Disorders of the JAK/STAT Pathway in T Cell Lymphoma Pathogenesis: Implications for Immunotherapy.

Common gamma receptor-dependent cytokines and their JAK/STAT pathways play pivotal roles in T cell immunity. Abnormal activation of this system was pervasive in diverse T cell malignancies assessed by pSTAT3/pSTAT5 phosphorylation. Activating mutations were described in some but not all cases. JAK1 and STAT3 were required for proliferation and survival of these T cell lines whether or not JAKs or STATs were mutated. Activating JAK and STAT mutations were not sufficient to initiate leukemic cell proliferation but rather only augmented signals from upstream in the cytokine pathway. Activation required the full pathway, including cytokine receptors acting as scaffolds and docking sites for required downstream JAK/STAT proteins. JAK kinase inhibitors have depressed leukemic T cell line proliferation. The insight that JAK/STAT system activation is pervasive in T cell malignancies suggests novel therapeutic approaches that include antibodies to common gamma cytokines, inhibitors of cytokine-receptor interactions, and JAK kinase inhibitors that may revolutionize therapy for T cell malignancies.

Arginine methylation controls the strength of γc-family cytokine signaling in T cell maintenance.

The methylation of arginine residues in proteins is a post-translational modification that contributes to a wide range of biological processes. Many cytokines involved in T cell development and activation utilize the common cytokine receptor γ-chain (γc) and the kinase JAK3 for signal transduction, but the regulatory mechanism that underlies the expression of these factors remains unclear. Here we found that the arginine methyltransferase PRMT5 was essential for the maintenance of invariant natural killer T cells (iNKT cells), CD4+ T cells and CD8+ T cells. T cell-specific deletion of Prmt5 led to a marked reduction in signaling via γc-family cytokines and a substantial loss of thymic iNKT cells, as well as a decreased number of peripheral CD4+ T cells and CD8+ T cells. PRMT5 induced the symmetric dimethylation of Sm proteins that promoted the splicing of pre-mRNA encoding γc and JAK3, and this critically contributed to the expression of γc and JAK3. Thus, arginine methylation regulates strength of signaling via γc-family cytokines by facilitating the expression of signal-transducing components.

PGE2 inhibits TIL expansion by disrupting IL-2 signalling and mitochondrial function.

Expansion of antigen-experienced CD8+ T cells is critical for the success of tumour-infiltrating lymphocyte (TIL)-adoptive cell therapy (ACT) in patients with cancer1. Interleukin-2 (IL-2) acts as a key regulator of CD8+ cytotoxic T lymphocyte functions by promoting expansion and cytotoxic capability2,3. Therefore, it is essential to comprehend mechanistic barriers to IL-2 sensing in the tumour microenvironment to implement strategies to reinvigorate IL-2 responsiveness and T cell antitumour responses. Here we report that prostaglandin E2 (PGE2), a known negative regulator of immune response in the tumour microenvironment4,5, is present at high concentrations in tumour tissue from patients and leads to impaired IL-2 sensing in human CD8+ TILs via the PGE2 receptors EP2 and EP4. Mechanistically, PGE2 inhibits IL-2 sensing in TILs by downregulating the IL-2Rγc chain, resulting in defective assembly of IL-2Rß-IL2Rγc membrane dimers. This results in impaired IL-2-mTOR adaptation and PGC1α transcriptional repression, causing oxidative stress and ferroptotic cell death in tumour-reactive TILs. Inhibition of PGE2 signalling to EP2 and EP4 during TIL expansion for ACT resulted in increased IL-2 sensing, leading to enhanced proliferation of tumour-reactive TILs and enhanced tumour control once the cells were transferred in vivo. Our study reveals fundamental features that underlie impairment of human TILs mediated by PGE2 in the tumour microenvironment. These findings have therapeutic implications for cancer immunotherapy and cell therapy, and enable the development of targeted strategies to enhance IL-2 sensing and amplify the IL-2 response in TILs, thereby promoting the expansion of effector T cells with enhanced therapeutic potential.

