Summary
Neutrophils enter sites of infection, where they can eliminate pathogenic bacteria in an oxidative manner. Despite their predominance in active tuberculosis lesions, the function of ...neutrophils in this important human infection is still highly controversial. We observed that virulent Mycobacterium tuberculosis survived inside human neutrophils despite prompt activation of these defence cells' microbicidal effectors. Survival of M. tuberculosis was accompanied by necrotic cell death of infected neutrophils. Necrotic cell death entirely depended on radical oxygen species production since chronic granulomatous disease neutrophils were protected from M. tuberculosis‐triggered necrosis. More, importantly, the M. tuberculosisΔRD1 mutant failed to induce neutrophil necrosis rendering this strain susceptible to radical oxygen species‐mediated killing. We conclude that this virulence function is instrumental for M. tuberculosis to escape killing by neutrophils and contributes to pathogenesis in tuberculosis.
Background Inherited deficiencies of IL-10 or IL-10 receptor (IL-10R) lead to immune dysregulation with life-threatening early-onset enterocolitis. Objectives We sought to gather clinical data of ...IL-10/IL-10R–deficient patients and devise guidelines for diagnosis and management, including hematopoietic stem cell transplantation (HSCT). Methods We enrolled 40 patients with early-onset enterocolitis and screened for mutations in IL10 / IL10R using genetic studies, functional studies, or both of the IL-10 signaling pathway. Medical records of IL-10/IL-10R–deficient patients were reviewed and compiled. Results Of 40 patients, we identified 7 with novel mutations, predominantly in consanguineous families with more than 1 affected member. IL-10/IL-10R–deficient patients had intractable enterocolitis, perianal disease, and fistula formation. HSCT was carried out in 2 patients with IL-10 deficiency and 1 patient with IL-10R α chain deficiency and proved to be an effective therapy, leading to rapid improvement of clinical symptoms and quality of life. Conclusion Because the defect in patients with IL-10/IL-10R deficiency resides in hematopoietic lineage cells and their colitis is resistant to standard immunosuppressive therapy, HSCT should be considered early as a potentially curative therapeutic option.
Dectin-1/CLEC7A is a pattern recognition receptor that recognizes β-1,3 glucans, and its stimulation initiates signaling events characterized by the production of inflammatory cytokines from human ...dendritic cells (DCs) required for antifungal immunity. β-glucans differ greatly in size, structure, and ability to activate effector immune responses from DC; as such, small particulate β-glucans are thought to be poor activators of innate immunity. We show that β-glucan particle size is a critical factor contributing to the secretion of cytokines from human DC; large β-glucan-stimulated DC generate significantly more IL-1β, IL-6, and IL-23 compared to those stimulated with the smaller β-glucans. In marked contrast, the secretion of TSLP and CCL22 were found to be insensitive to β-glucan particle size. Furthermore, we show that the capacity to induce phagocytosis, and the relative IL-1β production determined by β-glucan size, regulates the composition of the cytokine milieu generated from DC. This suggests that β-glucan particle size is critically important in orchestrating the nature of the immune response to fungi.
The innate immune system is a critical component of host defence against microbial pathogens, but effective responses require an ability to distinguish between infectious and non-infectious insult to ...prevent inappropriate inflammation. Using the important obligate intracellular human pathogen Chlamydia trachomatis; an organism that causes significant immunopathology, we sought to determine critical host and pathogen factors that contribute to the induction of inflammasome activation. We assayed inflammasome activation by immunoblotting and ELISA to detect IL-1β processing and LDH release to determine pyroptosis. Using primary murine bone marrow derived macrophages or human monocyte derived dendritic cells, infected with live or attenuated Chlamydia trachomatis we report that the live organism activates both canonical and non-canonical inflammasomes, but only canonical inflammasomes controlled IL-1β processing which preceded pyroptosis. NADPH oxidase deficient macrophages were permissive to Chlamydia trachomatis replication and displayed elevated type-1 interferon and inflammasome activation. Conversely, attenuated, non-replicating Chlamydia trachomatis, primed but did not activate inflammasomes and stimulated reduced type-1 interferon responses. This suggested bacterial replication or metabolism as important factors that determine interferon responses and inflammasome activation. We identified STING but not cGAS as a central mediator of interferon regulated inflammasome activation. Interestingly, exogenous delivery of a Chlamydia trachomatis metabolite and STING ligand-cyclic di-AMP, recovered inflammasome activation to attenuated bacteria in a STING dependent manner thus indicating that a bacterial metabolite is a key factor initiating inflammasome activation through STING, independent of cGAS. These data suggest a potential mechanism of how the innate immune system can distinguish between infectious and non-infectious insult and instigate appropriate immune responses that could be therapeutically targeted.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In contrast to adult-onset inflammatory bowel disease (IBD), where many genetic loci have been shown to be involved in complex disease etiology, early-onset IBD (eoIBD) and associated syndromes can ...sometimes present as monogenic conditions. As a result, the clinical phenotype and ideal disease management in these patients often differ from those in adult-onset IBD. However, due to high costs and the complexity of data analysis, high-throughput screening for genetic causes has not yet become a standard part of the diagnostic work-up of eoIBD patients.
We selected 28 genes of interest associated with monogenic IBD and performed targeted panel sequencing in 71 patients diagnosed with eoIBD or early-onset chronic diarrhea to detect causative variants. We compared these results to whole-exome sequencing (WES) data available for 25 of these patients.
