Identification of interleukin-16 production on tumor aggravation in hepatocellular carcinoma by a proteomics approach.

BACKGROUND: Cytokines play an important role in the immune response, angiogenesis, cell growth, and differentiation in hepatocellular carcinoma (HCC). OBJECTIVE: We performed a comprehensive study to identify tumor-related cytokines and pathways involved in HCC pathogenesis. METHODS: Cytokine production was evaluated in human HCC tissues and adjacent non-tumor tissues using an antibody-based protein array technique. We compared cytokine expression in HCC tissues with that of hepatic hemangioma (HH), liver metastasis of colorectal cancer, and noncancerous liver tissues from transplantation donors. The protein levels and localization of the candidate cytokines were analyzed by western blotting and immunohistochemistry. RESULTS: Increased expression of interleukin (IL)-1 receptor antagonist, macrophage migration inhibitory factor, and IL-16 was observed in HCC and paired adjacent non-tumor tissues compared with noncancerous livers. In addition, there were increased IL-16 levels in HCC tissues compared with HH. IL-16 treatment significantly increased cell proliferation in vitro. The expression of extracellular signal-regulated kinase (ERK)1/2 and cyclin D1 was markedly increased in cells from two HCC cell lines, Huh7 and HepG2, in a dose- and time-dependent manner. Phosphorylated to total ERK1/2 ratio was increased in Huh7 cells following IL-16 50 ng/ml, but not HepG2 cells. ERK phosphorylation have occurred earlier than protein accumulation at 48 h. Pretreatment with the ERK inhibitor, FR18024, or an anti-IL-16 antibody reduced the increase in IL-16 production in HCC cells. CONCLUSIONS: These results suggest that cell proliferation induced by IL-16 is mediated through the ERK pathway, thus, we identified a new factor associated with HCC tumor growth.

LncRNA SNHG12 downregulates RAGE to attenuate hypoxia-reoxygenation-induced apoptosis in H9c2 cells.

Ischemia-reperfusion (I/R) injury causes cardiac dysfunction through several mechanisms including the irregular expression of some long noncoding RNA. However, the role of SNHG12 in myocardial I/R injury remains unclear. Here, we found the increase of the SNHG12 level in hypoxia-reoxygenation (H/R)-injured-H9c2 cells. SNHG12 silencing enhanced the apoptosis of H/R-injured H9c2 cells, while SNHG12 overexpression relieved the cardiomyocyte apoptosis induced by H/R stimulation. Additionally, the suppression of SNHG12 significantly boosted the H/R-induced expression and the production of TNF-α, IL-6, and IL-1ß, as well as the activation of NF-κB, which were fully reversed after overexpression of SNHG12. Mechanistically, SNHG12 adversely regulated the production of receptor for advanced glycation end products (RAGE) in H/R-stimulated H9c2 cells. Antibody blocking of RAGE alleviated the apoptosis of H/R-injured H9c2 cells. Collectively, we have determined a valuable mechanism by which the high level of SNHG12 contributes to H9c2 cells against H/R injury through the reduction of RAGE expression.

High-Dose Dexamethasone Alters the Increase in Interleukin-16 Level in Adult Immune Thrombocytopenia.

Adult primary immune thrombocytopenia (ITP) is an autoimmune-mediated haemorrhagic disorder. Interleukin-16 (IL-16) can directly affect cellular or humoural immunity by mediating the cellular cross-talk among T cells, B cells and dendritic cells. Several studies have focused on IL-16 as an immunomodulatory cytokine that takes part in Th1 polarization in autoimmune diseases. In this study, we investigated IL-16 expression in the bone marrow supernatant and plasma of ITP patients and healthy controls. What's more, we detected IL-16 expression in ITP patients with the single-agent 4-day high-dose dexamethasone (HD-DXM) therapy. In patients with active ITP, bone marrow supernatant and plasma IL-16 levels increased (P < 0.05) compared with those of healthy controls. In the meantime, the mRNA expression in BMMCs (pro-IL-16, caspase-3) and PBMCs (pro-IL-16, caspase-3 and T-bet) of ITP patients was increased (P < 0.05) relative to those of healthy controls. In patients who responded to HD-DXM therapy, both plasma IL-16 levels and gene expression in PBMCs (pro-IL-16, caspase-3, and T-bet) were decreased (P < 0.05). In summary, the abnormal level of IL-16 plays important roles in the pathogenesis of ITP. Regulating Th1 polarization associated with IL-16 by HD-DXM therapy may provide a novel insight for immune modulation in ITP.

