Heat shock protein 70 (Hsp70) is an intracellular chaperone protein with regulatory and cytoprotective functions. Hsp70 can also be found in the extracellular milieu, as a result of active secretion or passive release from damaged cells. The role of extracellular Hsp70 is not fully understood. Some studies report that it activates monocytes, macrophages and dendritic cells through innate immune receptors (such as Toll-like receptors, TLRs), while others report that Hsp70 is a negative regulator of the inflammatory response. In order to address this apparent inconsistency, in this study we evaluated the response of human monocytes to a highly purified recombinant Hsp70.

Alzheimer’s disease (AD) is a neuropathology strongly associated with the activation of inflammatory pathways. Accordingly, inflammation resulting from obesity exacerbates learning and memory deficits in humans and in animal models of AD. Consequently, the long-term use of non-steroidal anti-inflammatory agents diminishes the risk for developing AD, but the side effects produced by these drugs limit their prophylactic use. Thus, plants natural products have become an excellent option for modern therapeutics. Malva parviflora is a plant well known for its anti-inflammatory properties. The present study was aimed to determine the anti-inflammatory potential of M. parviflora leaf hydroalcoholic extract (MpHE) on AD pathology in lean and obese transgenic 5XFAD mice, a model of familial AD. The inflammatory response and Amyloid β (Aβ) plaque load in lean and obese 5XFAD mice untreated or treated with MpHE was evaluated by immunolocalization (Iba-1 and GFAP) and RT-qPCR (TNF) assays and thioflavin-S staining, respectively. Spatial learning memory was assessed by the Morris Water Maze behavioral test. Microglia phagocytosis capacity was analyzed in vivo and by ex vivo and in vitro assays, and its activation by morphological changes (phalloidin staining) and expression of CD86, Mgl1, and TREM-2 by RT-qPCR. The mechanism triggered by the MpHE was characterized in microglia primary cultures and ex vivo assays by immunoblot (PPAR-γ) and RT-qPCR (CD36) and in vivo by flow cytometry, using GW9662 (PPAR-γ inhibitor) and pioglitazone (PPAR-γ agonist). The presence of bioactive compounds in the MpHE was determined by HPLC. MpHE efficiently reduced astrogliosis, the presence of insoluble Aβ peptides in the hippocampus and spatial learning impairments, of both, lean, and obese 5XFAD mice. This was accompanied by microglial cells accumulation around Aβ plaques in the cortex and the hippocampus and decreased expression of M1 inflammatory markers. Consistent with the fact that the MpHE rescued microglia phagocytic capacity via a PPAR-γ/CD36-dependent mechanism, the MpHE possess oleanolic acid and scopoletin as active phytochemicals. M. parviflora suppresses neuroinflammation by inhibiting microglia pro-inflammatory M1 phenotype and promoting microglia phagocytosis. Therefore, M. parviflora phytochemicals represent an alternative to prevent cognitive impairment associated with a metabolic disorder as well as an effective prophylactic candidate for AD progression.

Mycobacterium tuberculosis (M. tuberculosis), an intracellular pathogenic Gram-positive bacterium, is the cause of Tuberculosis, a major worldwide human infectious disease. The innate immune system is the first host defense against M. tuberculosis. The recognition of this pathogen is mediated by several classes of pattern recognition receptors (PRRs) expressed on the host innate immune cells, including Toll-like receptors, Nod-like receptors and C-type lectin receptors like Dectin-1, the Mannose receptor, and DC-SIGN. M. tuberculosis interaction with any of these receptors activates multiple signaling pathways among which the PKC, the MAPK and the NFκB pathways have been widely studied. These pathways have been implicated in macrophage invasion, M. tuberculosis survival and impaired immune response, thus promoting a successful infection and disease. Interestingly, the Wnt signaling pathway, classically regarded as a pathway involved in the control of cell proliferation, migration and differentiation in embryonic development, has recently been involved in immunoregulatory mechanisms in infectious and inflammatory diseases, such as tuberculosis, sepsis, psoriasis, rheumatoid arthritis and atherosclerosis. In this review we present the current knowledge supporting a role for the Wnt signaling pathway during macrophage infection by M. tuberculosis and the regulation of the immune response against M. tuberculosis. Understanding the cross-talk between different signaling pathways activated by M. tuberculosis, will impact on the search for new therapeutic targets to fuel the rational design of drugs aimed to restore the immunological response against M. tuberculosis.

Obesity-induced inflammation, triggered by lipid-mediated activation of the Nlrp3 inflammasome, results in glucose metabolism alterations and type 2 diabetes. This knowledge has been generated using animals deficient for any of the different components of this inflammasome (Caspase-1, Asc or Nlrp3) in the C57BL/6 background. Unlike C57BL/6 mice, which carry allele 2 of the Nlrp1b gene (Nlrp1b2), Balb/c mice that carry allele 1 (Nlrp1b1) are less prone to develop alterations in the glucose metabolism when fed with a high fat diet. However, the molecular bases for these metabolic differences are unknown. Here we show that the Nlrp1b1 allele down regulates the adipose tissue inflammatory response attenuating glucose intolerance and insulin resistance in obese C57BL/mice. Our results indicate that the positive effects of the Nlrp1b1 inflammasome on glucose tolerance and insulin sensitivity involve IL-18-mediated effects on lipolysis, pointing out that differential expression of allelic variants of genes coding for inflammasome components might control susceptibility or resistance to develop diabetes in obese individuals.