The expanding family of innate lymphoid cells: regulators and effectors of immunity and tissue remodeling.

Research has identified what can be considered a family of innate lymphoid cells (ILCs) that includes not only natural killer (NK) cells and lymphoid tissue-inducer (LTi) cells but also cells that produce interleukin 5 (IL-5), IL-13, IL-17 and/or IL-22. These ILC subsets are developmentally related, requiring expression of the transcriptional repressor Id2 and cytokine signals through the common γ-chain of the IL-2 receptor. The functional differentiation of ILC subsets is orchestrated by distinct transcription factors. Analogous to helper T cell subsets, these evolutionarily conserved yet distinct ILCs seem to have important roles in protective immunity, and their dysregulation can promote immune pathology.

Keratinocytes activated by IL-4/IL-13 express IL-2Rγ with consequences on epidermal barrier function.

Atopic dermatitis (AD) is a Th2-type inflammatory disease characterized by an alteration of epidermal barrier following the release of IL-4 and IL-13. These cytokines activate type II IL-4Rα/IL-13Rα1 receptors in the keratinocyte. Whilst IL-2Rγ, that forms type I receptor for IL-4, is only expressed in haematopoietic cells, recent studies suggest its induction in keratinocytes, which questions about its role. We studied expression of IL-2Rγ in keratinocytes and its role in alteration of keratinocyte function and epidermal barrier. IL-2Rγ expression in keratinocytes was studied using both reconstructed human epidermis (RHE) exposed to IL-4/IL-13 and AD skin. IL-2Rγ induction by type II receptor has been analyzed using JAK inhibitors and RHE knockout (KO) for IL13RA1. IL-2Rγ function was investigated in RHE KO for IL2RG. In RHE, IL-4/IL-13 induce expression of IL-2Rγ at the mRNA and protein levels. Its mRNA expression is also visualized in keratinocytes of lesional AD skin. IL-2Rγ expression is low in RHE treated with JAK inhibitors and absent in RHE KO for IL13RA1. Exposure to IL-4/IL-13 alters epidermal barrier, but this alteration is absent in RHE KO for IL2RG. A more important induction of IL-13Rα2 is reported in RHE KO for IL2RG than in not edited RHE. These results demonstrate IL-2Rγ induction in keratinocytes through activation of type II receptor. IL-2Rγ is involved in the alteration of the epidermal barrier and in the regulation of IL-13Rα2 expression. Observation of IL-2Rγ expression by keratinocytes inside AD lesional skin suggests a role for this receptor subunit in the disease.

Interleukin-2 at the crossroads of effector responses, tolerance, and immunotherapy.

Interleukin-2 (IL-2) is a pleiotropic cytokine produced after antigen activation that plays pivotal roles in the immune response. Discovered as a T cell growth factor, IL-2 additionally promotes CD8(+) T cell and natural killer cell cytolytic activity and modulates T cell differentiation programs in response to antigen, promoting naïve CD4(+) T cell differentiation into T helper 1 (Th1) and T helper 2 (Th2) cells while inhibiting T helper 17 (Th17) and T follicular helper (Tfh) cell differentiation. Moreover, IL-2 is essential for the development and maintenance of T regulatory cells and for activation-induced cell death, thereby mediating tolerance and limiting inappropriate immune reactions. In this review, we focus on the molecular mechanisms and complex cellular actions of IL-2, its cooperative and opposing effects with other cytokines, and how both promoting and blocking the actions of IL-2 are being utilized in clinical medicine.

Protein abundance of the cytokine receptor γc controls the thymic generation of innate-like T cells.

