Interleukin 16 contributes to gammaherpesvirus pathogenesis by inhibiting viral reactivation.

Gammaherpesviruses have evolved various strategies to take advantage of host cellular factors or signaling pathways to establish a lifelong latent infection. Like the human gammaherpesvirus Epstein-Barr virus, murine gammaherpesvirus 68 (MHV68) establishes and maintains latency in the memory B cells during infection of laboratory mice. We have previously shown that MHV68 can immortalize fetal liver-derived B cells that induce lymphomas when injected into immunodeficient mice. Here we identify interleukin 16 (IL16) as a most abundantly expressed cytokine in MHV68-immortalized B cells and show that MHV68 infection elevates IL16 expression. IL16 is not important for MHV68 lytic infection but plays a critical role in MHV68 reactivation from latency. IL16 deficiency increases MHV68 lytic gene expression in MHV68-immortalized B cells and enhances reactivation from splenic latency. Correlatively, IL16 deficiency increases the frequency of MHV68-infected plasma cells that can be attributed to enhanced MHV68 reactivation. Furthermore, similar to TPA-mediated lytic replication of Kaposi's sarcoma-associated herpesvirus, IL16 deficiency markedly induces Tyr705 STAT3 de-phosphorylation and elevates p21 expression, which can be counteracted by the tyrosine phosphatase inhibitor orthovanadate. Importantly, orthovanadate strongly blocks MHV68 lytic gene expression mediated by IL16 deficiency. These data demonstrate that virus-induced IL16 does not directly participate in MHV68 lytic replication, but rather inhibits virus reactivation to facilitate latent infection, in part through the STAT3-p21 axis.

Preliminary indications that recombinant human IL-16 attracts and stimulates lymphocytes of the amphibian, Xenopus laevis implying an ancestral role for CD4 as a cytokine receptor.

The D1 domain of the CD4 co-receptor interacts with MHC class II during Helper CD4+ Th-cell activation and effector function in all gnathostomes but the sequence and structure of this region are not well conserved through phylogeny. Conversely, the proximal D4 domain of CD4 is the binding site of the cytokine IL-16 and is highly conserved, allowing for promiscuous binding of IL-16 to CD4 between disparate gnathostomes. We report here that recombinant human IL-16 (rhIL-16) bound to Xenopus lymphocytes to allow separation on a magnetic column. Incubation with rhIL-16 resulted in an increased expression of MHC class II mRNA by Xenopus CD8- cells more than by CD8+ cells. An in vivo assay demonstrated that rhIL-16 can recruit lymphocytes of Xenopus frogs. Our data suggest that a subset of Xenopus laevis lymphocytes express a CD4 homolog on their surface that is capable of binding IL-16. These results imply that CD4 most likely arose from a primordial cytokine receptor.

IL-38 inhibits microglial inflammatory mediators and is decreased in amygdala of children with autism spectrum disorder.

Autism spectrum disorder (ASD) is characterized by impaired social interactions and communication. The pathogenesis of ASD is not known, but it involves activation of microglia. We had shown that the peptide neurotensin (NT) is increased in the serum of children with ASD and stimulates cultured adult human microglia to secrete the proinflammatory molecules IL-1ß and CXCL8. This process is inhibited by the cytokine IL-37. Another cytokine, IL-38, has been reported to have antiinflammatory actions. In this report, we show that pretreatment of cultured adult human microglia with recombinant IL-38 (aa3-152, 1-100 ng/mL) inhibits (P < 0.0001) NT-stimulated (10 nM) secretion of IL-1ß (at 1 ng/mL) and CXCL8 (at 100 ng/mL). In fact, IL-38 (aa3-152, 1 ng/mL) is more potent than IL-37 (100 ng/mL). Here, we report that pretreatment with IL-38 (100 ng/mL) of embryonic microglia (HMC3), in which secretion of IL-1ß was undetectable, inhibits secretion of CXCL8 (P = 0.004). Gene expression of IL-38 and its receptor IL-36R are decreased (P = 0.001 and P = 0.04, respectively) in amygdala from patients with ASD (n = 8) compared to non-ASD controls (n = 8), obtained from the University of Maryland NeuroBioBank. IL-38 is increased (P = 0.03) in the serum of children with ASD. These findings indicate an important role for IL-38 in the inhibition of activation of human microglia, thus supporting its development as a treatment approach for ASD.

Cytokine Diversity in Human Peripheral Blood Eosinophils: Profound Variability of IL-16.