Elevated IL-16 expression is associated with development of immune dysfunction in children with autism.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in communication skills and social behaviors. Several studies have suggested that neuroimmune dysfunction plays a significant role in the pathogenesis of ASD; however, its exact etiology is unknown. Interleukin-16 (IL-16), a chemoattractant, is associated with various inflammatory processes. However, its role in children with ASD is unclear. This study aimed to investigate whether IL-16 expression is associated with immune dysfunction in children with ASD. We examined IL-16 expression in CD4+, CD8+, CD14+, CCR3+, and CXCR7+ cells in typically developing (TD) controls and children with ASD using flow cytometry in peripheral blood mononuclear cells (PBMCs). We also investigated the expression of IL-1ß+IL-16+, IL-6+IL-16+, and TNF-α+IL-16+ in TD controls and children with ASD. We further explored IL-16 mRNA and protein expression using RT-PCR and western blotting. CD4+IL-16+, CD8+IL-16+, CD14+IL-16+, CCR3+IL-16+, and CXCR7+IL-16+ cells increased significantly in children with ASD compared with TD controls. We also showed that expression of IL-1ß+IL-16+, IL-6+IL-16+, and TNF-α+IL-16+ was elevated in children with ASD compared with TD controls. Moreover, IL-16 mRNA and protein expression was significantly induced in children with ASD compared with TD controls. These results suggest that IL-16 expression could play an essential role in immune alteration in children with ASD.

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.

IL-17A Promotes RANTES Expression, But Not IL-16, in Orbital Fibroblasts Via CD40-CD40L Combination in Thyroid-Associated Ophthalmopathy.

PURPOSE: This present study aims to investigate the phenotype of IL-17A-producing T cells in thyroid-associated ophthalmopathy (TAO) and the role of IL-17A on RANTES and IL-16 expression in orbital fibroblasts (OFs) from TAO patients. METHODS: Blood samples were obtained from TAO patients and healthy controls and were subjected to ELISA and flow cytometry analysis. Primary human OFs cultured from surgical wastes were stimulated with IL-17A in the presence or absence of CD40L and were examined by qRT-PCR, ELISA, Western blotting, and apoptosis assays. RESULTS: We reported upregulated IL-17A, IFN-γ, RANTES, and IL-16 serum levels and increased frequency of IL-17A- and IFN-γ-producing T cells in peripheral blood mononuclear cells from patients with TAO compared with healthy controls. In addition, TAO orbital tissues were rich in T lymphocytes, expressing more IL-17A, IFN-γ, RANTES, and IL-16. Moreover, IL-17A could enhance the expression of RANTES, but not IL-16, in cultured primary OFs in cooperation with CD40L. We further validated that MAPK signaling was largely responsible for RANTES production in IL-17A-treated OFs. Finally, we demonstrated that IL-17A could not promote apparent apoptosis in OFs from TAO patients and healthy controls. CONCLUSIONS: Our results indicate the potent effect of IL-17A-induced RANTES expression on OFs and elaborate a possible mechanism in understanding Th17 cells in the pathology of TAO and its potential as a target to immunotherapy of TAO and other autoimmune disorders.

Human Carotid Plaques With High Levels of Interleukin-16 Are Associated With Reduced Risk for Cardiovascular Events.