Innate-like T (iT) cells comprise a population of immunoregulatory T cells whose effector function is imposed during their development in the thymus to provide protective immunity prior to antigen encounter. The molecular mechanism that drives the generation of iT cells remains unclear. Here, we report that the cytokine receptor γc plays a previously unappreciated role for thymic iT cells by controlling their cellular abundance, lineage commitment, and subset differentiation. As such, γc overexpression on thymocytes dramatically altered iT cell generation in the thymus, as it skewed the subset composition of invariant NKT (iNKT) cells and promoted the generation of IFNγ-producing innate CD8 T cells. Mechanistically, we found that the γc-STAT6 axis drives the differentiation of IL-4-producing iNKT cells, which in turn induced the generation of innate CD8 T cells. Collectively, these results reveal a cytokine-driven circuity of thymic iT cell differentiation that is controlled by the abundance of γc proteins.

MK-6, a novel not-α IL-2, elicits a potent antitumor activity by improving the effector to regulatory T cell balance.

IL-2 is a pleiotropic cytokine that regulates immune cell homeostasis. Its immunomodulatory function has been used clinically as an active immunotherapy agent for metastatic cancers. However, severe adverse effects, including the vascular leak syndrome and the preferential stimulation of anti-immunogenic Treg rather than effector T cells, have been obstacles. We newly designed a mutein IL-2, Mutakine-6 (MK-6), with reduced IL-2Rα-binding capability. MK-6 induced comparable cell growth potential toward IL-2Rßγ-positive T cells but was far less efficient in in vitro Treg proliferation and STAT5 activation. Unlike IL-2, in vivo administration of MK-6 produced minimal adverse effects. Using CT26 and B16F10-syngeneic tumor models, we found MK-6 was highly efficacious on tumor regression. Serum albumin conjugation to MK-6 prolonged in vivo half-life and accumulated in CT26 tumors, showing enhanced antitumor effect. Tumor-infiltrating leukocytes analysis revealed that albumin-fused MK-6 increased the ratio of effector CD8+ T cells to CD4+ Treg cells. These results demonstrated that MK-6 is an efficient immunomodulator potentially used for improved immunotherapy with decreased adverse effects and attenuated Treg stimulation.

Ubiquitin-specific protease 22 is critical to in vivo angiogenesis, growth and metastasis of non-small cell lung cancer.

BACKGROUND: Loss of monoubiquitination of histone H2B (H2Bub1) was found to be associated with poor differentiation, cancer stemness, and enhanced malignancy of non-small cell lung cancer (NSCLC). Herein, we investigated the biological significance and therapeutic implications of ubiquitin-specific protease 22 (USP22), an H2Bub1 deubiquitinase, in non-small cell lung cancer (NSCLC). METHODS: USP22 expression and its clinical relevance were assessed in NSCLC patients. The effects of USP22 knockout on sensitivity to cisplatin and irradiation, and growth, metastasis of NSCLC xenografts, and survival of cancer-bearing mice were investigated. The underlying mechanisms of targeting USP22 were explored. RESULTS: Overexpression of USP22 was observed in 49.0% (99/202) of NSCLC tissues; higher USP22 immunostaining was found to be associated with enhanced angiogenesis and recurrence of NSCLC. Notably, USP22 knockout dramatically suppressed in vitro proliferation, colony formation; and angiogenesis, growth, metastasis of A549 and H1299 in mouse xenograft model, and significantly prolonged survival of metastatic cancer-bearing mice. Furthermore, USP22 knockout significantly impaired non-homologous DNA damage repair capacity, enhanced cisplatin and irradiation-induced apoptosis in these cells. In terms of underlying mechanisms, RNA sequencing and gene ontology enrichment analysis demonstrated that USP22 knockout significantly suppressed angiogenesis, proliferation, EMT, RAS, c-Myc pathways, concurrently enhanced oxidative phosphorylation and tight junction pathways in A549 and H1299 NSCLC cells. Immunoblot analysis confirmed that USP22 knockout upregulated E-cadherin, p16; reduced ALDH1A3, Cyclin E1, c-Myc, and attenuated activation of AKT and ERK pathways in these cells. CONCLUSIONS: Our findings suggest USP22 plays critical roles in the malignancy and progression of NSCLC and provide rationales for targeting USP22, which induces broad anti-cancer activities, as a novel therapeutic strategy for NSCLC patient.

