NOD2 receptor is crucial for protecting against the digestive form of Chagas disease.

Digestive and cardiodigestive forms of Chagas' disease are observed in 2% to 27% of the patients, depending on their geographic location, Trypanosoma cruzi strain and immunopathological responses. The aim of this work was to evaluate the role of NOD2 innate immune receptor in the pathogenesis of the digestive system in Chagas' disease. Patients with digestive form of the disease showed lower mRNA expression of NOD2, higher expression of RIP2 and α-defensin 6, compared to indeterminate form, detected by Real-time PCR in peripheral blood mononuclear cells. In addition, there was a negative correlation between the expression of NOD2 and the degree of dilation of the esophagus, sigmoid and rectum in those patients. The infection of NOD2-/- mice with T. cruzi strain isolated from the digestive patient induced a decrease in intestinal motility. Histopathological analysis of the colon and jejunum of NOD2-/- and wild type C57BL/6 animals revealed discrete inflammatory foci during the acute phase of infection. Interestingly, during the chronic phase of the infection there was inflammation and hypertrophy of the longitudinal and circular muscular layer more pronounced in the colon and jejunum from NOD2-/- animals, when compared to wild type C57BL/6 mice. Together, our results suggest that NOD2 plays a protective role against the development of digestive form of Chagas' disease.

Leukotriene B4 is essential for lung host defence and alpha-defensin-1 production during Achromobacter xylosoxidans infection.

Leukotriene B4 (LTB4) is essential for host immune defence. It increases neutrophil recruitment, phagocytosis and pathogen clearance, and decreases oedema and inflammasome activation. The host response and the role of LTB4 during Achromobacter xylosoxidans infection remain unexplored. Wild-type (129sv) and LTB4 deficient (Alox5 -/-) mice were intratracheally infected with A. xylosoxidans. Wild-type 129sv infected mice survived beyond the 8th day post-infection, exhibited increased levels of LTB4 in the lung on the 1st day, while levels of PGE2 increased on the 7th day post-infection. Infected Alox5 -/- mice showed impaired bacterial clearance, increased lung inflammation, and succumbed to the infection by the 7th day. We found that exogenous LTB4 does not affect the phagocytosis of A. xylosoxidans by alveolar macrophages in vitro. However, treatment of infected animals with LTB4 protected from mortality, by reducing the bacterial load and inflammation via BLT1 signalling, the high affinity receptor for LTB4. Of importance, we uncovered that LTB4 induces gene and protein expression of α-defensin-1 during the infection. This molecule is essential for bacterial clearance and exhibits potent antimicrobial activity by disrupting A. xylosoxidans cell wall. Taken together, our data demonstrate a major role for LTB4 on the control of A. xylosoxidans infection.

Bifidobacterium infantis NLS Super Strain Reduces the Expression of α-Defensin-5, a Marker of Innate Immunity, in the Mucosa of Active Celiac Disease Patients.

BACKGROUND: We have previously shown a reduction of gastrointestinal symptoms after the oral administration of Bifidobacterium infantis Natren Life Start super strain (NLS-SS) in untreated celiac disease (CD) patients. The symptomatic improvement was not associated with changes in intestinal permeability or serum levels of cytokines, chemokines, or growth factors. Therefore, we hypothesized that the beneficial symptomatic effect observed previously in patients with CD treated with B. infantis may be related to the modulation of innate immunity. GOALS: To investigate the potential mechanisms of a probiotic B. infantis Natren Life Start super strain on the mucosal expression of innate immune markers in adult patients with active untreated CD compared with those treated with B. infantis×6 weeks and after 1 year of gluten-free diet (GFD). METHODS: Numbers of macrophages and Paneth cells and α-defensin-5 expression were assessed by immunohistochemistry in duodenal biopsies. RESULTS: We showed that GFD decreases duodenal macrophage counts in CD patients more effectively than B. infantis. In contrast, B. infantis decreases Paneth cell counts and expression of α-defensin-5 in CD (P<0.001). CONCLUSIONS: The results identify differential innate immune effects of treatment with B. infantis compared with 1 year of GFD. Further studies are needed to investigate synergistic effects of GFD and B. infantis supplementation in CD.

LL-37, HNP-1, and HBD2/3 modulate the secretion of cytokines TNF-α, IL-6, IFN-γ, IL-10 and MMP1 in human primary cell cultures.

