Interleukin-9 Promotes Chemoresistance in B-ALL Which Correlates with Decreased Bim and c-Raf Protein Expression

Background: According to the National Cancer Institute, B-cell acute lymphoblastic leukemia (B-ALL) is the most common cancer of children and adolescents (ALL, NCI, PDQ, accessed 8/2/2021). Recently, obesity has been identified as a risk factor which is associated with poor survival outcomes (Butturini et al., 2007; Eissa et al., 2017; Ethier et al., 2012) which is concerning due to the obesity rates in children and adolescents having tripled since the 1970's (Ogden et al., 2006; Ogden et al., 2020). Indeed, survival rates in obese pediatric patients with B-ALL can decline by as much as 30% relative to outcomes observed in lean patients, with obese patients more commonly presenting with treatment-related adverse events (Butturini et al., 2007; Eissa et al., 2017; Ethier et al., 2012). A hallmark of obesity is the accumulation of adipocytes, an endocrine cell type which can promote chemoresistance (Ehsanipour et al., 2013; Sheng et al., 2016; Mittelman., 2021). The mechanistic understanding of how adipocytes promote chemoresistance in B-ALL is still under investigation and further insight into this relationship could lead to the rational design of effective therapeutic strategies for obese patients with limited treatment options. Methods: A cytokine/chemokine array was performed on adipocyte and stromal cell secretomes to identify potential adipocyte-secreted inflammatory mediators, which may promote chemoresistance in human B-ALL cells. Once candidate cytokines were identified, we performed in vitro assays to measure how the addition or neutralization of proteins of interest impacted the proliferation, activation of signaling pathways, steady-state mitochondrial protein levels, and survival of human B-ALL cells in the absence or presence of chemotherapy treatment. Additionally, we mined publicly available databases to determine how protein-coding genes of interest were associated with patient survival. Furthermore, we have used the diet-induced murine model of obesity to determine how targeting candidate cytokines impact B-ALL pathogenesis. Results: We have made the novel finding that interleukin-9 (IL-9) levels are higher in adipose-rich microenvironments and activates pro-survival pathways that promote chemoresistance in human B-ALL cells. We have found that obese mice lacking IL-9 are more resistant to B-ALL development due to significant increases in survival outcomes compared to lean mice transplanted with B-ALL cells. Furthermore, we have discovered that human B-ALL cells upregulate the interleukin-9 receptors (IL-9R) when exposed to the adipocyte secretome. This potential feedback loop may increase the responsiveness of leukemia cells to local IL-9 levels. These observations were supported by our data mining results, which revealed that IL-9R gene expression levels were higher in more aggressive subtypes of B-ALL, including Ph-like B-ALL. When human B-ALL cells were treated with recombinant IL-9 (rIL-9), chemoresistance to methotrexate and doxorubicin was observed. Mechanistically, rIL-9 treatment of human B-ALL cells also downregulated the protein expression of the pro-apoptotic mitochondrial-associated protein Bim and pro-proliferative protein Raf. In all, our experiments have identified IL-9 as an adipocyte-enriched cytokine, which promotes pan-chemoresistance in human B-ALL cells. Furthermore, we have shown that this effect maybe mediated in part by suppressing the protein of expression of pro-apoptotic and proliferative proteins. Conclusions: To our knowledge, our results represent the first reports of IL-9 mediated chemoresistance in human B-ALL and the first to demonstrate that IL-9 regulates the protein homeostasis of anti- and pro-apoptotic mitochondrial proteins. In ongoing studies, we are conducting in vitro and murine studies with parental and IL-9R-deficient B-ALL cells to determine how B-ALL pathogenesis and chemosensitivity are impacted. Subsequent studies will be conducted in lean and obese mice transplanted with B-ALL cells who receive chemotherapy treatment alone or in combination with IL-9 neutralizing antibody administration. Disclosures Lee: PureTech Health: Research Funding. Henry: PureTech Health: Research Funding.

Interleukin-9 Facilitates Osteoclastogenesis in Rheumatoid Arthritis

In rheumatoid arthritis (RA), inflammatory cytokines play a pivotal role in triggering abnormal osteoclastogenesis leading to articular destruction. Recent studies have demonstrated enhanced levels of interleukin-9 (IL-9) in the serum and synovial fluid of patients with RA. In RA, strong correlation has been observed between tissue inflammation and IL-9 expression in synovial tissue. Therefore, we investigated whether IL-9 influences osteoclastogenesis in patients with RA. We conducted the study in active RA patients. For inducing osteoclast differentiation, mononuclear cells were stimulated with soluble receptor activator of NF-kB ligand (sRANKL) and macrophage-colony-stimulating factor (M-CSF) in the presence or absence of recombinant (r) IL-9. IL-9 stimulation significantly enhanced M-CSF/sRANKL-mediated osteoclast formation and function. Transcriptome analysis revealed differential gene expression induced with IL-9 stimulation in the process of osteoclast differentiation. IL-9 mainly modulates the expression of genes, which are involved in the metabolic pathway. Moreover, we observed that IL-9 modulates the expression of matrix metalloproteinases (MMPs), which are critical players in bone degradation. Our results indicate that IL-9 has the potential to influence the structural damage in the RA by promoting osteoclastogenesis and modulating the expression of MMPs. Thus, blocking IL-9 pathways might be an attractive immunotherapeutic target for preventing bone degradation in RA.