T cell receptor-dependent regulation of lipid rafts controls naive CD8+ T cell homeostasis.

T cell receptor (TCR) contact with self ligands keeps T cells alive and is shown here to cause naive CD8(+), but not CD4(+), T cells to be hypersensitive to certain gamma(c) cytokines, notably interleukin (IL)-2, IL-15, and IL-7. Hypersensitivity of CD8(+) T cells to IL-2 was dependent on a low-level TCR signal, associated with high expression of CD5 and GM1, a marker for lipid rafts, and was abolished by disruption of lipid rafts. By contrast, CD4(+) T cells expressed low amounts of GM1 and were unresponsive to IL-2. Physiologically, sensitivity to IL-7 and IL-15 maintains survival of resting CD8(+) T cells, whereas sensitivity to IL-2 may be irrelevant for normal homeostasis but crucial for the immune response. Thus, TCR contact with antigen upregulates GM1 and amplifies responsiveness of naive CD8(+) T cells to IL-2, thereby making the cells highly sensitive to exogenous IL-2 from CD4(+) T helper cells.

Cutting Edge: Differential Fine-Tuning of IL-2- and IL-15-Dependent Functions by Targeting Their Common IL-2/15Rß/γc Receptor.

Interleukin 2 and IL-15 are two closely related cytokines, displaying important functions in the immune system. They share the heterodimeric CD122/CD132 receptor to deliver their signals within target cells. Their specificity of action is conferred by their α receptor chains, IL-2Rα and IL-15Rα. By combining an increased affinity for CD122 and an impaired recruitment of CD132, we have generated an original molecule named IL-2Rß/γ (CD122/CD132) inhibitor (BiG), targeting the CD122/CD132 receptor. BiG efficiently inhibited IL-15- and IL-2-dependent functions of primary cells, including CD8 T and NK cells, in vitro and in vivo. We also report a differential dynamic of action of these cytokines by highlighting a major role played by the IL-2Rα receptor. Interestingly, due to the presence of IL-2Rα, BiG had no impact on IL-2-dependent regulatory T cell proliferation. Thus, by acting as a fine switch in the immune system, BiG emphasizes the differential roles of these two cytokines.

Staphylococcal enterotoxin A (SEA) stimulates STAT3 activation and IL-17 expression in cutaneous T-cell lymphoma.

Cutaneous T-cell lymphoma (CTCL) is characterized by proliferation of malignant T cells in a chronic inflammatory environment. With disease progression, bacteria colonize the compromised skin barrier and half of CTCL patients die of infection rather than from direct organ involvement by the malignancy. Clinical data indicate that bacteria play a direct role in disease progression, but little is known about the mechanisms involved. Here, we demonstrate that bacterial isolates containing staphylococcal enterotoxin A (SEA) from the affected skin of CTCL patients, as well as recombinant SEA, stimulate activation of signal transducer and activator of transcription 3 (STAT3) and upregulation of interleukin (IL)-17 in immortalized and primary patient-derived malignant and nonmalignant T cells. Importantly, SEA induces STAT3 activation and IL-17 expression in malignant T cells when cocultured with nonmalignant T cells, indicating an indirect mode of action. In accordance, malignant T cells expressing an SEA-nonresponsive T-cell receptor variable region ß chain are nonresponsive to SEA in monoculture but display strong STAT3 activation and IL-17 expression in cocultures with SEA-responsive nonmalignant T cells. The response is induced via IL-2 receptor common γ chain cytokines and a Janus kinase 3 (JAK3)-dependent pathway in malignant T cells, and blocked by tofacitinib, a clinical-grade JAK3 inhibitor. In conclusion, we demonstrate that SEA induces cell cross talk-dependent activation of STAT3 and expression of IL-17 in malignant T cells, suggesting a mechanism whereby SEA-producing bacteria promote activation of an established oncogenic pathway previously implicated in carcinogenesis.

