Pharmacological blockade of CCR1 ameliorates murine arthritis and alters cytokine networks in vivo.

BACKGROUND AND PURPOSE: The chemokine receptor CCR1 is a potential target for the treatment of rheumatoid arthritis. To explore the impact of CCR1 blockade in experimental arthritis and the underlying mechanisms, we used J-113863, a non-peptide antagonist of the mouse receptor. EXPERIMENTAL APPROACH: Compound J-113863 was tested in collagen-induced arthritis (CIA) and three models of acute inflammation; Staphylococcus enterotoxin B (SEB)-induced interleukin-2 (IL-2), delayed-type hypersensitivity (DTH) response, and lipopolysaccharide (LPS)-induced tumour necrosis factoralpha (TNFalpha) production. In the LPS model, CCR1 knockout, adrenalectomised, or IL-10-depleted mice were also used. Production of TNFalpha by mouse macrophages and human synovial membrane samples in vitro were also studied. KEY RESULTS: Treatment of arthritic mice with J-113863 improved paw inflammation and joint damage, and dramatically decreased cell infiltration into joints. The compound did not inhibit IL-2 or DTH, but reduced plasma TNFalpha levels in LPS-treated mice. Surprisingly, CCR1 knockout mice produced more TNFalpha than controls in response to LPS, and J-113863 decreased TNFalpha also in CCR1 null mice, indicating that its effect was unrelated to CCR1. Adrenalectomy or neutralisation of IL-10 did not prevent inhibition of TNFalpha production by J-113863. The compound did not inhibit mouse TNFalpha in vitro, but did induce a trend towards increased TNFalpha release in cells from synovial membranes of rheumatoid arthritis patients. CONCLUSIONS AND IMPLICATIONS: CCR1 blockade improves the development of CIA, probably via inhibition of inflammatory cell recruitment. However, results from both CCR1-deficient mice and human synovial membranes suggest that, in some experimental settings, blocking CCR1 could enhance TNF production.

Neutrophil function in severe sepsis.

Sepsis and septic shock continue to be a major cause of morbidity and mortality in critically ill patients. During the onset of sepsis, several inflammatory mediators, including cytokines, chemokines and nitric oxide are released systemically and mediate most of the pathophysiological events present in sepsis and septic shock, such as cardiovascular dysfunction and target-organ lesions. Polymorphonuclear leukocytes are critical effector cells during the inflammatory process and their migration to the infection focus is extremely important for the local control of bacterial growth and consequently for the prevention of bacterial dissemination. In experimental models and in human sepsis a profound failure of neutrophil migration to the infection focus is observed. It seems that the failure of neutrophil migration is dependent on toll-like receptor 4 (TLR4) and mediated by cytokines and chemokines, which induce the production of nitric oxide that inhibits neutrophil adhesion to venular endothelium and also the neutrophil chemotactic ability.

Failure of neutrophil migration to infectious focus and cardiovascular changes on sepsis in rats: Effects of the inhibition of nitric oxide production, removal of infectious focus, and antimicrobial treatment.

Recently, we demonstrated that mice under lethal sepsis present failure of neutrophil migration (FNM) to infectious focus, which is mediated by nitric oxide. The aims of the present study were to investigate whether FNM is also observed in severe sepsis induced by cecal ligation and puncture in rats and the effects of the prevention of nitric oxide production and of the elimination of the infectious focus through peritoneal lavage or by antimicrobial treatment on FNM and disease outcome. Rats were submitted to several septic stimuli (low, moderate, and severe) by cecal ligation and puncture. Severe septic stimulus animals presented FNM to the peritoneal cavity that was accompanied by large numbers of bacteria in the peritoneal cavity, blood, and liver and lung tissues; high cytokines (tumor necrosis factor alpha, interleukin [IL] 1beta, IL-6, cytokine-induced neutrophil chemoattractant 1, and IL-10) concentrations in the infection site, sera, and lung tissues; marked hypotension; and high mortality rate. The exhaustive lavage of the peritoneal cavity to reduce the infectious focus did not ameliorate the disease outcome. The association of lavage procedure with aminoguanidine treatment re-established neutrophil migration, but only delayed the death of the animals. In contrast, the antimicrobial treatment of severe septic stimulus animals with sulfamethoxazole and trimethoprim significantly improved the survival rate of the severe septic stimulus but did not re-establish neutrophil migration. However, the association of aminoguanidine plus sulfamethoxazole and trimethoprim brought about a significant increase in the survival rate and re-established neutrophil migration to infectious focus; reduced the colony-forming units in the peritoneal cavity, blood, and lung tissues; and caused an improvement in the cardiovascular performance. The results showed, for the first time, that the pharmacological prevention of FNM to the infectious focus associated with the antimicrobial therapy could be a new beneficial strategy for the treatment of sepsis syndrome.

Role of nitric oxide in the failure of neutrophil migration in sepsis.

The cecal ligation and puncture (CLP) model was used to investigate whether failure of neutrophil migration occurs in sepsis and whether it correlates with disease outcome. It was observed that the severity of sepsis correlates with the number of punctures in the cecum: mice with 2 punctures (sublethal [SL]-CLP) developed mild peritonitis (100% survived), whereas mice with 12 punctures (lethal [L]-CLP) developed severe peritonitis and bacteremia that evolved to sepsis (none survived). The production of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-10 was higher in L-CLP than in SL-CLP mice. The impairment of neutrophil migration to the peritoneum and to the cecum wall was observed only in L-CLP mice. This phenomenon was shown to be mediated by nitric oxide, because aminoguanidine prevented the failure of neutrophil migration and improved the survival of L-CLP animals. In conclusion, impairment of neutrophil migration is a crucial event in the worsening of sepsis, and nitric oxide seems to be responsible for the phenomenon.