BACKGROUND AND PURPOSE: Interleukin-16 (IL-16) functions as a regulator of T-cell growth and acts as an inducer of cell migration. The aim of this study was to determine whether IL-16 measured in human carotid plaques was associated with symptoms (eg, stroke, transient ischemic attack, or amaurosis fugax), markers of plaque stability, and postoperative cardiovascular events. METHODS: Plaques obtained from patients who had ≥1 cerebrovascular ischemic events within 1 month before endarterectomy (n=111) were compared with plaques from patients without symptoms (n=95). Neutral lipids, smooth muscle cell, and macrophage contents were evaluated histologically, and collagen, elastin, and caspase-3 activity were measured biochemically. IL-16, matrix metalloproteinases, and tissue inhibitors of metalloproteinases were measured in plaque homogenates using a multiplex immunoassay. IL-16, CD3, CD4, and FoxP3 mRNA expressions in carotid plaques were analyzed with quantitative real-time polymerase chain reaction. RESULTS: Carotid plaques from asymptomatic patients had higher levels of IL-16 mRNA. High plaque IL-16 protein levels (above median) were associated with reduced incidence of postoperative cardiovascular events during a mean follow-up of 21 months (hazard ratio, 0.47; 95% confidence interval, 0.22-0.99; P=0.047). IL-16 levels correlated with the plaque-stabilizing components: elastin, collagen, matrix metalloproteinase-2, tissue inhibitors of metalloproteinase-1, tissue inhibitors of metalloproteinase-2 and FoxP3 mRNA. CONCLUSIONS: This study shows that high levels of IL-16 are associated with asymptomatic carotid plaques, expression of factors contributing to plaque stability, and decreased risk of new cardiovascular events during a 2-year period after surgery, suggesting that IL-16 might have a protective role in human atherosclerotic disease.

[Increased expression of IL-16 in mouse skin allograft].

OBJECTIVE: To detect the expression of interleukin 16 (IL-16) in skin allografts of recipient mice and the serum level of IL-16. METHODS: Two different mouse models of skin allografts were used: the isotransplant group (C57BL/6--C57BL/6, n=45) and the allotransplantation group (BALB/c--C57BL/6, n=45). The level of IL-16 in sera and skin graft homogenates was tested by ELISA at 1, 3, 5 and 7 days after transplantation and the expression of IL-16 mRNA in skin allografts was measured by reverse transcription PCR at the same time points. RESULTS: At 3, 5 and 7 days after skin transplantation, the levels of IL-16 protein and mRNA in the skin allografts and serum level of IL-16 in the allotransplantation group were significantly higher than those in the isotransplant group. CONCLUSION: The expression of IL-16 is increased in the mouse skin allografts.

Tumor-Promoting Effects of Myeloid-Derived Suppressor Cells Are Potentiated by Hypoxia-Induced Expression of miR-210.

Myeloid-derived suppressor cells (MDSC) contribute significantly to the malignant characters conferred by hypoxic tumor microenvironments. However, selective biomarkers of MDSC function in this critical setting have not been defined. Here, we report that miR-210 expression is elevated by hypoxia-inducible factor-1α (HIF1α) in MDSC localized to tumors, compared with splenic MDSC from tumor-bearing mice. In tumor MDSC, we determined that HIF1α was bound directly to a transcriptionally active hypoxia-response element in the miR-210 proximal promoter. miR-210 overexpression was sufficient to enhance MDSC-mediated T-cell suppression under normoxic conditions, while targeting hypoxia-induced miR-210 was sufficient to decrease MDSC function against T cells. Mechanistic investigations revealed that miR-210 modulated MDSC function by increasing arginase activity and nitric oxide production, without affecting reactive oxygen species, IL6, or IL10 production or expression of PD-L1. In splenic MDSC, miR-210 regulated Arg1, Cxcl12, and IL16 at the levels of both mRNA and protein, the reversal of which under normoxic conditions decreased T-cell-suppressive effects and IFNγ production. Interestingly, miR-210 overexpression or targeting IL16 or CXCL12 enhanced the immunosuppressive activity of MDSC in vivo, resulting in increased tumor growth. Taken together, these results provide a preclinical rationale to explore miR-210 inhibitory oligonucleotides as adjuvants to boost immunotherapeutic responses in cancer patients.

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.

Intratracheal instillation of high dose adenoviral vectors is sufficient to induce lung injury and fibrosis in mice.