The Potential Role of a Soluble γ-Chain Cytokine Receptor as a Regulator of IL-7-Induced Lymphoproliferative Disorders.

IL-7 is an essential, nonredundant growth factor for T and B cell generation and maintenance. While IL-7 deficiency results in lymphopenia, overexpression of IL-7 can cause neoplasia in experimental models. IL-7's involvement in neoplasia has been appreciated through studies of IL-7 transgenic (Tg) mice models and human lymphoma patients. Since we recently found that a soluble form of the common γ-chain (γc) cytokine receptor (sγc) antagonistically regulates IL-7 signaling, IL-7 and sγc double-Tg mice were generated to investigate the effects of sγc overexpression in IL-7-mediated lymphoproliferative disorders (LPDs). The overexpression of sγc prevents IL-7Tg-induced abnormal increase of LN cell numbers and the development of splenomegaly, resulting in striking amelioration of mortality and disease development. These results suggest that modification of γc cytokine responsiveness by sγc molecules might control various γc cytokine-associated hematologic malignancy, and also provide an alternative view to approach antitumor therapy.

Glomerular common gamma chain confers B- and T-cell-independent protection against glomerulonephritis.

Crescentic glomerulonephritis is a life-threatening renal disease that has been extensively studied by the experimental anti-glomerular basement membrane glomerulonephritis (anti-GBM-GN) model. Although T cells have a significant role in this model, athymic/nude mice and rats still develop severe renal disease. Here we further explored the contribution of intrinsic renal cells in the development of T-cell-independent GN lesions. Anti-GBM-GN was induced in three strains of immune-deficient mice (Rag2-/-, Rag2-/-Il2rg-/-, and Rag2-/-Il2rb-/-) that are devoid of either T/B cells or T/B/NK cells. The Rag2-/-Il2rg-/- or Rag2-/-Il2rb-/- mice harbor an additional deletion of either the common gamma chain (γC) or the interleukin-2 receptor ß subunit (IL-2Rß), respectively, impairing IL-15 signaling in particular. As expected, all these strains developed severe anti-GBM-GN. Additionally, bone marrow replenishment experiments allowed us to deduce a protective role for the glomerular-expressed γC during anti-GBM-GN. Given that IL-15 has been found highly expressed in nephritic kidneys despite the absence of lymphocytes, we then studied this cytokine in vitro on primary cultured podocytes from immune-deficient mice (Rag2-/-Il2rg-/- and Rag2-/-Il2rb-/-) compared to controls. IL-15 induced downstream activation of JAK1/3 and SYK in primary cultured podocytes. IL-15-dependent JAK/SYK induction was impaired in the absence of γC or IL-2Rß. We found γC largely induced on podocytes during human glomerulonephritis. Thus, renal lesions are indeed modulated by intrinsic glomerular cells through the γC/IL-2Rß receptor response, to date classically described only in immune cells.

Murine Th17 cells utilize IL-2 receptor gamma chain cytokines but are resistant to cytokine withdrawal-induced apoptosis.

Adoptive cellular therapy (ACT) with the Th17 subset of CD4+ T cells can cure established melanoma in preclinical models and holds promise for treating human cancer. However, little is known about the growth factors necessary for optimal engraftment and anti-tumor activity of Th17 cells. Due to the central role of IL-2 receptor gamma chain (IL2Rγ-chain) cytokines (IL-2, IL-7, and IL-15) in the activity and persistence of many T cell subsets after adoptive transfer, we hypothesized that these cytokines are important for Th17 cells. We found that Th17 cells proliferated in response to IL-2, IL-7, and IL-15 in vitro. However, in contrast to many other T cell subsets, including conventionally activated CD8+ T cells, we found that Th17 cells were resistant to apoptosis in the absence of IL2Rγ-chain cytokines. To determine whether Th17 cells utilize IL2Rγ-chain cytokines in vivo, we tracked Th17 cell engraftment after adoptive transfer with or without cytokine depletion. Depletion of IL-7 and/or IL-2 decreased initial engraftment, while depletion of IL-15 did not. Supplementation of IL-2 increased initial Th17 engraftment. To assess the clinical relevance of these findings, we treated melanoma-bearing mice with Th17 cell adoptive transfer and concurrent cytokine depletion or supplementation. We found that simultaneous depletion of IL-2 and IL-7 decreased therapeutic efficacy, depletion of IL-15 had no effect, and IL-2 supplementation increased therapeutic efficacy. Our results show that Th17 cells are responsive to IL2Rγ-chain cytokines, and provide insight into the application of these cytokines for Th17-based therapeutic strategies.

