A negative role for the interleukin-2-inducible T-cell kinase (ITK) in human Foxp3+ TREG differentiation

Reigniting hope in cancer treatment: the promise and pitfalls of IL-2 and IL-2R targeting strategies

Interleukin-2 (IL-2) and its receptor (IL-2R) are essential in orchestrating immune responses. Their function and expression in the tumor microenvironment make them attractive targets for immunotherapy, leading to the development of IL-2/IL-2R-targeted therapeutic strategies. However, the dynamic interplay between IL-2/IL-2R and various immune cells and their dual roles in promoting immune activation and tolerance presents a complex landscape for clinical exploitation. This review discusses the pivotal roles of IL-2 and IL-2R in tumorigenesis, shedding light on their potential as diagnostic and prognostic markers and their therapeutic manipulation in cancer. It underlines the necessity to balance the anti-tumor activity with regulatory T-cell expansion and evaluates strategies such as dose optimization and selective targeting for enhanced therapeutic effectiveness. The article explores recent advancements in the field, including developing genetically engineered IL-2 variants, combining IL-2/IL-2R-targeted therapies with other cancer treatments, and the potential benefits of a multidimensional approach integrating molecular profiling, immunological analyses, and clinical data. The review concludes that a deeper understanding of IL-2/IL-2R interactions within the tumor microenvironment is crucial for realizing the full potential of IL-2-based therapies, heralding the promise of improved outcomes for cancer patients.

MicroRNA-155 acts as an anti-inflammatory factor in orbital fibroblasts from Graves’ orbitopathy by repressing interleukin-2-inducible T-cell kinase

To investigate the role of microRNA (miR)-155 in inflammation in an in-vitro model of Graves’ orbitopathy (GO). The expression levels of miR-155 were compared between GO and non-GO orbital tissues. The effects of inflammatory stimulation of interleukin (IL)-1β and tumour necrosis factor alpha (TNF-α) on miR-155 expression on GO and non-GO orbital fibroblasts (OFs) were investigated. The effects of miR-155 mimics and inhibitors of inflammatory proteins and IL-2-inducible T-cell kinase (ITK) expression were examined, along with those related to the knockdown of ITK with siITK transfection on inflammatory proteins. We also examined how ITK inhibitors affect miR-155 expression in GO and non-GO OFs. The expression levels of miR-155 were higher in GO orbital tissues than in non-GO tissue. The overexpression of miR-155 was induced by IL-1β and TNF-α in OFs from GO and non-GO patients. IL-1β-induced IL-6 (ICAM1) protein production was significantly reduced (increased) by miR-155 mimics and inhibitors. The mRNA and protein levels of ITK were downregulated by overexpressed miR-155 via miR-155 mimics. Knockdown of ITK via siITK transfection induced a decrease in the expression levels of ITK, IL-17, IL-6, IL-1β, and TNF-α protein. The expression of miR-155 was significantly downregulated by treatment with ITK inhibitors and Bruton’s tyrosine kinase (BTK)/ITK dual inhibitors in a time-dependent manner. Our results indicated a potential relationship between miR-155 and ITK in the context of GO OFs. The overexpression of miR-155 repressed ITK expression and relieved inflammation. Thus, miR-155 appears to have anti-inflammatory effects in GO OFs. This discovery provides a new concept for developing GO treatment therapeutics.

ITK independent development of Th17 responses during hypersensitivity pneumonitis driven lung inflammation

T helper 17 (Th17) cells develop in response to T cell receptor signals (TCR) in the presence of specific environments, and produce the inflammatory cytokine IL17A. These cells have been implicated in a number of inflammatory diseases and represent a potential target for ameliorating such diseases. The kinase ITK, a critical regulator of TCR signals, has been shown to be required for the development of Th17 cells. However, we show here that lung inflammation induced by Saccharopolyspora rectivirgula (SR) induced Hypersensitivity pneumonitis (SR-HP) results in a neutrophil independent, and ITK independent Th17 responses, although ITK signals are required for γδ T cell production of IL17A. Transcriptomic analysis of resultant ITK independent Th17 cells suggest that the SR-HP-induced extrinsic inflammatory signals may override intrinsic T cell signals downstream of ITK to rescue Th17 responses in the absence of ITK. These findings suggest that the ability to pharmaceutically target ITK to suppress Th17 responses may be dependent on the type of inflammation.

Targeting of the Tec Kinase ITK Drives Resolution of T Cell-Mediated Colitis and Emerges as Potential Therapeutic Option in Ulcerative Colitis

BACKGROUND & AIMS

The molecular checkpoints driving T cell activation and cytokine responses in ulcerative colitis (UC) are incompletely understood. Here, we studied the Tec kinase ITK in UC.

