Unraveling the immune function of mineralocorticoid receptor (MR) and aldosterone in animal models.

Inflammation is a physiological response that could be triggered by endogenous and exogenous stimulus. During inflammation the response is auto limited and regulated to keep homeostasis, because uncontrolled response could lead to death. Inflammatory response is complex and involves many systems of the body which crosstalk each with other. In this line, hormones and its cognate receptors have been described as modulator of immune response, for example glucocorticoids and its knowing immunosuppressive role have been very useful to treat cancer and autoimmune diseases. Aldosterone is another adrenal hormone, that under non-pathological condition controls renal excretion of water and electrolytes to keep blood pressure. This hormone conventionally acts through mineralocorticoid receptor (MR) which is a ligand dependent transcription factor mainly expressed in juxtaglomerular epithelial cells in kidneys. However, MR is also expressed in cells of the immune system, adipose tissue, liver and brain, indicating that could be paying a role. Up to date, it has been described that high levels of aldosterone in vivo and in vitro are related with the induction of inflammatory phenotype in cardiac diseases, atherosclerosis, obesity, insulin resistance and autoimmunity. Aimed to describe the immunological role in which MR and aldosterone are involved, we used two models to study it. The first model was designed to understand whether MRaldosterone was related with TLR4 expression. According to our findings we described that aldosterone via MR induces the expression of tlr4 in wild type (WT) bone marrow-derived dendritic cells (DCs). Oppositely, the trl4 expression in DCs derived from myeloid MR conditional knockout mice (MyMRKO) did not show to be modulated by aldosterone, indeed these cells displayed impaired capacity to response to LPS stimulation. Finally, in a model of sub-lethal endotoxemia, we found that mice pre-treated with aldosterone succumbs after LPS challenge in contrast to placebo treated mice, mainly due to a multi-organic failure. In conclusion our results suggest that aldosterone-MR axis is involved in the regulation of tlr4 expression, and in consequently modulating the DCs response to TLR4 agonist, LPS. Because the first model was focused in septic inflammation, the second model that we used was focused in aseptic chronic inflammation in which MR and renin-angiotensinaldosterone system (RAAS) played a role. We induced non-alcoholic steatohepatitis (NASH) in LM/WT and MyMRKO mice with methionine-choline deficient diet (MCD). We found that MyMRKO mice fed with MCD diet presented lower lipid accumulation in livers than controls. This finding was also related with lower number of CD8+ T lymphocytes infiltration in livers of MyMRKO. This cells also displayed lower expression CD25 activation receptor, indicating that antigen presenting cells (APC) derived from MyMRKO could be having impairments promoting the immune response. In vitro cocultures performed with CD4+ or CD8+ T lymphocytes plus DCs derived from MyMRKO mice displayed that only CD8+ response was impaired and is related with the phenotype seen in mice. Summarizing the results, we described that aldosterone through MR are involved in tlr4 expression, because the loss of MR in myeloid DCs impacted in the levels of tlr4 expressed, indeed at basal condition. This result also affected the capacity of MyMRKO DCs to sense and responds to LPS, which is a maturation stimulus, but in these cells failed to induced a proinflammatory prone phenotype. These results are in accordance with the lowest capacity of DCs to drive immune response of CD8+ T lymphocytes impacting in lower steatosis in NASH model. In conclusion, all abovementioned results indicated that loss of MR in myeloid cells impacts in the adaptive CD8+ immune response. However, further analysis about how MR modulates antigen presenting cells to impair CD8+ T lymphocytes function is needed.Inflammation is a physiological response that could be triggered by endogenous and exogenous stimulus. During inflammation the response is auto limited and regulated to keep homeostasis, because uncontrolled response could lead to death. Inflammatory response is complex and involves many systems of the body which crosstalk each with other. In this line, hormones and its cognate receptors have been described as modulator of immune response, for example glucocorticoids and its knowing immunosuppressive role have been very useful to treat cancer and autoimmune diseases. Aldosterone is another adrenal hormone, that under non-pathological condition controls renal excretion of water and electrolytes to keep blood pressure. This hormone conventionally acts through mineralocorticoid receptor (MR) which is a ligand dependent transcription factor mainly expressed in juxtaglomerular epithelial cells in kidneys. However, MR is also expressed in cells of the immune system, adipose tissue, liver and brain, indicating that could be paying a role. Up to date, it has been described that high levels of aldosterone in vivo and in vitro are related with the induction of inflammatory phenotype in cardiac diseases, atherosclerosis, obesity, insulin resistance and autoimmunity. Aimed to describe the immunological role in which MR and aldosterone are involved, we used two models to study it. The first model was designed to understand whether MRaldosterone was related with TLR4 expression. According to our findings we described that aldosterone via MR induces the expression of tlr4 in wild type (WT) bone marrow-derived dendritic cells (DCs). Oppositely, the trl4 expression in DCs derived from myeloid MR conditional knockout mice (MyMRKO) did not show to be modulated by aldosterone, indeed these cells displayed impaired capacity to response to LPS stimulation. Finally, in a model of sub-lethal endotoxemia, we found that mice