Eosinophilic leukocytes develop in the bone marrow and migrate from peripheral blood to tissues, where they maintain homeostasis and promote dysfunction via release of preformed immunomodulatory mediators. In this study, we explore human eosinophil heterogeneity with a specific focus on naturally occurring variations in cytokine content. We found that human eosinophil-associated cytokines varied on a continuum from minimally (coefficient of variation [CV] ≤ 50%) to moderately variable (50% < CV ≤ 90%). Within the moderately variable group, we detected immunoreactive IL-27 (953 ± 504 pg/mg lysate), a mediator not previously associated with human eosinophils. However, our major finding was the distinct and profound variability of eosinophil-associated IL-16 (CV = 103%). Interestingly, eosinophil IL-16 content correlated directly with body mass index (R 2 = 0.60, ***p < 0.0001) in one donor subset. We found no direct correlation between eosinophil IL-16 content and donor age, sex, total leukocytes, lymphocytes, or eosinophils (cells per microliter), nor was there any relationship between IL-16 content and the characterized -295T/C IL-16 promoter polymorphism. Likewise, although eosinophil IL-1ß, IL-1α, and IL-6 levels correlated with one another, there was no direct association between any of these cytokines and eosinophil IL-16 content. Finally, a moderate increase in total dietary fat resulted in a 2.7-fold reduction in eosinophil IL-16 content among C57BL/6-IL5tg mice. Overall, these results suggest that relationships between energy metabolism, eosinophils, and IL-16 content are not direct or straightforward. Nonetheless, given our current understanding of the connections between asthma and obesity, these findings suggest important eosinophil-focused directions for further exploration.

Changes in the Structure of Mouse Kidney in the Acute Period after Infection with Influenza Viruses A/H5N1 and A/H1N1.

Changes in the kidney structure in outbred and inbred male BALB/c mice were analyzed in the acute period after infection with influenza viruses A/H5N1 (10 MLD50; 10 days) and A/H1N1 (1 MLD50; 30 days). Antibodies to influenza viruses of both strains were most often expressed by endothelial cells of the glomeruli and arterioles and were rarely expressed by mesangiocytes and tubule epithelial cells. In the kidney, destructive processes induced by viruses and by ischemia due to massive blood vessel thrombosis. Mesangiocytes expressed factors, indicating that they could be qualified as M1 and M2 macrophages. Kidney destruction was more significant after infection of mice with the A/H5N1 virus, but in both experiments cell infiltrates were actually absent, probably due to blood vessel thrombosis and limited possibility of migration of mononuclear phagocytes and lymphocytes to the kidney.

IL-16 regulates macrophage polarization as a target gene of mir-145-3p.

BACKGROUND: Interleukin 16 is an immunomodulatory chemokine that signals through CD4 + T cells, monocytes, macrophages and dendritic cells. Its expression in immune-related cells enhances the antimicrobial effect and inhibits HIV replication in macrophages. However, the role of IL-16 in macrophage polarization is uncertain. Mir-145 was reported to regulate IL-10 expression by targeting histone deacetylase 11 and promotes alternatively activated macrophage (M2) polarization. Mir-145 was also predicted to target IL-16 mRNA. We aimed to explore the roles of IL-16 and mir-145 in macrophage polarization and antimicrobial functions. METHODS: THP1 monocytes were employed in this study, and their cell activity when incubated with different concentrations of IL-16 was evaluated using the CCK-8 cell counting kit. To obtain polarized macrophages, THP-1 cells were induced by IL-4 and IL-13 following PMA incubation (M2 polarized macrophages) or induced by IFN-gamma and LPS (M1 classical macrophage activation). The influence of IL-16 on macrophage phagocytosis was quantified by the amount of chicken red blood cell phagocytized. IL-16, IL-10 and miR-145 expression in THP1 monocytes and induced macrophages was quantified by quantitative PCR. The miR-145 and IL-16 targeting relationship was verified by the dual luciferase reporter assay. The influence of IL-16 and mir-145 on macrophage polarization was evaluated by M1 and M2 macrophage characterized marker gene expression. RESULTS: The M0 macrophage subtype was induced by PMA. The M1 and M2 subtypes of macrophage were successfully induced by M1- and M2-specific induction. M1 macrophages express higher levels of IL-16 than M2 macrophages but express lower levels of IL-10 and mir-145 than M2 cells. IL-16 with a concentration up to 150 ng/mL has no influence on THP-1 cell proliferation but improves macrophage phagocytosis ability with the down-expression of IL-10 and up-expression of pro-inflammatory cytokines such as IL-1a and IL-6. Knockdown with its target siRNA is beneficial for macrophage maintenance but reduces phagocytosis ability. Mir-145 specifically targets the IL-16 3'UTR verified by the dual luciferase reporter assay. Mir-145 downregulates IL-16 expression and upregulates IL-10 expression, thereby promoting M2 macrophage polarization. CONCLUSION: IL-16 modulates macrophage polarization through regulating IL-10, IL-1a and IL-6 expression. Mir-145 is involved in M2 macrophage polarization by targeting IL-16 and enhancing IL-10 expression.

