Cyclooxygenase-1 orchestrates germinal center formation and antibody class-switch via regulation of IL-17

Characteristics and impact of infiltration of B-cells from systemic sclerosis patients in a 3D healthy skin model

Introduction

In systemic sclerosis (SSc), B-cells are activated and present in the skin and lung of patients where they can interact with fibroblasts. The precise impact and mechanisms of the interaction of B-cells and fibroblasts at the tissular level are poorly studied.

Objective

We investigated the impact and mechanisms of B-cell/fibroblast interactions in cocultures between B-cells from patients with SSc and 3-dimensional reconstituted healthy skin model including fibroblasts, keratinocytes and extracellular matrix.

Methods

The quantification and description of the B-cell infiltration in 3D cocultures were performed using cells imagery strategy and cytometry. The effect of coculture on the transcriptome of B-cells and fibroblasts was studied with bulk and single-cell RNA sequencing approaches. The mechanisms of this interaction were studied by blocking key cytokines like IL-6 and TNF.

Results

We showed a significant infiltration of B-cells in the 3D healthy skin model. The amount but not the depth of infiltration was higher with B-cells from SSc patients and with activated B-cells. B-cell infiltrates were mainly composed of naïve and memory cells, whose frequencies differed depending on B-cells origin and activation state: infiltrated B-cells from patients with SSc showed an activated profile and an overexpression of immunoglobulin genes compared to circulating B-cells before infiltration. Our study has shown for the first time that activated B-cells modified the transcriptomic profile of both healthy and SSc fibroblasts, toward a pro-inflammatory (TNF and IL-17 signaling) and interferon profile, with a key role of the TNF pathway.

Conclusion

B-cells and 3D skin cocultures allowed the modelization of B-cells infiltration in tissues observed in SSc, uncovering an influence of the underlying disease and the activation state of B-cells. We showed a pro-inflammatory effect on skin fibroblasts and pro-activation effect on infiltrating B-cells during coculture. This reinforces the role of B-cells in SSc and provide potential targets for future therapeutic approach in this disease.

Redox Imbalance and Its Metabolic Consequences in Tick-Borne Diseases

One of the growing global health problems are vector-borne diseases, including tick-borne diseases. The most common tick-borne diseases include Lyme disease, tick-borne encephalitis, human granulocytic anaplasmosis, and babesiosis. Taking into account the metabolic effects in the patient's body, tick-borne diseases are a significant problem from an epidemiological and clinical point of view. Inflammation and oxidative stress are key elements in the pathogenesis of infectious diseases, including tick-borne diseases. In consequence, this leads to oxidative modifications of the structure and function of phospholipids and proteins and results in qualitative and quantitative changes at the level of lipid mediators arising in both reactive oxygen species (ROS) and ROS enzyme-dependent reactions. These types of metabolic modifications affect the functioning of the cells and the host organism. Therefore, links between the severity of the disease state and redox imbalance and the level of phospholipid metabolites are being searched, hoping to find unambiguous diagnostic biomarkers. Assessment of molecular effects of oxidative stress may also enable the monitoring of the disease process and treatment efficacy.

Targeting the Retinoid X Receptor Pathway Prevents and Ameliorates Murine Chronic Graft-Versus-Host Disease

Most allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients receive peripheral blood stem cell grafts resulting in a 30%-70% incidence of chronic graft-versus-host disease (cGVHD), a major cause of mortality and morbidity in long-term survivors. While systemic steroids remain the standard of care for first-line therapy, patients may require long-term administration, and those with steroid-resistant or refractory cGVHD have a worse prognosis. Although durable and deep responses with second-line therapies can be achieved in some patients, there remains an urgent need for new therapies. In this study, we evaluated the efficacy of IRX4204, a novel agonist that activates RXRs and is in clinical trials for cancer treatment to prevent and treat cGVHD in two complementary murine models. In a major histocompatibility complex mismatched, non-sclerodermatous multiorgan system model with bronchiolitis obliterans, IRX4204 prevented and reversed cGVHD including associated pulmonary dysfunction with restoration of germinal center T-follicular helper: T-follicular regulatory cell balance. In a minor histocompatibility antigen disparate sclerodermatous model, IRX4204 treatment significantly prevented and ameliorated skin cGVHD by reducing Th1 and Th17 differentiation due to anti-inflammatory properties. Together, these results indicate that IRX4204 is a promising therapeutic option to treat cGVHD with bronchiolitis obliterans or sclerodermatous manifestations.

