Interleukin-17 (IL-17) and IL-17 receptor (IL-17R) signaling are essential for regulating mucosal host defense against many invading pathogens. Commensal bacteria, especially segmented filamentous ...bacteria (SFB), are a crucial factor that drives T helper 17 (Th17) cell development in the gastrointestinal tract. In this study, we demonstrate that Th17 cells controlled SFB burden. Disruption of IL-17R signaling in the enteric epithelium resulted in SFB dysbiosis due to reduced expression of α-defensins, Pigr, and Nox1. When subjected to experimental autoimmune encephalomyelitis, IL-17R-signaling-deficient mice demonstrated earlier disease onset and worsened severity that was associated with increased intestinal Csf2 expression and elevated systemic GM-CSF cytokine concentrations. Conditional deletion of IL-17R in the enteric epithelium demonstrated that there was a reciprocal relationship between the gut microbiota and enteric IL-17R signaling that controlled dysbiosis, constrained Th17 cell development, and regulated the susceptibility to autoimmune inflammation.
•SFB-induced Th17 cell expansion in the gut controls the degree of SFB colonization•IL-17R-dependent regulation of α-defensin, Nox1, and Pigr controls SFB•Intestinal IL-17R signaling regulates dysbiosis and autoimmune inflammation.
Segmented filamentous bacteria (SFB) regulate Th17 cell development in the gastrointestinal tract. Kolls and colleagues find that intestinal IL-17R signaling regulates the abundance of the gut microbiota and SFB specifically by promoting expression of antimicrobial factors. Abrogation of intestinal IL-17R signaling results in bacterial overgrowth and enhanced susceptibility to autoimmune inflammation.
Cryptococcal meningoencephalitis is responsible for upwards of 15% of HIV-related deaths worldwide and is currently the most common cause of non-viral meningitis in the US, affecting both previously ...healthy and people with immune suppression caused by cancer chemotherapy, transplantation, and biologic therapies. Despite a continued 30-50% attributable mortality, recommended therapeutic strategies have remained largely unchanged since the 1950s. Recent murine models and human studies examining the role of the immune system in both susceptibility to the infection as well as host damage have begun to influence patient care decisions. The Damage Framework Response, originally proposed in 1999, was recently used to discuss dichotomous etiologies of host damage in cryptococcal disease. These include patients suffering microbiological damage with low host immunity (especially those immunosuppressed with HIV) and those having low (live) microbiological burden but high immune-mediated damage (HIV-related immune reconstitution syndrome and non-HIV-related postinfectious inflammatory response syndrome). Cryptococcal disease in previously healthy hosts, albeit rare, has been known for a long time. Immunophenotyping and dendritic cell-T cell signaling studies on cerebral spinal fluid of these rare patients reveal immune capacity for recognition and T-cell activation pathways including increased levels of HLA-DR and CD56. However, despite effective T-cell signals, brain biopsy and autopsy specimens demonstrated an M2 alternative macrophage polarization and poor phagocytosis of fungal cells. These studies expand the paradigm for cryptococcal disease susceptibility to include a prominent role for immune-mediated damage and suggest a need for careful individual consideration of immune activation during therapy of cryptococcal disease in diverse hosts.
The cytokine IL-17, and signaling via its heterodimeric IL-17RA/IL-17RC receptor, is critical for host defense against extracellular bacterial and fungal pathogens. Polarized lung epithelial cells ...express IL-17RA and IL-17RC basolaterally. However, their contribution to IL-17-dependent pulmonary defenses in vivo remains to be determined. To address this, we generated mice with conditional deletion of Il17ra or Il17rc in Scgb1a1-expressing club cells, a major component of the murine bronchiolar epithelium. These mice displayed an impaired ability to recruit neutrophils into the airway lumen in response to IL-17, a defect in bacterial clearance upon mucosal challenge with the pulmonary pathogen Klebsiella pneumoniae, and substantially reduced epithelial expression of the chemokine Cxcl5. Neutrophil recruitment and bacterial clearance were restored by intranasal administration of recombinant CXCL5. Our data show that IL-17R signaling in the lung epithelium plays a critical role in establishing chemokine gradients that are essential for mucosal immunity against pulmonary bacterial pathogens.