RATIONALE: Replication deficient adenoviruses (Ad) vectors are common tools in gene therapy. Since Ad vectors are known to activate innate and adaptive immunity, we investigated whether intratracheal administration of Ad vectors alone is sufficient to induce lung injury and pulmonary fibrosis. METHODS: We instilled Ad viruses ranging from 107 to 1.625×109 ifu/mouse as well as the same volume of PBS and bleomycin. 14 and 21 days after administration, we collected bronchoalveolar lavage fluid (BALF) and mouse lung tissues. We measured the protein concentration, total and differential cell counts, and TGF-ß1 production, performed Trichrome staining and Sircol assay, determined gene and protein levels of profibrotic cytokines, MMPs, and Wnt signaling proteins, and conducted TUNEL staining and co-immunofluorescence for GFP and α-SMA staining. RESULTS: Instillation of high dose Ad vectors (1.625×109 ifu/mouse) into mouse lungs induced high levels of protein content, inflammatory cells, and TGF-ß1 in BALF, comparable to those in bleomycin-instilled lungs. The collagen content and mRNA levels of Col1a1, Col1a2, PCNA, and α-SMA were also increased in the lungs. Instillation of both bleomycin and Ad vectors increased expression levels of TNFα and IL-1ß but not IL-10. Instillation of bleomycin but not Ad increased the expression of IL-1α, IL-13 and IL-16. Treatment with bleomycin or Ad vectors increased expression levels of integrin α1, α5, and αv, MMP9, whereas treatment with bleomycin but not Ad vectors induced MMP2 expression levels. Both bleomycin and Ad vectors induced mRNA levels of Wnt2, 2b, 5b, and Lrp6. Intratracheal instillation of Ad viruses also induced DNA damages and Ad viral infection-mediated fibrosis is not limited to the infection sites. CONCLUSIONS: Our results suggest that administration of Ad vectors induces an inflammatory response, lung injury, and pulmonary fibrosis in a dose dependent manner.

Depletion of tristetraprolin in breast cancer cells increases interleukin-16 expression and promotes tumor infiltration with monocytes/macrophages.

The RNA-binding protein tristetraprolin (TTP) destabilizes target messenger RNAs (mRNAs) containing AU-rich elements within their 3' untranslated region. Thereby, it controls the expression of multiple inflammatory and tumor-associated transcripts. Moreover, a loss of TTP in tumors predicts disease-associated survival. Although tumor intrinsic functions of TTP have previously been studied, the impact of TTP on the interaction of tumors with their microenvironment remains elusive. As immune cell infiltration into tumors is a critical determinant for tumor progression, this study aimed at determining the influence of tumor cell TTP on the interaction between tumor and immune cells, specifically monocytes (MO)/macrophages (MΦ). Knockdown (k/d) of TTP in T47D breast cancer cells enhanced tumor growth both in vitro and in vivo and increased infiltration of MO into 3D tumor spheroids in vitro and of MΦ into tumor xenografts in vivo. Enhanced migration of MO toward supernatants of TTP-deficient tumor spheroids was determined as the underlying principle. Interestingly, we noticed interleukin-16 (IL-16) mRNA stabilization when TTP was depleted. In line, IL-16 protein levels were elevated in TTP-deficient spheroids and their supernatants as well as in TTP k/d tumor xenografts and critically contributed to the enhanced chemotactic behavior. In summary, we show that the loss of TTP in tumors not only affects tumor cell proliferation and survival but also enhances infiltration of MO/MΦ into the tumors, which is typically associated with poor prognosis. Moreover, we identified IL-16 as a critical TTP-regulated chemotactic factor that contributes to MO/MΦ migration.

Changes of immunomodulatory cytokines associated with omalizumab therapy for severe persistent asthma.