Cyclooxygenase-1 Regulates the Development of Follicular Th Cells via Prostaglandin E2

Cyclooxygenase (COX)-1, one of the critical enzymes required for the conversion of arachidonic acid to PGs, has been demonstrated to play an important role not only in the cardiovascular system but also in the immune system. COX-1 has been found to regulate early B cell differentiation, germinal center formation, and Ab production of B cells. However, the underlying mechanisms of COX-1-mediated B cell activation remains not fully understood. In this study, we reported that COX-1 is a potential regulator for the development of follicular Th (T_FH) cells. COX-1-deficient (COX-1^-/- ) mice displayed a significant reduction of T_FH cells upon influenza infection or immunization with keyhole limpet hemocyanin, which led to a severe impairment of germinal center responses. We further demonstrated that COX-1-derived PGE_2, via binding with its receptors EP2/EP4, represents the underlying mechanism. The administration of EP2/EP4 agonists or PGE₂ almost completely rescued the defective T_FH cell generation in COX-1^-/- mice. Taken together, our observations indicate that COX-1 plays an important role in the development of T_FH cells.

A Novel Supplementation Approach to Enhance Host Response to Sublingual Vaccination

Sublingual immunization is emerging as an alternative to nasal immunization and induction of mucosal IgA responses. Using Bacillus anthracis edema toxin (EdTx) as an adjuvant, we previously showed that innate responses triggered after sublingual immunization could limit generation of IgA responses. We tested whether co-administration of a neutrophil elastase inhibitor (NEI) could rescue the ability of EdTx to induce broad antibody responses, including mucosal IgA. NEI supplementation of sublingual vaccines containing EdTx promoted antigen-specific serum IgA responses but also enhanced serum IgG1, and IgG2b responses. This enhancing effect of NEI did not extend to all antibody isotypes and IgG sublclasses, since NEI  reduced serum IgE responses and did not affect IgG2a/c and IgG3 responses. NEI supplementation also promoted anti-Bacillus anthracis protective antigen (PA) neutralizing antibodies and enhanced high affinity IgG1 and IgA antibodies. In addition to serum IgA, NEI supplementation stimulated antigen-specific mucosal IgA responses in the GI tract, and enhanced antigen-specific IgG responses in vaginal washes. Analysis of CD4⁺ T helper cell responses revealed that co-administration of NEI broadened the profile of cytokine responses, by stimulating Th1, Th2, Th17, and Tfh cytokines. We also noted that NEI had a higher stimulatory effect on IL-5, IL-10, IL-17 responses.

Eicosanoid Control Over Antigen Presenting Cells in Asthma

Asthma is a common lung disease affecting 300 million people worldwide. Allergic asthma is recognized as a prototypical Th2 disorder, orchestrated by an aberrant adaptive CD4+ T helper (Th2/Th17) cell immune response against airborne allergens, that leads to eosinophilic inflammation, reversible bronchoconstriction, and mucus overproduction. Other forms of asthma are controlled by an eosinophil-rich innate ILC2 response driven by epithelial damage, whereas in some patients with more neutrophilia, the disease is driven by Th17 cells. Dendritic cells (DCs) and macrophages are crucial regulators of type 2 immunity in asthma. Numerous lipid mediators including the eicosanoids prostaglandins and leukotrienes influence key functions of these cells, leading to either pro- or anti-inflammatory effects on disease outcome. In this review, we will discuss how eicosanoids affect the functions of DCs and macrophages in the asthmatic lung and how this leads to aberrant T cell differentiation that causes disease.

Metabolites of prostaglandin synthases as potential biomarkers of Lyme disease severity and symptom resolution

Background

Lyme disease or Lyme borreliosis (LB) is the commonest vector-borne disease in the North America. It is an inflammatory disease caused by the bacterium Borrelia burgdorferi. The role of the inflammatory processes mediated by prostaglandins (PGs), thromboxanes and leukotrienes (LTs) in LB severity and symptoms resolution is yet to be elucidated.

Objectives

We aim to systematically review and evaluate the role of PGs and related lipid mediators in the induction and resolution of inflammation in LB.

Methods

We conducted a comprehensive search in PubMed, Ovid MEDLINE(R), Embase and Embase Classic to identify cell-culture, animal and human studies reporting the changes in PGs and related lipid mediators of inflammation during the course of LB.