METHODS

We analyzed patients with inflammatory bowel disease (n = 223) and evaluated ITK activity as well as the functional effects of cyclosporine-A (CsA). In addition, 3 independent murine colitis models were used to investigate the functional role of ITK. Finally, the activity of ITK was blocked via pharmacological inhibitors and genetically engineered mice. Readout parameters were mini-endoscopy, histopathology, mucosal T cell apoptosis, and cytokine production.

RESULTS

We found an expansion of pITK-expressing mucosal CD4+ T cells in UC rather than Crohn's disease that correlated with disease severity. CsA suppressed activation of ITK in cultured CD4+ T cells and calcineurin-containing microclusters adjacent to the T cell receptor signaling complex. Functionally, the capacity of CsA to suppress activity of experimental colitis was critically dependent on ITK. Genetic inactivation of Itk via gene targeting or induction of allele-sensitive Itk mutants prevented experimental colitis in 3 colitis models, and treatment with pharmacological ITK blockers suppressed established colitis. In addition, ITK controlled apoptosis and activation of mucosal Th2 and Th17 lymphocytes via NFATc2 signaling pathways.

CONCLUSIONS

ITK activation was detected in UC and could be down-regulated in cultured T cells by CsA administration. Selective targeting of ITK emerges as an attractive approach for treatment of chronic intestinal inflammation and potentially UC by driving resolution of mucosal inflammation.

Epstein-Barr Virus in Inborn Immunodeficiency-More Than Infection

Simple Summary

Epstein–Barr Virus (EBV) is a common virus that is readily controlled by a healthy immune system and rarely causes serious problems in infected people. However, patients with certain genetic defects of their immune system might have difficulties controlling EBV and often develop severe and life-threatening conditions, such as severe inflammation and malignancies. In this review, we provide a summary of inherited immune diseases that lead to a high susceptibility to EBV infection and discuss how this infection is associated with cancer development.

Abstract

Epstein–Barr Virus (EBV) is a ubiquitous virus affecting more than 90% of the world’s population. Upon infection, it establishes latency in B cells. It is a rather benign virus for immune-competent individuals, in whom infections usually go unnoticed. Nevertheless, EBV has been extensively associated with tumorigenesis. Patients suffering from certain inborn errors of immunity are at high risk of developing malignancies, while infection in the majority of immune-competent individuals does not seem to lead to immune dysregulation. Herein, we discuss how inborn mutations in TNFRSF9, CD27, CD70, CORO1A, CTPS1, ITK, MAGT1, RASGRP1, STK4, CARMIL2, SH2D1A, and XIAP affect the development, differentiation, and function of key factors involved in the immunity against EBV, leading to increased susceptibility to lymphoproliferative disease and lymphoma.

Targeting ITK signaling for T cell-mediated diseases

The focus of this review is to examine the role of ITK signaling in multiple diseases and investigate the clinical potential of ITK inhibition. The diseases and potential interventions reviewed include T cell-derived malignancies as well as other neoplastic diseases, allergic diseases such as asthma and atopic dermatitis, certain infectious diseases, several autoimmune disorders such as rheumatoid arthritis and psoriasis, and finally the use of ITK inhibition in both solid organ and bone marrow transplantation recipients.

Engaging the Innate and Adaptive Antitumor Immune Response in Lymphoma

Immunotherapy has emerged as a powerful therapeutic strategy for many malignancies, including lymphoma. As in solid tumors, early clinical trials have revealed that immunotherapy is not equally efficacious across all lymphoma subtypes. For example, immune checkpoint inhibition has a higher overall response rate and leads to more durable outcomes in Hodgkin lymphomas compared to non-Hodgkin lymphomas. These observations, combined with a growing understanding of tumor biology, have implicated the tumor microenvironment as a major determinant of treatment response and prognosis. Interactions between lymphoma cells and their microenvironment facilitate several mechanisms that impair the antitumor immune response, including loss of major histocompatibility complexes, expression of immunosuppressive ligands, secretion of immunosuppressive cytokines, and the recruitment, expansion, and skewing of suppressive cell populations. Accordingly, treatments to overcome these barriers are being rapidly developed and translated into clinical trials. This review will discuss the mechanisms of immune evasion, current avenues for optimizing the antitumor immune response, clinical successes and failures of lymphoma immunotherapy, and outstanding hurdles that remain to be addressed.

Overcoming the Hurdles of Autologous T-Cell-Based Therapies in B-Cell Non-Hodgkin Lymphoma

Simple Summary

The activity of novel therapies that utilize patient’s own T-cells to induce remission of B-cell non-Hodgkin lymphoma (B-NHL), including chronic lymphocytic leukemia (CLL), is still suboptimal. In this review, we summarize the clinical efficacy of T-cell-based therapies in B-NHL and provide a biologic rationale for the observed (lack of) responses. We describe and compare the acquired T-cell dysfunctions that occur in the different subtypes of B-NHL. Furthermore, we discuss new insights that could enhance the efficacy of T-cell-based therapies for B-NHL and CLL.

