Cell death induced by NLRP3-palmitate axis impairs pulmonary damage tolerance and aggravates immunopathology during obesity-tuberculosis comorbidity.

A low-grade and persistent inflammation, which is the hallmark of obesity, requires the participation of NLRP3 and cell death. During Mycobacterium tuberculosis infection, NLRP3 signaling is important for bacterial killing by macrophages in vitro but was shown to be dispensable for host protection in vivo. We hypothesized that during obesity-tuberculosis (TB) comorbidity, NLRP3 signaling might play a detrimental role by inducing excessive inflammation. We employed a model of high-fat-diet-induced obesity, followed by M. tuberculosis infection in C57BL/6 mice. Obese mice presented increased susceptibility to infection and pulmonary immunopathology compared to lean mice. Using treatment with NLRP3 antagonist and Nlrp3-/- mice, we showed that NLRP3 signaling promoted cell death, with no effect in bacterial loads. The levels of palmitate were higher in the lungs of obese infected mice compared to lean counterparts, and we observed that this lipid increased M. tuberculosis-induced macrophage death in vitro, which was dependent on NLRP3 and caspase-1. At the chronic phase, although lungs of obese Nlrp3-/- mice showed an indication of granuloma formation compared to obese wild-type mice, there was no difference in the bacterial load. Our findings indicate that NLRP3 may be a potential target for host-directed therapy to reduce initial and severe inflammation-mediated disease and to treat comorbidity-associated TB. © 2022 The Pathological Society of Great Britain and Ireland.

Gut microbial metabolite butyrate protects against proteinuric kidney disease through epigenetic- and GPR109a-mediated mechanisms.

Butyrate is a short-chain fatty acid derived from the metabolism of indigestible carbohydrates by the gut microbiota. Butyrate contributes to gut homeostasis, but it may also control inflammatory responses and host physiology in other tissues. Butyrate inhibits histone deacetylases, thereby affecting gene transcription, and also signals through the metabolite-sensing G protein receptor (GPR)109a. We produced an mAb to mouse GPR109a and found high expression on podocytes in the kidney. Wild-type and Gpr109a-/- mice were induced to develop nephropathy by a single injection of Adriamycin and treated with sodium butyrate or high butyrate-releasing high-amylose maize starch diet. Butyrate improved proteinuria by preserving podocyte at glomerular basement membrane and attenuated glomerulosclerosis and tissue inflammation. This protective phenotype was associated with increased podocyte-related proteins and a normalized pattern of acetylation and methylation at promoter sites of genes essential for podocyte function. We found that GPR109a is expressed by podocytes, and the use of Gpr109a-/- mice showed that the protective effects of butyrate depended on GPR109a expression. A prebiotic diet that releases high amounts of butyrate also proved highly effective for protection against kidney disease. Butyrate and GPR109a play a role in the pathogenesis of kidney disease and provide one of the important molecular connections between diet, the gut microbiota, and kidney disease.-Felizardo, R. J. F., de Almeida, D. C., Pereira, R. L., Watanabe, I. K. M., Doimo, N. T. S., Ribeiro, W. R., Cenedeze, M. A., Hiyane, M. I., Amano, M. T., Braga, T. T., Ferreira, C. M., Parmigiani, R. B., Andrade-Oliveira, V., Volpini, R. A., Vinolo, M. A. R., Mariño, E., Robert, R., Mackay, C. R., Camara, N. O. S. Gut microbial metabolite butyrate protects against proteinuric kidney disease through epigenetic- and GPR109a-mediated mechanisms.

Metformin exerts antitumor activity via induction of multiple death pathways in tumor cells and activation of a protective immune response.