pre-treated with aldosterone succumbs after LPS challenge in contrast to placebo treated mice, mainly due to a multi-organic failure. In conclusion our results suggest that aldosterone-MR axis is involved in the regulation of tlr4 expression, and in consequently modulating the DCs response to TLR4 agonist, LPS. Because the first model was focused in septic inflammation, the second model that we used was focused in aseptic chronic inflammation in which MR and renin-angiotensinaldosterone system (RAAS) played a role. We induced non-alcoholic steatohepatitis (NASH) in LM/WT and MyMRKO mice with methionine-choline deficient diet (MCD). We found that MyMRKO mice fed with MCD diet presented lower lipid accumulation in livers than controls. This finding was also related with lower number of CD8+ T lymphocytes infiltration in livers of MyMRKO. This cells also displayed lower expression CD25 activation receptor, indicating that antigen presenting cells (APC) derived from MyMRKO could be having impairments promoting the immune response. In vitro cocultures performed with CD4+ or CD8+ T lymphocytes plus DCs derived from MyMRKO mice displayed that only CD8+ response was impaired and is related with the phenotype seen in mice. Summarizing the results, we described that aldosterone through MR are involved in tlr4 expression, because the loss of MR in myeloid DCs impacted in the levels of tlr4 expressed, indeed at basal condition. This result also affected the capacity of MyMRKO DCs to sense and responds to LPS, which is a maturation stimulus, but in these cells failed to induced a proinflammatory prone phenotype. These results are in accordance with the lowest capacity of DCs to drive immune response of CD8+ T lymphocytes impacting in lower steatosis in NASH model. In conclusion, all abovementioned results indicated that loss of MR in myeloid cells impacts in the adaptive CD8+ immune response. However, further analysis about how MR modulates antigen presenting cells to impair CD8+ T lymphocytes function is needed.Inflammation is a physiological response that could be triggered by endogenous and exogenous stimulus. During inflammation the response is auto limited and regulated to keep homeostasis, because uncontrolled response could lead to death. Inflammatory response is complex and involves many systems of the body which crosstalk each with other. In this line, hormones and its cognate receptors have been described as modulator of immune response, for example glucocorticoids and its knowing immunosuppressive role have been very useful to treat cancer and autoimmune diseases. Aldosterone is another adrenal hormone, that under non-pathological condition controls renal excretion of water and electrolytes to keep blood pressure. This hormone conventionally acts through mineralocorticoid receptor (MR) which is a ligand dependent transcription factor mainly expressed in juxtaglomerular epithelial cells in kidneys. However, MR is also expressed in cells of the immune system, adipose tissue, liver and brain, indicating that could be paying a role. Up to date, it has been described that high levels of aldosterone in vivo and in vitro are related with the induction of inflammatory phenotype in cardiac diseases, atherosclerosis, obesity, insulin resistance and autoimmunity. Aimed to describe the immunological role in which MR and aldosterone are involved, we used two models to study it. The first model was designed to understand whether MRaldosterone was related with TLR4 expression. According to our findings we described that aldosterone via MR induces the expression of tlr4 in wild type (WT) bone marrow-derived dendritic cells (DCs). Oppositely, the trl4 expression in DCs derived from myeloid MR conditional knockout mice (MyMRKO) did not show to be modulated by aldosterone, indeed these cells displayed impaired capacity to response to LPS stimulation. Finally, in a model of sub-lethal endotoxemia, we found that mice pre-treated with aldosterone succumbs after LPS challenge in contrast to placebo treated mice, mainly due to a multi-organic failure. In conclusion our results suggest that aldosterone-MR axis is involved in the regulation of tlr4 expression, and in consequently modulating the DCs response to TLR4 agonist, LPS. Because the first model was focused in septic inflammation, the second model that we used was focused in aseptic chronic inflammation in which MR and renin-angiotensinaldosterone system (RAAS) played a role. We induced non-alcoholic steatohepatitis (NASH) in LM/WT and MyMRKO mice with methionine-choline deficient diet (MCD). We found that MyMRKO mice fed with MCD diet presented lower lipid accumulation in livers than controls. This finding was also related with lower number of CD8+ T lymphocytes infiltration in livers of MyMRKO. This cells also displayed lower expression CD25 activation receptor, indicating that antigen presenting cells (APC) derived from MyMRKO could be having impairments promoting the immune response. In vitro cocultures performed with CD4+ or CD8+ T lymphocytes plus DCs derived from MyMRKO mice displayed that only CD8+ response was impaired and is related with the phenotype seen in mice. Summarizing the results, we described that aldosterone through MR are involved in tlr4 expression, because the loss of MR in myeloid DCs impacted in the levels of tlr4 expressed, indeed at basal condition. This result also affected the capacity of MyMRKO DCs to sense and responds to LPS, which is a maturation stimulus, but in these cells failed to induced a proinflammatory prone phenotype. These results are in accordance with the lowest capacity of DCs to drive immune response of CD8+ T lymphocytes impacting in lower steatosis in NASH model. In conclusion, all abovementioned results indicated that loss of MR in myeloid cells impacts in the adaptive CD8+ immune response. However, further analysis about how MR modulates antigen presenting cells to impair CD8+ T lymphocytes function is needed.