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•IL-17 receptor signaling in the lung epithelium is required for neutrophil recruitment•Conditional deletion of IL-17R in the lung epithelium impairs bacterial clearance•Expression of the chemokine Cxcl5 is reduced in the IL-17R-deficient epithelium•Recombinant CXCL5 administration restores neutrophil recruitment and bacterial clearance
IL-17 plays key roles in host defense, but the target cells in the lung are unclear. Chen et al. show that pulmonary epithelial IL-17R signaling is essential for regulating chemokine gradients, neutrophil recruitment, and bacterial clearance in the lungs. Epithelial administration of an IL-17R agonist may benefit patients with pneumonia.
Inducible bronchus-associated lymphoid tissue (iBALT) is an ectopic lymphoid structure composed of highly organized T cell and B cell zones that forms in the lung in response to infectious or ...inflammatory stimuli. Here, we develop a model for fungal-mediated iBALT formation, using infection with Pneumocystis that induces development of pulmonary lymphoid follicles. Pneumocystis-dependent iBALT structure formation and organization required CXCL13 signaling. Cxcl13 expression was regulated by interleukin (IL)-17 family members, as Il17ra−/−, Il17rb−/−, and Il17rc−/− mice failed to develop iBALT. Interestingly, Il17rb−/− mice have intact Th17 responses, but failed to generate an anti-Pneumocystis Th2 response. Given a role for Th2 and Th17 immunity in iBALT formation, we demonstrated that primary pulmonary fibroblasts synergistically upregulated Cxcl13 transcription following dual stimulation with IL-13 and IL-17A in a STAT3/GATA3-dependent manner. Together, these findings uncover a role for Th2/Th17 cells in regulating Cxcl13 expression and provide an experimental model for fungal-driven iBALT formation.
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•Pneumocystis infection results in development of iBALT in a CXCL13-dependent manner•Pneumocystis-driven iBALT formation requires both Th2 and Th17 immunity•Pulmonary fibroblasts treated with IL-13 and IL-17A synergistically induce Cxcl13•IL-17A/IL-13 stimulation requires STAT3, STAT6, and GATA3 for induction of Cxcl13
Eddens et al. develop a model for fungal-inducible bronchus-associated lymphoid tissue (iBALT) formation driven by infection or exposure to Pneumocystis. Pneumocystis induces Th2 and Th17 immunity, both of which are required for iBALT formation.
Interleukin (IL)-17 signaling to the intestinal epithelium regulates the intestinal microbiome. Given the reported links between intestinal dysbiosis, bacterial translocation, and liver disease, we ...hypothesize that intestinal IL-17R signaling plays a critical role in mitigating hepatic inflammation. To test this, we study intestinal epithelium-specific IL-17RA-deficient mice in an immune-driven hepatitis model. At the naive state, these mice exhibit microbiome dysbiosis and increased translocation of bacterial products (CpG DNA), which drives liver IL-18 production. Upon disease induction, absence of enteric IL-17RA signaling exacerbates hepatitis and hepatocyte cell death. IL-18 is necessary for disease exacerbation and is associated with increased activated hepatic lymphocytes based on Ifng and Fasl expression. Thus, intestinal IL-17R regulates translocation of TLR9 ligands and constrains susceptibility to hepatitis. These data connect enteric Th17 signaling and the microbiome in hepatitis, with broader implications on the effects of impaired intestinal immunity and subsequent release of microbial products observed in other extra-intestinal pathologies.
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•Disruption of intestinal IL-17RA signaling exacerbates immune-mediated hepatitis•Enhanced disease is microbiome- and IL-18-dependent•Intestinal IL-17RA constrains translocation of unmethylated CpG DNA to the liver•Intestinal IL-17RA constrains hepatic FasL and type I responses by regulating IL-18
Castillo-dela Cruz et al. describe a unique protective role of intestinal IL-17RA in hepatitis. Disruption of intestinal IL-17RA signaling results in microbiome dysbiosis and translocation of bacterial products, specifically unmethylated CpG DNA, to the liver. This promotes IL-18 production and subsequent lymphocyte activation and cell death to exacerbate liver inflammation.
