Serum levels of IL-9 and IL-11 serve as predictors for the occurrence of early neurologic deterioration in patients with cerebral infarction

BACKGROUND AND AIM

Early neurological deterioration (END) is a common complication of cerebral infarction and a significant contributor to poor prognosis. Our study aimed to investigate the predictive value of interleukin-9 (IL-9) and interleukin-11 (IL-11) in relation to the occurrence of END in patients with cerebral infarction.

MATERIALS AND METHODS

102 patients with cerebral infarction and 64 healthy controls were collected. Patients were categorized into two groups based on the development of END following admission: the END group (n = 44) and the non-END group (n = 58). Enzyme-linked immunosorbent assay was used to determine the serum levels of IL-9, IL-11, and BDNF.

RESULTS

Serum IL-9 was higher and IL-11 lower in the END group than those in the non-END group (P < 0.01). IL-9 correlated positively with NIHSS score (r = 0.627) and infarction volume (r = 0.686), while IL-11 correlated negatively (r = -0.613, -0.679, respectively). Logistic regression identified age, NIHSS score, and IL-9 as risk factors (P < 0.01), and IL-11 as protective (P < 0.01). Combined IL-9 and IL-11 had an ROC curve area of 0.849. BDNF correlated negatively with IL-9 (r = -0.703) and positively with IL-11 (r = 0.711).

CONCLUSION

Serum IL-9 and IL-11 levels can predict the occurrence of END in patient with cerebral infarction and are correlated with serum BDNF levels.

Immunofluorescence analysis of human eosinophils

A prominent inflammatory cell type in allergic diseases is the eosinophil, a granulated white blood cell that releases pro-inflammatory cytokines. Eosinophil-derived cytokines, including interleukin-9 (IL-9) and interleukin-13 (IL-13), can skew the immune response towards an allergic phenotype. Unfortunately, it is challenging to immunolabel and collect quantifiable images of eosinophils given their innate autofluorescence and ability to nonspecifically bind to antibodies. Hence, it is important to optimize permeabilization, blocking, and imaging conditions for eosinophils. Here, we show enhanced protocols to ensure that measured immunofluorescence represents specific immunolabelling. To test this, eosinophils were purified from human blood, adhered to glass coverslips, stimulated with or without platelet-activating factor (PAF), fixed with paraformaldehyde, and then permeabilized with Triton X-100 or saponin. Cells were then blocked with goat serum or human serum and incubated with antibodies labelling cytokines (IL-9 and IL-13) and secretory organelles (CD63 for crystalloid granules and transferrin receptor [TfnRc] for recycling endosomes). Carefully selected isotype controls were used throughout, and cells were imaged using Deltavision super-resolution microscopy. Intensities of fluorescent probes were quantified using Volocity software. Our findings show that permeabilization with saponin, blockage with human serum, and using concentrations of antibodies up to 10 μg/ml allowed us to detect marked differences in fluorescence intensities between isotypes and test antibodies. With the achievement of sufficient qualitative and quantitative measures of increased test probe intensity compared to respective isotypes, these results indicate that our protocol allows for optimal immunolabelling of eosinophils. Using this protocol, future studies may provide further insights into trafficking mechanisms within this important inflammatory cell type.

Interleukin-9 rescues class switching of Memory B cells derived from Common variable immunodeficiency patients

Impaired class switch memory (CSM) B cell formation is the hallmark of common variable immunodeficiency (CVID). Various T cell abnormalities have been observed in CVID patients indicating inadequate T-cell help to B cells. A major setback in understanding its pathogenesis is due to diverse clinical presentation. Therefore, we performed extensive immunological investigation in a cohort of CVID patients with similar clinical findings in order to unravel the T cell dysfunction and its influence on the defective humoral immune response. All recruited CVID patients exhibited B cells in the normal range, but reduced CSM B cells. However, patients showed reduced T cell proliferation, reduced level of serum Interleukin-9 (IL-9) and frequency of IL-9 expressing CD4 (Th-9) cells. IL-9 supplementation along with CD40 engagement was effective in inducing in vitro CSM B cells formation in CVID patients. Thus, IL-9 supplementation has the potential to restore impaired CSM B cell formation in CVID.