Abstract

The next frontier towards a cure for B-cell non-Hodgkin lymphomas (B-NHL) is autologous cellular immunotherapy such as immune checkpoint blockade (ICB), bispecific antibodies (BsAbs) and chimeric antigen receptor (CAR) T-cells. While highly successful in various solid malignancies and in aggressive B-cell leukemia, this clinical success is often not matched in B-NHL. T-cell subset skewing, exhaustion, expansion of regulatory T-cell subsets, or other yet to be defined mechanisms may underlie the lack of efficacy of these treatment modalities. In this review, a systematic overview of results from clinical trials is given and is accompanied by reported data on T-cell dysfunction. From these results, we distill the underlying pathways that might be responsible for the observed differences in clinical responses towards autologous T-cell-based cellular immunotherapy modalities between diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). By integration of the clinical and biological findings, we postulate strategies that might enhance the efficacy of autologous-based cellular immunotherapy for the treatment of B-NHL.

Affinity and Selectivity Assessment of Covalent Inhibitors by Free Energy Calculations

Covalent inhibitors have been gaining increased attention in drug discovery due to their beneficial properties such as long residence time, high biochemical efficiency, and specificity. Optimization of covalent inhibitors is a complex task that involves parallel monitoring of the noncovalent recognition elements and the covalent reactivity of the molecules to avoid potential idiosyncratic side effects. This challenge calls for special design protocols, including a variety of computational chemistry methods. Covalent inhibition proceeds through multiple steps, and calculating free energy changes of the subsequent binding events along the overall binding process would help us to better control the design of drug candidates. Inspired by the recent success of free energy calculations on reversible binders, we developed a complex protocol to compute free energies related to the noncovalent and covalent binding steps with thermodynamic integration and hybrid quantum mechanical/molecular mechanical (QM/MM) potential of mean force (PMF) calculations, respectively. In optimization settings, we examined two therapeutically relevant proteins complexed with congeneric sets of irreversible cysteine targeting covalent inhibitors. In the selectivity paradigm, we studied the irreversible binding of covalent inhibitors to phylogenetically close targets by a mutational approach. The results of the calculations are in good agreement with the experimental free energy values derived from the inhibition and kinetic constants (K_i and k_inact) of the enzyme-inhibitor binding. The proposed method might be a powerful tool to predict the potency, selectivity, and binding mechanism of irreversible covalent inhibitors.

Inhibition of interleukin-2-inducible T-cell kinase causes reduction in imiquimod-induced psoriasiform inflammation through reduction of Th17 cells and enhancement of Treg cells in mice

Psoriasis is a debilitating chronic skin disease with a worldwide prevalence. Its main features include well-marked silvery scales on the skin of hands and feet and back which arise due to hyperproliferation of keratinocytes and infiltration of immune cells in the skin. Multiple interactions exist between adaptive immune cells such as T cells and innate immune cells such as neutrophils and macrophages which are key players in the pathogenesis of psoriasis. Interleukin-2-inducible T-cell kinase (ITK) plays a key role in Th17 cell development through control of several transcription factors. ITK has been shown to control NFATc1, NFkB and STAT3 in CD4⁺ T cells. Effect of ITK inhibitor in imiquimod (IMQ)-induced psoriasiform inflammation remains to be explored. In the current examination, role of ITK signaling and its inhibition blockade were evaluated on NFATc1, NFkB and STAT3, IL-17A, TNF-α, IFN-γ, Foxp3, IL-10 in CD4⁺ T cells in IMQ model. Our data display that ITK signaling is involved in IMQ-induced psoriatic inflammation as paralleled by enhancement of p-ITK, NFATc1, p-NFkB and p-STAT3 in CD4⁺ T cells. It was associated with enhancement of Th17/Th1 cells and neutrophilic inflammation in the skin. Preventive treatment with ITK inhibitor led to a reduction in Th17/Th1 cells and enhancement of Treg cells. Overall, this study suggests that ITK signaling is an important modulator of transcription factor signaling in CD4⁺ T cells which is associated with Th17/Th1 cells and psoriasiform inflammation in mice. ITK signaling blockade could be a therapeutic target for the treatment of psoriatic inflammation.

ITK inhibition promotes long-term survival of cardiac allografts by regulating T cell PLCγ phosphorylation

BACKGROUND

T cells express interleukin-2 inducible T-cell kinase (ITK), which is an essential modulator of T-cell signaling and function. However, the role of ITK in solid organ transplantation has not been investigated to date. Here, we studied the function of ITK in a murine cardiac transplantation model.

