European Journal of Microbiology & Immunology最新文献

Application of the proteasome inhibitor Bortezomib for the treatment of haematopoietic malignancies such as multiple myeloma significantly improves the average overall survival of patients. However, one of the most severe side effects is the development of peripheral neuropathies caused by neurotoxic effects of Bortezomib limiting its therapeutic efficacy. With ONX-0914 a specific inhibitor of the β5i (LMP7)-immunosubunit containing proteasomes was developed that targets exclusively the proteasome subtypes mainly expressed in immune cells including B lymphocytes as the origin of multiple myeloma. Furthermore, immunosubunitspecific inhibitors have been shown to be promising tools for the therapy of autoimmune disorders. In the presented study, we analysed the concentration-dependent impact of both inhibitors on primary neurons regarding survival rate, morphological changes, and overall viability. Our results clearly demonstrate that ONX-0914, compared to Bortezomib, is less neurotoxic suggesting its potential as a putative antineoplastic drug and as a candidate for the treatment of autoimmune disorders affecting the peripheral and/or central nervous system.

The rising incidences of infections with multidrug-resistant (MDR) Gram-negative bacteria including Pseudomonas aeruginosa (PA) have gained increasing attention in medicine, but also in the general public and global health politics. The mechanisms underlying opportunistic pathogen-host interactions are unclear, however. To address this, we challenged secondary abiotic IL10^-/- mice deficient for Toll-like receptor-4 (TLR4^-/- × IL10^-/-), the main receptor of the Gram-negative cell wall constituent lipopolysaccharide, with a clinical MDR PA isolate. Despite higher intestinal colonization densities, apoptotic colonic epithelial cell numbers were lower in TLR4^-/- × IL10^-/- mice as compared to IL10^-/- controls at day 14 postinfection (p.i.), whereas proliferating/regenerating cells had increased in the latter only. Furthermore, PA-colonized TLR4^-/- × IL10^-/- mice displayed less distinct innate and adaptive immune cell responses in the colon as compared to IL10^-/- counterparts that were accompanied by lower nitric oxide concentrations in mesenteric lymph nodes in the former at day 14 p.i. Conversely, splenic NO levels were higher in both naive and PA-colonized TLR4-deficient IL10^-/- mice versus IL10^-/- controls. Remarkably, intestinal MDR PA was able to translocate to extra-intestinal including systemic compartments of TLR4^-/- × IL10^-/- mice only. Hence, MDR PA-induced intestinal and systemic immune responses observed in secondary abiotic IL10^-/- mice are TLR4-dependent.

The World Health Organization has rated multidrug-resistant (MDR) Pseudomonas aeruginosa as a critical threat to human health. In the present study, we performed a survey of intestinal colonization, and local and systemic immune responses following peroral association of secondary abiotic mice with either a clinical MDR P. aeruginosa or a commensal murine Escherichia coli isolate. Depletion of the intestinal microbiota following antibiotic treatment facilitated stable intestinal colonization of both P. aeruginosa and E. coli that were neither associated with relevant clinical nor histopathological sequelae. Either stable bacterial colonization, however, resulted in distinct innate and adaptive immune cell responses in the intestines, whereas a pronounced increase in macrophages and monocytes could be observed in the small as well as large intestines upon P. aeruginosa challenge only, which also applied to colonic T lymphocytes. In addition, TNF secretion was exclusively elevated in large intestines of P. aeruginosa-colonized mice. Strikingly, association of secondary abiotic mice with MDR P. aeruginosa, but not commensal E. coli, resulted in pronounced systemic pro-inflammatory responses, whereas anti-inflammatory responses were dampened. Hence, intestinal carriage of MDR P. aeruginosa as compared to a mere commensal Gram-negative strain in otherwise healthy individuals results in distinct local and systemic pro-inflammatory sequelae.