Thrombopoietin-independent Megakaryocyte Differentiation of Hematopoietic Progenitor Cells from Patients with Myeloproliferative Neoplasms

Primary hematopoietic stem and progenitor cell (HSPC)-derived megakaryocytes are a valuable tool for translational research interrogating disease pathogenesis and developing new therapeutic avenues for patients with hematologic disorders including myeloproliferative neoplasms (MPNs). Thrombopoietin (TPO)-independent proliferation and megakaryocyte differentiation play a central role in the pathogenesis of essential thrombocythemia and myelofibrosis, two MPN subtypes that are characterized by increased numbers of bone marrow megakaryocytes and somatic mutations in either JAK2, CALR, or MPL. However, current culture strategies generally use healthy HSPCs for megakaryocyte production and are not optimized for the investigation of TPO-independent or TPO-hypersensitive growth and megakaryocyte-directed differentiation of primary patient-derived HSPCs. Here, we describe a detailed protocol covering all necessary steps for the isolation of CD34⁺ HSPCs from the peripheral blood of MPN patients and the subsequent TPO-independent differentiation into CD41⁺ megakaryocytes using both a collagen-based colony assay and a liquid culture assay. This protocol provides a novel, reproducible, and cost-effective approach for investigating megakaryocyte growth and differentiation properties from primary MPN patient cells that can be easily adapted for research on other megakaryocyte-related disorders. This protocol was validated in: EMBO Rep (2022), DOI: 10.15252/embr.202152904 Graphical abstract Schematic representation of the isolation of CD34+ progenitor cells and subsequent TPO-independent megakaryocyte differentiation.

IL-9 stimulates an anti-tumor immune response and facilitates immune checkpoint blockade in the CMT167 mouse model

OBJECTIVES

There is mounting evidence that interleukin-9 (IL-9) is associated with various cancers although its function in lung cancer remains elusive. This study aimed to elucidate the role(s) of IL-9 in lung cancer and the mechanisms involved.

MATERIALS AND METHODS

Expression of IL-9 receptor (IL-9R) in two murine lung cancer cell lines: CMT167 and Lewis lung carcinoma (LLC) were assessed and syngeneic murine lung cancer models were established. Tumor growth, intratumoral immune responses and downstream signaling pathways in tumor-bearing mice were analyzed upon IL-9 treatment. Human lung cancer cell lines A549 and H1975 were included for in vitro validation. Synergistic effects and immune responses of IL-9 in combination with anti-PD-1 were studied.

RESULTS

IL-9R expression was only detected in CMT167 but not LLC cells. IL-9 suppressed CMT167 tumor growth and enhanced anti-tumor T cell responses, both of which were absent in IL-9R-deficient LLC model and lost upon IL-9R knockdown in CMT167 model. In CMT167 tumors, while IL-9 increased CD4⁺ and CD8⁺ T cells and dendritic cells, the cytotoxic T subset was the key driver of IL-9-induced tumor suppression. Consistently, in CMT167 and A549 cells, IL-9/IL-9R signaling promoted MHC class I upregulation. Inhibition of ERK signaling abolished IL-9-mediated MHC class I upregulation in CMT167 cells. IL-9 induced expression of PD-1 and PD-L1 on CD8⁺ T lymphocytes and CMT167 cells respectively. Combined IL-9 treatment with PD-1 blockade further upregulated tumor-infiltrating CD8⁺ T cell frequencies and synergistically suppressed tumor growth in CMT167 model.

CONCLUSION

IL-9 suppresses tumor growth by promoting tumor-derived MHC class I presentation and enhancing cytotoxic T cell immunity. Expression of IL-9R might be used as a biomarker for identification of potential target population susceptible to IL-9 treatment. Our study proposes IL-9 as a promising therapeutic immunomodulatory agent that can be used in combination with PD-1 blockade in lung cancer.

[Interleukin-9 promotes the activation of hepatic stellate cells in mice infected with Schistosoma japonicum]

OBJECTIVE

To investigate the effects of interleukin-9 (IL-9) in the activation of hepatic stellate cells (HSCs) in mice infected with Schistosoma japonicum.

METHODS

Primary HSCs were isolated from mice 7 weeks post-infection with S. japonicum using the in situ liver perfusion and density gradient centrifugation, and cultured in vitro. HSCs were randomly assigned to the PBS control group and IL-9 stimulation group (stimulation with 20 ng/mL IL-9). HSCs were harvested 48 h and 72 h poststimulation, and the expression of α-smooth muscle actin (α-SMA), type I collagen (Col I) and type III collagen (Col III) was determined in HSCs using Western blotting.

RESULTS

Following stimulation with 20 ng/mL IL-9 for 48 h, the expression of α-SMA [(0.87 ± 0.02) vs. (0.69 ± 0.01); t = 17.39, P < 0.01], Col I [(0.74 ± 0.02) vs. (0.65 ± 0.01); t = 9.56, P < 0.01] and Col III [(0.94 ±0.04) vs. (0.75 ± 0.03); t = 6.15, P < 0.01] was significantly greater in HSCs in the IL-9 stimulation group than in the PBS control group. Following stimulation with 20 ng/mL IL-9 for 72 h, the expression of α-SMA was significantly greater in HSCs in the IL-9 stimulation group than in the PBS control group[(0.76 ± 0.02) vs. (0.58 ± 0.02); t = 12.52, P < 0.01]; however, there were no significant differences between the two groups in terms of Col I [(0.68 ± 0.02) vs. (0.66 ± 0.02); t = 1.15, P > 0.05] or Col III expression [(0.75 ± 0.01) vs. (0.72 ± 0.02); t = 2.22, P > 0.05].

