An ongoing pulmonary cowpox virus infection suppresses an immune response to OVA peptide delivered to the lungs

Cowpox virus (CPXV), a close relative of variola virus, the orthopoxvirus that causes smallpox, can suppress the immune system through a large array of immunosuppressive gene products. We developed a murine model in which DO11.10 T cells specific for an OVA peptide were transferred into BALB/c mice to assess the impact of a pulmonary CPXV infection on DO11.10 T cell proliferation in lung draining lymph nodes following intranasal OVA peptide delivery. High and low-dose CPXV infections were compared. Both doses lead to clinical illness including ruffled coat and weight loss, but the high dose is lethal and is characterized by viral dissemination to the spleen. A high-dose infection reduced DO11.10 T cell proliferation, but a low-dose infection did not. At the time that proliferation of T cells was assessed (6d post infection), 15±1% of lung dendritic cells (DCs) were infected at the high-dose, but only 5±1% of DCs at the low-dose. At both doses, infected and uninfected lung DCs had decreased expression of MHC class II and the co-stimulatory molecules CD80 and CD86. DCs and T cells were not infected in the lymph nodes at either dose, but lymph node DCs also showed a reduction in antigen-presenting molecules. We speculated that the lung microenvironment created by infection, rather than direct infection of the DCs, suppressed DC antigen-specific T cell activation. In support, we found that alveolar lavage fluid and supernatant derived from lung homogenates from infected mice suppressed the function of uninfected lung DCs in vitro. Furthermore, the suppressive activity was more highly concentrated in lungs from high-dose infected mice. Cytokine analysis revealed the presence of IL-10, an immunosuppressive cytokine, in lung supernatants in mice receiving a high-dose of CPXV. We used IL-10 knockout mice in our adoptive transfer model to examine a role for IL-10 in T cell suppression in the lymph nodes. However, the knockout mice behaved similarly to BALB/c, with lack of DO11.10 T cell proliferation in the high-dose, but not the low-dose, and concluded IL-10 does not prevent T cell proliferation at the high-dose. Finally, we examined a possible virally encoded immunomodulatory protein, a soluble IFNγ receptor (IFNγR), to determine if sequestration of host-produced IFNγ contributed to the immune suppression seen in the high-dose. A mutant virus lacking the IFNγR behaved similarly to wild-type virus, and the survival and day 6 lung titers were comparable. Other virally encoded factors may play a role in suppressing DO11.10 T cell proliferation and should be examined in future experiments. These studies strongly suggest that orthopoxvirus infections create an immunosuppressive microenvironment that compromises the host pulmonary immune responses

Asthma-associated genetic variants induce IL33 differential expression through an enhancer-blocking regulatory region

Genome-wide association studies (GWAS) have implicated the IL33 locus in asthma, but the underlying mechanisms remain unclear. Here, we identify a 5 kb region within the GWAS-defined segment that acts as an enhancer-blocking element in vivo and in vitro. Chromatin conformation capture showed that this 5 kb region loops to the IL33 promoter, potentially regulating its expression. We show that the asthma-associated single nucleotide polymorphism (SNP) rs1888909, located within the 5 kb region, is associated with IL33 gene expression in human airway epithelial cells and IL-33 protein expression in human plasma, potentially through differential binding of OCT-1 (POU2F1) to the asthma-risk allele. Our data demonstrate that asthma-associated variants at the IL33 locus mediate allele-specific regulatory activity and IL33 expression, providing a mechanism through which a regulatory SNP contributes to genetic risk of asthma.This work was supported by NIH grants R01 HL118758, R01 HL128075, R01 HL119577, R01 HL085197, U19 AI095230, UG3 OD023282 and UM1 AI114271

Skewed Lung CCR4 to CCR6 CD4+ T Cell Ratio in Idiopathic Pulmonary Fibrosis is Associated with Pulmonary Function

