Oral administration of Lactobacillus delbrueckii UFV-H2b20 protects mice against Aspergillus fumigatus lung infection.

INTRODUCTION: Probiotics provide therapeutic benefits not only in the gut but also other mucosal organs, including the lungs. OBJECTIVE AND DESIGN: To evaluate the effects of the probiotic strain L. delbrueckii UFV-H2b20 oral administration in an experimental murine model of A. fumigatus pulmonary infection. BALB/c mice were associated with L. delbrueckii and infected with Aspergillus fumigatus and compared with non-associated group. METHODS: We investigated survival, respiratory mechanics, histopathology, colony forming units, cytokines in bronchoalveolar lavage, IgA in feces, efferocytosis, production of reactive oxygen species and the cell population in the mesenteric lymph nodes. RESULTS: L. delbrueckii induces tolerogenic dendritic cells, IL-10+macrophages and FoxP3+regulatory T cells in mesenteric lymph nodes and increased IgA levels in feces; after infection with A. fumigatus, increased survival and decreased fungal burden. There was decreased lung vascular permeability without changes in the leukocyte profile. There was enhanced neutrophilic response and increased macrophage efferocytosis. L. delbrueckii-treated mice displayed more of FoxP3+Treg cells, TGF-ß and IL-10 levels in lungs, and concomitant decreased IL-1ß, IL-17 A, and CXCL1 production. CONCLUSION: Uur results indicate that L. delbrueckii UFV H2b20 ingestion improves immune responses, controlling pulmonary A. fumigatus infection. L. delbrueckii seems to play a role in pathogenesis control by promoting immune regulation.

The transcription factors Thpok and LRF are necessary and partly redundant for T helper cell differentiation.

T helper (Th) cells are critical for defenses against infection and recognize peptides bound to class II major histocompatibility complex (MHC II) molecules. Although transcription factors have been identified that direct Th cells into specific effector fates, whether a "master" regulator controls the developmental program common to all Th cells remains unclear. Here, we showed that the two transcription factors Thpok and LRF share this function. Although disruption of both factors did not prevent the generation of MHC II-specific T cells, these cells failed to express Th cell genes or undergo Th cell differentiation in vivo. In contrast, T cells lacking Thpok, which only displayed LRF-dependent functions, contributed to multiple effector responses, both in vitro and in vivo, with the notable exception of Th2 cell responses that control extracellular parasites. These findings identify the Thpok-LRF pair as a core node of Th cell differentiation and function.

Essential role for retinoic acid in the promotion of CD4(+) T cell effector responses via retinoic acid receptor alpha.

Vitamin A and its metabolite, retinoic acid (RA) are implicated in the regulation of immune homeostasis via the peripheral induction of regulatory T cells. Here we showed RA was also required to elicit proinflammatory CD4(+) helper T cell responses to infection and mucosal vaccination. Retinoic acid receptor alpha (RARα) was the critical mediator of these effects. Antagonism of RAR signaling and deficiency in RARα (Rara(-/-)) resulted in a cell-autonomous CD4(+) T cell activation defect, which impaired intermediate signaling events, including calcium mobilization. Altogether, these findings reveal a fundamental role for the RA-RARα axis in the development of both regulatory and inflammatory arms of adaptive immunity and establish nutritional status as a broad regulator of adaptive T cell responses.

Intestinal microbiota regulates tryptophan metabolism following oral infection with Toxoplasma gondii.

INTRODUCTION: The intestinal microbiota plays an important role in modulating host immune responses. Oral Toxoplasma gondii infection can promote intestinal inflammation in certain mice strains. The IDO-AhR axis may control tryptophan (Trp) metabolism constituting an important immune regulatory mechanism in inflammatory settings. AIMS: In the present study, we investigated the role of the intestinal microbiota on Trp metabolism during oral infection with T gondii. METHODS AND RESULTS: Mice were treated with antibiotics for four weeks and then infected with T gondii by gavage. Histopathology and immune responses were evaluated 8 days after infection. We found that depletion of intestinal microbiota by antibiotics contributed to resistance against T gondii infection and led to reduced expression of AhR on dendritic and Treg cells. Mice depleted of Gram-negative bacteria presented higher levels of systemic Trp, downregulation of AhR expression and increased resistance to infection whereas depletion of Gram-positive bacteria did not affect susceptibility or expression of AhR on immune cells. CONCLUSION: Our findings indicate that the intestinal microbiota can control Trp availability and provide a link between the AhR pathway and host-microbiota interaction in acute infection with T gondii.