The antitumor effect of metformin has been demonstrated in several types of cancer; however, the mechanisms involved are incompletely understood. In this study, we showed that metformin acts directly on melanoma cells as well as on the tumor microenvironment, particularly in the context of the immune response. In vitro, metformin induces a complex interplay between apoptosis and autophagy in melanoma cells. The anti-metastatic activity of metformin in vivo was assessed in several mouse models challenged with B16F10 cells. Metformin's activity was, in part, immune system-dependent, whereas its antitumor properties were abrogated in immunodeficient (NSG) mice. Metformin treatment increased the number of lung CD8-effector-memory T and CD4+Foxp3+IL-10+ T cells in B16F10-transplanted mice. It also decreased the levels of Gr-1+CD11b+ and RORγ+ IL17+CD4+ cells in B16F10-injected mice and the anti-metastatic effect was impaired in RAG-1-/- mice challenged with B16F10 cells, suggesting an important role for T cells in the protection induced by metformin. Finally, metformin in combination with the clinical metabolic agents rapamycin and sitagliptin showed a higher antitumor effect. The metformin/sitagliptin combination was effective in a BRAFV600E/PTEN tamoxifen-inducible murine melanoma model. Taken together, these results suggest that metformin has a pronounced effect on melanoma cells, including the induction of a strong protective immune response in the tumor microenvironment, leading to tumor growth control, and the combination with other metabolic agents may increase this effect.

Mesenchymal Stromal Cell-Derived Microvesicles Regulate an Internal Pro-Inflammatory Program in Activated Macrophages.

Mesenchymal stromal cells (MSCs) are multipotent cells with abilities to exert immunosuppressive response promoting tissue repair. Studies have shown that MSCs can secrete extracellular vesicles (MVs-MSCs) with similar regulatory functions to the parental cells. Furthermore, strong evidence suggesting that MVs-MSCs can modulate several immune cells (i.e., Th1, Th17, and Foxp3+ T cells). However, their precise effect on macrophages (Mϕs) remains unexplored. We investigated the immunoregulatory effect of MVs-MSCs on activated M1-Mϕs in vitro and in vivo using differentiated bone marrow Mϕs and an acute experimental model of thioglycollate-induced peritonitis, respectively. We observed that MVs-MSCs shared surface molecules with MSCs (CD44, CD105, CD90, CD73) and expressed classical microvesicle markers (Annexin V and CD9). The in vitro treatment with MVs-MSCs exerted a regulatory-like phenotype in M1-Mϕs, which showed higher CD206 level and reduced CCR7 expression. This was associated with decreased levels of inflammatory molecules (IL-1ß, IL-6, nitric oxide) and increased immunoregulatory markers (IL-10 and Arginase) in M1-Mϕs. In addition, we detected that MVs-MSCs promoted the downregulation of inflammatory miRNAs (miR-155 and miR-21), as well as, upregulated its predicted target gene SOCS3 in activated M1-Mϕs. In vivo MVs-MSCs treatment reduced the Mϕs infiltrate in the peritoneal cavity inducing a M2-like regulatory phenotype in peritoneal Mϕs (higher arginase activity and reduced expression of CD86, iNOS, IFN-γ, IL-1ß, TNF-α, IL-1α, and IL-6 molecules). This in vivo immunomodulatory effect of MVs-MSCs on M1-Mϕs was partially associated with the upregulation of CX3CR1 in F4/80+/Ly6C+/CCR2+ Mϕs subsets. In summary, our findings indicate that MVs-MSCs can modulate an internal program in activated Mϕs establishing an alternative regulatory-like phenotype.

Stem cells from human-exfoliated deciduous teeth reduce tissue-infiltrating inflammatory cells improving clinical signs in experimental autoimmune encephalomyelitis.

Stem cells from human exfoliated deciduous teeth (SHED) have great therapeutic potential and here, by the first time, we evaluated their immunomodulatory effect on experimental model of autoimmune encephalomyelitis (EAE). Specifically, we investigated the effect of SHED administration on clinical signs and cellular patterns in EAE model using Foxp3 GFP + transgenic mice (C57Bl/6-Foxp3GFP). The results showed that SHED infusion ameliorated EAE clinical score with reduced number of infiltrating IFN-γ+CD8+, IL-4+CD8+, IFN-γ+CD4+ and IL-4+CD4+ T cells into the central nervous system (CNS). In addition, we observed that SHED promoted a significant increase in CD4+FOXP3+ T cells population in the spleen of EAE-affected animals. Taken together, our results provide strong evidence that SHED can modulate peripherally the CD4+ T cell responses suggesting that SHED would be explored as part of cellular therapy in autoimmune diseases associated with CNS.