CONCLUSIONS

IL-9 promotes the activation of HSCs in mice infected with S. japonicum.

Crosstalk between the Producers and Immune Targets of IL-9

IL-9 has been reported to play dual roles in the pathogenesis of autoimmune disorders and cancers. The collaboration of IL-9 with microenvironmental factors including the broader cytokine milieu and other cellular components may provide important keys to explain its conflicting effects in chronic conditions. In this review, we summarize recent findings on the cellular sources of, and immunological responders to IL-9, in order to interpret the role of IL-9 in the regulation of immune responses. This knowledge will provide new perspectives to improve clinical benefits and limit adverse effects of IL-9 when treating pathologic conditions.

Unravelling the expression of interleukin-9 in chronic rhinosinusitis: A possible role for Staphylococcus aureus

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a Th2 biased inflammation, associated with nasal colonization of Staphylococcus (S.) aureus. Interleukin (IL)-9 is a pro-inflammatory Th2 cytokine with a pivotal role in asthma, allergy and chronic obstructive pulmonary disease (COPD), but is less studied in CRSwNP. We aimed to characterize the expression and cellular source of IL-9 and examined S. aureus as potential local trigger in CRSwNP. We showed increased numbers of interleukin-9 producing neutrophils and mononuclear cells in the tissue of CRSwNP patients. This interleukin-9 production was stimulated by S. aureus and its enterotoxin B in vitro. These findings underline the contribution of S. aureus and define IL-9 as another relevant cytokine in type 2 CRSwNP.

Interleukin-9 regulates macrophage activation in the progressive multiple sclerosis brain

Background

Multiple sclerosis (MS) is an immune-mediated, chronic inflammatory, and demyelinating disease of the central nervous system (CNS). Several cytokines are thought to be involved in the regulation of MS pathogenesis. We recently identified interleukin (IL)-9 as a cytokine reducing inflammation and protecting from neurodegeneration in relapsing–remitting MS patients. However, the expression of IL-9 in CNS, and the mechanisms underlying the effect of IL-9 on CNS infiltrating immune cells have never been investigated.

Methods

To address this question, we first analyzed the expression levels of IL-9 in post-mortem cerebrospinal fluid of MS patients and the in situ expression of IL-9 in post-mortem MS brain samples by immunohistochemistry. A complementary investigation focused on identifying which immune cells express IL-9 receptor (IL-9R) by flow cytometry, western blot, and immunohistochemistry. Finally, we explored the effect of IL-9 on IL-9-responsive cells, analyzing the induced signaling pathways and functional properties.

Results

We found that macrophages, microglia, and CD4 T lymphocytes were the cells expressing the highest levels of IL-9 in the MS brain. Of the immune cells circulating in the blood, monocytes/macrophages were the most responsive to IL-9. We validated the expression of IL-9R by macrophages/microglia in post-mortem brain sections of MS patients. IL-9 induced activation of signal transducer and activator of transcription (STAT)1, STAT3, and STAT5 and reduced the expression of activation markers, such as CD45, CD14, CD68, and CD11b in inflammatory macrophages stimulated in vitro with lipopolysaccharide and interferon (IFN)-γ. Similarly, in situ the number of activated CD68⁺ macrophages was significantly reduced in areas with high levels of IL-9. Moreover, in the same conditions, IL-9 increased the secretion of the anti-inflammatory cytokine, transforming growth factor (TGF)-β.

Conclusions

These results reveal a new cytokine expressed in the CNS, with a role in the context of MS. We have demonstrated that IL-9 and its receptor are both expressed in CNS. Moreover, we found that IL-9 decreases the activation state and promotes the anti-inflammatory properties of human macrophages. This mechanism may contribute to the beneficial effects of IL-9 that are observed in MS, and may be therapeutically potentiated by modulating IL-9 expression in MS.

Targeting the IL-9 pathway in cancer immunotherapy

Interleukin (IL)-9 is a pleiotropic cytokine, which can function as a positive or negative regulator of immune responses on multiple types of cells. The role of IL-9 was originally known in allergic disease and parasite infections. Interestingly, recent studies demonstrate its presence in the tumor tissues of mice and humans, and the association between IL-9 and tumor progression has been revisited following the discovery of T helper (Th) 9 cells. Tumor-specific Th9 cells are considered to be the main subset of CD4⁺ T cells that produce high level of IL-9 and exhibit an IL-9-dependent robust anti-cancer function in solid tumors. IL-9 exerts an unprecedented anti-tumor immunity not only by inducing innate and adaptive immune responses but also directly promoting apoptosis of tumor cells. The objective of this review is to summarize the latest advances regarding the anti-tumor mechanisms of IL-9 and Th9 cells.