Pituitary adenylate cyclase activating polypetide (PACAP) constitutes a neuropeptide that is widely distributed in the host exerting essential cytoprotective properties, whereas PACAP^-/- mice display increased susceptibility to distinct immunopathological conditions. The orchestrated interplay between the gut microbiota and the host is pivotal in immune homeostasis and resistance to disease. Potential pertubations of the intestinal microbiota in PACAP^-/- mice, however, have not been addressed so far. For the first time, we performed a comprehensive survey of the intestinal microbiota composition in PACAP^-/- and wildtype (WT) mice starting 2 weeks postpartum until 18 months of age applying quantitative culture-independent techniques. Fecal enterobacteria and enterococci were lower in PACAP^-/- than WT mice aged 1 month and ≥6 months, respectively. Whereas Mouse Intestinal Bacteroides were slightly higher in PACAP^-/- versus WT mice aged 1 and 6 months, this later in life held true for Bacteroides/Prevotella spp. (≥12 months) and lactobacilli (>15 months of age). Strikingly, health-beneficial bifidobacteria were virtually absent in the intestines of PACAP^-/- mice, even when still breastfed. In conclusion, PACAP deficiency is accompanied by distinct changes in fecal microbiota composition with virtually absent bifidobacteria as a major hallmark that might be linked to increased susceptibility to disease.

Fibroblasts are present in all tissues but predominantly in connective tissues. Some of their functions include contractility, locomotion, collagen and elastin fiber production, and the regulation and degradation of the extracellular matrix. Also, fibroblasts act as sentinels to produce inflammatory mediators in response to several microorganisms. There is evidence that fibroblasts can synthesize toll-like receptors (TLRs), antimicrobial peptides, proinflammatory cytokines, chemokines, and growth factors, which are important molecules involved in innate immune response against microorganisms. Fibroblasts can express TLRs (TLR-1 to TLR-10) to sense microbial components or microorganisms. They can synthesize antimicrobial peptides, such as LL-37, defensins hBD-1, and hBD-2, molecules that perform antimicrobial activity. Also, they can produce proinflammatory cytokines, such as TNFα, INFγ, IL-6, IL-12p70, and IL-10; other chemokines, such as CCL1, CCL2, CCL5, CXCL1, CXCL8, CXCL10, and CX3CL1; and the growth factors granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) to induce and recruit inflammatory cells. According to their immunological attributes, we can conclude that fibroblasts are sentinel cells that recognize pathogens, induce the recruitment of inflammatory cells via cytokines and growth factors, and release antimicrobial peptides, complying with the characteristics of real sentinels.

Human immunodeficiency virus (HIV) infections cause severe CD4+ T cell depletion leading to chronic inflammation and immune activation, impaired barrier function, and microbial translocation. Even under effective antiretroviral therapy, these processes persist, leading to gut microbiome dysbiosis and disturbance of microbiome-host homeostasis. This systematic review aims at analyzing how gut microbiome and host immune system influence each other during HIV pathogenesis. An online search applying the PubMed database was conducted. The number of total results (n = 35) was narrowed down to 5 relevant studies focusing on the interaction between the host and gut microbiome, whereas strict exclusion criteria were applied, thereby assuring that no other comorbidities impacted study results. Our analyses revealed that gut microbiome diversity correlated positively with CD4+ T cell counts and negatively with microbial translocation markers. However, quantitative changes in bacterial richness did not consistently correlate with the numbers of metabolically active bacterial populations. Despite the reported increase in potentially pathogenic bacteria and, conversely, decrease in protective populations, the gut microbiota exhibited immune-modulating qualities given that mucosal inflammatory sequelae were dampened by decreasing pro-inflammatory and accelerating anti-inflammatory cytokine responses. Future research is needed to further elucidate these findings, to gain a deeper insight into host-microbiota interactions and to develop novel therapeutic strategies.

Diarrheagenic Escherichia coli (DEC) is important bacteria of children's endemic and epidemic diarrhea worldwide. The aim of this study was to determine the prevalence of DEC isolated from stool samples collected from children with acute diarrhea living in Ouagadougou, Burkina Faso. From August 2013 to October 2015, stool samples were collected from 315 children under 5 years of age suffering from diarrhea in the "Centre Médical avec Antenne Chirurgicale (CMA)" Paul VI and the CMA of Schiphra. E. coli were isolated and identified by standard microbiological methods, and the 16-plex PCR method was used to further characterize them. Four hundred and nineteen (419) E. coli strains were characterized, of which 31 (7.4%) DEC pathotypes were identified and classified in five E. coli pathotypes: 15 enteroaggregative E. coli (EAEC) (48.4%), 8 enteropathogenic E. coli (EPEC) (25.8%) with 4 typical EPEC and 4 atypical EPEC, 4 enteroinvasive E. coli (EIEC) (12.9%), 3 enterohemorrhagic E. coli (EHEC) 9.67%, and 1 enterotoxigenic E. coli (ETEC) 3.2%. The use of multiplex PCR as a routine in clinical laboratory for the detection of DEC would be a useful mean for a rapid management of an acute diarrhea in children.