Results

We identified 18 studies to be included into this systematic review. The selected reports consisted of seven cell-culture studies, seven animal studies, and four human studies (from three patient populations). Results from cell-culture and animal studies suggest that PGs and other lipid mediators of inflammation are elevated in LB and may contribute to disease development. The limited number of human studies showed that subjects with Lyme meningitis, Lyme arthritis (LA) and antibiotic-refractory LA had increased levels of an array of PGs and lipid mediators (e.g., LTB_4, 8-isoPGF_2α, and phospholipases A₂ activity). Levels of these markers were significantly reduced following the treatment with antibiotics or non-steroidal anti-inflammatory drugs.

Conclusion

Dysregulation of prostaglandins and related lipid mediators may play a role in the etiology of LB and persistence of inflammation that may lead to long-term complications. Further investigation into the precise levels of a wide range of PGs and related factors is critical as it may propose novel markers that can be used for early diagnosis.

Electronic supplementary material

The online version of this article (10.1007/s00011-018-1180-5) contains supplementary material, which is available to authorized users.

Brucella Omp25 Upregulates miR-155, miR-21-5p, and miR-23b to Inhibit Interleukin-12 Production via Modulation of Programmed Death-1 Signaling in Human Monocyte/Macrophages

Brucella spp. infection results in compromised Type1 (Th1) cellular immune response. Several reports have described an immunomodulatory function for Brucella major outer membrane protein Omp25. However, the mechanism by which Omp25 modulates macrophage dysfunction has not been defined. Herein, we reported that Omp25-deficient mutant of Brucella suis exhibited an enhanced ability to induce interleukin (IL)-12 whereas ectopic expression of Omp25 protein inhibited TLR agonists-induced IL-12 p70 production through suppression of both IL-12 p40 and p35 subunit expression in THP-1 cells. In addition, Omp25 significantly upregulated miR-155, -23b and -21-5p, as well as the immunomodulator molecule programmed death-1 (PD-1) in monocyte/macrophages. The upregulation of miR-155 and -23b correlated temporally with decreased TAB2 levels, IκB phosphorylation and IL-12 p40 levels by targeting TAB2 and il12B 3' untranslated region (UTR), respectively, while miR-21-5p increase directly led to the reduction of lipopolysaccharide (LPS)/R848-induced IL-12 p35 protein by targeting il12A 3'UTR. Consistent with this finding, reduction of miR-155 and -23b attenuated the inhibitory effects of Omp25 on LPS/R848-induced IL-12 p40 expression at both transcriptional and posttranscriptional levels, while reduction of miR-21-5p attenuated the inhibitory effects of Omp25 on LPS/R848-induced IL-12 p35 expression at the posttranscriptional level, together significantly enhanced IL-12 p70 production upon LPS/R848 stimulation. We also found that blocking PD-1 signaling decreased the expression of miR-155, -23b and -21-5p induced by Omp25 and enhanced IL-12 production in monocyte/macrophages. Altogether, these data demonstrate that Brucella Omp25 induces miR-155, -23b and -21-5p to negatively regulate IL-12 production at both transcriptional and posttranscriptional levels via regulation of PD-1 signaling, which provides an entirely new mechanism underlying monocyte/macrophages dysfunction during Brucella spp. infection.

Ablation of IL-17 expression moderates experimental autoimmune myasthenia gravis disease severity

An array of cytokines influences the pathogenesis of early onset myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG). Patients with MG, in particular those with more severe weakness, have elevations of the pro-inflammatory cytokine IL-17 in the blood. We assessed the role of IL-17A in autoimmunity by inducing EAMG in mice with knockout of IL-17 and found a reduction of EAMG severity, but not a complete ablation of disease. The IL-17^ko mice had no evidence of weakness, low levels of acetylcholine receptor antibodies, and retention of acetylcholine receptor at the neuromuscular junction. Splenic germinal center size was reduced in EAMG IL-17^ko mice along with elevations of Foxp3 and BCL-6 gene expression, suggesting a shift away from pro-inflammatory signals. The results emphasize the importance of IL-17 in EAMG development and that IL-17 independent pathways drive the autoimmune reaction.

Directed transport of neutrophil-derived extracellular vesicles enables platelet-mediated innate immune response

The innate immune response to bacterial infections requires the interaction of neutrophils and platelets. Here, we show that a multistep reciprocal crosstalk exists between these two cell types, ultimately facilitating neutrophil influx into the lung to eliminate infections. Activated platelets adhere to intravascular neutrophils through P-selectin/P-selectin glycoprotein ligand-1 (PSGL-1)-mediated binding, a primary interaction that allows platelets glycoprotein Ibα (GPIbα)-induced generation of neutrophil-derived extracellular vesicles (EV). EV production is directed by exocytosis and allows shuttling of arachidonic acid into platelets. EVs are then specifically internalized into platelets in a Mac1-dependent fashion, and relocated into intracellular compartments enriched in cyclooxygenase1 (Cox1), an enzyme processing arachidonic acid to synthesize thromboxane A₂ (TxA₂). Finally, platelet-derived-TxA₂ elicits a full neutrophil response by inducing the endothelial expression of ICAM-1, intravascular crawling, and extravasation. We conclude that critical substrate–enzyme pairs are compartmentalized in neutrophils and platelets during steady state limiting non-specific inflammation, but bacterial infection triggers regulated EV shuttling resulting in robust inflammation and pathogen clearance.