Effects of Various Densities of 50 Hz Electromagnetic Field on Serum IL-9, IL-10, and TNF-α Levels

Background:

Extremely low-frequency electromagnetic fields (ELF-EMFs) are abundantly produced in modern societies. In recent years, interest in the possible effects of ELF-EMFs on the immune system has progressively increased.

Objective:

To examine the effects of ELF-EMFs with magnetic flux densities of 1, 100, 500, and 2000 µT on the serum levels of interleukin (IL)-9, IL-10, and tumor necrosis factor-alpha (TNF-α).

Methods:

80 adult male rats were exposed to ELF-EMFs at a frequency of 50 Hz for 2 h/day for 60 days. The serum cytokines were measured at two phases of pre- and post-stimulation of the immune system by human serum albumin (HSA).

Results:

Serum levels of IL-9 and TNF-α, as pro-inflammatory cytokines, were decreased due to 50 Hz EMFs exposure compared with the controls in the pre- and post-stimulation phases. On the contrary, exposures to 1 and 100 µT 50 Hz EMFs increased the levels of antiinflammatory cytokine, and IL-10 only in the pre-stimulation phase. In the post-stimulation phase, the mean level of serum IL-10 was not changed in the experimental groups.

Conclusion:

The magnetic flux densities of 1 and 100 µT 50 Hz EMFs had more immunological effects than EMFs with higher densities. Exposure to 50 Hz EMFs may activate anti-inflammatory effects in rats, by down-modulation of pro-inflammatory cytokines (IL-9 and TNF-α) and induction of the anti-inflammatory cytokine (IL-10).

Interleukin-9 promotes tumorigenesis through augmenting angiogenesis in non-small cell lung cancer

IL-9 is a proinflammatory cytokine that plays a critical role in autoimmunity and inflammatory diseases. However, its role in tumorigenesis has not been well studied. In this study, we found that IL-9 expression was significantly increased and associated with poor progression in human non-small cell lung cancer (NSCLC). Ectopic expression of IL-9 in NSCLC cells did not affect cell proliferation and apoptosis in vitro, but markedly promoted tumor growth in vivo. Immune-profile analysis showed no significant changes in the frequencies of infiltrated immune cells in the tumor site, neither in nude mice nor in immune-competent mice. However, we found that VEGF and microvessel density (MVD) were significantly increased in xenografts. IL-9 could promote cell growth and tube formation of HUVEC cells in vitro. In addition, correlation analysis implied a significant positive relationship between the density of IL-9 and VEGF, as well as MVD in human NSCLC tissues. Finally, we found that IL-9 stimulated tumor angiogenesis via STAT3 signaling. Together, our findings demonstrate a promoting role of IL-9 in lung cancer development, probably through promoting tumor angiogenesis. IL-9 thus may represent a new prognostic marker and therapeutic target for NSCLC.

Th9 Cells as a New Player in Inflammatory Skin Disorders

CD4+T cells are composed of different subpopulations that differ in developmental pathways, surface markers, and their products. Among the catalog of these cells is Th9 cell subset that has a great capacity of Interleukin (IL)-9 production. They could be involved in the pathogenic or protective immune responses. Therefore, it is important to know how Th9 cells and cytokines influence the function of the human immune system as multitasking machinery, both in isolation or after the interaction with other surrounding cells. Since an important characteristic of Th9 cells is their tropism for skin, this article reviews the physiological and pathophysiological functions of Th9 and its cytokines under normal conditions and inflammatory skin disorders.

Th9 lymphocytes and functions of interleukin 9 with the focus on IBD pathology

The work presents the newest knowledge on a new phenotype of T helper lymphocytes (Th9) and on Interleukin 9 (IL-9). Processes leading to transformation of naïve T lymphocyte into Th9 lymphocytes are presented, including the role of IL-4 and TGFβ signaling. Involvement of transcription factor network in production of IL-9 is described. Other cells capable of expressing IL-9 and secreting IL-9 are portrayed. Diversity of IL-9 effects caused by activation of IL-9 receptors on various types of cells is presented. Principal effects of the activation of IL-9 receptor on T-cells seem to be antiapoptotic and stimulatory which leads to enhanced defense against parasitic infection and cancer development but, from the other side, it perpetuate chronic inflammation in autoimmune diseases and allergic processes. In the last years the role of IL-9 in autoimmune diseases such as rheumatic diseases and inflammatory bowel disease gained importance since the increased expression of this cytokine has been observed in animal models of intestinal inflammation and in groups of patients with ulcerative colitis. It was also noted that neutralization of IL-9 in animal models of ulcerative colitis leads to amelioration of inflammatory process, what could have significance in the treatment of this disease in humans in the future.

