MASTer cell: chief immune modulator and inductor of antimicrobial immune response.

Mast cells have long been recognized for their involvement in allergic pathology through the immunoglobulin E (IgE)-mediated degranulation mechanism. However, there is growing evidence of other "non-canonical" degranulation mechanisms activated by certain pathogen recognition receptors. Mast cells release several mediators, including histamine, cytokines, chemokines, prostaglandins, and leukotrienes, to initiate and enhance inflammation. The chemical nature of activating stimuli influences receptors, triggering mechanisms for the secretion of formed and new synthesized mediators. Mast cells have more than 30 known surface receptors that activate different pathways for direct and indirect activation by microbes. Different bacterial strains stimulate mast cells through various ligands, initiating the innate immune response, which aids in clearing the bacterial burden. Mast cell interactions with adaptative immune cells also play a crucial role in infections. Recent publications revealed another "non-canonical" degranulation mechanism present in tryptase and chymase mast cells in humans and connective tissue mast cells in mice, occurring through the activation of the Mas-related G protein-coupled receptor (MRGPRX2/b2). This receptor represents a new therapeutic target alongside antibiotic therapy. There is an urgent need to reconsider and redefine the biological role of these MASTer cells of innate immunity, extending beyond their involvement in allergic pathology.

Nitric oxide determines the development of actinomycetoma by Nocardia brasiliensis in eNOS knockout C57BL/6 mice.

Mycetoma is a chronic human infectious disease that produces severe deformation frequently in the lower extremities. Etiological agents include fungi (eumycetoma) and bacteria (actinomycetoma) that produce similar clinical and microscopic changes. The clinical appearance includes swelling, abscesses, ulcers, scars and sinuses that drain purulent material with microbe microcolonies. The pathogenesis of actinomycetoma has been studied mainly in rodents. Using this approach, it was found that Nocardia brasiliensis produces proteases that may play a role in tissue damage, as well as immunosuppressive molecules, such as brasilicardin A. Nitric oxide (NO) is a molecule with biological activities depending on its local concentration. Its effect on killing intracellular bacteria such as Mycobacterium tuberculosis has been known for decades. NO plays an important role in innate and adaptive immunity. It can promote or suppress some biological activities despite its short half-ife. NO is produced by three different nitric oxide synthases (NOS). We used the genetic blockade of eNOS in C57BL/6 mice to demonstrate the role of NO in actinomycetoma development. Inflammation and actinomycetoma were prevented in genetically modified mice infected with N. brasiliensis. T cell proliferation was increased in these rodents, and antibody production, IL-6 and IL-10 expression were similar and TNF-α was lower.

Chemoresistance in Breast Cancer Patients Associated With Changes in P2X7 and A2A Purinergic Receptors in CD8+ T Lymphocytes.

Breast cancer (BRCA) is the most frequent cancer type that afflicts women. Unfortunately, despite all the current therapeutic strategies, many patients develop chemoresistance hampering the efficacy of treatment. Hence, an early indicator of therapy efficacy might aid in the search for better treatment and patient survival. Although emerging evidence indicates a key role of the purinergic receptors P2X7 and A2A in cancer, less is known about their involvement in BRCA chemoresistance. In this sense, as the chemotherapeutic treatment stimulates immune system response, we evaluated the expression and function of P2X7 and A2A receptors in CD8+ T cells before and four months after BRCA patients received neoadjuvant chemotherapy. The results showed an increase in the levels of expression of P2X7 and a decrease in the expression of A2A in CD8+ T cells in non-chemoresistant (N-CHR) patients, compared to chemoresistant (CHR) patients. Interestingly, in CHR patients, reduced expression of P2X7 occurs along with a decrease in the CD62L shedding and the production of IFN-γ. In the case of the A2A function, the inhibition of IFN-γ production was not observed after chemotherapy in CHR patients. A possible relationship between the modulation of the expression and function of the P2X7 and A2A receptors was found, according to the molecular subtypes, where the patients that were triple-negative and human epidermal growth factor receptor 2 (HER2)-enriched presented more alterations. Comorbidities such as overweight/obesity and type 2 diabetes mellitus (T2DM) participate in the abnormalities detected. Our results demonstrate the importance of purinergic signaling in CD8+ T cells during chemoresistance, and it could be considered to implement personalized therapeutic strategies.

Decreased levels and activity of Sirt1 are modulated by increased miR-34a expression in adipose tissue mononuclear cells from subjects with overweight and obesity: A pilot study.