Interaction between platelets and neutrophils promotes neutrophil activation. Here the authors show that neutrophils initiate the cross-talk with platelets by shuttling arachidonic acid via extracellular vesicles, which platelets convert to thromboxane A₂ that then elicits neutrophil activation.

Present and future of biologic drugs in primary Sjögren's syndrome

INTRODUCTION

Primary Sjögren's (pSS) syndrome is a chronic, autoimmune, and systemic disease characterized by xerostomia, xerophthalmia, muscle pain and fatigue. The disease may be complicated by a systemic involvement, such as a pulmonary fibrosis or the development of lymphoma which severely worsens the prognosis. Actually, there are no recommendations for the management of pSS. However, recent advances in the understanding of its pathogenesis have uncovered some pathways that have potential as therapeutic targets. Areas covered: In this review, the authors present the biologic drugs potentially valuable to the treatment of pSS in light of its physiopathology with a 'bird's eye' view of future prospects. The authors took into account relevant studies published from 2004 to 2016. Expert opinion: Biological treatment in pSS is a promising opportunity to potentially control disease activity and prevent its complication. Currently, inhibition of B-cell and IL-17 pathways seem to be the most promising avenues. New achievements in the knowledge of pSS pathophysiology are necessary in order to try to simultaneously predict the predominant pathogenic pathway, the kind of patients at major risk to develop a more severe disease, and the appropriate biological therapy to use.

Interleukin-17A promotes the growth of human germinal center derived non-Hodgkin B cell lymphoma

Interleukin (IL)-17A belongs to IL-17 superfamily and binds the heterodimeric IL-17 receptor (R)(IL-17RA/IL-17RC). IL-17A promotes germinal center (GC) formation in mouse models of autoimmune or infectious diseases, but the role of IL-17A/IL-17AR complex in human neoplastic GC is unknown. In this study, we investigated expression and function of IL-17A/IL-17AR in the microenvironments of 44 B cell non-Hodgkin lymphomas (B-NHL) of GC origin (15 follicular lymphomas, 17 diffuse large B cells lymphomas and 12 Burkitt lymphomas) and 12 human tonsil GC. Furthermore, we investigated the role of IL-17A in two in vivo models of GC B cell lymphoma, generated by s.c. injection of SU-DHL-4 and OCI-Ly8 cell lines in Severe combined immunodeficiency (SCID)/Non Obese Diabetic (NOD) mice. We found that: (i) B-NHL cell fractions and tonsil GC B cells expressed IL-17RA/IL-17RC, (ii) IL-17A signaled in both cell types through NF-kBp65, but not p38, ERK-1/2, Akt or NF-kBp50/105, phosphorylation, (iii) IL-17A was expressed in T cells and mast cells from neoplastic and normal GC microenvironments, (iv) IL-17A rendered tonsil GC B cells competent to migrate to CXCL12 and CXCL13 by downregulating RGS16 expression; (v) IL-17A stimulated in vitro proliferation of primary B-NHL cells; (vi) IL-17A (1 μg/mouse-per dose) stimulated B-NHL growth in two in vivo models by enhancing tumor cell proliferation and neo-angiogenesis. This latter effect depended on IL-17A-mediated induction of pro-angiogenic gene expression in tumor cells and direct stimulation of endothelial cells. These data define a previously unrecognized role of human IL-17A in promoting growth of GC-derived B-NHL and modulating normal GC B cell trafficking.

Proinflammatory cytokine responses correspond with subjective side effects after influenza virus vaccination

BACKGROUND

Though typically mild, side effects to the influenza virus vaccine are common and may contribute to negative perceptions including the belief that the vaccine can cause the flu. However, the extent to which subjective symptoms correspond with biological response indicators is poorly understood.

METHODS

This study examined associations among subjective side effects (soreness at the site of injection and illness-like symptoms), serum proinflammatory cytokines and body temperature a baseline, 1, 2, and 3 days following receipt of trivalent inactivated influenza vaccine (IIV3) in a sample of 56 women 18-40 years in age.