Caloric Restriction Is More Efficient than Physical Exercise to Protect from Cisplatin Nephrotoxicity via PPAR-Alpha Activation.

The antineoplastic drug cisplatin promotes renal injury, which limits its use. Protocols that reduce renal cisplatin toxicity will allow higher doses to be used in cisplatin treatment. Here, we compare physical exercise and caloric restriction (CR) as protocols to reduce cisplatin renal injury in mice. Male C57BL/6 were divided into four groups: Control, cisplatin, exercise + cisplatin, and 30% CR + cisplatin. Animals were injected with a single dose of cisplatin (20 mg/kg i.p.) and sacrificed 96 h after injection. Quantitative real time PCR, histological analyses, immunohistochemistry, and biochemical measurements were performed to investigate renal injury, necrosis, apoptosis, and inflammatory mechanisms. Both protocols protected against cisplatin renal injury, but CR was more effective in reducing uraemia and renal necrosis. The CR + Cisplatin group exhibited reduced serum IL-1ß and TNF-α levels. No differences were noted in the renal mRNA expression of cytokines. Both interventions reduced apoptosis, but only the CR + Cisplatin group decreased TNFR2 protein expression. PPAR-α was activated in mice after CR. An antagonist of PPAR-α blocked the protective effect of CR. Both interventions attenuated the nephrotoxicity caused by cisplatin injection, but CR + Cisplatin showed a better response by modulating TNFR2. Moreover, part of the CR benefit depends on PPAR-α activation.

Intravenous administration of bone marrow-derived multipotent mesenchymal stromal cells enhances the recruitment of CD11b(+) myeloid cells to the lungs and facilitates B16-F10 melanoma colonization.

The discovery that the regenerative properties of bone marrow multipotent mesenchymal stromal cells (BM-MSCs) could collaterally favor neoplastic progression has led to a great interest in the function of these cells in tumors. However, the effect of BM-MSCs on colonization, a rate-limiting step of the metastatic cascade, is unknown. In this study, we investigated the effect of BM-MSCs on metastatic outgrowth of B16-F10 melanoma cells. In in vitro experiments, direct co-culture assays demonstrated that BM-MSCs stimulated the proliferation of B16-F10 cells in a dose-dependent manner. For in vivo experiments, luciferase-expressing B16-F10 cells were injected through tail vein and mice were subsequently treated with four systemic injections of BM-MSCs. In vivo bioluminescent imaging during 16 days demonstrated that BM-MSCs enhanced the colonization of lungs by B16-F10 cells, which correlated with a 2-fold increase in the number of metastatic foci. Flow cytometry analysis of lungs demonstrated that although mice harboring B16-F10 metastases displayed more endothelial cells, CD4 T and CD8 T lymphocytes in the lungs in comparison to metastases-free mice, BM-MSCs did not alter the number of these cells. Interestingly, BM-MSCs inoculation resulted in a 2-fold increase in the number of CD11b(+) myeloid cells in the lungs of melanoma-bearing animals, a cell population previously described to organize "premetastatic niches" in experimental models. These findings indicate that BM-MSCs provide support to B16-F10 cells to overcome the constraints that limit metastatic outgrowth and that these effects might involve the interplay between BM-MSCs, CD11b(+) myeloid cells and tumor cells.

Gut Bacteria Products Prevent AKI Induced by Ischemia-Reperfusion.

