Exogenous interleukin-16 inhibits antigen-induced airway hyper-reactivity, eosinophilia and Th2-type cytokine production in mice

Comparison of Pulmonary Function and Inflammation in Children/Adolescents with New-Onset Asthma with Different Adiposity Statuses

(1) Background: The relationship between obesity and asthma is still uncertain. This study aimed to investigate the effect of overweight/obesity on the pulmonary function of patients with new-onset pediatric asthma and explore the possible causative factors related to concomitant obesity and asthma. (2) Methods: Patients aged 5 to 17 years old with newly diagnosed mild to moderate asthma were recruited from June 2018 to May 2019, from a respiratory clinic in Shanghai, China. Participants were categorized into three groups: normal weight, overweight, and obese asthma. A family history of atopy and patients’ personal allergic diseases were recorded. Pulmonary function, fractional exhaled nitric oxide (FeNO), eosinophils, serum-specific immunoglobulins E (sIgE), serum total IgE (tIgE), and serum inflammatory biomarkers (adiponectin, leptin, Type 1 helper T, and Type 2 helper T cytokines) were tested in all participants. (3) Results: A total of 407 asthma patients (197 normal weight, 92 overweight, and 118 obese) were enrolled. There was a reduction in forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC), FEV1/FVC%, and FEF25–75% in the overweight/obese groups. No difference was found between the study groups in the main allergy characteristics. Leptin levels were higher while adiponectin was lower in asthmatics with obesity. Higher levels of IL-16 were found in overweight/obese asthmatic individuals than in normal-weight individuals. (4) Conclusions: Obesity may have an effect on impaired pulmonary function. While atopic inflammation plays an important role in the onset of asthma, nonatopic inflammation (including leptin and adiponectin) increases the severity of asthma in overweight/obese patients. The significance of different levels of IL-16 between groups needs to be further studied.

Vaccine Potential of Mycobacterial Antigens against Asthma

Asthma is a cause of substantial burden of disease in the world, including both premature deaths and reduced quality of life. A leading hypothesis to explain the worldwide increase of asthma is the "hygiene hypothesis," which suggests that the increase in the prevalence of asthma is due to the reduction in exposure to infections/microbial antigens. In allergic asthma, the most common type of asthma, antigen-specific T helper (Th)2 and Th17 cells and their cytokines are primary mediators of the pathological consequences. In contrast, Th1 and T regulatory (Treg) cells and their cytokines play a protective role. This article aims to review the information on the effect of mycobacteria and their antigens in modulating Th2/Th17 responses towards Th1/Treg responses and protection against asthma in humans and animal models.

Interleukin-16 aggravates ovalbumin-induced allergic inflammation by enhancing Th2 and Th17 cytokine production in a mouse model

Asthma is a chronic inflammatory disease that involves a variety of cytokines and cells. Interleukin-16 (IL-16) is highly expressed during allergic airway inflammation and is involved in its development. However, its specific mechanism of action remains unclear. In the present study, we used an animal model of ovalbumin (OVA)-induced allergic asthma with mice harboring an IL-16 gene deletion to investigate the role of this cytokine in asthma, in addition to its underlying mechanism. Increased IL-16 expression was observed during OVA-induced asthma in C57BL/6J mice. However, when OVA was used to induce asthma in IL-16^-/- mice, a diminished inflammatory reaction, decreased bronchoalveolar lavage fluid (BALF) eosinophil numbers, and the suppression of OVA-specific IgE levels in the serum and BALF were observed. The results also demonstrated decreased levels of T helper type 2 (Th2) and Th17 cytokines upon OVA-induced asthma in IL-16^-/- mice. Hence, we confirmed that IL-16 enhances the lung allergic inflammatory response and suggest a mechanism possibly associated with the up-regulation of IgE and the promotion of Th2 and Th17 cytokine production. This work explored the mechanism underlying the regulation of IL-16 in asthma and provides a new target for the clinical treatment of asthma.

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.

Interleukin 16 and CCL17/thymus and activation-regulated chemokine in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Interleukin (IL) 16 and thymus and activation-regulated cytokine (TARC) are chemoattractant cytokines for eosinophils and T_H2 cells. Differential levels of these components in aspirin-exacerbated respiratory disease (AERD) and allergic rhinitis with asthma (ARwA) may be related to a different inflammatory response in both asthma phenotypes.