Repetitive Exposure of IL-17 Into the Murine Air Pouch Favors the Recruitment of Inflammatory Monocytes and the Release of IL-16 and TREM-1 in the Inflammatory Fluids.

The infiltration of Th17 cells in tissues and organs during the development of many autoimmune diseases is considered a key step toward the establishment of chronic inflammation. Indeed, the localized and prolonged release of IL-17 in specific tissues has been associated with an increased severity of the inflammatory response that remains sustained over time. The cellular and molecular mechanisms behind these effects are far from being clear. In this study we investigated the effects of two repetitive administration of recombinant IL-17 into the murine air pouch to simulate a scenario where IL-17 is released over time in a pre-inflamed tissue. Consistent with our previous observations, mice receiving a single dose of IL-17 showed a transitory influx of neutrophils into the air pouch that peaked at 24 h and declined at 48 h. Conversely, mice receiving a double dose of the cytokine-one at time 0 and the second after 24 h-showed a more dramatic inflammatory response with almost 2-fold increase in the number of infiltrated leukocytes and significant higher levels of TNF-α and IL-6 in the inflammatory fluids. Further analysis of the exacerbated inflammatory response of double-injected IL-17 mice showed a unique cellular and biochemical profile with inflammatory monocytes as the second main population emigrating to the pouch and IL-16 and TREM-1 as the most upregulated cytokines found in the inflammatory fluids. Most interestingly, mice receiving a double injection of IL-1ß did not show any change in the cellular or biochemical inflammatory response compared to those receiving a single injection or just vehicle. Collectively these results shed some light on the function of IL-17 as pro-inflammatory cytokine and provide possible novel ways to target therapeutically the pathogenic effects of IL-17 in autoimmune conditions.

IL-16/miR-125a axis controls neutrophil recruitment in pristane-induced lung inflammation.

Severe lung inflammation and alveolar hemorrhage can be life-threatening in systemic lupus erythematosus (SLE) patients if not treated early and aggressively. Neutrophil influx is the driver key of this pathology, but little is known regarding the molecular events regulating this recruitment. Here, we uncover a role for IL-16/mir-125a in this pathology and show not only that IL-16 is a target for miR-125a but that reduced miR-125a expression in SLE patients associates with lung involvement. Furthermore, in the pristane model of acute "SLE-like" lung inflammation and alveolar hemorrhage, we observed reduced pulmonary miR-125a and enhanced IL-16 expression. Neutrophil infiltration was markedly reduced in the peritoneal lavage of pristane-treated IL-16-deficient mice and elevated following i.n. delivery of IL-16. Moreover, a miR-125a mimic reduced pristane-induced IL-16 expression and neutrophil recruitment and rescued lung pathology. Mechanistically, IL-16 acts directly on the pulmonary epithelium and markedly enhances neutrophil chemoattractant expression both in vitro and in vivo, while the miR-125a mimic can prevent this. Our results reveal a role for miR-125a/IL-16 in regulating lung inflammation and suggest this axis may be a therapeutic target for management of acute lung injury in SLE.

Molecular characterization and expression analysis of large yellow croaker (Larimichthys crocea) interleukin-12A, 16 and 34 after poly I:C and Vibrio anguillarum challenge.