RESULTS

In relation to local reactions, women reporting being very sore at the injection site at 1 day post-vaccination exhibited greater increases in serum TNF-α and MIF in the days following vaccination compared to those with no or mild soreness. In addition, higher basal body temperature was observed in this group compared to other groups (98.7°F versus 98.0-98.1°). In relation to systemic reactions, women endorsing illness-like symptoms (headache, fatigue, nausea, sore throat, dizziness, achiness, or mild fever) exhibited marginally higher IL-6 at baseline (p=0.055) and greater increases in serum MIF at 2 days post-vaccination than those reporting no systemic symptoms. Associations of systemic symptoms with inflammatory responses were not accounted for by concomitant local reactions. As expected, antibody responses to the vaccine were highly similar in women regardless of local or systemic symptoms.

CONCLUSIONS

These results are consistent with the notion that subjective reports of local and systemic reactions following vaccination may be predicted by and correspond with biological indicators of inflammatory status, but are not meaningful predictors of antibody responses. To improve adherence to vaccine recommendations, clinicians should provide assurance that such symptoms may be related to normal mild inflammatory responses to the vaccine and do not reflect immunogenicity.

Infection of Interleukin 17 Receptor A-Deficient C3H Mice with Borrelia burgdorferi Does Not Affect Their Development of Lyme Arthritis and Carditis

Recently, a number of studies have reported the presence of interleukin 17 (IL-17) in patients with Lyme disease, and several murine studies have suggested a role for this cytokine in the development of Lyme arthritis. However, the role of IL-17 has not been studied using the experimental Lyme borreliosis model of infection of C3H mice with Borrelia burgdorferi. In the current study, we investigated the role of IL-17 in the development of experimental Lyme borreliosis by infecting C3H mice devoid of the common IL-17 receptor A subunit (IL-17RA) and thus deficient in most IL-17 signaling. Infection of both C3H and C3H IL-17RA(-/-) mice led to the production of high levels of IL-17 in the serum, low levels in the heart tissue, and no detectable IL-17 in the joint tissue. The development and severity of arthritis and carditis in the C3H IL-17RA(-/-) mice were similar to what was seen in wild-type C3H mice. In addition, development of antiborrelia antibodies and clearance of spirochetes from tissues were similar for the two mouse strains. These results demonstrate a limited role for IL-17 signaling through IL-17RA in the development of disease following infection of C3H mice with B. burgdorferi.

COX-1-derived thromboxane A2 plays an essential role in early B-cell development via regulation of JAK/STAT5 signaling in mouse

Cyclooxygenases (COXs) and their prostanoid products play important roles in a diverse range of physiological processes, including in the immune system. Here, we provide evidence that COX-1 is an essential regulator in early stages of B-cell development. COX-1-deficient mice displayed systematic reduction in total B cells, which was attributed to the arrest of early B-cell development from pro-B to pre-B stage. We further demonstrated that this defect was mediated through downregulation of the Janus kinase/signal transducer and activator of transcription 5 (JAK/STAT5) signaling and its target genes, including Pax5, in COX-1(-/-) mice. Mechanistic studies revealed that COX-1-derived thromboxane A2 (TxA2) could regulate JAK3/STAT5 signaling through the cyclic adenosine monophosphate-protein kinase A pathway, via binding with its receptor thromboxane A2 receptor (TP). Administration of the TP agonist could rescue the defective B-cell development and JAK/STAT5 signaling activity in COX-1-deficient mice. Moreover, administration of low-dose aspirin caused a significant reduction in total B cells in peripheral blood of healthy human volunteers, coincidentally with reduced TxA2 production and downregulation of JAK/STAT5 signaling. Taken together, our results demonstrate that COX-1-derived TxA2 plays a critical role in the stage transition of early B-cell development through regulation of JAK/STAT5 signaling and indicate a potential immune-suppressive effect of low-dose aspirin in humans.

The role of eicosanoids in experimental Lyme arthritis

Experimental Lyme arthritis is an inflammatory arthritis caused by infection of mice with the spirochete, Borrelia burgdorferi. It recapitulates many of the disease parameters seen in human patients with Lyme arthritis, and thus serves as a model system for the investigation of disease pathogenesis. While much progress has been made in defining components of the immune response to Borrelia infection, an overall understanding of the host response leading to arthritis resistance or susceptibility remains elusive. In this review, we will focus on recent advancements of our understanding of the roles of eicosanoids as inflammatory mediators in the regulation of experimental Lyme arthritis. Eicosanoids, such as PGE₂ and LTB₄, are powerful regulators of inflammatory responses and thus may be important mediators of Lyme arthritis.