Role of Th9 cells and IL-9 in inflammatory bowel disease

Th9 cells, a novel subset of CD4⁺ T cells, mainly produce IL-9 and have a critical role in allergic disease, autoimmune disease, and tumors. IL-9 can promote inflammation by increasing the number of inflammatory cells and the secretion of inflammatory mediators and thus play an important role in the development of inflammatory bowel disease (IBD). Th9 cells and IL-9 aggravate inflammation of the colon in both experimental models of colitis and in patients with IBD. The blockade of IL-9 is suited to significantly ameliorate the disease activity and severity of IBD.

CXCL10-induced IL-9 promotes liver fibrosis via Raf/MEK/ERK signaling pathway. Biomed Pharmacother. 2018;105:282-289. [PMID: 29860220 DOI: 10.1016/j.biopha.2018.05.128]

Liver fibrosis is a typical complication of chronic liver diseases resulting in cirrhosis that remains a major public health problem. The aim of the present study was to identify the role of interleukin-9 (IL-9), an important regulator of inflammation and autoimmune diseases, in hepatic fibrosis progression. It was found that the expression of IL-9 was significantly increased in liver tissues of liver cirrhosis patients compared with that in healthy controls. Moreover, CXCL10, not CXCL9 or CXCL11, induced IL-9 expression in the liver tissue. Overexpression of IL-9 enhanced the severity of liver fibrosis in the carbon tetrachloride (CCl₄)-induced liver fibrosis model. Western Blotting analysis revealed that this pro-fibrosis bioactivity of IL-9 was attributed to its selective activation of Raf/MEK/ERK signaling. Finally, administration of neutralizing anti-IL-9 antibody ameliorated liver fibrosis and attenuated the activation of hepatic stellate cells in mice. All these findings indicate that IL-9 plays a deleterious role in the development and progression of liver fibrosis, and IL-9 based immunotherapy may prove to be a promising strategy for the treatment of liver fibrosis.

Ectopically Expressed Membrane-bound Form of IL-9 Exerts Immune-stimulatory Effect on CT26 Colon Carcinoma Cells

IL-9 is a known T cell growth factor with pleiotropic immunological functions, especially in parasite infection and colitis. However, its role in tumor growth is controversial. In this study, we generated tumor clones expressing the membrane-bound form of IL-9 (MB-IL-9) and investigated their influences on immune system. MB-IL-9 tumor clones showed reduced tumorigenicity but shortened survival accompanied with severe body weight loss in mice. MB-IL-9 expression on tumor cells had no effect on cell proliferation or major histocompatibility complex class I expression in vitro. MB-IL-9 tumor clones were effective in amplifying CD4⁺ and CD8⁺ T cells and increasing cytotoxic activity against CT26 cells in vivo. We also observed a prominent reduction in body weights and survival period of mice injected intraperitoneally with MB-IL-9 clones compared with control groups. Ratios of IL-17 to interferon (IFN)-γ in serum level and tumor mass were higher in mice implanted with MB-IL-9 tumor clones than those observed in mice implanted with control cells. These results indicate that the ectopic expression of the MB-IL-9 on tumor cells exerts an immune-stimulatory effect with toxicity. To exploit its benefits as a tumor vaccine, a strategy to control the toxicity of MB-IL-9 tumor clones should be developed.

IL-9: Function, Sources, and Detection

IL-9 is a pleiotropic cytokine produced in different amounts by a wide variety of cells including mast cells, NKT cells, Th2, Th17, Treg, ILC2, and Th9 cells. Th9 cells are considered to be the main CD4+ T cells that produce IL-9. IL-9 exerts its effects on multiple types of cells and different tissues. To date, its main role has been found in the immune responses against parasites and pathogenesis of allergic diseases such as asthma and bronchial hyperreactivity. Additionally, it induces the proliferation of hematologic neoplasias, including Hodgkin's lymphoma in humans. However, IL-9 also has antitumor properties in solid tumors such as melanoma. The objective of this review is to describe IL-9, its function, sources, and methods of detection.

Investigating the roles of regulatory T cells, mast cells and interleukin-9 in the control of skin inflammation by vitamin D