Omalizumab is an anti-IgE monoclonal antibody that was proven effective for the treatment of severe asthma. IgE plays a central role in allergic asthma, and an anti-allergic effect of omalizumab has been confirmed in terms of its impact on Th2 cytokines. The objective of the present study is to determine the influence of omalizumab on clinical parameters and circulating immuoregulatory cytokines. Patients with severe allergic asthma were enrolled and given four months of omalizumab therapy. Changes of symptoms and other parameters were assessed, including the asthma control test (ACT) score, morning peak expiratory flow (PEF), peripheral eosinophil count, total serum IgE, and pulmonary function tests. The use of corticosteroids and short-acting bronchodilators, as well as the number of unscheduled hospital visits, were monitored. Circulating levels of cytokines were analyzed with a multiplex cytokine immunoassay in patients with or without omalizumab therapy. Asthma symptoms (evaluated by the ACT score and morning PEF) improved with omalizumab treatment, while total IgE was elevated. Use of corticosteroids and short-acting bronchodilators and the number of unscheduled hospital visits for exacerbation of asthma were all reduced by omalizumab treatment. The level of macrophage inflammatory protein 1-δ (MIP1-δ) was significantly reduced after omalizumab therapy and was high in patients without omalizumab. IL-16 also tended to decrease with omalizumab therapy. Both MIP1-δ and IL-16 decreased as asthma improved over the 4-month period of omalizumab therapy. These findings suggest that omalizumab may act via IgE-mediated immunoregulation of MIP1-δ and IL-16.

Tissue expression of IL16 in prostate cancer and its association with recurrence after radical prostatectomy.

BACKGROUND: Genetic polymorphism located within the IL16 gene has been reported to be associated with aggressive prostate cancer (PCa). Our aim was to establish whether the tissue expression of IL16 is a prognostic factor of survival in PCa. METHODS: The files of patients who underwent radical prostatectomy (RP) between 1995 and 2001 were reviewed. The cases were selected and classified according to the D'Amico classification for risk of recurrence (intermediate or high). The value of IL16 and its receptor CCR5 (chemokine (C-C motif) receptor 5) expression levels were determined as witness of aggressiveness patterns and markers of biological relapse in patients with PCa treated by RP. A tissue microarray of 304 cases was constructed. IL16 and CCR5 expression levels were characterized by immunohistochemistry. RESULTS: IL16 expression was correlated with high Gleason score (i.e., >7) (P < 0.01). It was not significant for CCR5. IL16 and CCR5 were not associated with prostate-specific antigen (PSA) or capsular extension of the disease. The accurate prediction of disease outcome, using stratification of cases, according to negative margins and D'Amico classification was significantly enhanced by status of IL16 expression (P ≤ 0.01). In univariate analyses, Gleason score, PSA level, stage and loss of IL16 expression were related to better biological-free survival (P < 0.05) but not CCR5. In a multivariate analysis, IL16 expression, Gleason score, and tumor stage were independent factors for biochemical-free survival (P = 0.001). CONCLUSIONS: IL16 appears to be a useful prognostic factor in PCa. Its expression in PCa tissue was correlated to tumor aggressiveness and biochemical relapse of the disease.

Transforming growth factor beta1 and laminin-111 cooperate in the induction of interleukin-16 expression in synovial fibroblasts from patients with rheumatoid arthritis.

OBJECTIVES: In synovial tissues of patients with rheumatoid arthritis (RA), strong expression of laminins and integrins co-localises with increased expression of inflammatory cytokines. Synovial fibroblasts (SF) contribute to the pathogenesis of RA through increased expression of cytokines and chemoattractant factors, one of which is interleukin-16 (IL16). A study was undertaken to investigate the regulatory pathways of IL16 in SF from patients with RA (RA-SF) and osteoarthritis (OA-SF). METHODS: SF were seeded in laminin-coated flasks and activated by the addition of cytokines. The expression of IL16 was investigated by quantitative RT-PCR, immunoblotting and ELISA; its biological activity was determined by a cell migration assay. Cell-matrix interactions were investigated by cell binding and attachment assays. Relevant intracellular signalling pathways were studied by immunoblotting and with pharmacological blocking reagents. RESULTS: Stimulation of SF with transforming growth factor beta(1)(TGF-beta(1)) and growth on laminin-111 (LM-111) significantly increased the expression of IL16. Binding to LM-111 induced significantly more IL16 mRNA in RA-SF than in OA-SF (p<0.05). The IL16 cytokine was detected in supernatants of TGF-beta(1)-activated and in LM-111+TGF-beta(1)-activated RA-SF (38 to 62 pg/ml), but not in supernatants of OA-SF. This IL16 regulation involved p38MAPK, ERK1/2 and SMAD2 signalling, but not NFkappaB. CONCLUSIONS: Binding of RA-SF to LM-111 in the presence of TGF-beta(1) triggers a significant IL16 response and thus may contribute to the infiltration of CD4+ lymphocytes into synovial tissues. This mode of IL16 induction represents a novel pathway leading to IL16 production in RA-SF but not in OA-SF, which operates independently of NFkappaB signalling.