It is not clear whether infection with cytomegalovirus (CMV) is associated with hypertensive disorders in pregnant women. Through a case-control study design, 146 women suffering from hypertensive disorders in pregnancy (cases) and 146 age-matched normotensive pregnant women (controls) were examined for the presence of anti-CMV IgG and IgM antibodies with enzyme-linked immunoassays. IgM seropositive samples were further assayed by enzyme-linked fluorescent assay (ELFA). Anti-CMV IgG antibodies were found in 138 (94.5%) controls and in 136 (93.2%) cases (odds ratio [OR] = 0.78; 95% confidence interval [CI]: 0.30-2.05; P = 0.62). High (>18 IU/ml) levels of anti-CMV IgG antibodies were found in 37.7% of the 138 seropositive controls and in 34.6% of the 136 seropositive cases (OR = 0.87; 95% CI: 0.53-1.43; P = 0.59). Anti-CMV IgM antibodies were found in 1 (0.7%) of the controls but in none of the cases using ELFA (P = 1.0). Seropositivity to CMV was not associated with a previous preeclampsia and was similar among cases regardless their mean systolic and diastolic blood pressures, and mean arterial blood pressure. No serological evidence of an association between CMV infection and hypertensive disorders of pregnancy was found. Further research to elucidate the role of CMV in hypertensive disorders in pregnancy should be conducted.

Host immune responses are crucial for combating enteropathogenic infections including Campylobacter jejuni. Within 1 week following peroral C. jejuni infection, secondary abiotic IL-10^-/- mice develop severe immunopathological sequelae affecting the colon (ulcerative enterocolitis). In the present study, we addressed whether pathogen-induced pro-inflammatory immune responses could also be observed in the small intestines dependent on the innate receptor nucleotide-oligomerization-domain-protein 2 (Nod2). Within 7 days following peroral infection, C. jejuni stably colonized the gastrointestinal tract of both IL-10^-/- mice lacking Nod2 (Nod2^-/- IL-10^-/-) and IL-10^-/- controls displaying bloody diarrhea with similar frequencies. Numbers of apoptotic and regenerating epithelial cells increased in the small intestines of C. jejuni-infected mice of either genotype that were accompanied by elevated ileal T and B lymphocyte counts. Notably, ileal T cell numbers were higher in C. jejuni-infected Nod2^-/- IL-10^-/- as compared to IL-10^-/- counterparts. Furthermore, multifold increased concentrations of pro-inflammatory cytokines including IFN-γ, TNF, and MCP-1 could be measured in small intestinal ex vivo biopsies derived from C. jejuni-infected mice of either genotype. In conclusion, C. jejuni-induced pro-inflammatory immune responses affected the small intestines of both Nod2^-/- IL-10^-/- and IL-10^-/- mice, whereas ileal T lymphocyte numbers were even higher in the former.

Using quantitative phosphopeptide sequencing of unstimulated versus stimulated primary murine Foxp3⁺ regulatory and Foxp3^- conventional T cells (Tregs and Tconv, respectively), we detected a novel and differentially regulated tyrosine phosphorylation site within the C1 domain of the guanine-nucleotide exchange factor CalDAG GEFI. We hypothesized that the Treg-specific and activation-dependent reduced phosphorylation at Y523 allows binding of CalDAG GEFI to diacylglycerol, thereby impacting the formation of a Treg-specific immunological synapse. However, diacylglycerol binding assays of phosphomutant C1 domains of CalDAG GEFI could not confirm this hypothesis. Moreover, CalDAG GEFI^-/- mice displayed normal Treg numbers in thymus and secondary lymphoid organs, and CalDAG GEFI^-/- Tregs showed unaltered in vitro suppressive capacity when compared to CalDAG GEFI^+/+ Tregs. Interestingly, when tested in vivo, CalDAG GEFI^-/- Tregs displayed a slightly reduced suppressive ability in the transfer colitis model when compared to CalDAG GEFI^+/+ Tregs. Additionally, CRISPR-Cas9-generated CalDAG GEFI^-/- Jurkat T cell clones showed reduced adhesion to ICAM-1 and fibronectin when compared to CalDAG GEFI-competent Jurkat T cells. Therefore, we speculate that deficiency in CalDAG GEFI impairs adherence of Tregs to antigen-presenting cells, thereby impeding formation of a fully functional immunological synapse, which finally results in a reduced suppressive potential.