Reduced B lymphoid kinase (Blk) expression enhances proinflammatory cytokine production and induces nephrosis in C57BL/6-lpr/lpr mice

BLK, which encodes B lymphoid kinase, was recently identified in genome wide association studies as a susceptibility gene for systemic lupus erythematosus (SLE), and risk alleles mapping to the BLK locus result in reduced gene expression. To determine whether BLK is indeed a bona fide susceptibility gene, we developed an experimental mouse model, namely the Blk^+/−.lpr/lpr (Blk^+/−.lpr) mouse, in which Blk expression levels are reduced to levels comparable to those in individuals carrying a risk allele. Here, we report that Blk is expressed not only in B cells, but also in IL-17-producing γδ and DN αβ T cells and in plasmacytoid dendritic cells (pDCs). Moreover, we found that solely reducing Blk expression in C57BL/6-lpr/lpr mice enhanced proinflammatory cytokine production and accelerated the onset of lymphoproliferation, proteinuria, and kidney disease. Together, these findings suggest that BLK risk alleles confer susceptibility to SLE through the dysregulation of a proinflammatory cytokine network.

The immunobiology of the mammalian epididymis: the black box is now open!

Spermatozoa represent an immunologic challenge for the mammalian males. They are produced long after the establishment of the immune library of the individual and harbor specific spermatic antigens that are found nowhere else in other organs, tissues and cells. Consequently, spermatozoa are somehow “foreign” to the male adaptive immune system. In order not to elicit autoimmune responses that would be detrimental for male fertility, spermatozoa should be either physically separated from the adaptive immune response and/or, the immune system challenged by spermatic antigens must be efficiently silenced. Within the mammalian male genital tract it becomes more and more obvious that a range of strategies are at stake to ensure that the immune-stranger spermatozoa do not constitute an immunological issue. In this review the focus will be on the immune status of the epididymis tubule, in which spermatozoa that have left the testes will mature for approximately 2 weeks and may be stored for prolonged period of time. How the epididymal immune environment compares to that of the testis and what are the immune regulatory processes at work in the epididymal compartment will only be briefly described. Instead, this review will focus on recent data that highlight epididymal immune regulatory actors that partly explain/illustrate the rather complicated, fragile but nevertheless robust immune environment of the epididymis.

Indoleamine 2,3-dioxygenase 1 (ido1) is involved in the control of mouse caput epididymis immune environment

The epididymis maintains a state of immune tolerance towards spermatozoa while also protecting them and itself against infection and acute inflammation. The immunosuppressive enzyme indoleamine 2,3-dioxygenase 1 (Ido1) participates in this delicate local equilibrium. Using the mouse Ido1(-/-) model, we show here that the absence of IDO1 expression leads in the epididymis but not in serum to (1) an increase in the inflammatory state as evidenced by changes in the content of cytokines and chemokines, (2) the engagement of a Th1-driven inflammatory response as evidenced by changes in the Th17/Treg as well as Th1/Th2 equilibria, as well as (3) differences in the content of lipid intermediates classically involved in inflammation. Despite this more pronounced inflammatory state, Ido1(-/-) animals succeed in preserving the local epididymal immune situation due to the activation of compensatory mechanisms that are discussed.

IL-17A produced by αβ T cells drives airway hyper-responsiveness in mice and enhances mouse and human airway smooth muscle contraction

Emerging evidence suggests that the T_H17 subset of αβ T cells contributes to the development of allergic asthma. In this study we found that mice lacking αvβ8 on dendritic cells failed to generate T_H17 cells in the lung and were protected from AHR in response to house dust mite and ovalbumin sensitization and challenge. Because loss of T_H17 cells inhibited airway narrowing without obvious effects on airway inflammation or epithelial morphology, we examined the direct effects of T_H17 cytokines on mouse and human airway smooth muscle function. IL-17A enhanced contractile force generation through a NF-κB/RhoA/ROCK2 signaling cascade. Mice lacking integrin αvβ8 on dendritic cells showed impaired activation of this pathway after OVA sensitization and challenge, and the diminished contraction of tracheal rings from these mice was reversed by IL-17A. These data indicate that IL-17A produced by T_H17 cells contributes to allergen-induced AHR through direct effects on airway smooth muscle.