OBJECTIVE

To assess the nasal lavage immunoreactivity of IL-16 and TARC cytokines.

METHODS

We used multienzyme-linked immunosorbent assays to detect IL-5, IL-13, IL-16, IL-33, I-309/CCL1, TARC/CCL17, monocyte-derived chemokine/CCL22, periostin, and eosinophil cationic protein levels in nasal lavages from patients with AERD and patients with ARwA.

RESULTS

The IL-13, IL-16, TARC, and periostin levels were significantly higher in patients with AERD compared with those of patients with ARwA. Correlation analysis of mediator levels in AERD revealed a possible role of IL-16 and TARC in eosinophil recruitment and activation.

CONCLUSION

IL-16, TARC, and periostin distinguish between patients with AERD and those with ARwA. These mediators, taken together rather than individually, may comprise good specific nasal markers in patients with AERD. The effects of IL-16 and TARC on T_H1, T_H2, and T-regulatory cell functions in AERD cannot be disregarded.

Cytokine and Chemokine Profiles in Patients with Neuromyelitis Optica Spectrum Disorder

OBJECTIVE

To screen cytokines and chemokines and determine their dynamic changes in the serum and cerebrospinal fluid (CSF) of patients with neuromyelitis optica spectrum disorder (NMOSD).

METHODS

Eight NMOSD with seropositive aquaporin-4 antibody (AQP4-IgG) were enrolled, as well as 8 matched patients with multiple sclerosis (MS) and 8 with noninflammatory neurological diseases, who were included as controls. In total, 102 cytokines and 34 chemokines were detected in the CSF and serum of NMOSD patients and controls.

RESULTS

CSF interleukin (IL)-17A levels were significantly higher in NMOSD patients in the relapsing phase (27.15 ± 11.33) than in those in the remitting phase (10.04 ± 3.11, p = 0.0017), and patients with MS (14.72 ± 3.20, p = 0.0283) and other controls (10.39 ± 11.38, p = 0.0021). CSF IL-6 levels were higher in the NMOSD patients in the relapsing phase (12.23 ± 3.47) than in those in the remitting phase (5.87 ± 2.78, p = 0.0001), and MS patients (7.38 ± 2.35, p = 0.0033) and other controls (7.50 ± 0.37, p = 0.0043). CSF CCL19 levels were also significantly higher in NMOSD patients in the relapsing phase (35.87 ± 27.07) than in those in the remitting phase (10.71 ± 3.62, p = 0.0215). Serum IL-19 levels were lower in NMOSD patients in the relapsing phase (6.23 ± 1.95) than in those in the remitting phase (10.72 ± 4.46, p = 0.0092). Further, there was a positive, significant correlation between serum IL-9 concentration and the Expanded Disability Status Scale score in the NMOSD patients in the relapsing phase (p = 0.04).

CONCLUSION

In addition to IL-6 and IL-17A, IL-16 and CCL19 act as proinflammatory cytokines/chemokines, while IL-19 plays a protective role in NMOSD pathogenesis.

Transcriptome analysis of the endangered Chinese giant salamander (Andrias davidianus): Immune modulation in response to Aeromonas hydrophila infection

The endangered Chinese giant salamander (Andrias davidianus) is the largest extant amphibian species. Disease outbreaks represent one of the major factors threatening A. davidianus populations in the wild and the viability of artificial breeding programmes. Development of future immune therapies to eliminate infectious disease in A. davidianus is dependent on a thorough understanding of the immune mechanisms elicited by pathogen encounters. To this end we have undertaken, for the first time in amphibians, differential transcriptome analysis of the giant salamander response to Aeromonas hydrophila, one of the most devastating pathogens affecting amphibian populations. Out of 87,204 non-redundant consensus unigenes 19,216 were annotated, 6834 of which were upregulated and 906 down-regulated following bacterial infection. 2058 unigenes were involved with immune system processes, including 287 differentially expressed unigenes indicative of the impact of bacterial infection on several innate and adaptive immune pathways in the giant salamander. Other pathways not directly associated with immune-related activity were differentially expressed, including developmental, structural, molecular and growth processes. Overall, this work provides valuable insights into the underlying immune mechanisms elicited during bacterial infection in amphibians that may aid in the future development of disease control measures in protecting the Chinese giant salamander. With the unique position of amphibians in the transition of tetrapods from aquatic to terrestrial habitats, our study will also be invaluable towards the further understanding of the evolution of tetrapod immunity.