Rationale: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease. While it has been suggested that T cells may contribute to IPF pathogenesis, these studies have focused primarily on T cells outside of the pulmonary interstitium. Thus, the role of T cells in the diseased lung tissue remains unclear. Objective: To identify whether specific CD4 T cell subsets are differentially represented in lung tissue from patients with IPF. Methods: CD4 T cells subsets were measured in lung tissue obtained from patients with IPF at the time of lung transplantation, and from age- and gender-matched organ donors with no known lung disease. Subsets were identified by their surface expression of CCR4, CCR6, and CXCR3 chemokine receptors. CD4 T cell subsets were correlated with measurements of lung function obtained prior to transplantation.Results: Compared to controls, IPF patients had a higher proportion of lung CD4 T cells, a higher proportion of CCR4 CD4 T cells, and a lower proportion of CCR6 CD4 T cells. The increase in CCR4 CD4 T cells in IPF lung tissue was not due to increased Tregs. Intriguingly, the increase in the ratio of CCR4 cells to CCR6 cells correlated significantly with better lung function. Conclusions: Our findings suggest a new paradigm that not all T cell infiltrates in IPF lungs are detrimental, but instead, specialized subsets may actually be protective. Thus, augmentation of the chemokines that recruit protective T cells, while blocking chemokines that recruit detrimental T cells, may constitute a novel approach to IPF therapy

Mapping Variation in Cellular and Transcriptional Response to 1,25-Dihydroxyvitamin D3 in Peripheral Blood Mononuclear Cells

The active hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25D) is an important modulator of the immune system, inhibiting cellular proliferation and regulating transcription of immune response genes. In order to characterize the genetic basis of variation in the immunomodulatory effects of 1,25D, we mapped quantitative traits of 1,25D response at both the cellular and the transcriptional level. We carried out a genome-wide association scan of percent inhibition of cell proliferation (Imax) induced by 1,25D treatment of peripheral blood mononuclear cells from 88 healthy African-American individuals. Two genome-wide significant variants were identified: rs1893662 in a gene desert on chromosome 18 (p = 2.32 x 10−8) and rs6451692 on chromosome 5 (p = 2.55 x 10−8), which may influence the anti-proliferative activity of 1,25D by regulating the expression of nearby genes such as the chemokine gene, CCL28, and the translation initiation gene, PAIP1. We also identified 8 expression quantitative trait loci at a FDRmax and the response eQTL mapping enabled identification of putative Imax-associated candidate genes such as PAIP1 and the transcriptional repressor gene ZNF649. Overall, the variants identified in this study are strong candidates for immune traits and diseases linked to vitamin D, such as multiple sclerosis

Additional file 1: of Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

Figure S1. Enrollment. Between July 1, 2013, and October 24, 2014, there were weeks when no patient was considered for enrollment, during which 33 patients had S. aureus bacteremia. (PPTX 3105 kb

Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

Abstract Background The dysregulated host immune response that defines sepsis varies as a function of both the immune status of the host and the distinct nature of the pathogen. The degree to which immunocompromising comorbidities or immunosuppressive medications affect the immune response to infection is poorly understood because these patients are often excluded from studies about septic immunity. The objectives of this study were to determine the immune response to a single pathogen (Staphylococcus aureus) among a diverse case mix of patients and to determine whether comorbidities affect immune and clinical outcomes. Methods Blood samples were drawn from 95 adult inpatients at multiple time points after the first positive S. aureus blood culture. Cox proportional hazards modeling was used to determine the associations between admission neutrophil counts, admission lymphocyte counts, cytokine levels, and 90-day mortality. A nested case-control flow cytometric analysis was conducted to determine T-helper type 1 (Th1), Th2, Th17, and regulatory T-cell (Treg) subsets among a subgroup of 28 patients. In a secondary analysis, we categorized patients as either having immunocompromising disorders (human immunodeficiency virus and hematologic malignancies), receiving immunosuppressive medications, or being not immunocompromised. Results Higher neutrophil-to-lymphocyte count ratios and higher Th17 cytokine responses relative to Th1 cytokine responses early after infection were independently associated with mortality and did not depend on the immune state of the patient (HR 1.93, 95% CI 1.17–3.17, p = 0.01; and HR 1.13, 95% CI 1.01–1.27, p = 0.03, respectively). On the basis of flow cytometric analysis of CD4 T-helper subsets, an increasing Th17/Treg response over the course of the infection was most strongly associated with increased mortality (HR 4.41, 95% CI 1.69–11.5, p < 0.01). This type of immune response was most common among patients who were not immunocompromised. In contrast, among immunocompromised patients who died, a decreasing Th1/Treg response was most common. Conclusions The association of both increased Th17 responses and increased neutrophil counts relative to lymphocyte counts with mortality suggests that an overwhelming inflammatory response is detrimental. However, the differential responses of patients according to immune state suggest that immune status is an important clinical indicator that should be accounted for in the management of septic patients, as well as in the development of novel immunomodulatory therapies