Interleukin-12, 16 and 34 are important pro-inflammatory cytokines, some of the most important components of the innate immunity system. Herein, we identified interleukin-12A (lcIL12A), 16 (lcIL16) and 34 (lcIL34) in large yellow croaker (Larimichthys crocea), and determined their expression profile in unchallenged and challenged tissues. The coding sequence (CDS) of lcIL12A comprised 600 bp long encoding a protein of 199 amino acids (aa), the CDS of lcIL16 was 2454 bp encoding a protein of 817 aa, and the CDS of lcIL34 was 657 bp encoding a protein of 267 aa. Phylogenetic analysis revealed similar results to homology comparison that lcIL12A was closest to IL12A of Dicentrarchus labrax (73%) and Serola dumerili (73%), while lcIL16 had the closest relation to Lates calcarofer (72.6%), and lcIL34 to Sparus aurata (88.9%). Multiple sequence alignment showed these interleukins were highly conserved with other vertebrate interleukins in their functional domains. Further, quantitative real time PCR (qPCR) analysis revealed that lcIL12A, lcIL16 and lcIL34 were constitutively expressed in all examined tissues, with significantly higher expression in spleen, liver and kidney. This was especially true for lcIL34 gene. Importantly, when challenged with polyinosinic:polycytidylic acid (poly I:C) and Vibrio anguillarum (V. anguillarum), the mRNA expressions of these interleukins were up-regulated in liver, spleen and kidney. Their top values got over 4 folds at least relative to their expression at time 0, and even lcIL12 reached 13.37 fold at 12-h point in spleen. These suggested their anti-viral and anti-bacterial roles and their involvement in the innate immune response of Larimichthys crocea. These results would have major implications in improving our understanding of the functions of interleukins to defend against pathogen infections in teleost species.

Identification and characterization of pro-interleukin-16 from mud crab Scylla paramamosain: The first evidence of proinflammatory cytokine in crab species.

IL-16 is a pro-inflammatory cytokine originally designated as a lymphocyte chemoattractant factor. In mammal and avian, it has been characterized as an essential regulator of various cellular processes including cell recruitment and activation against pathogen invasion. So far, neither of the full-length of IL-16 homologue nor the response mechanism against pathogen was reported in crab species. In the present study, the pro-IL-16 homologue was firstly cloned and characterized from mud crab Scylla paramamosain. The full-length Sp-pro-IL-16 consisted of 4107 bp with an opening reading frame encoding 1369 amino acids. Multiple alignment analysis showed the putative amino acid sequence of Sp-pro-IL-16 had about 73.86% identity with Litopenaeus vannamei pro-IL-16. Additionally, two conserved PDZ domains and protein binding sites were found in Sp-pro-IL-16 and showed high similarities about 94.19% and 51.14% with their Litopenaeus vannamei and Mus musculus counterparts. RT-PCR analysis indicated that Sp-pro-IL-16 transcripts were constitutively expressed in all tissues examined with an extreme high level in hepatopancreas. Moreover, Sp-pro-IL-16 transcripts in hepatopancreas were significantly up-regulated 15-fold at 72 h after Vibrio alginolyticus challenge and 3.5-fold at 12 h after virus-analog Poly (I:C) challenge. The Western blot analysis revealed that Sp-pro-IL-16 can be cleaved to its bioactive form, an approximately 35 kDa mature IL-16, and the protein levels of both pro-IL-16 and mature IL-16 increased after Vibrio alginolyticus challenge. It is the first experimental identification of pro-inflammatory cytokine IL-16 in arthropods. This study could shed new light on further understanding of the response mechanism of pro-inflammatory cytokine IL-16 in Scylla paramamosain against pathogens. Meanwhile, it brought new insight into the origin and evolution of IL-16 in crab species.

Th-17 regulatory cytokines IL-21, IL-23, and IL-6 enhance neutrophil production of IL-17 cytokines during asthma.

BACKGROUND: In a subset of severe asthma patients, chronic airway inflammation is associated with infiltration of neutrophils, Th-17 cells and elevated expression of Th-17-derived cytokines (e.g., interleukin [IL]-17, IL-21, IL-22). Peripheral neutrophils from allergic asthmatics are known to express higher IL-17 cytokine levels than those from healthy subjects, but the regulatory mechanisms involved are not well understood. We hypothesize that Th-17 regulatory cytokines could modulate IL-17 expression in neutrophils. METHODS: Peripheral blood neutrophils isolated from asthmatics were stimulated with IL-21, IL-23, and IL-6 cytokines and their ability to produce IL-17A and IL-17F was determined relative to healthy controls. Signal transducer and activator of transcription 3 (STAT3) phosphorylation levels were measured in stimulated neutrophil using flow cytometry. The requirement for STAT3 phosphorylation was determined by blocking its activation using a specific chemical inhibitor. RESULTS: Stimulating asthmatic neutrophils with IL-21, 23, and 6 enhanced the production of IL-17A and IL-17F at significantly higher levels comparatively to healthy controls. Stimulating neutrophils with IL-21, IL-23, and IL-6 cytokines enhanced STAT3 phosphorylation, in all cases. Interestingly, inhibiting STAT3 phosphorylation using a specific chemical inhibitor dramatically blocked the ability of neutrophils to produce IL-17, demonstrating that STAT3 activation is the major factor mediating IL-17 gene expression. CONCLUSIONS: These findings suggest that neutrophil infiltration in lungs of severe asthmatics may represent an important source of pro-inflammatory IL-17A and -F cytokines, a production enhanced by Th-17 regulatory cytokines, and thus providing a feedback mechanism that sustains inflammation. Our results suggest that STAT3 pathway could be a potential target for regulating neutrophilic inflammation during severe asthma.