Short-chain fatty acids (SCFAs) are fermentation end products produced by the intestinal microbiota and have anti-inflammatory and histone deacetylase-inhibiting properties. Recently, a dual relationship between the intestine and kidneys has been unraveled. Therefore, we evaluated the role of SCFA in an AKI model in which the inflammatory process has a detrimental role. We observed that therapy with the three main SCFAs (acetate, propionate, and butyrate) improved renal dysfunction caused by injury. This protection was associated with low levels of local and systemic inflammation, oxidative cellular stress, cell infiltration/activation, and apoptosis. However, it was also associated with an increase in autophagy. Moreover, SCFAs inhibited histone deacetylase activity and modulated the expression levels of enzymes involved in chromatin modification. In vitro analyses showed that SCFAs modulated the inflammatory process, decreasing the maturation of dendritic cells and inhibiting the capacity of these cells to induce CD4(+) and CD8(+) T cell proliferation. Furthermore, SCFAs ameliorated the effects of hypoxia in kidney epithelial cells by improving mitochondrial biogenesis. Notably, mice treated with acetate-producing bacteria also had better outcomes after AKI. Thus, we demonstrate that SCFAs improve organ function and viability after an injury through modulation of the inflammatory process, most likely via epigenetic modification.

Kinin B1 receptor deficiency attenuates cisplatin-induced acute kidney injury by modulating immune cell migration.

UNLABELLED: Cisplatin is a chemotherapeutic agent that causes severe renal dysfunction. The kinin B1 receptor has been associated with the migration of immune cells to injured tissue as well as with renal inflammation. To examine the role of the kinin B1 receptor in cisplatin-induced acute kidney injury, we used kinin B1 receptor knockout mice and treatment with a receptor antagonist before and after cisplatin administration. Cisplatin injection caused exacerbation of renal macrophage and neutrophil migration, higher levels of serum creatinine and blood urea, upregulation of B1 receptor mRNA and an increase in pro-inflammatory cytokines expression. B1 receptor knockout mice exhibited a reduction in serum creatinine and blood urea levels, diminished apoptosis, and decreased cisplatin-induced upregulation of inflammatory components. Moreover, treatment with the B1 receptor antagonist prior to cisplatin administration normalized serum creatinine, blood urea levels, protected from acute tubular necrosis, apoptosis-related genes, and prevented upregulation of pro-inflammatory cytokines. Thus, we propose that kinins have an important role in cisplatin-induced acute kidney injury by impairing immune cells migration to renal tissue during cisplatin nephrotoxicity. KEY MESSAGE: Kinin B1 receptor is upregulated after cisplatin exposure. Kinin B1 receptor deficiency diminishes the nephrotoxicity caused by cisplatin. Kinin B1 receptor deficiency ameliorates the inflammatory response. Kinin B1 receptor deficiency diminishes apoptosis caused by cisplatin. Kinin B1 receptor antagonism ameliorates renal function after cisplatin injection.

In search of mechanisms associated with mesenchymal stem cell-based therapies for acute kidney injury.

Acute kidney injury (AKI) is classically described as a rapid loss of kidney function. AKI affects more than 15% of all hospital admissions and is associated with elevated mortality rates. Although many advances have occurred, intermittent or continuous renal replacement therapies are still considered the best options for reversing mild and severe AKI syndrome. For this reason, it is essential that innovative and effective therapies, without side effects and complications, be developed to treat AKI and the end-stages of renal disease. Mesenchymal stem cell (MSC) based therapies have numerous advantages in helping to repair inflamed and damaged tissues and are being considered as a new alternative for treating kidney injuries. Numerous experimental models have shown that MSCs can act via differentiation-independent mechanisms to help renal recovery. Essentially, MSCs can secrete a pool of cytokines, growth factors and chemokines, express enzymes, interact via cell-to-cell contacts and release bioagents such as microvesicles to orchestrate renal protection. In this review, we propose seven distinct properties of MSCs which explain how renoprotection may be conferred: 1) anti-inflammatory; 2) pro-angiogenic; 3) stimulation of endogenous progenitor cells; 4) anti-apoptotic; 5) anti-fibrotic; 6) anti-oxidant; and 7) promotion of cellular reprogramming. In this context, these mechanisms, either individually or synergically, could induce renal protection and functional recovery. This review summarises the most important effects and benefits associated with MSC-based therapies in experimental renal disease models and attempts to clarify the mechanisms behind the MSC-related renoprotection. MSCs may prove to be an effective, innovative and affordable treatment for moderate and severe AKI. However, more studies need to be performed to provide a more comprehensive global understanding of MSC-related therapies and to ensure their safety for future clinical applications.