Impact of tofacitinib treatment on human B-cells in vitro and in vivo.

B-cells are pivotal to the pathogenesis of rheumatoid arthritis and tofacitinib, a JAK inhibitor, is effective and safe in its treatment. Tofacitinib interferes with signal transduction via cytokine receptors using the common γ-chain. Despite extensive data on T-lymphocytes, the impact of tofacitinib on B-lymphocytes is poorly understood. In this study we assessed the effect of tofacitinib on B-lymphocyte differentiation and function. Tofacitinib treatment strongly impaired in vitro plasmablast development, immunoglobulin secretion and induction of B-cell fate determining transcription factors, Blimp-1, Xbp-1, and IRF-4, in naïve B-cells. Interestingly, class switch and activation-induced cytidine deaminase (AICDA) induction was only slightly reduced in activated naïve B-cells. The effect of tofacitinib on plasmablast formation, immunoglobulin secretion and proliferation was less profound, when peripheral blood B-cells, including not only naïve but also memory B-cells, were stimulated. In line with these in vitro results, the relative distribution of B-cell populations remained stable in tofacitinib treated patients. Nevertheless, a temporary increase in absolute B-cell numbers was observed 6-8 weeks after start of treatment. In addition, B-cells isolated from tofacitinib treated patients responded rapidly to in vitro activation. We demonstrate that tofacitinib has a direct impact on human naïve B-lymphocytes, independently from its effect on T-lymphocytes, by impairing their development into plasmablasts and immunoglobulin secretion. The major effect of tofacitinib on naïve B-lymphocyte development points to the potential inability of tofacitinib-treated patients to respond to novel antigens, and suggests planning vaccination strategies prior to tofacitinib treatment.

Novel RAG1 mutation and the occurrence of mycobacterial and Chromobacterium violaceum infections in a case of leaky SCID.

Severe combined immunodeficiency (SCID) is a potentially fatal primary immunodeficiency (PID) that is caused by mutations in genes such as IL2RG, JAK3, IL7RA, RAG1, RAG2, and ADA. The products of these genes are involved in the development of several immune cells such as T, B and natural killer (NK) cells. Most of the SCID forms are autosomal recessive with the exception of IL2RG defects that cause an X-linked SCID. Among the different SCID types, there is a rare SCID form called leaky SCID, which is less severe when compared to the other classical SCID phenotypes. Leaky SCID can be caused by hypomorphic mutations in RAG1 and RAG2 that result in only partial loss of enzymatic function of the proteins respectively encoded by these genes. Here we report a novel missense mutation (c. 307C > T/p.H103Y) in the RAG1 gene in a patient with leaky SCID. In addition, we characterize the clinical and immunological features of this patient that developed along with other severe and recurrent infections such as mycobacterial diseases (BCGitis and pulmonary tuberculosis), the first occurrence of Chromobacterium violaceum in a patient with SCID. Understanding the increased susceptibility to mycobacteria presented by the patient, in which a functional investigation of IL-12/IFN-γ axis was performed, which demonstrated reduced production of IFN-γ in the supernatans of peripheral blood mononuclear cell cultures from the patient compared with those from healthy subjects. In conclusion, our data expands the molecular and clinical spectrum associated with the leaky SCID phenotype.

Endogenous retrovirus induces leukemia in a xenograft mouse model for primary myelofibrosis.