Topical application of biologically active vitamin D [1,25-dihydroxyvitamin D (1,25(OH)₂D)], or low-calcemic analogues, curb skin inflammation through mechanisms that involve migratory dendritic cells (DCs) and regulatory T (T_Reg) cells. 1,25(OH)₂D also promotes immunoregulation by mast cells, and inhibits the development of T helper type-9 (Th9) cells that secrete interleukin-9 (IL-9). Here, we investigated the ability of topical 1,25(OH)₂D to suppress contact dermatitis through an IL-9-dependent process, examining mast cells and IL-9-secreting T cells. Contact dermatitis was modelled in adult BALB/c female mice by initiating a "biphasic ear swelling response" following a single application of 2,4-dinitrofluorobenzene (DNFB). Topical 1,25(OH)₂D (125 ng) applied to ear pinnae prior to (but not after) DNFB sensitisation suppressed the efferent phase of the ear swelling response. This dose of 1,25(OH)₂D did not cause hypercalcemia. At the peak of the efferent ear swelling response, proportions of T_Reg (CD3 + Foxp3+) cells and numbers of mast cells were increased in ear skin of 1,25(OH)₂D-treated mice. Topical 1,25(OH)₂D increased the proportion of Foxp3 + IL-9 + T_Reg cells and the capacity of T_Reg cells to secrete IL-9 ex vivo. However, the proportion of the IL-9 + cells of the total T_Reg cell population was small (< 1%), and the amount of IL-9 secreted by T_Reg cells from mice treated with IL-9 was low (< 50 pg/ml). Furthermore, injection of anti-IL-9 neutralising antibody (100 µg, intraperitoneally) prior to sensitisation did not significantly reverse the suppressive effects of 1,25(OH)₂D. In conclusion, topically applied 1,25(OH)₂D suppressed the efferent phase of a biphasic cutaneous ear swelling response through mechanism(s) that may be dependent on mast cells and T_Reg cells; however, the role of IL-9 in mediating these responses is uncertain. More studies are needed to further characterise the mechanisms by which topical 1,25(OH)₂D modulates cell-mediated immune responses central to its suppressive effects upon contact dermatitis.

Synovial IL-9 facilitates neutrophil survival, function and differentiation of Th17 cells in rheumatoid arthritis

Background

Role of Th9 cells and interleukin-9 (IL-9) in human autoimmune diseases such as psoriasis and ulcerative colitis has been explored only very recently. However, their involvement in human rheumatoid arthritis (RA) is not conclusive. Pathogenesis of RA is complex and involves various T cell subsets and neutrophils. Here, we aimed at understanding the impact of IL-9 on infiltrating immune cells and their eventual role in synovial inflammation in RA.

Methods

In vitro stimulation of T cells was performed by engagement of anti-CD3 and anti-CD28 monoclonal antibodies. Flow cytometry was employed for measuring intracellular cytokine, RORγt in T cells, evaluating apoptosis of neutrophils. ELISA was used for measuring soluble cytokine, Western blot analysis and confocal microscopy were used for STAT3 phosphorylation and nuclear translocation.

Results

We demonstrated synovial enrichment of Th9 cells and their positive correlation with disease activity (DAS28-ESR) in RA. Synovial IL-9 prolonged the survival of neutrophils, increased their matrix metalloprotienase-9 production and facilitated Th17 cell differentiation evidenced by induction of transcription factor RORγt and STAT3 phosphorylation. IL-9 also augmented the function of IFN-γ + and TNF-α + synovial T cells.

Conclusions

We provide evidences for critical role of IL-9 in disease pathogenesis and propose that targeting IL-9 may be an effective strategy to ameliorate synovial inflammation in RA. Inhibiting IL-9 may have wider impact on the production of pathogenic cytokines involved in autoimmune diseases including RA and may offer better control over the disease.

Electronic supplementary material

The online version of this article (10.1186/s13075-017-1505-8) contains supplementary material, which is available to authorized users.

Bone marrow mesenchymal stem cells suppress IL-9 in adjuvant-induced arthritis

Interleukin-9 (IL-9) has been shown to be upregulated in rheumatoid arthritis (RA). The exact role of IL-9 has not yet been effectively studied. Mesenchymal stem cells (MSCs) have shown a promising immunomodulatory role towards repairing cartilage and restoring joint function. One of the key problems influencing the therapeutic efficacy of stem cell therapy is the poor cell survival following transplantation. This is attributed to oxidative and inflammatory stresses at the injured sites. Hesperidin (Hsd), a flavanone present in citrus fruits, has been studied as potential therapeutic agents that have anti-oxidant and anti-inflammatory activities. The objective of this study is to evaluate the therapeutic paracrine action of bone marrow MSCs on the IL-9 level in adjuvant-induced arthritis (AIA) and the enhancement effect of Hsd on transplanted MSCs. Articular tissue inflammation and cartilage damage were assessed by histological scoring. Antinuclear autoantibodies, tumour necrosis factor-alpha (TNF-α), IL-9, IL-4, interferon gamma (IFN-δ), and transforming growth factor-beta1 (TGF-β1), as well as malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) levels, were assessed in spleen tissue homogenates after treatment with MSCs either alone or combined with Hsd for 4 weeks in an AIA rat model. Results of this study confirmed that MSCs decreased IL-9 levels in AIA and provide novel insights into the application of Hsd on MSC-based treatments. Highlights Adjuvant-induced arthritis (AIA) is one of the most widely used models that has a great similarity to rheumatoid arthritis (RA). Few studies in recent years have estimated IL-9 in rheumatic diseases and it remains an understudied cytokine. For the first time, bone marrow mesenchymal stem cells (MSCs) therapy has a vital role in splenocytes IL-9 level and further studies are required. Combined therapy of MSCs with antioxidants as hesperidin (Hsd) can alleviate oxidative stress and enhance stem cells immunomodulatory action.

