Summary: In different inflammatory disease models, heat‐shock proteins (hsp) and hsp‐derived peptides have been demonstrated to possess anti‐inflammatory properties. While some studies have shown that hsp can directly interact with antigen‐presenting cells, others report that bacterial hsp can induce specific T cells with regulatory phenotypes. Effective characterization of the immunomodulatory effects of hsp 70, however, has historically been confounded by lipopolysaccharide (LPS) contamination. In this study, we compared the effects of LPS‐free Mycobacterial tuberculosis hsp 70 (TBhsp70) and its possible contaminants on dendritic cells (DC). We demonstrate herein that LPS‐free TBhsp70 inhibits murine DC maturation in vitro, while LPS‐contaminated TBhsp70 induces DC maturation. Mock recombinant preparations have no effect. In contrast to LPS, TBhsp70 does not induce tumour necrosis factor‐α production by DC, but interleukin‐10. In vivo, only LPS‐contaminated TBhsp70 induces up‐regulation of CD86 in splenic mature DC. Finally, TBhsp70 inhibited phytohaemagglutinin‐induced T‐cell proliferation. Our results support the hypothesis that TBhsp70 does not have inflammatory potential, but rather has immunosuppressive properties.

Cytokines are key modulators of the immune responses that take place in the inflamed synovium of arthritis patients. Consequently, substances that can reverse the inflammatory profile of the inflamed joint are potential tools for clinical management of the disease. Mycobacterial heat shock protein 70 (MTBHSP70) has been found to protect rats from experimentally induced arthritis through the induction of interleukin (IL)‐10‐producing T cells. In this study, we have demonstrated that MTBHSP70 induces IL‐10 production in synoviocytes from arthritis patients and peripheral blood monoculear cells (PBMCs) from both patients and healthy controls. IL‐10 production was accompanied by a decrease in tumour necrosis factor (TNF)‐α production by synovial cells. Separation studies showed that the target cells were mainly monocytes. Accordingly, we observed that MTBHSP70 delayed maturation of murine bone marrow‐derived dendritic cells. Our results suggest that MTBHSP may act on antigen‐presenting cells (APCs) to modulate the cytokine response in arthritis and support an anti‐inflammatory role for this protein, suggesting that it may be of therapeutic use in the modulation of arthritis.

Aedes mosquitoes are important vectors for emerging diseases caused by arboviruses, such as chikungunya (CHIKV). These viruses’ main transmitting species are Aedes aegypti and Ae. albopictus, which are present in tropical and temperate climatic areas all over the globe. Knowledge of vector characteristics is fundamentally important to the understanding of virus transmission. Only female mosquitoes are able to transmit CHIKV to the vertebrate host since they are hematophagous. In addition, mosquito microbiota is fundamentally important to virus infection in the mosquito. Microorganisms are able to modulate viral transmission in the mosquito, such as bacteria of the Wolbachia genus, which are capable of preventing viral infection, or protozoans of the Ascogregarina species, which are capable of facilitating virus transmission between mosquitoes and larvae. The competence of the mosquito is also important in the transmission of the virus to the vertebrate host, since their saliva has several substances with biological effects, such as immunomodulators and anticoagulants, which are able to modulate the host’s response to the virus, interfering in its pathogenicity and virulence. Understanding the Aedes vector-chikungunya interaction is fundamentally important since it can enable the search for new methods of combating the virus’ transmission.