Exequibility of differential gene expression analysis by DDRT-PCR in murine bone marrow cells / Exequibilidade do DDRT-PCR para análise da expressão gênica diferencial em células de medula óssea murina

Model of study: Experimental study. Introduction: Recently, stem cell research has generated great interest due to its applicability in regenerative medicine. Bone marrow is considered the most important source of adult stem cells and the establishment of new methods towards gene expression analysis regarding stem cells has become necessary. Thus Differential Display Reverse Transcription Polymerase Chain Reaction (DDRT-PCR) may be an accessible tool to investigate small differences in the gene expression of different stem cells in distinct situations. Aim: In the present study, we investigated the exequibility of DDRT-PCR to identify differences in global gene expression of mice bone marrow cells under two conditions. Methods: First, bone marrow cells were isolated fresh and a part was cultivated during one week without medium replacement. Afterwards, both bone marrow cells (fresh and cultivated) were submitted to gene expression analyses by DDRT-PCR...

Modelo do estudo: Estudo Experimental. Introdução: Atualmente a pesquisa com células-tronco tem gerado grande interesse devido a sua aplicabilidade no campo na medicina regenerativa. A medula óssea é considerada a maior fonte de células-tronco adultas e o estabelecimento de novos métodos para a análise da expressão gênica torna-se estritamente necessário. Desse modo, o "Differential Display Reverse Transcription Polymerase Chain Reaction (DDRT-PCR)", pode ser uma ferramenta acessível para investigação de pequenas diferenças no nível de expressão gênica em diferentes tipos celulares, sob distintas condições. Objetivo: Neste presente trabalho nós investigamos a exequibilidade do DDRT-PCR na identificação de diferenças no nível de expressão gênica global em células da medula óssea de camundongos sob duas condições. Métodos: Primeiramente, a medula óssea foi isolada frescamente e uma secunda parte foi cultivada por uma semana sem troca de meio. Posteriormente, as células da medula (fresca e cultivada) foram submetidas a análise da expressão gênica, seguindo a metodologia de DDRT-PCR...

Immune regulatory properties of allogeneic adipose-derived mesenchymal stem cells in the treatment of experimental autoimmune diabetes.

Adipose-derived mesenchymal stem cells (ADMSCs) display immunosuppressive properties, suggesting a promising therapeutic application in several autoimmune diseases, but their role in type 1 diabetes (T1D) remains largely unexplored. The aim of this study was to investigate the immune regulatory properties of allogeneic ADMSC therapy in T cell-mediated autoimmune diabetes in NOD mice. ADMSC treatment reversed the hyperglycemia of early-onset diabetes in 78% of diabetic NOD mice, and this effect was associated with higher serum insulin, amylin, and glucagon-like peptide 1 levels compared with untreated controls. This improved outcome was associated with downregulation of the CD4(+) Th1-biased immune response and expansion of regulatory T cells (Tregs) in the pancreatic lymph nodes. Within the pancreas, inflammatory cell infiltration and interferon-γ levels were reduced, while insulin, pancreatic duodenal homeobox-1, and active transforming growth factor-ß1 expression were increased. In vitro, ADMSCs induced the expansion/proliferation of Tregs in a cell contact-dependent manner mediated by programmed death ligand 1. In summary, ADMSC therapy efficiently ameliorates autoimmune diabetes pathogenesis in diabetic NOD mice by attenuating the Th1 immune response concomitant with the expansion/proliferation of Tregs, thereby contributing to the maintenance of functional ß-cells. Thus, this study may provide a new perspective for the development of ADMSC-based cellular therapies for T1D.