METHOD

Murine heart transplantation was performed using BALB/C mice as donors and C57BL/6 mice as recipients. Subsequent intraperitoneal injections of an ITK-specific inhibitor (BMS-509744) were performed to assess the effects of the kinase following cardiac transplantation. Additionally, naive T cells were isolated to investigate the inhibitor's potential effects in the alloimmune responses.

RESULTS

ITK inhibition was found to promote long-term cardiac allograft survival compared with the control group of 36.0 ± 3.8 days vs. 7.0 ± 0.7 days, respectively (P < 0.01). While the Th1/Th17 percentages showed a decrease in prevalence (P < 0.001), the CD4⁺CD25⁺Foxp3⁺ percentages were not markedly affected. In vitro treatment of CD4⁺ T cells with the ITK inhibitor downregulated the proliferation, possibly by regulating the phosphorylation of PLCγ.

CONCLUSION

ITK inhibition resulted in lower Th1/Th17 responses after cardiac transplantation and markedly prolonged the mean survival time of the cardiac allografts. Thus, ITK inhibition might be a promising therapeutic target to alleviate alloimmune responses in the cardiac transplantation.

Tuning T helper cell differentiation by ITK

CD4+ effector T cells effectuate T cell immune responses, producing cytokines to orchestrate the nature and type of immune responses. The non-receptor tyrosine kinase IL-2 inducible T cell kinase (ITK), a mediator of T cell Receptor signaling, plays a critical role in tuning the development of these effector cells. In this review we discussed the role that signals downstream of ITK, including the Ras/MAPK pathway, play in differentially controlling the differentiation of TH17, Foxp3+ T regulatory (Treg) cells, and Type 1 regulatory T (Tr1) cells, supporting a model of ITK signals controlling a decision point in the effector T cell differentiation process.

Blockade of interleukin-2-inducible T-cell kinase signaling attenuates acute lung injury in mice through adjustment of pulmonary Th17/Treg immune responses and reduction of oxidative stress

Acute lung injury (ALI) is linked with considerable morbidity and mortality. ALI can be caused by various agents, one of them being sepsis. ALI is characterized by injury to vascular endothelium and alveolar epithelium that results in edema, pulmonary immune cells infiltration and hypoxemia. Neutrophils and T cells particularly play a huge role in amplification of pulmonary inflammation through release of multiple inflammatory mediators. Recent reports suggest a strong involvement of Th17 cells and oxidative stress in initiation/amplification of pulmonary inflammation during ALI. Interleukin-2-inducible T-cell kinase (ITK) plays a key role in Th17 cell development through control of several transcription factors. Therefore, our study explored the role of ITK on airway inflammation (total/neutrophilic cell counts, myeloperoxidase activity, E-cadherin expression, histopathological analyses) and effect of its inhibition on various inflammatory/anti-inflammatory pathways during ALI [phosphorylated-ITK (p-ITK), NFATc1, IL-17A, STAT3, Foxp3, IL-10, iNOS, nitrotyrosine, lipid peroxides). ALI was associated with increased total/neutrophilic cell counts and myeloperoxidase activity, and decreased E-cadherin expression in airway epithelial cells (AECs) which was concurrent with upregulation of p-ITK, NFATc1, IL-17A, STAT3 in CD4+ T cells and iNOS/nitrotyrosine in AECs. Treatment with ITK inhibitor reversed ALI-induced changes in airway inflammation and Th17 cells/oxidative stress. Treatment with ITK inhibitor further expanded Treg cells in mice with ALI. In short, our study proposes that ITK signaling plays a significant role in sepsis-induced ALI through upregulation of Th17 cells and oxidative stress. Further, findings provide evidence that ITK blockade could be a potential treatment strategy to attenuate airway inflammation associated with ALI.

Ibrutinib resistance in a patient with transformed diffuse large B-cell lymphoma from primary pulmonary mucosa-associated lymphoid tissue lymphoma

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma is rare among lung neoplasia cases, representing only 0.5%-1% of newly diagnosed primary lung lymphoma. MALT lymphoma with relapsed refractory and malignant transformation is highly heterogeneous and consensus therapy remains undetermined. We report a 55 year-old woman with a 3 year history of primary pulmonary MALT lymphoma confined to the lung presenting with massive pleural effusion. After two cycles of R-CHOP and six cycles of R2-CHOP, pleural effusion disappeared but the pulmonary mass remained persistent. Second-line therapies R2-GemOx failed to make any substantial improvement. Core-needle puncture biopsy of the pulmonary mass was obtained and pathological testing revealed transformed diffuse large B-cell lymphoma of germinal center B-cell subtype. Next-generation sequencing confirmed BN2 subtype. The mass showed no reduction after three cycles of R-MINE, following which the BTK inhibitor ibrutinib was administered to this patient. Unfortunately, after two months of ibrutinib treatment, the patient rapidly developed an enlarged mass and hyperprogressive disease, to which she subsequently succumbed.