IL-16 variability and modulation by antiallergic drugs in a murine experimental allergic rhinitis model.

BACKGROUND: Interleukin-16 (IL-16) is a cytokine that induces selective migration of CD4+ cells and participates in inflammatory diseases including allergic rhinitis. Histamine and prostaglandin D(2) are important chemical mediators of allergic inflammation, and antiallergic drugs are commonly used for the treatment of allergic rhinitis. It remains unknown whether treatment with the drugs affects IL-16. OBJECTIVE: We evaluated the variability of IL-16 and the effects of the antiallergic drugs fexofenadine (40 mg/kg/day) and ramatroban (30 mg/kg/day) on IL-16 in an OVA-sensitized BALB/c murine experimental allergic rhinitis model. METHODS: We measured the expression level of IL-16 protein in the mouse nasal septal mucosa by immunohistochemistry, and the serum level of IL-16 by ELISA. Several other parameters associated with allergic rhinitis (nasal symptoms, OVA-specific IgE, eosinophil and T cell infiltration) were also measured. RESULTS: Local and systemic expressions of IL-16 were significantly increased in OVA-sensitized mice when compared to the nonsensitized group. Fexofenadine and ramatroban significantly inhibited the following OVA-induced allergic features when compared to the nontreated sensitized group: sneezing, nasal rubbing, eosinophil infiltration, IL-16 expressions in nasal tissue, and serum IL-16 level. Serum OVA-specific IgE and local T cell infiltration were reduced, but they did not reach significant values. CONCLUSIONS: These results suggest that IL-16 was both systemically and locally upregulated in the murine allergic rhinitis model and that IL-16 changed in parallel to allergic state by treatment with the drugs.

Immunosuppressive effect on T cell activation by interleukin-16- and interleukin-10-cDNA-double-transfected human squamous cell line.

It is well known that induction of immunotolerance with allogeneic skin transplantation is generally difficult. This study attempted to find an immunosuppressive protocol for skin allograft rejection involving interleukin-16 (IL-16) and interleukin-10 (IL-10), because both are known to inhibit mixed lymphocyte reaction (MLR). The data indicated that IL-16 enhanced the immunosuppressive effect of IL-10. IL-16-cDNA- and IL-10-cDNA-double-transfected squamous cell carcinoma cell line were used as an in vitro model and they produced more than 20 ng/ml of IL-16 and 100 pg/ml of IL-10 in the supernatant, which significantly inhibited MLR and also the activation of allogeneic lymphocytes, which were stimulated directly by allogeneic double-cDNA-transfectant cells. Thus allogeneic skin graft producing IL-16 and IL-10 might have a local immunosuppressive action that could prolong graft survival.

IL-12 p40 homodimer, but not IL-12 p70, induces the expression of IL-16 in microglia and macrophages.

IL-16, a leukocyte chemoattractant factor (LCF), is involved in the disease process of multiple sclerosis and other autoimmune disorders. However, mechanisms by which this LCF is expressed are poorly understood. The present study underlines the importance of IL-12 p40 homodimer (p40(2)), the so-called biologically inactive molecule, in inducing the expression of IL-16 in primary mouse and human microglia, mouse BV-2 microglial cells, mouse peritoneal macrophages, and RAW264.7 cells. In contrast, IL-12 p70, the bioactive heterodimeric cytokine, was unable to induce the expression of IL-16 in any of these cell types. Similarly IL-12 p40(2) also induced the activation of IL-16 promoter in microglia. Among various stimuli tested, p40(2) was the most potent one followed by p40 monomer, IL-16 and IL-23 in inducing the activation of IL-16 promoter in microglial cells. Furthermore, induction of IL-16 mRNA expression by over-expression of p40, but not p35, cDNA and induction of IL-16 expression by p40(2) in microglia isolated from IL-12p35 (-/-) mice confirm that p40, but not p35, is responsible for the induction of IL-16. Finally, by using primary microglia isolated from IL-12Rbeta1 (-/-) and IL-12Rbeta2 (-/-) mice, we demonstrate that p40(2) induces the expression of this LCF via IL-12Rbeta1 but not IL-12Rbeta2. These results delineate a novel biological function of p40(2) and raise the possibility that biological function of IL-12 p40(2) may be different from IL-12 p70.