Differences in immune responses between CMV-seronegative and -seropositive patients with myocardial ischemia and reperfusion

CMV infection is responsible for acceleration of immune senescence and linked to systemic pathologies, including cardiovascular diseases. In this study, we investigated differences in the immune response between CMV-seropositive and seronegative patients undergoing primary percutaneous coronary intervention (PPCI) for acute myocardial infarction (MI). Peripheral blood samples were taken at six different time points: pre-, 15, 30, 90 min, 24 h after PPCI and at 3 months after MI. Absolute counts of lymphocyte subpopulations, immune response to specific and nonspecific stimulation, serum cytokines and levels of CMV-IgG, cardiolipin-IgG, and anti-endothelial cell antibodies were assessed. CMV-seropositive patients with MI showed a twofold higher IFN-γ production to PHA-stimulation, up to 2.5-fold higher levels of IP-10 in serum and up to 30% lower serum levels of IL-16 compared to CMV-seronegative individuals. CMV-seropositive patients could be divided into two subgroups with high (IL-10Hi) and low (IL-10Lo) IL-10 serum levels during the acute stage of MI. The IL-10Hi CMV-seropositive subgroup showed an increased exit of late-differentiated T lymphocytes, NK and NKT-like cells from the circulation, which may potentially enhance cytotoxic damage in the ischemic myocardium. Finally, we did not observe an acceleration of autoimmunity by MI in CMV-seropositive individuals. The immune response during acute MI showed characteristic differences between CMV seronegative and seropositive patients, with a stronger pro-inflammatory response in seropositive patients. The effects of IP-10, IL-16, and IL-10 on characteristics of acute immune responses and formation of different immune profiles in CMV-seropositive individuals require further investigation.

Interleukin-16 deficiency suppresses the development of chronic rejection in murine cardiac transplantation model

BACKGROUND

IL-16 promotes the recruitment of various cells expressing CD4, a receptor for IL-16. The precise role of IL-16 in transplant rejection remains unknown; therefore, the present study investigated the contribution of IL-16 to the development of chronic rejection in heart transplants.

METHODS

C-H-2(bm12)KhEg (H-2(bm12)) donor hearts were transplanted into (1) IL-16-deficient (IL-16(-/-)) C57BL/6J or (b) wild type (WT) control recipients (MHC class II mismatch). Grafts were harvested at 52 days, parenchymal rejection was assessed by the ISHLT grading system, and CAV was examined morphometrically. Graft infiltrating cells were detected 10 and 52 days after transplantation. Intragraft cytokine and chemokine profiles were assessed. To confirm the role of IL-16 in CAV development, C-H-2(bm12)KhEg (H-2(bm12)) donor hearts were transplanted into C57BL/6J WT recipients treated with (1) anti-IL-16-neutralization monoclonal antibody or (b) control immunoglobulin G. Grafts were harvested at 52 days, and CAV was quantified morphometrically. Graft-infiltrating cells were examined histologically.

RESULTS

Parenchymal rejection and CAV was significantly attenuated in donor hearts transplanted into IL-16(-/-) recipient mice compared with WT controls. Donor hearts transplanted into IL-16(-/-) recipients had a significant reduction in coronary artery luminal occlusion, intima-to-media ratio, and percentage of diseased vessels. CAV was associated with decreased donor organ inflammation, as well as donor organ cytokine (IL-1β and IL-6) and chemokine (MCP-1 and KC) protein expression. Intimal proliferation and inflammatory cell infiltration were significantly reduced in hearts transplanted into recipients treated with an IL-16-neutralization antibody.

CONCLUSIONS

IL-16-deficiency reduced graft inflammatory cell recruitment, and allograft inflammatory cytokine and chemokine production. Therefore, IL-16 neutralization may provide a potential target for novel therapeutic treatment for cardiac allograft rejection.