Frequency of CDH1 germline variants and contribution of dietary habits in early age onset gastric cancer patients in Brazil.

INTRODUCTION: The contribution of CDH1 germline variants to gastric cancer burden among young adults is unknown in Brazil. We aimed to evaluate the frequency of CDH1 germline variants and the diet/lifestyle habits in early age onset gastric cancer (EOGC, ≤ 55 years old) patients. METHODOLOGY: From 2013 to 2015, a total of 88 unrelated and consecutive patients diagnosed with EOGC were enrolled. All CDH1 exons and intronic boundaries were sequenced, and large genomic rearrangements were screened by MLPA. CDH1 transcription analysis was performed for variants that could potentially induce an effect on splicing. The diet and lifestyle habits of EOGC patients were compared to Brazilian population diet and lifestyle, obtained from governmental databases. RESULTS: Of 88 patients, the mean age at EOGC diagnosis was 39 years and 55% fulfilled the criteria for hereditary diffuse gastric cancer. The majority of the tumors were diffuse (74%) and poorly differentiated (80%). In total, 4 novel missense variants of uncertain significance (VUS) were identified: c.313T>A, c.387G>T, c.1676G>A, and c.1806C>A. The MLPA results revealed no rearrangements and CDH1 transcription analysis for variants of interest were inconclusive. EOGC patients had a higher red (OR:2.6, 95%CI:1.4-4.9) and processed (OR:3.1, 95%CI:1.6-6.0) meat intake and higher fruit consumption (OR:0.4, 95%IC:0.3-0.7) compared to eating habits of the Brazilian population. CONCLUSIONS: No unequivocal pathogenic germline CDH1 variants were identified in Brazilian EOGC patients. Dietary habits may be associated with the EOGC development.

Decrease of Foxp3+ Treg cell number and acquisition of effector cell phenotype during lethal infection.

Using a model of lethal oral infection with Toxoplasma gondii, we examined the fate of both induced and natural regulatory T (Treg) cells in the face of strong inflammatory responses occurring in a tolerogenic-prone environment. We found that during highly T helper 1 (Th1) cell-polarized mucosal immune responses, Treg cell numbers collapsed via multiple pathways, including blockade of Treg cell induction and disruption of endogenous Treg cell homeostasis. In particular, shutdown of interleukin 2 (IL-2) in the highly Th1 cell-polarized environment triggered by infection directly contributes to Treg cell incapacity to suppress effector responses and eventually leads to immunopathogenesis. Furthermore, we found that environmental cues provided by both local dendritic cells and effector T cells can induce the expression of T-bet transcription factor and IFN-gamma by Treg cells. These data reveal a mechanism for Th1 cell pathogenicity that extends beyond their proinflammatory program to limit Treg cell survival.

Prognostic Value of ADAMTS Proteases and Their Substrates in Epithelial Ovarian Cancer.

BACKGROUND: ADAMTS are metalloproteases with disintegrin and thrombospondin motifs. They are secreted proteases playing a role in biological processes such as inflammation, angiogenesis, and urogenital development. ADAMTS have specific substrates, such as the proteoglycans (PG) versican, aggrecan, and brevican. Despite data indicating a role of ADAMTS in tumor invasion and metastases, effects played by these molecules in cancer progression are still controversial. In ovarian cancer, the importance of ADAMTS gene mutations was recently described and related to chemotherapy outcome. OBJECTIVE: To analyze protein levels of ADAMTS-1, -4, and -5, and TIMP-3 in human ovarian cancer classified as benign, borderline, or malignant. We also assessed the expression of the ADAMTS substrates aggrecan, brevican, and versican in these neoplasms. Correlations between overall survival and protein expression were performed. METHODS: Tumors were classified according to the WHO Classification of Tumors of Female Reproductive Organs. Protein and PG expression was studied by immunohistochemistry. Differences in labeling were analyzed by percent measurements of stained areas. RESULTS: ADAMTS-1, ADAMTS-5, and its tissue inhibitor TIMP-3 are increased in borderline and malignant tumors compared to benign neoplasms. Aggrecan and versican levels were increased in malignant subtypes compared to benign ovarian cancer. Higher ADAMTS-1, TIMP-3, and versican expression was associated with a shorter overall survival. CONCLUSIONS: Comparison of protease, TIMP-3, and substrate expression showed that in malignant tumors all ADAMTS and TIMP-3 expression levels were significantly raised compared to the substrates studied.