Target coverage was significantly higher in the targeted gene panel approach compared with WES, whereas the cost of the panel was considerably lower (approximately 25% of WES). Disease-causing variants affecting protein function were identified in 5 patients (7%), located in genes of the IL10 signaling pathway (3), WAS (1), and DKC1 (1). The functional effects of 8 candidate variants in 5 additional patients (7%) are under further investigation. WES did not identify additional causative mutations in 25 patients.
Targeted gene panel sequencing is a fast and effective screening method for monogenic causes of eoIBD that should be routinely established in national referral centers.
Thymic stromal lymphopoietin (TSLP) is a functionally pleotropic cytokine important in immune regulation, and TSLP dysregulation is associated with numerous diseases. TSLP is produced by many cell ...types, but has predominantly been characterized as a secreted factor from epithelial cells which activates dendritic cells (DC) that subsequently prime T helper (T
) 2 immunity. However, DC themselves make significant amounts of TSLP in response to microbial products, but the functional role of DC-derived TSLP remains unclear. We show that TSLPR signaling negatively regulates IL-1β production during dectin-1 stimulation of human DC. This regulatory mechanism functions by dampening Syk phosphorylation and is mediated via NADPH oxidase-derived ROS, HIF-1α and pro-IL-1β expression. Considering the profound effect TSLPR signaling has on the metabolic status and the secretome of dectin-1 stimulated DC, these data suggest that autocrine TSLPR signaling could have a fundamental role in modulating immunological effector responses at sites removed from epithelial cell production of TSLP.
Background A subset of patients with common variable immunodeficiency (CVID) have debilitating inflammatory complications strongly associated with cytomegalovirus (CMV) infection and a ...hyperproliferative CMV-specific T-cell response. Objectives We studied the T-cell response to CMV and the global effect of this virus on immune effector cell populations in patients with CVID. Methods Antibody staining, peptide stimulation, and proliferation assays were used to profile CMV-specific T-cell function. Results CMV infection drives the CD4/CD8 ratio inversion that is characteristic of CVID. The late effector CD8+ T-cell subset is expanded in CMV-infected patients with CVID. This expansion is largely attributable to CMV-specific cells and correlates with inflammatory disease; within the CMV-specific population, the frequency of late effector cells correlates inversely with the frequency of cells expressing programmed death 1. Supernatants from proliferating CMV-specific CD8+ cells from patients with inflammatory disease can confer proliferative potential on cells from patients with noninflammatory CVID and healthy subjects. Blocking experiments showed that this proliferation is mediated in part by IFN-γ and TNF-α. Conclusions These data strengthen the association of CMV with inflammatory pathology in patients with CVID, explain some of the well-known T-cell abnormalities associated with this condition, and provide a plausible mechanism for the documented therapeutic activity of anti–TNF-α and antiviral chemotherapy in managing CVID-associated inflammatory disease.
...there was no difference between intravenous or subcutaneous route of infusion to the profile of PCP-Ab (P = .90; 2-tailed Mann-Whitney test) and HIB-Ab (P = .33; 2-tailed Mann-Whitney test). ......our findings showed a consistent relationship between PCP-Ab and HIB-Ab with total IgG; in general, higher total IgG correlates with higher pathogen-specific antibody levels.
Background Common variable immunodeficiency is the most common primary immunodeficiency. A subset of patients has debilitating inflammatory complications. Objectives We investigated the role of ...cytomegalovirus (CMV), and the T-cell response targeted at this virus, in this inflammatory disease. Methods Phenotypic and functional assays were used to profile CMV-specific T cells in patients with common variable immunodeficiency with and without inflammatory complications. Highly sensitive immunohistochemistry was used to detect CMV antigens at sites of inflammation. Results Cytomegalovirus was significantly associated with inflammatory disease, which occurred in 31 of 43 (72%) virus-exposed patients and 8 of 31 (26%) naive patients ( P = .0001). CMV pp65-NLVPMVATV epitope–specific CD8+ T-cell frequencies were significantly elevated in inflammatory patients, but these cells did not show evidence of exhaustion, with low levels of programmed death-1 and high T-cell receptor avidity. Rather, they showed features consistent with high in vivo functionality and proliferative activity including reduced levels of the anti-inflammatory marker CD73 (1.67% of NLV+ cells were CD73+ vs 42.01% in noninflammatory patients; P = .004) and increased Ki-67 expression (37% vs 2% in noninflammatory patients; P < .0001). In vitro , the CMV-specific T cells showed high antigen-specific proliferative potential compared with cells from noninflammatory patients. By using sensitive immunohistochemistry, we detected for the first time viral antigen at the sites of inflammation, indicative of active viral replication. Conclusion Our data strongly support a direct role for CMV and a hyperreactive CMV-specific immune response in the debilitating chronic inflammatory complications of common variable immunodeficiency.
Common variable immunodeficiency (CVID) represents a heterogeneous group of primary antibody deficiency disorders characterized by recurrent infection and by inflammatory, granulomatous, and ...autoimmune complications. Recently, there have been significant advances in understanding the pathogenesis of the disease, with five genetic mutations identified in patients who have a CVID phenotype. Clinical care also has progressed with refinements in treatment and the development of classification schemes for prognostic and research purposes. Significant delays in diagnosis remain, however. It is likely that more genetic defects will be identified in the future, further shrinking the pool of patients who have CVID of unknown cause.
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