BACKGROUND AND AIMS: Overweight and obesity are important risk factors for chronic disorders. Fat accumulation is one of the central manifestations; it occurs via a complex mechanism where multiple metabolic signals converge. Sirtuins are an enzyme family with deacetylase functions that are implicated in the regulation of several genes. Sirt1 and its upstream regulator (miR-34a) are elements of a converging mechanism that integrates the dynamic metabolic state. In this work, we hypothesized that elevated levels of miR-34a in overweight/obese group inhibits Sirt1 activity. Therefore, we studied the miR-34a/Sirt1 axis in mononuclear cells obtained from adipose tissue. METHODS: Adipose tissue samples were collected from 36 subjects, and they were categorized according to body mass index (BMI) as overweight/obesity and normoweight. Subcutaneous adipose tissue samples were enzymatically dissociated, and mononuclear cells from adipose tissue were isolated by Ficoll Hypaque. Sirt1-positive cells and relative Sirt1 expression were determined by flow cytometry and real-time polymerase chain reaction (qPCR), respectively. Finally, Sirt1 activity was measured with a luminescence assay. RESULTS: The percentage of Sirt1-positive mononuclear cells from adipose tissue decreased along with Sirt1 enzymatic activity in overweight/obese participants. miR-34a expression increased in the overweight/obese group compared to normoweight individuals. There was a negative association between the relative miR-34a expression and Sirt1-positive cells and a synergistic effect on Sirt1-positive cells mediated by the miR-34a inhibitor and Sirt1 agonist. CONCLUSIONS: Our results describe for the first time the presence of miR-34a and Sirt1 in mononuclear cells isolated from subcutaneous adipose tissue. Additionally, these results suggest altered sirtuin function in overweight/obese patients and open the possibility for new therapies that involve these metabolic targets.

Altered levels of sirtuin genes (SIRT1, SIRT2, SIRT3 and SIRT6) and their target genes in adipose tissue from individual with obesity.

INTRODUCTION: Sirtuins regulate energy metabolism and insulin sensitivity through their ability to act as energy sensors and regulators in several metabolic tissues. AIM: To evaluate the expression levels of sirtuin genes SIRT1, SIRT2, SIRT3 and SIRT6 and their target genes (PPAR-α, PGC1-α, NRF1, DGAT1, PPAR-γ and FOXO3a) in subcutaneous adipose tissue collected from individuals with normoweight, overweight and obesity. METHODS: Adipose tissue samples, obtained by lipoaspiration during liposuction surgery, were processed to obtain RNA, which was reverse-transcribed to cDNA. Then, we measured the expression levels of each gene by qPCR. RESULTS: We found differences in the mRNA expression of SIRT1, SIRT2, SIRT3 and SIRT6 and their target genes (PPAR-α, PGC1-α, NRF1, DGAT1, PPAR-γ and FOXO3a) in adipose tissue from overweight or obese subjects when compared to normoweight subjects. All genes analyzed, except SIRT2, showed correlation with BMI. CONCLUSIONS: Our findings in human subcutaneous adipose tissue show that increased body mass index modifies the expression of genes encoding sirtuins and their target genes, which are metabolic regulators of adipose tissue. Therefore, these could be used as biomarkers to predict the ability of adipose tissue to gain mass of adipose tissue.

Type-2 diabetes alters the basal phenotype of human macrophages and diminishes their capacity to respond, internalise, and control Mycobacterium tuberculosis.

BACKGROUND: Type 2 diabetes (T2D) is a risk factor for the development of tuberculosis (TB), although the associated mechanisms are not known. OBJECTIVES: To study the association between T2D and the basal phenotype of macrophages, and their immune response to Mycobacterium tuberculosis (Mtb) infection. METHODS: We evaluated the influence of T2D on the response of monocyte-derived macrophages (MDM) to Mtb in patients with T2D (n = 10) compared to healthy subjects (n = 9), before and after infection with Mtb clinical isolates bearing different degrees of virulence. The levels of cell surface markers for activation secreted cytokines and chemokines, bacterial association, and intracellular bacterial growth were evaluated. FINDINGS: The expression levels of HLA-DR, CD80, and CD86 were low while those of of PD-L1 were high in uninfected MDMs derived from patients with diabetes; as a result of Mtb infection, changes were only observed in the expression levels of PD-L1. The levels of cytokines (e.g., IL-6, IL-1ß, IL-10, and IL-12) and chemokines (e.g., MCP-1, MIG, and RANTES) are perturbed in MDMs derived from patients with diabetes, both before infection and in response to Mtb infection. In response to the more virulent Mtb strains, the levels of association and bacterial clearance were diminished in MDMs derived from patients with diabetes. CONCLUSIONS: T2D affects the basal activation state of the macrophages and its capacity to respond and control Mtb infection.