Interleukin-10 alters effector functions of multiple genes induced by Borrelia burgdorferi in macrophages to regulate Lyme disease inflammation

Interleukin-10 (IL-10) modulates inflammatory responses elicited in vitro and in vivo by Borrelia burgdorferi, the Lyme disease spirochete. How IL-10 modulates these inflammatory responses still remains elusive. We hypothesize that IL-10 inhibits effector functions of multiple genes induced by B. burgdorferi in macrophages to control concomitantly elicited inflammation. Because macrophages are essential in the initiation of inflammation, we used mouse J774 macrophages and live B. burgdorferi spirochetes as the model target cell and stimulant, respectively. First, we employed transcriptome profiling to identify genes that were induced by stimulation of cells with live spirochetes and that were perturbed by addition of IL-10 to spirochete cultures. Spirochetes significantly induced upregulation of 347 genes at both the 4-h and 24-h time points. IL-10 inhibited the expression levels, respectively, of 53 and 65 of the 4-h and 24-h genes, and potentiated, respectively, at 4 h and 24 h, 65 and 50 genes. Prominent among the novel identified IL-10-inhibited genes also validated by quantitative real-time PCR (qRT-PCR) were Toll-like receptor 1 (TLR1), TLR2, IRAK3, TRAF1, IRG1, PTGS2, MMP9, IFI44, IFIT1, and CD40. Proteome analysis using a multiplex enzyme-linked immunosorbent assay (ELISA) revealed the IL-10 modulation/and or potentiation of RANTES/CCL5, macrophage inflammatory protein 2 (MIP-2)/CXCL2, IP-10/CXCL10, MIP-1α/CCL3, granulocyte colony-stimulating factor (G-CSF)/CSF3, CXCL1, CXCL5, CCL2, CCL4, IL-6, tumor necrosis factor alpha (TNF-α), IL-1α, IL-1β, gamma interferon (IFN-γ), and IL-9. Similar results were obtained using sonicated spirochetes or lipoprotein as stimulants. Our data show that IL-10 alters effectors induced by B. burgdorferi in macrophages to control concomitantly elicited inflammatory responses. Moreover, for the first time, this study provides global insight into potential mechanisms used by IL-10 to control Lyme disease inflammation.

Helicobacter felis--associated gastric disease in microbiota-restricted mice

Human Helicobacter pylori infection leads to multiple pathological consequences, including gastritis and adenocarcinoma. Although this association has led to the classification of H. pylori as a type 1 carcinogen, it is not clear if additional nonhelicobacter gastric microbiota play a role in these diseases. In this study, we utilized either specific pathogen-free C57BL/6 mice (B6.SPF) or mice colonized with altered Schaedler flora (B6.ASF) to evaluate the role of nonhelicobacter gastric microbiota in disease development after Helicobacter felis infection. Despite similar histological changes, H. felis persisted in B6.ASF stomachs, while H. felis could no longer be detected in the majority of B6.SPF mice. The B6.SPF mice also acquired multiple Lactobacillus spp. in their stomachs after H. felis infection. Our data indicate that potential mechanisms responsible for the ineffective H. felis clearance in the B6.ASF model include the absence of new gastric microbiota to compete for the gastric niche, the lack of expression of new gastric mucins, and a reduced ratio of H. felis-specific IgG2c:IgG1 serum antibodies. These data suggest that although H. felis is sufficient to initiate gastric inflammation and atrophy, bacterial eradication and the systemic immune response to infection are significantly influenced by pre-existing and acquired gastric microbiota.

Effect of gestational hypercholesterolemia and maternal immunization on offspring plasma eicosanoids

OBJECTIVE

Maternal immunization with oxidized low-density lipoprotein prior to pregnancy prevents pathogenic in utero programming by gestational hypercholesterolemia, but it is unknown whether gestational hypercholesterolemia and maternal immunization affect similar pathways.

STUDY DESIGN

A lipidomic approach was used for unbiased plasma eicosanoid profiling in adult offspring of immunized and nonimmunized normocholesterolemic or hypercholesterolemic rabbit mothers.

RESULTS

Gestational hypercholesterolemia was associated with increased levels of some eicosanoids formed by the cyclooxygenase and 12-lipoxygenase pathways only (including thromboxane B2, prostaglandin [PG] F2α, PGE2, and PGD2). Immunization of hypercholesterolemic or normocholesterolemic mothers reduced 9 of 14 eicosanoids of the cyclooxygenase pathway, 21 of 23 eicosanoids of the 5- and 12-lipoxygenase pathways (eg, 5-hydroxyeicosatetraenoic acid, hepoxilin B3, 12-hydroxyeicosatetraenoic acid), 8 of 19 eicosanoids of the cytochrome P-450 pathway, and all metabolites of the nonenzymatic pathway.