Induction of protective immunity against Eimeria tenella, Eimeria maxima, and Eimeria acervulina infections using dendritic cell-derived exosomes

This study describes a novel immunization strategy against avian coccidiosis using exosomes derived from Eimeria parasite antigen (Ag)-loaded dendritic cells (DCs). Chicken intestinal DCs were isolated and pulsed in vitro with a mixture of sporozoite-extracted Ags from Eimeria tenella, E. maxima, and E. acervulina, and the cell-derived exosomes were isolated. Chickens were nonimmunized or immunized intramuscularly with exosomes and subsequently noninfected or coinfected with E. tenella, E. maxima, and E. acervulina oocysts. Immune parameters compared among the nonimmunized/noninfected, nonimmunized/infected, and immunized/infected groups were the numbers of cells secreting T(h)1 cytokines, T(h)2 cytokines, interleukin-16 (IL-16), and Ag-reactive antibodies in vitro and in vivo readouts of protective immunity against Eimeria infection. Cecal tonsils, Peyer's patches, and spleens of immunized and infected chickens had increased numbers of cells secreting the IL-16 and the T(h)1 cytokines IL-2 and gamma interferon, greater Ag-stimulated proliferative responses, and higher numbers of Ag-reactive IgG- and IgA-producing cells following in vitro stimulation with the sporozoite Ags compared with the nonimmunized/noninfected and nonimmunized/infected controls. In contrast, the numbers of cells secreting the T(h)2 cytokines IL-4 and IL-10 were diminished in immunized and infected chickens compared with the nonimmunized/noninfected and the nonimmunized/infected controls. Chickens immunized with Ag-loaded exosomes and infected in vivo with Eimeria oocysts had increased body weight gains, reduced feed conversion ratios, diminished fecal oocyst shedding, lessened intestinal lesion scores, and reduced mortality compared with the nonimmunized/infected controls. These results suggest that successful field vaccination against avian coccidiosis using exosomes derived from DCs incubated with Ags isolated from Eimeria species may be possible.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

IL-16 effects on A549 lung epithelial cells: dependence on CD9 as an IL-16 receptor?

Interleukin-16 (IL-16) is a pro-inflammatory cytokine released by many types of cells found in the lungs, including normal airway and alveolar epithelial cells. Though a chemotactin for CD4(+) cells and eosinophils, IL-16 also modulates their production of factors that influence inflammatory lung diseases, e.g., asthma and allergic rhinitis. To date, little is known about any potential autocrine-like regulatory effects of IL-16. Using a model human alveolar basal epithelial A549 cell line, the present study sought to assess lung epithelial cell responses to IL-16. Potential induced effects on cell growth/function were assessed using MTT reduction, lactate dehydrogenase release, and 5-bromo-2-deoxyuridine incorporation assays. As IL-16 (at locally high levels) can induce CD4(+) cell death via apoptosis, this potential outcome among the A549 cells was also evaluated using TUNEL and changes in expression of caspase-3 and the pro-apoptotic and anti-apoptotic proteins of Bcl-2 family. The data here indicated that IL-16 inhibited A549 cell growth/function and this was associated with a marked increase in apoptosis characterized by DNA fragmentation, activation of caspase-3, and altered pro-apoptotic protein expression. Since lung epithelial cells lack the CD4 that may bind IL-16, it has been suggested that CD9 may act as an alternate receptor for this cytokine (i.e., an IL-16R). Thus, these studies also sought to determine the extent of CD9 expression on A549 cells and if any/all observed IL-16-induced changes were mediated by CD9. Flow cytometric analyses revealed the cells to be CD9(+)CD4(-). However, neutralization of the purported IL-16R with anti-CD9 antibody could not block the cytotoxic/growth inhibiting effects of IL-16. The only exception appeared to be a mitigation of a chemotactic effect of IL-16; however, studies with an equal amount of non-specific antibody (of same isotype as the anti-CD9) revealed this effect to be artefactual. The neutralization study results thus suggest to us that as-yet undefined pathway(s) exist through which IL-16 may act to exert growth inhibiting/apoptosis-inducing effects on A549 cells, a cell line routinely used as a model for lung epithelial cells.

Effects of tobacco smoke on IL-16 in CD8+ cells from human airways and blood: a key role for oxygen free radicals?