pneumonia is the most common serious opportunistic infection in patients with HIV/AIDS. Furthermore,
pneumonia is a feared complication of the immunosuppressive drug regimens used to treat ...autoimmunity, malignancy, and posttransplantation rejection. With an increasing at-risk population, there is a strong need for novel approaches to discover diagnostic and vaccine targets. There are multiple challenges to finding these targets, however. First,
has a largely unannotated genome. To address this, we evaluated each protein encoded within the
genome by comparisons to proteins encoded within the genomes of other fungi using NCBI BLAST. Second,
relies on a multiphasic life cycle, as both the transmissible form (the ascus) and the replicative form (the trophozoite troph) reside within the alveolar space of the host. To that end, we purified asci and trophs from
and utilized transcriptomics to identify differentially regulated genes. Two such genes,
and
, are differentially regulated in the ascus and the troph, respectively, and can be utilized to characterize the state of the
life cycle
, encoding a β-1,3-glucan synthase with a large extracellular domain previously identified using surface proteomics, was more highly expressed on the ascus form of
GSC-1 ectodomain immunization generated a strong antibody response that demonstrated the ability to recognize the surface of the
asci. GSC-1 ectodomain immunization was also capable of reducing ascus burden following primary challenge with
Finally, mice immunized with the GSC-1 ectodomain had limited fungal burden following natural transmission of
using a cohousing model.
The current report enhances our understanding of
biology in a number of ways. First, the current study provided a preliminary annotation of the
genome, addressing a long-standing issue in the field. Second, this study validated two novel transcripts enriched in the two predominant life forms of
These findings allow better characterization of the
life cycle
and could be valuable diagnostic tools. Furthermore, this study outlined a novel pipeline of -omics techniques capable of revealing novel antigens (e.g., GSC-1) for the development of vaccines against
.
Differential influences mediated by PARP‐1 on the balance of pro‐neutrophilic or pro‐macrophagic stimulatory factors may govern the nature of airway inflammation in response to different stimuli.
We ...reported that PARP‐1 exhibits differential roles in expression of inflammatory factors. Here, we show that PARP‐1 deletion was associated with a significant reduction in inflammatory cell recruitment to mouse airways upon intratracheal administration of LPS. However, PARP‐1 deletion exerted little effect in response to TNF exposure. LPS induced massive neutrophilia and moderate recruitment of macrophages, and TNF induced recruitment of primarily macrophages with smaller numbers of neutrophils in the lungs. Following either exposure, macrophage recruitment was blocked severely in PARP‐1−/− mice, and this was associated with a marked reduction in MCP‐1 and MIP‐1α. This association was corroborated partly by macrophage recruitment in response to intratracheal administration of MCP‐1 in PARP‐1−/− mice. Surprisingly, although neutrophil recruitment was reduced significantly in LPS‐treated PARP‐1−/− mice, neutrophil numbers increased in TNF‐treated mice, suggesting that PARP‐1 deletion may promote a macrophagic‐to‐neutrophilic shift in the inflammatory response upon TNF exposure. Neutrophil‐specific chemokines mKC and MIP‐2 were reduced significantly in lungs of LPS‐treated but only partially reduced in TNF‐treated PARP‐1−/− mice. Furthermore, the MIP‐2 antagonist abrogated the shift to a neutrophilic response in TNF‐exposed PARP‐1−/− mice. Although CXCR2 expression increased in response to either stimulus in PARP‐1+/+ mice, the DARC increased only in lungs of TNF‐treated PARP‐1+/+ mice; both receptors were reduced to basal levels in treated PARP‐1−/− mice. Our results show that the balance of pro‐neutrophilic or pro‐macrophagic stimulatory factors and the differential influence of PARP‐1 on these factors are critical determinants for the nature of the airway inflammatory response.