Predictors of asthma following severe respiratory syncytial virus (RSV) bronchiolitis in early childhood.

BACKGROUND: We sought to identify predictors of asthma development following severe early childhood RSV bronchiolitis. Different definitions of asthma were also compared. METHODS: This longitudinal, observational study (N = 343) followed patients (<2 years old) from a placebo-controlled trial (N = 979) of montelukast after RSV bronchiolitis to identify clinical, demographic, or biochemical predictors of asthma, atopic disorders, and chronic asthma therapy use at 6 years of age (Clinical Trials Registry Number: NCT01140048). Asthma (primary definition) was based on parental identification of wheeze at 6 AND 12 months before 6 years of age; definitions based on physician diagnosis as well as parental identification of wheeze at 6 OR 12 months (to consider seasonal effect) were also assessed. Post-hoc analyses evaluated agreement among asthma diagnosis criteria. RESULTS: Prevalence of asthma (primary definition by parental identification), asthma (physician diagnosis), atopic disorders, and chronic asthma therapy use (parental identification) was 6.1%, 22.4%, 36.2%, and 14.5%, respectively. Predictors for asthma (primary definition) included male gender, a relative with asthma, and RAST positive for dog dander; for physician diagnosis of asthma, high severity score for RSV bronchiolitis, high respiratory rate, and asthma diagnosis before enrollment. Predictors of atopic disorders included allergic rhinitis before enrollment, a relative with asthma, and the plasma biomarkers IL-5, IL-16, and IL-18. Predictors of chronic asthma therapy use included asthma diagnosis before enrollment and geographic region (Europe and Africa). Only 42% of patients with asthma (primary definition) also met the asthma definition by physician diagnosis and chronic asthma therapy use. CONCLUSION: Among children with early RSV bronchiolitis, hereditary factors (i.e., having a relative with asthma) and RSV bronchiolitis severity were predictors of asthma and atopic disorders at 6 years of age. Of interest, there was poor agreement among the asthma definitions evaluated. Pediatr Pulmonol. 2016;51:1382-1392. © 2016 Wiley Periodicals, Inc.

Emerging role of IL-16 in cytokine-mediated regulation of multiple sclerosis.

Cytokines are pleiotropic soluble mediators of cellular functions. Cytokines are critical in immune pathogenesis of human diseases, including autoimmune CD4(+) T cell mediated chronic inflammatory, demyelinating and neurodegenerative diseases of the central nervous system (CNS), multiple sclerosis (MS). In MS and its experimental model, experimental autoimmune encephalomyelitis (EAE), chronic persistence and/or reoccurrence of inflammation in the CNS causes chronic progressive or relapsing disease, accompanied with demyelination and damage to axons and oligodendrocytes, which ultimately leads to paralysis and disability. As opposed to other cytokines, whose effects are not limited to the CD4(+) T cell subset, IL-16 exerts its biological properties by exclusive binding and signaling through CD4 receptor. IL-16 selectively regulates migration of all CD4 expressing T cells regardless of their activation state, which is of critical importance for immune modulation and potential therapy of MS. Other major biological properties of IL-16 essential for the function of CD4(+) T cells include regulation of: T cell activation, CD25 expression, MHC class II expression, dendritic cell (DC)-T cell cooperation, B cell-T cell and T cell-T cell cooperation, inflammatory cytokine production and modulation of chemokine regulated T cell chemo-attraction. In this article we outline immune pathogenesis of the disease necessary to understand significance of cytokines and IL-16 in MS regulation. We revisit cytokine regulation with emphasis on involvement of IL-16 mechanisms, implicated in MS progression and important for development of new therapies. We emphasize the significance of similar IL-16 mechanisms for other chronic inflammatory CNS diseases.

