ABSTRACT
Osteoarticular complications are common in human brucellosis, but the pathogenic mechanisms involved are largely unknown. In this manuscript, we described an immune mechanism for inflammatory bone loss in response to infection by Brucella abortus. We established a requirement for MyD88 and TLR2 in TNF-α-elicited osteoclastogenesis in response to B. abortus infection. CS from macrophages infected with B. abortus induced BMM to undergo osteoclastogenesis. Although B. abortus-infected macrophages actively secreted IL-1ß, IL-6, and TNF-α, osteoclastogenesis depended on TNF-α, as CS from B. abortus-infected macrophages failed to induce osteoclastogenesis in BMM from TNFRp55â»/â» mice. CS from B. abortus-stimulated MyD88â»/â» and TLR2â»/â» macrophages failed to express TNF-α, and these CS induced no osteoclast formation compared with that of the WT or TLR4â»/â» macrophages. Omp19, a B. abortus lipoprotein model, recapitulated the cytokine production and subsequent osteoclastogenesis induced by the whole bacterium. All phenomena were corroborated using human monocytes, indicating that this mechanism could play a role in human osteoarticular brucellosis. Our results indicate that B. abortus, through its lipoproteins, may be involved in bone resorption through the pathological induction of osteoclastogenesis.
Subject(s)
Brucella abortus/physiology , Macrophages, Peritoneal/physiology , Myeloid Differentiation Factor 88/physiology , Osteoclasts/physiology , Toll-Like Receptor 2/physiology , Tumor Necrosis Factor-alpha/physiology , Animals , Antigens, Bacterial/pharmacology , Bacterial Outer Membrane Proteins/pharmacology , Brucellosis/immunology , Cell Differentiation/drug effects , Cells, Cultured/drug effects , Cells, Cultured/physiology , Culture Media, Conditioned/pharmacology , Cytokines/biosynthesis , Female , Humans , Lipoproteins/pharmacology , Macrophages, Peritoneal/drug effects , Mice , Mice, Inbred C57BL , Monocytes/drug effects , Monocytes/physiology , Myeloid Differentiation Factor 88/deficiency , Myeloid Differentiation Factor 88/genetics , RANK Ligand/biosynthesis , Toll-Like Receptor 2/deficiency , Toll-Like Receptor 2/genetics , Toll-Like Receptor 4/deficiency , Transforming Growth Factor beta/biosynthesis , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
Larrea divaricata Cav. (Zygophyllaceae) is used in popular medicine as anti-inflammatory and anti-rheumatic drug, containing higher amounts of nordihydroguaiaretic acid, a well-known free radical scavenger. Here we describe the gastric anti-ulcerogenic effect of the methanolic extract of Larrea divaricata (LdME) leaves in rat, using absolute ethanol and HCl 0.6N as necrotizing agents, and the effect of blocking endogenous sulfhydryl (SH) groups with N-ethylmaleimide (NEM). We also studied the anti-inflammatory activity of LdME in two rat experimental models: cotton pellet induced granuloma and arthritis induced by adjuvant-carrageenan. Influence of treatment in body weight and some lymphoid organs was evaluated. Finally, the free radical scavenging capacity of LdME was determined by the method of 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibition. LdME demonstrated anti-ulcerogenic effect in rats, and it was shown that the endogenous SH compounds were not involved in the mechanism of action. LdME also showed inhibitory activity in the applied models of inflammation, being more effective in the acute phase. No effect was observed concerning the weight of spleen, thymus and body. The extract proved to possess elevated free radical scavenging capacity which may contribute to the observed gastric anti-ulcerogenic and anti-inflammatory activity.