EGFR-HIF1α signaling positively regulates the differentiation of IL-9 producing T helper cells

Interleukin 9 (IL-9)-producing helper T (Th9) cells are essential for inducing anti-tumor immunity and inflammation in allergic and autoimmune diseases. Although transcription factors that are essential for Th9 cell differentiation have been identified, other signaling pathways that are required for their generation and functions are yet to be explored. Here, we identify that Epidermal Growth Factor Receptor (EGFR) is essential for IL-9 induction in helper T (Th) cells. Moreover, amphiregulin (Areg), an EGFR ligand, is critical for the amplification of Th9 cells induced by TGF-β1 and IL-4. Furthermore, our data show that Areg-EGFR signaling induces HIF1α, which binds and transactivates IL-9 and NOS2 promoters in Th9 cells. Loss of EGFR or HIF1α abrogates Th9 cell differentiation and suppresses their anti-tumor functions. Moreover, in line with its reliance on HIF1α expression, metabolomics profiling of Th9 cells revealed that Succinate, a TCA cycle metabolite, promotes Th9 cell differentiation and Th9 cell-mediated tumor regression.

Interleukin-9 promotes intestinal barrier injury of sepsis: a translational research

Background Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Intestinal mucosal barrier injury is one of the important manifestations of sepsis. Interleukin-9 (IL-9) and IL-9-producing CD4(+) T cells were emerging pro-inflammatory mediators with development of intestinal injury. However, it is unclear whether IL-9 is related to the intestinal barrier injury of sepsis. Methods To investigate the roles of IL-9-producing CD4(+) T cells and IL-9 in the process of barrier injury in sepsis, serum IL-9-producing CD4(+) T cell percentages, IL-9, and D-lactate levels were measured in septic patients and controls. The markers of barrier function in serum and intestinal tissue were also collected in septic rats. Moreover, the barrier injury degree and survival rate of septic rats were also investigated after increasing or interfering with IL-9 expression. Results The serum IL-9-producing CD4(+) T cell percentages, IL-9, and D-lactate levels were significantly higher in septic patients or rats than those in controls. IL-9-producing CD4(+) T cells and IL-9 levels were positively correlated with D-lactate levels and had a high predictive value of 28-day mortality in septic patients. The non-survivors had significantly higher serum T cell percentages, IL-9, and D-lactate levels compared with survivors. In septic rats, IL-9 increased the expression levels of D-lactate, whereas that decreased the expression levels of zonula occludens 1. Moreover, the barrier injury was aggravated or alleviated by increasing or interfering with IL-9 expression, respectively. Survival rate analysis also showed that IL-9 decreased the 14-day survival rate of septic rats. Conclusion IL-9 is closely related to intestinal mucosal barrier injury and mortality in sepsis. IL-9 blockade has the potential to improve the barrier injury in sepsis. Trial registration The study was registered at ClinicalTrials.gov (ID: NCT03791866, Date: December 2018).

Therapeutic Evaluation of Antibody-Based Targeted Delivery of Interleukin 9 in Experimental Pulmonary Hypertension

Background and Aims: Pulmonary hypertension (PH) is a heterogeneous disorder associated with poor prognosis. For the majority of patients, only limited therapeutic options are available. Thus, there is great interest to develop novel treatment strategies focusing on pulmonary vascular and right ventricular remodeling. Interleukin 9 (IL9) is a pleiotropic cytokine with pro- and anti-inflammatory functions. The aim of this study was to evaluate the therapeutic activity of F8IL9F8 consisting of IL9 fused to the F8 antibody, specific to the alternatively-spliced EDA domain of fibronectin, which is abundantly expressed in pulmonary vasculature and right ventricular myocardium in PH. Methods: The efficacy of F8IL9F8 in attenuating PH progression in the monocrotaline mouse model was evaluated in comparison to an endothelin receptor antagonist (ERA) or an IL9 based immunocytokine with irrelevant antibody specificity (KSFIL9KSF). Treatment effects were assessed by right heart catheterization, echocardiography as well as histological and immunohistochemical tissue analyses. Results: Compared to controls, systolic right ventricular pressure (RVPsys) was significantly elevated and a variety of right ventricular echocardiographic parameters were significantly impaired in all MCT-induced PH groups except for the F8IL9F8 group. Both, F8IL9F8 and ERA treatments lead to a significant reduction in RVPsys and an improvement of echocardiographic parameters when compared to the MCT group not observable for the KSFIL9KSF group. Only F8IL9F8 significantly reduced lung tissue damage and displayed a significant decrease of leukocyte and macrophage accumulation in the lungs and right ventricles. Conclusions: Our study provides first pre-clinical evidence for the use of F8IL9F8 as a new therapeutic agent for PH in terms of a disease-modifying concept addressing cardiovascular remodeling.

Therapeutic Potential of IL-9 in Allergic and Autoimmune Diseases

Interleukin-9 (IL-9) is a pleiotropic cytokine produced by several immune and epithelial cells. Recently, many studies have eluded the physiological and pathological roles of IL-9 and its lineage-specific helper T cell subset (Th9). In this chapter, we will focus on the immunological role of Interleukin 9 (IL-9) in allergy and autoimmunity. We will introduce the basics of IL-9 and describe the cells involved in the secretion, signaling, and regulation of IL-9. After establishing the background, we will discuss the pathogenesis and regulation of IL-9 in allergic and autoimmune diseases. We will conclude the chapter by providing an updated therapeutics that target IL-9 and their potential uses in autoimmune and allergic diseases.