Type-2 diabetes alters the basal phenotype of human macrophages and diminishes their capacity to respond, internalise, and control Mycobacterium tuberculosis

BACKGROUND Type 2 diabetes (T2D) is a risk factor for the development of tuberculosis (TB), although the associated mechanisms are not known. OBJECTIVES To study the association between T2D and the basal phenotype of macrophages, and their immune response to Mycobacterium tuberculosis (Mtb) infection. METHODS We evaluated the influence of T2D on the response of monocyte-derived macrophages (MDM) to Mtb in patients with T2D (n = 10) compared to healthy subjects (n = 9), before and after infection with Mtb clinical isolates bearing different degrees of virulence. The levels of cell surface markers for activation secreted cytokines and chemokines, bacterial association, and intracellular bacterial growth were evaluated. FINDINGS The expression levels of HLA-DR, CD80, and CD86 were low while those of of PD-L1 were high in uninfected MDMs derived from patients with diabetes; as a result of Mtb infection, changes were only observed in the expression levels of PD-L1. The levels of cytokines (e.g., IL-6, IL-1β, IL-10, and IL-12) and chemokines (e.g., MCP-1, MIG, and RANTES) are perturbed in MDMs derived from patients with diabetes, both before infection and in response to Mtb infection. In response to the more virulent Mtb strains, the levels of association and bacterial clearance were diminished in MDMs derived from patients with diabetes. CONCLUSIONS T2D affects the basal activation state of the macrophages and its capacity to respond and control Mtb infection.

Expression and vitamin D-mediated regulation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in healthy skin and in diabetic foot ulcers.

Diabetic foot ulcers (DFUs) are chronic wounds with high matrix metalloproteinase (MMP) activity, and are a frequent complication on diabetics. This work studied the expression of selected MMP and tissue inhibitor of metalloproteinases (TIMP) gene family members in DFU and normal skin biopsies, and in vitamin D-treated keratinocytes cultured from those biopsies. We report for the first time the expression of some of these genes in healthy skin. Our results suggest that vitamin D may modulate the expression of some MMP gene family members in keratinocytes. Gene expression in DFU and in non-diabetic healthy skin (control) biopsies was evaluated by RT-qPCR for MMP-1, MMP-3, MMP-8, MMP-9, MMP-10, MMP-19, TIMP-1 and TIMP-2, and also by immunohistochemistry for MMP-1 and MMP-9. Primary keratinocytes cultured from DFU and healthy skin biopsies were used for gene expression analyses of selected MMPs and TIMPs by RT-qPCR, both in the presence and absence of calcitriol. The expression of MMP-1, MMP-8, MMP-9, MMP-10, and TIMP-2 in healthy skin is reported here for the first time. DFUs showed increased MMP-1, MMP-9 and TIMP-1 expression, compared to healthy skin. Calcitriol down-regulated MMP-1 and MMP-10 expression in DFU-derived keratinocytes but not in those derived from healthy skin. Our data demonstrate the expression of certain MMPs that had not been previously described in healthy skin, and further support previous reports of MMP and TIMP up-regulation in DFUs. Our results point to calcitriol as a potential modulator for the expression of certain MMP members in DFUs.

Vitamin D supplementation promotes macrophages' anti-mycobacterial activity in type 2 diabetes mellitus patients with low vitamin D receptor expression.

The increasing number of people with type 2 diabetes (DM2) is alarming and if it is taken into account that the relative odds of developing tuberculosis in diabetic patients ranges from 2.44 to 8.33 compared with non-diabetic patients, thus in developing countries where these two diseases are encountering face to face, there is a need for prophylaxis strategies. The role of vitamin D has been widely implicated in growth control of Mycobacterium tuberculosis (Mtb) during primary infection mainly through the induction of certain antimicrobial peptides (AMPs). In this study we evaluated the vitamin D serum levels, CYP27B1-hydroxylase enzyme, vitamin D receptor (VDR) and AMPs gene expression in Healthy donors, DM2 and TB patients. Results showed that DM2 group has lower VDR and AMPs expression levels. When Monocytes Derived Macrophages (MDM) from DM2 patients with low VDR expression were supplemented with vitamin D, MDMs eliminate efficiently M. tuberculosis. This preliminary study suggests the use of vitamin D as prophylaxis for tuberculosis in high DM2 endemic countries.

Differential expression of antimicrobial peptides in active and latent tuberculosis and its relationship with diabetes mellitus.

Tuberculosis (TB) is one of the most important infectious diseases, causing 1.8 million deaths annually worldwide. This problem has increased because of the association with human immmunodeficiency virus and diabetes mellitus type 2, mainly in developing countries. In the past few years it has been highlighted the significance of antimicrobial peptides in the immunopathogenesis of TB ex vivo and in experimental models studies. In this study we analyzed the expression of CAMP, DEFA1, DEFB4, and DEFB103A in patients with latent TB and progressive TB with and without comorbidity with diabetes mellitus type 2. Antimicrobial peptide gene expression increased during progressive TB, which could be used as a biomarker for reactivation. By contrast, patients with diabetes mellitus type 2 have lower antimicrobial peptides gene expression, suggesting that the lack of its proper production in these patients contribute to enhance the risk for TB reactivation.