Chronic exposure to tobacco smoke leads to an increase in the frequency of infections and in the number of CD8(+) and CD4(+) cells as well as the CD4(+) chemoattractant cytokine IL-16 in the airways. Here, we investigated whether tobacco smoke depletes intracellular IL-16 protein and inhibits de novo production of IL-16 in CD8(+) cells from human airways and blood while increasing extracellular IL-16 and whether oxygen free radicals (OFR) are involved. Intracellular IL-16 protein in CD8(+) cells and mRNA in all cells was decreased in bronchoalveolar lavage (BAL) samples from chronic smokers. This was also the case in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro, in which oxidized proteins were markedly increased. Extracellular IL-16 protein was increased in cell-free BAL fluid from chronic smokers and in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro. This was not observed in occasional smokers after short-term exposure to tobacco smoke. A marker of activation (CD69) was slightly increased, whereas other markers of key cellular functions (membrane integrity, apoptosis, and proliferation) in human blood CD8(+) cells in vitro were negatively affected by water-soluble tobacco smoke components. An OFR scavenger prevented these effects, whereas a protein synthesis inhibitor, a β-adrenoceptor, a glucocorticoid receptor agonist, a phosphodiesterase, a calcineurin phosphatase, and a caspase-3 inhibitor did not. In conclusion, tobacco smoke depletes preformed intracellular IL-16 protein, inhibits its de novo synthesis, and distorts key cellular functions in human CD8(+) cells. OFR may play a key role in this context.

The choroid plexus response to a repeated peripheral inflammatory stimulus

Background

Chronic systemic inflammation triggers alterations in the central nervous system that may relate to the underlying inflammatory component reported in neurodegenerative disorders such as multiple sclerosis and Alzheimer's disease. However, it is far from being understood whether and how peripheral inflammation contributes to induce brain inflammatory response in such illnesses. As part of the barriers that separate the blood from the brain, the choroid plexus conveys inflammatory immune signals into the brain, largely through alterations in the composition of the cerebrospinal fluid.

Results

In the present study we investigated the mouse choroid plexus gene expression profile, using microarray analyses, in response to a repeated inflammatory stimulus induced by the intraperitoneal administration of lipopolysaccharide every two weeks for a period of three months; mice were sacrificed 3 and 15 days after the last lipopolysaccharide injection. The data show that the choroid plexus displays a sustained response to the repeated inflammatory stimuli by altering the expression profile of several genes. From a total of 24,000 probes, 369 are up-regulated and 167 are down-regulated 3 days after the last lipopolysaccharide injection, while at 15 days the number decreases to 98 and 128, respectively. The pathways displaying the most significant changes include those facilitating entry of cells into the cerebrospinal fluid, and those participating in the innate immune response to infection.

Conclusion

These observations contribute to a better understanding of the brain response to peripheral inflammation and pave the way to study their impact on the progression of several disorders of the central nervous system in which inflammation is known to be implicated.

Preferential migration of T regulatory cells induced by IL-16

As a natural ligand for CD4, IL-16 has been shown to preferentially induce migration in Th1 cells, and, in long-term cultures with IL-2, IL-16 facilitates the expansion of CD4(+)CD25(+) cells. In addition, IL-16 has an immunomodulatory role in asthmatic inflammation, as exogenous administration significantly reduces inflammation and airway hyperreactivity. The mechanism for this, however, is not clear. Based on its functional characteristics and potential immunomodulatory role, we investigated the ability of IL-16 to recruit and influence the development of T regulatory (Treg) cells. We now demonstrate that IL-16 preferentially induces migration in a CD25(+)CTLA-4(+) human T cell subset and that responding cells produce IFNgamma and TGFbeta but not IL-10. These cells are relatively unresponsive to antigenic stimulation and can suppress proliferation and IL-5, but not IFNgamma, production by autologous T cells. We further demonstrate that IL-16-recruited cells are enriched for Forkhead box P3 (Foxp3). In addition, we find that IL-16 stimulation may facilitate de novo induction of Foxp3(+) Treg cells, because the stimulation of FoxP3-negative T cells for 48 h results in the expression of FoxP3 mRNA and protein. These data indicate that at sites of inflammation IL-16 may contribute to selective Treg cell expansion through the preferential induction of a migratory response from existing Treg cells, as well as by the induction of de novo generation of FoxP3(+) cells. These findings offer a potential mechanism for the immunosuppressive effects of IL-16 seen in Th2-mediated inflammation.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

Interleukin-16 Inhibits Immunoglobulin E Production by B Lymphocytes

BACKGROUND

The increased production of IgE is a hallmark of atopic disorders. CD4+ T cells regulate the production of Immunoglobulin (Ig) E by B cells. Interleukin (IL) 16, a CD4+ specific cytokine, is highly expressed at sites of allergic inflammation. Our aim was to determine the effect of IL-16 on IgE production in atopic subjects.