Additional file 4: of Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

Figure S3 Individual patient trajectories for T-cell subsets. T-cell subset percentages over time for each individual patient are shown, with survivors (at 90 days) indicated by a solid line and non-survivors indicated by a dashed line. (PPTX 670 kb

Additional file 5: of Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

Figure S4 Method for determining a patient’s T-cell subset levels. Linear regression was used to predict the change in each T-cell subset percentage per day for each patient. Each regression line was used to estimate a T-cell percentage at day 3 after infection. The day 3 value and change over time were used as predictor variables in Cox proportional hazards models. (PPTX 2104 kb

Additional file 2: of Distinct T-helper cell responses to Staphylococcus aureus bacteremia reflect immunologic comorbidities and correlate with mortality

Table S1. Associations between each cytokine level at time point 1 and death during the first 90 days after infection. Table S2. Associations between each cytokine level at time point 2 and death during the first 90 days after infection. Table S3. Method used to calculate Th17, Th1, and Th2 scores. Table S4. Associations between helper T cell scores at time point 2 and death during the first 90 days after S. aureus bacteremia. Table S5. Associations between the change in helper T cell scores per day and death during the first 90 days after S. aureus bacteremia. Table S6. Baseline characteristics of 95 patients with S. aureus bacteremia. Table S7. Comparison of clinical characteristics of 28 patients included (columns 1 and 2) and 67 patients not included (columns 3 and 4) in the flow cytometric analysis. Table S8. Cellular markers early after infection and over the course of the infection among 14 patients who died and 14 patients who survived. (DOCX 50 kb

Gut microbiota modulates bleomycin-induced acute lung injury response in mice

Background: Airway instillation of bleomycin (BLM) in mice is a widely used, yet challenging, model for acute lung injury (ALI) with high variability in treatment scheme and animal outcomes among investigators. Whether the gut microbiota plays any role in the outcome of BLM-induced lung injury is currently unknown. Methods: Intratracheal instillation of BLM into C57BL/6 mice was performed. Fecal microbiomes were analyzed by 16s rRNA amplicon and metagenomic sequencing. Germ-free mice conventionalization and fecal microbiota transfer between SPF mice were performed to determine dominant commensal species that are associated with more severe BLM response. Further, lungs and gut draining lymph nodes of the mice were analyzed by flow cytometry to define immunophenotypes associated with the BLM-sensitive microbiome. Results: Mice from two SPF barrier facilities at the University of Chicago exhibited significantly different mortality and weight loss during BLM-induced lung injury. Conventionalizing germ-free mice with SPF microbiota from two different housing facilities recapitulated the respective donors’ response to BLM. Fecal microbiota transfer from the facility where the mice had worse mortality into the mice in the facility with more survival rendered recipient mice more susceptible to BLM-induced weight loss in a dominant negative manner. BLM-sensitive phenotype was associated with the presence of Helicobacter and Desulfovibrio in the gut, decreased Th17-neutrophil axis during steady state, and augmented lung neutrophil accumulation during the acute phase of the injury response. Conclusion: The composition of gut microbiota has significant impact on BLM-induced wasting and death suggesting a role of the lung-gut axis in lung injury.</p