Elevated maternal IL-16 levels, enhanced IL-16 expressions in endothelium and leukocytes, and increased IL-16 production by placental trophoblasts in women with preeclampsia.

Cytokine IL-16 plays an important role in innate immune responses. However, little information is available about IL-16 function in human pregnancy. In this study, we collected maternal blood samples from 125 pregnant women between 26 and 41 wk of gestation, 63 from normal pregnant women and 62 from women with preeclampsia (PE). Serum IL-16C levels were measured by ELISA. We also examined IL-16C and IL-16N immunostaining in maternal vessels and protein expression in leukocytes from normal and PE pregnant women. In addition, IL-16C production by placental trophoblasts was also determined. Our results showed that IL-16C levels were significantly higher in severe PE than in mild PE and normal pregnant controls, 515 +/- 58 vs 287 +/- 46 (p < 0.05) and 163 +/- 9 pg/ml (p < 0.01), respectively, indicating that increased IL-16 levels in PE is associated with the severity of the disease. There was no difference for the IL-16C levels in normal pregnant women throughout the third trimester. The correlation of maternal IL-16C levels with labor and body mass index was also analyzed. IL-16C levels were neither associated with labor nor associated with body mass index. Moreover, increased IL-16C immunostaining in maternal vessel endothelium and enhanced IL-16C protein expression in leukocytes were observed in PE. We also found that IL-16C production was increased by trophoblasts from PE placentas. Our study demonstrated up-regulation of the IL-16 profile in both the maternal and the placental systems in PE, suggesting that IL-16 could be an important cytokine engaged in the altered immune system and exaggerated inflammatory response in PE syndrome.

IL-17 induces the production of IL-16 in rheumatoid arthritis.

The purpose of this study was to investigate the expression of IL-16 in the rheumatoid synovium and the role of inflammatory cytokines and Toll-like receptor (TLR) ligands in IL-16 production by fibroblast-like synoviocytes (FLS) of rheumatoid arthritis (RA) patients. Immunohistochemical staining was performed with a monoclonal antibody to IL-16 in synovial tissues from patients with RA and likewise in patients with osteoarthritis (OA). FLS were isolated from RA synovial tissues and stimulated with IL-15, IL-1beta, IFN-gamma, and IL-17. The IL-16 mRNA level was assessed by semiquantitative RT-PCR and real time (RT) PCR and a comparison was made between IL-16 mRNA levels produced by RA-FLS and OA-FLS. Production of IL-16 was identified by a western blot assay, and IL-16 production after stimulation by specific ligands of TLR2 and TLR4 was assessed by RT-PCR. While immunohistochemical staining demonstrated strong expression of IL-16 mRNA in synovial tissues from patients with RA, similar findings were not present in the OA group. Moreover, mRNA expression of IL-16 by RA-FLS increased after treatment with IL-17 but not with IL-15, IL-1beta, and IFN-gamma. Specifically, IL-17 increased IL-16 mRNA level by RA-FLS and peripheral blood mononuclear cells in a dose-dependent manner. However, IL-17 did not stimulate IL-16 production in OA-FLS. Peptidoglycan, a selective TLR2 ligand, also increased production of IL-16 by RA-FLS dose- dependently, whereas LPS, a selective TLR4 ligand, had no such stimulatory effect. The results from our data demonstrate that IL-17 and TLR2 ligands stimulate the production of IL-16 by RA-FLS.