METHODS

Freshly isolated peripheral blood mononuclear cells (PBMC) from atopic subjects were stimulated with recombinant IL (rIL) 4 and anti-CD40 antibody to promote IgE production in the presence or absence of rIL-16 added at different time intervals prior to stimulation. The levels of IgE in cell culture supernatants collected at day 14 were measured by ELISA. The effect of IL-16 on the expression of the Cepsilon transcript was evaluated by reverse-transcription polymerase chain reaction. To evaluate whether the modulatory effect of IL-16 on IgE production was mediated by interferon-gamma (IFN-gamma), anti-CD40/IL-4-stimulated PBMC were cultured in the presence of rIL-16 and neutralizing concentrations of anti-IFN-gamma antibody.

RESULTS

PBMC stimulated with rIL-4 (400 U/ml) and anti-CD40 monoclonal antibody (0.5 microg/ml) produced significant amounts of IgE (range: 1.3-46.0 ng/ml). The addition of rIL-16 twenty-four hours before stimulation significantly reduced the levels of IgE released by anti-CD40/IL-4-stimulated PBMC (0.5-29.6 ng/ml, p < 0.05). IL-16 reduced the expression of the Cepsilon transcript in stimulated PBMC. IL-16 induced the expression of IFN-gamma mRNA. However, the use of anti-IFN-gamma antibody did not alter the effect of IL-16 on IgE production. Rescue doses of IL-13 did not restore the production of IgE by PBMC treated with IL-16. IL-16 did not alter IgE production in CD14-depleted cell preparations suggesting that the IL-16-mediated effects on IgE production may be related to CD14+ cells.

CONCLUSION

These data show that IL-16 inhibits IgE production and therefore may play an important regulatory role in atopic disorders.

Interleukin-12 and interleukin-16 in periodontal disease

The immune system plays an important role in the pathological process of periodontitis. Interleukin-12 (IL-12) is produced by monocytes, macrophages and neutrophils. These cells are proinflammatory infiltrates in periodontitis tissues. High IL-12 will contribute to the immune reaction to Th1 type. IL-12 is an inducer of INF-r production. IFN-gamma itself can also activate IL-12 production. Lipopolysaccharides (LPS) of periodontopathogens are also activators of IL-12. Interleukin-16 (IL-16) can cause the high affinity of IL-2 receptors on CD4+ cells and is chemotaxis to Th1 cells and CD4+ T cells. IL-16 can stimulate monocytes to produce proinflammatory cytokines and is highly associated with inflammation including arthritis, enteritis and allergic rhinitis. However, the information on IL-12 and IL-16 in periodontitis is not clear. In this study, 105 GCF samples were collected from 19 periodontal disease patients and 6 healthy ones. The clinical periodontal indices, the habits of cigarette smoking and alcohol drinking were recorded. ELISA was used to determine the levels of IL-12 and IL16 in the GCF. In the non-smoking/non-alcohol-drinking individuals: (1) the total amount of IL-12 (but not IL-16) was significantly higher in chronic periodontitis (CP) sites than gingivitis (G) or healthy (H) sites; (2) the diseased sites (CP + G) had a significantly higher total amount of IL-12 (but not IL-16) than the H sites. Among CP sites, both the concentration and total amount of IL-16 (but not IL-12) were significantly higher in alcohol drinkers/cigarette smokers as compared to the non-drinkers/non-smokers. CP sites of the drinkers/smokers also had significantly deeper probing pocket depth than sites of those without these two habits. IL-12 and IL-16 may be related to the pathogenesis of periodontal disease, but within the periodontitis sites, IL-16 may be related to disease severity in alcohol drinkers/smokers.