The aim of this study was to evaluate the effects of the LL-37, HNP-1 and HBD2/3 peptides on cytokine and MMP production in human polymorphonuclear cells, mononuclear cells and chondrocytes. The levels of cytokines in supernatants from mononuclear and polymorphonuclear cell cultures were measured with a cytometric bead array by flow cytometry. Likewise, the levels of metalloproteinase/MMP-1, 3, and 13 were measured in supernatants from chondrocyte cultures using an ELISA. The expression of RANKL on lymphocytes was analyzed by flow cytometry. We observed increased levels of TNF-α, IL-6 and IL-10 in mononuclear and polymorphonuclear cell cultures stimulated with HBD-2/3. We also observed increased levels of IFN-γ, IL-10, and IL-6 in mononuclear cell cultures stimulated with HNP-1, and increased IL-6 levels were observed in polymorphonuclear cell cultures exposed to HNP-1. We also found that the MMP-1 level increased in the chondrocyte cultures stimulated with HBD-3, whereas the MMP-1 level was decreased in cultures exposed to LL-37. The present report is the first study to determine that HNP-1and HBD2/3 promote the secretion of pro-inflammatory cytokines by polymorphonuclear and mononuclear cells and the secretion of MMP by chondrocytes, whereas LL-37 diminishes MMP1 secretion. Our results suggest that HBD-2/3 and HNP1 might play a pathological role in rheumatoid arthritis, while LL-37 might have a protective role.

Human neutrophil peptide-1 decreases during ageing in selected Mexican population.

Antimicrobial peptide innate immunity plays a central role in the susceptibility to infectious diseases, as has been described extensively in different settings. However, the role that these molecules play in the immunity mediated by polymorphonuclear phagocytes as part of the innate immunity of ageing individuals has not been described. In the present study, we addressed the question whether antimicrobial activity in polymorphonuclear cells from elderly individuals was altered in comparison with young adults. We compared phagocytosis index, bacterial killing efficiency, myeloperoxidase activity and cathelicidin expression. Results showed that there were no statistical differences among groups. However, human neutrophil peptide-1 (HNP-1) was decreased in the elderly individuals group. Results suggest that the decreased HNP-1 production in the polymorphonuclear phagocytes form elderly individuals might have an important participation in the increased susceptibility to infectious diseases.

Behavior of calf Sertoli cells and fibroblast cells transfected with the human HNP-1 gene.

Human neutrophil peptide-1 (HNP-1) is an important defense molecule in neutrophils and Sertoli cells and plays an important role in the blood-testis barrier. In this study, we investigated the behavior of Sertoli cells transfected with the HNP-1 gene and compared the ability of Sertoli cells and fibroblast cells to resist transfection. Total RNA was isolated from human blood. The DNA coding sequence of HNP-1 was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and the eukaryotic expression vector pEGFP-N3-HNP-1 was identified by PCR, endonuclease digestion, and sequencing. Bovine Sertoli cells and fibroblast cells were transfected with pEGFP-N3-HNP-1 using Liposome reagent. The transfection efficiency and the behavior of the transfected cells were evaluated at 24, 48 and 72 h as well as at other times after transfection. The plasmid pEGFP-N3-HNP-1 was successfully constructed. The cells achieved maximum transfection efficiency at 48 h. Two weeks after transfection, the cells began to stop dividing. The ability of Sertoli cells to resist transfection was higher compared to fibroblast cells. The ability of the 2 cell types to resist transfection was higher with plasmid pEGFP-N3-HNP-1 than with the plasmid pEGFP-N3. The injury to Sertoli cells caused by transfection with the HNP-1 gene was less pronounced than in fibroblast cells, which may be closely correlated with the physiological function of Sertoli cells.

[Neutrophil extracellular traps: a 2-faced host defense mechanism]. / Trampas extracelulares de neutrófilos: un mecanismo de defensa con dos caras.

Neutrophils play a key role in the innate immune system, providing the first line of host defense. In addition to their ability to eliminate pathogens by phagocytosis and antimicrobial secretions, it has recently been shown that neutrophils can trap and kill microorganisms by the release of extracellular structures composed of DNA and antimicrobial proteins called neutrophil extracellular traps (NETs). Although physiological amounts of NETs are important as antimicrobial agents, high levels of NETs in circulation may result in severe tissue damage. Besides, the excessive generation of NETs or a disruption in their clearance mechanism might be associated with the development of certain autoimmune diseases. This review describes the structure, function and generation of NETs, and their possible implication in the initiation and/or progression of different diseases.