Dynamics of Th9 cells and their potential role in immunopathogenesis of murine schistosomiasis

Background

Th1, Th2, Th17, Treg and Tfh cells play important roles in schistosomiasis. Th9 cells secrete IL-9 as a signature cytokine and contribute to several classes of inflammatory disease. However, the effects of Th9 cells in schistosomiasis are unknown. We aimed to explore the dynamic changes and potential roles of Th9 cells in the pathogenesis of hepatic egg granulomatous inflammation in mice infected with Schistosoma japonicum.

Methods

Twenty mice with S. japonicum infection and five normal controls (NC) were used as models. The average areas of egg granulomas were estimated by hematoxylin-eosin (H & E) staining. Hepatic IL-9 and transcription factor PU.1 levels were detected by immunohistochemistry. Flow cytometry techniques were used to analyze the proportions of Th9 cells. With the help of ELISA, serum levels of IL-9 were examined.

Results

The egg granulomas began to form from four weeks after infection and continued to develop. In parallel with the development of egg granulomas, the hepatic levels of IL-9 and PU.1 increased very slowly during the first four weeks post-infection and increased rapidly thereafter. Moreover, the proportions of splenic Th9 cells and levels of serum IL-9 had similar developmental trends with the egg granulomas.

Conclusion

The proliferation of Th9 cells and levels of IL-9 were significantly higher in S. japonicum-infected mice compared to NC. In addition, dynamic changes of Th9 and IL-9 were synchronous with the developmental trend of hepatic egg granulomatous inflammation, suggesting that Th9 cells might be a new subset in the pathogenesis of schistosomiasis.

Evaluation of Interleukin-9 Expression as a Potential Therapeutic Target in Chronic Lymphocytic Leukemia in a Cohort of Egyptian Patients

Chronic lymphocytic leukemia (CLL) is a common lymphoid malignancy that has a highly variable clinical course. Genomic features as zeta-chain-associated protein kinase 70 (ZAP70) expression and CD38 expression provide further differentiation of disease prognosis. Extensive studies have confirmed the oncogenic activities of IL-9 in lymphoma. The aim of the current study was to investigate the contribution of IL-9 expression to the pathogenesis of CLL and its correlation to other prognostic parameters. This study was conducted on 80 patients at diagnosis with CLL and 80 healthy controls. Using real time polymerase chain reaction and enzyme linked immunosorbant assay, IL-9 mRNA expression and its serum level were compared between patients and controls. They were both correlated with other prognostic factors.

RESULTS

There was an overexpression of IL-9 in CLL patients that correlated with modified Rai staging, ZAP70, CD38 and all hallmarks of an active and aggressive disease. The correlation between IL-9 upregulation and patient characteristics provided direct clinical evidence for its contribution to the pathogenesis of CLL. In conclusion, significantly higher expression of IL-9 measured at both the mRNA and the protein levels in patients with CLL that correlates with more complex course of the disease and worse prognosis may allow one to speculate its importance in the pathogenesis of the disease and its possible impact on prognosis.

Evaluation of serum levels of IL-9 and IL-17 in human Schistosoma mansoni infection and their relationship with periportal fibrosis

Serum levels of IL-9 and IL-17 cytokines were evaluated in patients in the acute, chronic phases and clinical forms of human schistosomiasis and in different classifications of periportal fibrosis. No significant differences between the groups of the disease with serum levels of cytokine were found. However, this study discusses the results of some cytokines that have not fully defined roles in the pathology of human schistosomiasis. Furthermore, an examination was made of subjects in the acute phase. This is an important group that is difficult to identify in areas where the disease is endemic. More studies are being undertaken to study the role of IL-9 and IL-17 in human Schistosoma mansoni infection and their relationship with the immunopathogenesis of disease.

Interleukin-9 promotes cell survival and drug resistance in diffuse large B-cell lymphoma

Background

Interleukin-9 (IL-9) was discovered as a helper T cell growth factor. It has long been recognized as an important regulator in allergic inflammation. Recent years it was discovered to induce cell growth and differentiation of multiple transformed cells. However, its oncogenic activities in B-cell lymphomas have not been reported in detail.