IL-18 contributes to susceptibility to Leishmania amazonensis infection by macrophage-independent mechanisms.

We evaluated the role of IL-18 during Leishmania amazonensis infection in C57BL/6 mice, using IL-18KO mice. We showed that IL-18 is involved in susceptibility to L. amazonensis, since IL-18KO mice presented reduced lesions and parasite loads. Because macrophages are the host cells of the parasite, we investigated if macrophages were involved in IL-18-mediated susceptibility to L. amazonensis. We showed that macrophages obtained from WT or IL-18KO responded similarly to L. amazonensis infection. Moreover, we showed that C57BL/6 macrophages do not respond to IL-18, since they do not express IL-18R. Therefore, macrophages are not involved in IL-18-mediated susceptibility to L. amazonensis.

Annexin A1 improves immune responses and control of tissue parasitism during Leishmania amazonensis infection in BALB/c mice.

Leishmaniases, a group of diseases caused by the species of the protozoan parasite Leishmania, remains a significant public health concern worldwide. Host immune responses play a crucial role in the outcome of Leishmania infections, and several mediators that regulate inflammatory responses are potential targets for therapeutic approaches. Annexin A1 (AnxA1), an endogenous protein endowed with anti-inflammatory and pro-resolving properties, has emerged as a potential player. We have shown that during L. braziliensis infection, deficiency of AnxA1 exacerbates inflammatory responses but does not affect parasite burden. Here, we have investigated the role of AnxA1 in L. amazonensis infection, given the non-healing and progressive lesions characteristic of this infectious model. Infection of AnxA1 KO BALB/c mice resulted in increased lesion size and tissue damage associated with higher parasite burdens and enhanced inflammatory response. Notably, therapeutic application of the AnxA1 peptidomimetic Ac2-26 improves control of parasite replication and increases IL-10 production in vivo and in vitro, in both WT and AnxA1 KO mice. Conversely, administration of WRW4, an inhibitor of FPR2/3, resulted in larger lesions and decreased production of IL-10, suggesting that the effects of AnxA1 during L. amazonensis infection are associated with the engagement of these receptors. Our study illuminates the role of AnxA1 in L. amazonensis infection, demonstrating its impact on the susceptibility phenotype of BALB/c mice. Furthermore, our results indicate that targeting the AnxA1 pathway by using the Ac2-26 peptide could represent a promising alternative for new treatments for leishmaniasis.

Characterization of chronic cutaneous lesions from TNF-receptor-1-deficient mice infected by Leishmania major.

Leishmania major-infected TNF receptor 1 deficient (TNFR1 KO) mice resolve parasitism but fail to resolve lesions, while wild-type mice completely heal. We investigated the cell composition, cytokine production, and apoptosis in lesions from L. major-infected TNFR1 KO and wild-type (WT) mice. Chronic lesions from L. major-infected TNFR1 KO mice presented larger number of CD8+ T and Ly6G+ cells. In addition, higher concentrations of mRNA for IFN-γ CCL2 and CCL5, as well as protein, but lower numbers of apoptotic cells, were found in lesions from TNFR1 KO mice than in WT, at late time points of infection. Our studies showed that persistent lesions in L. major-infected TNFR1 KO mice may be mediated by continuous migration of cells to the site of inflammation due to the presence of chemokines and also by lower levels of apoptosis. We suggest that this model has some striking similarities to the mucocutaneous clinical form of leishmaniasis.