CONCLUSION

Maternal immunization not only counteracts in utero programming by gestational hypercholesterolemia but reduces a broad range of eicosanoid modulators of immunity and inflammation in offspring.

Activation and effector functions of human RORC+ innate lymphoid cells

Innate lymphoid cells expressing the nuclear hormone receptor RORC have emerged as important players in human mucosal immunity. These cells combine innate modes of activation such as Toll-like receptor signaling with secretion of adaptive effector molecules including IL-2, BAFF and the Th17 cytokines IL-17 and IL-22. This endows these cells with the ability to rapidly respond to changes in cytokine milieu as well as changes in microbial composition and to affect both intestinal homeostasis and activation of adaptive immune cells.

Dendritic cells, antibodies reactive with oxLDL, and inflammation

Periodontitis appears to promote chronic inflammatory diseases, including atherosclerosis, but relevant mechanisms need clarification. Oral bacteria induce antibodies that bind not only bacteria, but also oxLDL. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans induce remarkable IgG responses that are dominated by IgG2, and IgG2 is IFN-γ-dependent and is promoted by dendritic cells (DCs). LDL-reactive antibodies induced by P. gingivalis and A. actinomycetemcomitans include anti-phosphorylcholine (α-PC) and β2-glycoprotein-1-dependent anticardiolipin (α-CL), and these antibodies may link chronic inflammatory diseases at a mechanistic level. Antibody-mediated uptake of oxLDL or bacteria dramatically enhances DC-IL-12, and DC-IL-12 induces NK-cell-IFN-γ responses that promote Th-1 responses and sustained inflammation. DCs may be derived from monocytes, and this is striking in cultures of aggressive periodontitis (AgP) monocytes, where DC numbers are about double control levels. Moreover, serum α-CL levels in individuals with AgP are frequently elevated, and these antibodies promote atherosclerosis in persons with antiphospholipid syndrome. Elevated serum levels of soluble-intercellular adhesion molecule, soluble-vascular cell adhesion molecule, and soluble-E-selectin are atherosclerosis-associated indicators of vascular inflammation, and these markers are elevated in the subset of AgP patients with high α-CL. We reason that periodontitis patients with elevated antibodies reactive with oxLDL could be a subgroup at high risk for cardiovascular sequelae.

5-Lipoxygenase-deficient mice infected with Borrelia burgdorferi develop persistent arthritis

The enzyme 5-lipoxygenase (5-LO) catalyzes the conversion of arachidonic acid into the leukotrienes, which are critical regulators of inflammation and inflammatory diseases, such as asthma and arthritis. Although leukotrienes are present in the synovial fluid of Lyme disease patients, their role in the development of Lyme arthritis has not been determined. In the current study, we used a murine model of Lyme arthritis to investigate the role 5-LO products might have in the development of this inflammatory disease. After infection of Lyme arthritis-susceptible C3H/HeJ mice with Borrelia burgdorferi, mRNA expression of 5-LO and 5-LO-activating protein was induced in the joints, and the 5-LO product leukotriene B(4) was produced. Using C3H 5-LO-deficient mice, we demonstrated that 5-LO activity was not necessary for the induction of Lyme arthritis, but that its deficiency resulted in earlier joint swelling and an inability to resolve arthritis as demonstrated by sustained arthritis pathology through day 60 postinfection. Although production of anti-Borrelia IgG was decreased in 5-LO-deficient mice, bacterial clearance from the joints was unaffected. Phagocytosis of B. burgdorferi and efferocytosis of apoptotic neutrophils was defective in macrophages from 5-LO-deficient mice, and uptake of opsonized spirochetes by neutrophils was reduced. These results demonstrate that products of the 5-LO metabolic pathway are not required for the development of disease in all models of arthritis and that caution should be used when targeting 5-LO as therapy for inflammatory diseases.

The expanding family of innate lymphoid cells: regulators and effectors of immunity and tissue remodeling

Research has identified what can be considered a family of innate lymphoid cells (ILCs) that includes not only natural killer (NK) cells and lymphoid tissue-inducer (LTi) cells but also cells that produce interleukin 5 (IL-5), IL-13, IL-17 and/or IL-22. These ILC subsets are developmentally related, requiring expression of the transcriptional repressor Id2 and cytokine signals through the common γ-chain of the IL-2 receptor. The functional differentiation of ILC subsets is orchestrated by distinct transcription factors. Analogous to helper T cell subsets, these evolutionarily conserved yet distinct ILCs seem to have important roles in protective immunity, and their dysregulation can promote immune pathology.