fibroblasts. Taken together, our results suggest that CXCL12 increased CCL3, CXCL2, LTB4 and LTC4 production in pulmonary fibroblasts, activating different intracellular mechanisms, and playing an important role in production of pro-inflammatory mediators involved in the regulation...