Anti-IL-16 therapy reduces CD4+ T-cell infiltration and improves paralysis and histopathology of relapsing EAE

Infiltration of the central nervous system (CNS) by CD4+ Th1 cells precedes onset and relapses of experimental autoimmune encephalomyelitis (EAE). We reported that (B6xSJL) F1 (H-2b/s) mice with severe relapsing-remitting disease had extensive infiltration by CD4+ T cells compared to that in C57BL/6 (B6) (H-2b) mice, which developed mild low-relapsing disease in response to myelin oligodendrocyte peptide 35-55 (MOG(35-55)). This observation led us to search for mechanisms that specifically regulate trafficking of CD4+ cells in relapsing H-2b/s mice. We show that the CD4+ cell chemoattractant cytokine interleukin (IL)-16 has an important role in regulation of relapsing EAE induced by MOG(35-55) in the (B6xSJL) F1 (H-2b/s) mice. We found production of IL-16 in the CNS of mice with EAE. IL-16 levels in the CNS correlated well with the extent of CD4+ T-cell and B-cell infiltration during acute and relapsing disease. Infiltrating CD4+ T cells, B cells, and to a lesser extent CD8+ T cells all contained IL-16 immunoreactivity. Treatment with neutralizing anti-IL-16 antibody successfully reversed paralysis and ameliorated relapsing disease. In treated mice, diminished infiltration by CD4+ T cells, less demyelination, and more sparing of axons was observed. Taken together, our results show an important role for IL-16 in regulation of relapsing EAE. We describe a novel therapeutic approach to specifically impede CD4+ T cell chemoattraction in EAE based on IL-16 neutralization. Our findings have high relevance for the development of new therapies for relapsing EAE and potentially MS.

Interleukin-16 and peptide derivatives as immunomodulatory therapy in allergic lung disease

The therapeutic potential of interleukin (IL)-16 and derived peptides in allergic asthma is considered, focusing on key interactions with CD4 and associated chemokine receptors. IL-16 is a pleiotropic cytokine that has multiple effector functions with putative roles in varied T cell-mediated inflammatory diseases, such as asthma, inflammatory bowel disease and atopic dermatitis. Both in vitro and in vivo, IL-16 downregulates antigen-driven T cell activation, T helper 2 cytokine production and allergic airway inflammation. Peptides derived from the C-terminal bioactive portion of IL-16 offer advantages related to their retained immunomodulatory properties and absence of signalling in and chemoattraction to T cells.

Immunomodulatory cytokines in asthmatic inflammation

The development of asthmatic inflammation involves a complex array of cytokines that promote the recruitment and activation of a number of different immune cells. While factors involved in initiating and establishing inflammation are well characterized, the process by which this pro-inflammatory cascade is regulated is less well understood. The identification and characterization of immunomodulatory cytokines in asthma has been a difficult proposition. Many of the putative regulatory factors have pleiotropic bioactivities and have been characterized as pro-inflammatory in association with certain pathologic conditions. This chapter addresses the potential role of several endogenous factors which appear to attenuate asthmatic inflammation. Understanding the integration of these factors into the regulation of the inflammatory process will likely result in novel therapeutic approaches.

Sustained linked stimulation via CD3 and CD4 is required for the IL-4-independent development of IL-4 synthesizing CD4+ T cells

Previous work has shown that CD4 engagement can promote the development of interleukin-4-producing cells from naive CD4+ T cells activated with anti-CD3 antibody and interleukin-2 in the absence of other exogenous signals, including interleukin-4 itself. When CD44low CD4+ T cells were activated with immobilized anti-CD3 antibody and interleukin-2, they proliferated and produced interferon-gamma but not interleukin-4. Co-immobilization of antibodies to CD3 and CD4 enhanced cell recoveries and induced interleukin-4 as well as interferon-gamma synthesis. Here we show that these effects of CD4 ligation were not observed when anti-CD4 antibody was replaced with another CD4 ligand, interleukin-16, or when the anti-CD3 and anti-CD4 antibodies were spatially separated by immobilization on different beads. Removal of the anti-CD4 antibodies within the first three days of stimulation also prevented the development of detectable interleukin-4-producing cells. The data suggest that interleukin-4-independent priming of interleukin-4-producing cells in this system requires sustained stimulation via both the T cell receptor and CD4 with close physical association between the ligands for these two receptors.