CCR4+T cell recruitment to the skin in mycosis fungoides: potential contributions by thymic stromal lymphopoietin and interleukin-16.

Mycosis fungoides (MF) is characterized by skin accumulation of CCR4+CCR7- effector memory T cells; however the mechanism for their recruitment is not clearly identified. Thymic Stromal Lymphopoietin (TSLP) is a keratinocyte-derived cytokine that triggers Th2 immunity and is associated with T cell recruitment to the skin in atopic dermatitis. Interleukin-16 (IL-16) is a chemoattractant and growth factor for CD4+T cells. We hypothesized that TSLP and IL-16 could contribute to recruitment of malignant T cells in MF. We found elevated TSLP and IL-16 in very early stage patients' plasma and skin biopsies, prior to elevation in CCL22. Both TSLP and IL-16 induced migratory responses of CCR4+TSLPR+CD4+CCR7-CD31+cells, characteristic of malignant T cells in the skin. Co-stimulation also resulted in significant proliferative responses. We conclude that TSLP and IL-16, expressed at early stages of disease, function to recruit malignant T cells to the skin and contribute to their enhanced proliferation.

Secretion of IL-16 through TNFR1 and calpain-caspase signaling contributes to MRSA pneumonia.

Staphylococcus aureus is a major cause of severe pneumonia. Multiple mechanisms of proinflammatory signaling are activated to recruit immune cells into the airway in response to S. aureus. We found that interleukin-16 (IL-16), a T cell cytokine that binds CD4, is potently activated by S. aureus, specifically by protein A (SpA), and to a much greater extent than by Gram-negative pathogens or lipopolysaccharide. IL-16 production involved multiple signals including ligation of tumor necrosis factor receptor (TNFR) family members or epidermal growth factor receptor, both receptors for SpA and generation of Ca(2+) fluxes to activate calpains and caspase-3. Although human airway epithelial cells, vascular endothelial cells, THP-1 and Jurkat T cells released IL-16 in response to S. aureus in vitro, in a murine model of pneumonia, CD4(+) cells were the major source of IL-16 suggesting the involvement of an autocrine signaling pathway. The production of IL-16 contributed to lung damage as neutralization of IL-16 enhanced S. aureus clearance and resulted in diminished lung pathology in S. aureus pneumonia. Our results suggest that the ability of S. aureus to activate TNFR1 and Ca(2+)/calpain signaling contribute to T cell activation and excessive inflammation in the setting of acute pneumonia.

Interferon ß-1a reduces increased interleukin-16 levels in multiple sclerosis patients.

OBJECTIVES: There is convergent evidence for an important role of interleukin-16 (IL-16) in the pathogenesis of multiple sclerosis (MS). IL-16 serves as a chemoattractant for different immune cells that are involved in developing lesions. Here, we compared IL-16 levels of MS patients and controls and addressed the long-term effect of IFN-ß, the most common immunomodulatory MS therapy, on IL-16 serum levels in MS patients over 2 years. Beyond this, we analysed the expression of IL-16 in two CD4(+) T-cell subsets, Th1 and Th17 cells, which are important autoimmune mediators and affected by IFN-ß treatment, derived from myelin-specific T-cell transgenic mice. MATERIALS AND METHODS: IL-16 serum levels of 17 controls and of 16 MS patients before therapy and at months 1, 2, 3, 6, 9, 12 and 24 during IFN-ß1a therapy were determined by ELISA. MRI was performed before therapy, at months 12 and 24. IL-16 expression of in vitro differentiated murine myelin oligodendrocyte glycoprotein (MOG)-specific Th1 and Th17 cells was quantified by real-time PCR. RESULTS: Before therapy, MS patients showed significantly elevated IL-16 levels compared with controls irrespective of disease activity determined by MRI. Therapy with IFN-ß1a led to a significant linear decrease in IL-16 serum levels beginning after 2 months. MOG-specific Th17 cells expressed more IL-16 than Th1 cells. CONCLUSIONS: Reduction in increased IL-16 levels may be of relevance for the therapeutic effect of IFN-ß1a in MS. Easily accessible IL-16 serum levels hold a potential as biomarker of treatment efficacy in MS.

IL-16 induces intestinal inflammation via PepT1 upregulation in a pufferfish model: new insights into the molecular mechanism of inflammatory bowel disease.