Methods

Serum levels of IL-9 in DLBCL patients were quantified by ELISA, and its clinical significance was analysed. The expression of IL-9 receptor (IL-9R) was investigated in lymphoma cell lines by RT-PCR and western blot, respectively. In DLBCL cell lines LY1 and LY8, IL-9R genes were knocked down by RNA interference and stable transfected cells were selected with puromycin. Normal and final siIL-9R (and siControl) LY1 and LY8 cells were treated with IL-9 alone and in synergy with chemotherapeutic drugs. Cell proliferation and apoptosis were assessed by Brdu incorporation and flow cytometric analysis. The mRNA of apoptosis regulation genes were measured with real-time PCR.

Results

Elevated serum levels of IL-9 were detected in DLBCL patients (24/30) compared to healthy controls (0/15). Positive expression of IL-9 (defined as a serum level ≥1 pg/ml) was correlated with lower serum albumin levels and high international prognostic index (IPI) scores. IL-9R was expressed in both mRNA and protein levels in the five lymphoma cell lines, including LY1, LY8, MINO, SP53 and Jurkat. In vitro studies showed that IL-9 directly induced proliferation and inhibited apoptosis in LY1 and LY8 cells. It protects LY1 and LY8 cells from prednisolone induced apoptosis, and promotes their proliferation that were inhibited by rituximab, vincristine and prednisolone. Its molecular mechanism may be concerned with upregulating expression of p21CIP1 gene. Knock-down of IL-9R gene could reverse the effects of IL-9 on LY1 and LY8 cells.

Conclusions

IL-9 is associated with clinical features of DLBCL patients. It promotes survival of DLBCL cells and reduces the sensitivities of tumor cells to chemotherapeutic drugs via upregulation of p21CIP1 genes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0374-3) contains supplementary material, which is available to authorized users.

Circulatory Th9 cells in patients with hepatitis B associated liver cirrhosis

AIM: To investigate the phenotype and function of circulatory T-helper 9 (Th9) cells in patients with hepatitis B associated liver cirrhosis, as well as the impact of the macrophage inflammatory protein 3a (MIP-3a, CCL20)/CCR6 axis on Th9 cell expression.

METHODS: Peripheral blood and liver tissue samples were collected from 18 patients with hepatitis B associated cirrhosis and 6 healthy donors. Expression and phenotype of Th9 cells in the peripheral blood were tested by flow cytometry. Serum interleukin-9 (IL-9) and CCL20 levels were tested by enzyme-linked immunosorbent assay (ELISA). Immunohistochemical staining was used to detect the expression of CCR6 and CCL20 proteins in liver tissues.

RESULTS: Compared with normal controls, the frequency of Th9 cells in the hepatitis B-associated cirrhosis group and serum level of IL-9 significantly increased. The levels of Th9 cells and IL-9 were associated with severity of liver cirrhosis. In addition, expression of CCR4 and CCR6 chemokine receptors in Th9 cells was significantly increased. Immunohistochemistry showed that the expression of CCL20 and CCR6 proteins was significantly increased in the hepatitis B associated cirrhosis group.

CONCLUSION: Th9 cells may be involved in the development and progression of hepatitis B associated liver cirrhosis, and the CCL20/CCR6 axis may play a role in Th9 cell infiltration in liver tissue.

Effects of interleukin-9 blockade on chronic airway inflammation in murine asthma models

Purpose

Asthma is a chronic inflammatory disease of the airways associated with structural changes and airway remodeling. Interleukin (IL)-9 has pleiotropic effects on both inflammatory cells and airway structural cells, which are involved in asthma pathogenesis. We evaluated the effects of IL-9 blockade on chronic airway inflammation.

Methods

Acute airway inflammation was induced in Balb/c mice using aerosolized ovalbumin (OVA), whereas chronic asthma was induced by OVA exposure for 5 weeks with anti-IL-9 or isotype-matched antibody (Ab) treatment during the OVA challenge. Inflammatory cells in bronchoalveolar lavage fluid (BALF) were counted and lung tissues were stained to detect cellular infiltration, mucus deposition, and collagen accumulation. The levels of interferon (IFN)-γ, IL-4, IL-5, IL-9, IL-17, and immunoglobulin E (IgE) in BALF were measured using enzyme linked immunosorbent assays, and profiles of inflammatory cells and subsets of T helper (Th) cells were analyzed using flow cytometry.

Results

IL-9, IL-17, and IFN-γ levels were significantly increased in the chronic group compared to the acute asthma group. However, the number of IL-9-positive cells was not affected, with a decrease in Th17 cells in OVA-challenged caspase-1 knockout mice. Numbers of eosinophils, neutrophils, B cells, mast cells, and Th17 cells decreased after administration of anti-IL-9 Ab. Total IgE, IL-5, IL-9, and IL-17 levels were also lower in the anti-IL-9 group.

Conclusions

Our results suggest that anti-IL-9 Ab treatment inhibits pulmonary infiltration of inflammatory cells and cytokine production, especially IL-17. These results provide a basis for the use of an anti-IL-9 Ab to combat IL-17-mediated airway inflammation.