Macroautophagy/autophagy is a regulated cellular degradation process essential as a pro-survival mechanism and integral to the regulation of diverse cellular processes in eukaryotes. During cellular ...stress and nutrient sensing, SQSTM1/p62 (sequestosome 1) functions as a key receptor for selective autophagy by shuttling ubiquitinated cargoes toward autophagic degradation making it a useful marker for monitoring autophagic flux. We present a straightforward and rapid flow cytometric assay for the quantitative measurement of intracellular SQSTM1 with improved sensitivity to conventional immunoblotting and with the benefit of higher throughput and reduced requirements for starting cellular materials for adequate analysis. We demonstrate that flow cytometry is able to detect similar trends in the measurement of intracellular SQSTM1 levels following serum starvation, genetic manipulations, and bafilomycin A
1
/chloroquine treatments. The assays utilizes readily available reagents and equipment without the need for transfection and utilizes standard flow cytometry equipment. In the present studies, expression of reporter proteins was applied to a range of SQSTM1 expression levels generated by genetic and chemical manipulation in both mouse as well as human cells. In combination with appropriate controls and attention to cautionary issues, this assay offers the ability to assess an important measure of autophagic capacity and flux.
Abbreviations: ATG5: autophagy related 5 ATG7: autophagy related 7 BafA: bafilomycin A1 BMDM: bone marrow-derived macrophages CQ: chloroquine EBV: Epstein-Barr Virus EDTA: ethylenediaminetetraacetic acid FBS: fetal bovine serum gMFI: geometric mean fluorescent intensity HD: healthy donor MAP1LC3/LC3/Atg8: microtubule associated protein 1 light chain 3 MedianFI: median fluorescent intensity NTC: non-target control PBMC: peripheral blood mononuclear cells RPMI: Roswell Park Memorial Institution SQSTM1/p62: sequestosome 1 WT: wild type
IL-22-IL-22R signaling plays a crucial role in regulating host defenses against extracellular pathogens, particularly in the intestine, through the induction of antimicrobial peptides and chemotactic ...genes. However, the role of IL-22-IL-22R is understudied in Streptococcus pneumoniae lung infection, a prevalent pathogen of pneumonia. This paper presents the findings of IL-22 signaling during a murine model of pneumococcal pneumonia and improvement of bacterial burden upon IL-22 administration. IL-22 was rapidly induced in the lung during pneumococcal infection in wild-type mice, and Il22(-/-) mice had higher pneumococcal burdens compared with controls. Additionally, mice with hepatic-specific deletion of Il22ra1 also had higher bacterial burdens in lungs compared with littermate controls after intrapulmonary pneumococcal infection, suggesting that IL-22 signaling in the liver is important to control pneumococcal pneumonia. Thus, we hypothesized that enhancement of IL-22 signaling would control pneumococcal burden in lung tissues in an experimental pneumonia model. Administration of rIL-22 systemically to infected wild-type mice decreased bacterial burden in lung and liver at 24 h postinfection. Our in vitro studies also showed that mice treated with IL-22 had increased C3 expression in the liver compared with the isotype control group. Furthermore, serum from mice treated with IL-22 had improved opsonic capacity by increasing C3 binding on S. pneumoniae Taken together, endogenous IL-22 and hepatic IL-22R signaling play critical roles in controlling pneumococcal lung burden, and systemic IL-22 decreases bacterial burden in the lungs and peripheral organs by potentiating C3 opsonization on bacterial surfaces, through the increase of hepatic C3 expression.
Anti-CD20 antibody therapy has been a useful medication for managing non-Hodgkin's lymphoma as well as autoimmune diseases characterized by autoantibody generation. CD20 is expressed during most ...developmental stages of B lymphocytes; thus, CD20 depletion leads to B-lymphocyte deficiency. As the drug has become more widely used, there has been an increase in the number of case reports of patients developing Pneumocystis pneumonia. The role of anti-CD20 in Pneumocystis jirovecii infection is under debate due to the fact that most patients receiving it are on a regimen of multiple immunosuppressive medications. To address the specific role of CD20 depletion in host immunity against Pneumocystis, we examined a murine anti-CD20 depleting antibody. We demonstrated that anti-CD20 alone is permissive for Pneumocystis infection and that anti-CD20 impairs components of type II immunity, such as production of interleukin-4 (IL-4), IL-5, and IL-13 by whole-lung cells, in response to Pneumocystis murina. We also demonstrated that CD4(+) T cells from mice treated with anti-CD20 during Pneumocystis infection are incapable of mounting a protective immune response when transferred into Rag1(-/-) mice. Thus, CD20(+) cells are critical for generating protective CD4(+) T-cell immune responses against this organism.
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