Inflammatory bowel disease (IBD) has long been a worldwide health care problem with a persistently increasing incidence. Although its clinical features have been well described, its etiology and pathogenesis remain unclear. IL-16 is a chemoattractant cytokine with various effects on cellular activities and diseases. However, the involvement of IL-16 in IBD remains poorly understood. In this study, to our knowledge we report for the first time the mechanism by which IL-16 induces intestinal inflammation by upregulating the expression of oligopeptide transporter member 1 (PepT1) in a Tetraodon nigroviridis fish model. The dextran sodium sulfate-induced colitis model in this species revealed that IL-16 levels significantly increase accompanied by elevations in PepT1 in the colon. Moreover, the signs of colitis were dramatically attenuated by IL-16 depletion using anti-IL-16 Abs. In vivo IL-16 administration induced remarkable intestinal inflammation with typical ulcerative colitis-like features, including histologic damage, inflammatory cell infiltration, increased myeloperoxidase activity, and proinflammatory cytokines expression, which corresponded with significant PepT1 upregulation in the colon. The IL-16-induced PepT1 expression and its upregulated fMLF transport were also demonstrated in vitro. To our knowledge, our study provides the first evidence of the connection between IL-16 and PepT1, which provides new insights into the molecular mechanism underlying IBD development. Additionally, this study suggests that fish species are an attractive model for studying IBD. By providing a better understanding of IL-16 biology from fish to mammals, this study should aid the development of IL-16-based therapies for IBD.

Pro-IL-16 is associated with MHC class II-mediated negative regulation of mouse resting B cell activation through MAP kinases, NF-κB and Skp2-dependent p27kip regulation.

MHC class II molecules, in addition to their essential role as antigen-presenting molecules to CD4(+) T cell receptor, have a signal-transducing role related to B cell function. We identified pro-IL-16 as one of the proteins associated with MHC class II-mediated signalling in an analysis of MHC class II-associated molecules using immunoprecipitation and proteomics data obtained from the 38B9 resting B cell line, and investigated the role of pro-IL-16 in resting B cell activation. We found that pro-IL-16, rather than mature form of IL-16, is present both in the cytoplasm and nucleus of resting B cells, and its expression is influenced by MHC class II-mediated signalling. In addition, overexpression of pro-IL-16 impaired resting B cell proliferation and this inhibitory effect was mediated through regulating nuclear factor (NF)-κB activation. Knock-down of pro-IL-16 expression using siRNA decreased the level of cell-cycle inhibitor p27(kip) and increased the level of Skp2. In addition, knock-down of pro-IL-16 modulated mitogen-activated protein kinase activation. Given that IL-16 acts as an immunomodulator by impairing antigen-induced T cell activation and its precursor, pro-IL-16, plays a role in regulating the cell cycle in T lymphocytes and T cell lymphoma, we concluded that pro-IL-16 is involved in resting B cell proliferation, similar to its function in T lymphocytes.

Analysis of gene expression in canine sino-nasal aspergillosis and idiopathic lymphoplasmacytic rhinitis: a transcriptomic analysis.

Sino-nasal aspergillosis (SNA) and lymphoplasmacytic rhinitis (LPR) are two common causes of nasal discharge in dog. SNA is typically due to an invasion of Aspergillus fumigatus in the surface of nasal mucosa. The etiology of LPR is poorly understood and a possible implication of fungi is suspected. The purpose of the present study was to explore the immunopathogenesis of these diseases by comparing gene expression in the nasal mucosa from dogs affected by SNA or LPR with healthy dogs, using a canine-specific microarray and quantitative real-time reverse transcriptase polymerase chain reaction for confirmation of the findings of the microarray study. Total RNA was isolated from biopsies of nasal mucosa and gene expression was analyzed via hybridation to the Affymetrix GeneChip(®) Canine Genome 2.0 Array. Selected Affimetrix probes sets identifiers were downloaded into the Database for Annotation, Visualization and Integrated Discovery. Genes of interest were chosen after their fold change and their possible implication in immunopathogenesis of SNA or LPR. The results presented here were in concordance with previous studies on SNA and LPR and highlighted new molecules potentially involved in the pathogenesis of SNA. The over-expression of interleukin (IL)-16, natural killer cell group 7 and chemokine ligand 10 might be related to a potential protective Th1 immunity counterbalanced by other molecules such as DNA-binding protein Ikaros.