The compound immunodeficiencies in nonobese diabetic (NOD) inbred mice homozygous for the Prkdc(scid) and Il2rg(null) alleles (NSG mice) permit engraftment of a wide-range of primary human cells, enabling sophisticated modeling of human disease. In studies designed to define neoplastic stem cells of primary myelofibrosis (PMF), a myeloproliferative neoplasm characterized by profound disruption of the hematopoietic microenvironment, we observed a high frequency of acute myeloid leukemia (AML) in NSG mice. AML was of mouse origin, confined to PMF-xenografted mice, and contained multiple clonal integrations of ecotropic murine leukemia virus (E-MuLV). Significantly, MuLV replication was not only observed in diseased mice, but also in nontreated NSG controls. Furthermore, in addition to the single ecotropic endogenous retrovirus (eERV) located on chromosome 11 (Emv30) in the NOD genome, multiple de novo germ-line eERV integrations were observed in mice from each of four independent NSG mouse colonies. Analysis confirmed that E-MuLV originated from the Emv30 provirus and that recombination events were not necessary for virus replication or AML induction. Pathogenicity is thus likely attributable to PMF-mediated paracrine stimulation of mouse myeloid cells, which serve as targets for retroviral infection and transformation, as evidenced by integration into the Evi1 locus, a hotspot for retroviral-induced myeloid leukemia. This study thus corroborates a role of paracrine stimulation in PMF disease progression, underlines the importance of target cell type and numbers in MuLV-induced disease, and mandates awareness of replicating MuLV in NOD immunodeficient mice, which can significantly influence experimental results and their interpretation.

Immune activation and HIV persistence: implications for curative approaches to HIV infection.

Despite complete or near-complete suppression of human immunodeficiency virus (HIV) replication with combination antiretroviral therapy, both HIV and chronic inflammation/immune dysfunction persist indefinitely. Untangling the association between the virus and the host immune environment during therapy might lead to novel interventions aimed at either curing the infection or preventing the development of inflammation-associated end-organ disease. Chronic inflammation and immune dysfunction might lead to HIV persistence by causing virus production, generating new target cells, enabling infecting of activated and resting target cells, altering the migration patterns of susceptible target cells, increasing the proliferation of infected cells, and preventing normal HIV-specific clearance mechanisms from function. Chronic HIV production or replication might contribute to persistent inflammation and immune dysfunction. The rapidly evolving data on these issues strongly suggest that a vicious cycle might exist in which HIV persistence causes inflammation that in turn contributes to HIV persistence.

Targeting the binding interface on a shared receptor subunit of a cytokine family enables the inhibition of multiple member cytokines with selectable target spectrum.

The common γ molecule (γc) is a shared signaling receptor subunit used by six γc-cytokines. These cytokines play crucial roles in the differentiation of the mature immune system and are involved in many human diseases. Moreover, recent studies suggest that multiple γc-cytokines are pathogenically involved in a single disease, thus making the shared γc-molecule a logical target for therapeutic intervention. However, the current therapeutic strategies seem to lack options to treat such cases, partly because of the lack of appropriate neutralizing antibodies recognizing the γc and, more importantly, because of the inherent and practical limitations in the use of monoclonal antibodies. By targeting the binding interface of the γc and cytokines, we successfully designed peptides that not only inhibit multiple γc-cytokines but with a selectable target spectrum. Notably, the lead peptide inhibited three γc-cytokines without affecting the other three or non-γc-cytokines. Biological and mutational analyses of our peptide provide new insights to our current understanding on the structural aspect of the binding of γc-cytokines the γc-molecule. Furthermore, we provide evidence that our peptide, when conjugated to polyethylene glycol to gain stability in vivo, efficiently blocks the action of one of the target cytokines in animal models. Collectively, our technology can be expanded to target various combinations of γc-cytokines and thereby will provide a novel strategy to the current anti-cytokine therapies against immune, inflammatory, and malignant diseases.