Gamma Chain Research Articles

An overview of JAK/STAT pathways and JAK inhibition in alopecia areata.

Alopecia Areata (AA) is a common autoimmune disease characterized by non-scarring hair loss ranging from patches on the scalp to complete hair loss involving the entire body. Disease onset is hypothesized to follow the collapse of immune privilege of the hair follicle, which results in an increase in self-peptide/MHC expression along the follicular epithelium. Hair loss is associated with infiltration of the hair follicle with putatively self-reactive T cells. This process is thought to skew the hair follicle microenvironment away from a typically homeostatic immune state towards one of active inflammation. This imbalance is mediated in part by the dominating presence of specific cytokines. While interferon-γ (IFNγ) has been identified as the key player in AA pathogenesis, many other cytokines have also been shown to play pivotal roles. Mechanistic studies in animal models have highlighted the contribution of common gamma chain (γc) cytokines such as IL-2, IL-7, and IL-15 in augmenting disease. IFNγ and γc cytokines signal through pathways involving receptor activation of Janus kinases (JAKs) and signal transducers and activators of transcription (STATs). Based on these findings, JAK/STAT pathways have been targeted for the purposes of therapeutic intervention in the clinical setting. Case reports and series have described use of small molecule JAK inhibitors leading to hair regrowth among AA patients. Furthermore, emerging clinical trial results show great promise and position JAK inhibitors as a treatment strategy for patients with severe or recalcitrant disease. Demonstrated efficacy from large-scale clinical trials of the JAK inhibitor baricitinib led to the first-in-disease FDA-approved treatment for AA in June of 2022. This review aims to highlight the JAK/STAT signaling pathways of various cytokines involved in AA and how targeting those pathways may impact disease outcomes in both laboratory and clinical settings.

Gamma delta T-cell reconstitution after allogeneic HCT: A platform for cell therapy.

Allogeneic Hematopoietic stem cell transplantation (allo-HCT) is a curative platform for several hematological diseases. Despite its therapeutic benefits, the profound immunodeficiency associated with the transplant procedure remains a major challenge that renders patients vulnerable to several complications. Today, It is well established that a rapid and efficient immune reconstitution, particularly of the T cell compartment is pivotal to both a short-term and a long-term favorable outcome. T cells expressing a TCR heterodimer comprised of gamma (γ) and delta (δ) chains have received particular attention in allo-HCT setting, as a large body of evidence has indicated that γδ T cells can exert favorable potent anti-tumor effects without inducing severe graft versus host disease (GVHD). However, despite their potential role in allo-HCT, studies investigating their detailed reconstitution in patients after allo-HCT are scarce. In this review we aim to shed lights on the current literature and understanding of γδ T cell reconstitution kinetics as well as the different transplant-related factors that may influence γδ reconstitution in allo-HCT. Furthermore, we will present data from available reports supporting a role of γδ cells and their subsets in patient outcome. Finally, we discuss the current and future strategies to develop γδ cell-based therapies to exploit the full immunotherapeutic potential of γδ cells in HCT setting.

Direct chemical induction of hepatocyte-like cells with capacity for liver repopulation.

Cell fate can be directly reprogrammed from accessible cell types (e.g., fibroblasts) into functional cell types by exposure to small molecule stimuli. However, no chemical reprogramming method has been reported to date that successfully generates functional hepatocyte-like cells that can repopulate liver tissue, casting doubt over the feasibility of chemical reprogramming approaches to obtain desirable cell types for therapeutic applications. Here, through chemical induction of phenotypic plasticity, we provide a proof-of-concept demonstration of the direct chemical reprogramming of mouse fibroblasts into functional hepatocyte-like cells using exposure to small molecule cocktails in culture medium to successively stimulate endogenous expression of master transcription factors associated with hepatocyte development, such as hepatocyte nuclear factor 4a, nuclear receptor subfamily 1, group I, member 2, and nuclear receptor subfamily 1, group H, member 4. RNA sequencing analysis, metabolic assays, and in vivo physiological experiments show that chemically induced hepatocytes (CiHeps) exhibit comparable activity and function to primary hepatocytes, especially in liver repopulation to rescue liver failure in fumarylacetoacetate hydrolase -/- recombination activating gene 2 -/- interleukin 2 receptor, gamma chain -/- mice in vivo . Single-cell RNA-seq further revealed that gastrointestinal-like and keratinocyte-like cells were induced along with CiHeps, resembling the activation of an intestinal program within hepatic reprogramming as described in transgenic approaches. Our findings show that direct chemical reprogramming can generate hepatocyte-like cells with high-quality physiological properties, providing a paradigm for establishing hepatocyte identity in fibroblasts and demonstrating the potential for chemical reprogramming in organ/tissue repair and regeneration therapies.

MARKERS PROFILE OF PRIMARY SALIVARY GLAND TUMORS: A SYSTEMATIC REVIEW

<h3>Objectives</h3> The objective of this study was to perform a systematic review to integrate the proteomic markers profile of primary salivary gland tumors (SGT) detected by mass spectrometry-based proteome profile (MSBPP). <h3>Study Design</h3> An electronic search was carried out using the MEDLINE/PubMed, Embase, Web of Science, Scopus databases, and hand search to retrieve all the available articles published in the English-language literature regarding MSBPP in SGT. <h3>Results</h3> A total of 6 published articles were included in the qualitative synthesis. In total, 2.136 proteins were identified and quantified in 11 SGT type, representing 1980 differential proteins. Ninety-one proteins were proposed as markers in SGT, being 76 differential proteins. Fibrinogen beta chain was the most common protein marker identified in 10 SGT types. Nine protein markers (alpha-crystallin B chain, annexin A1, annexin A5, guanine nucleotide-binding protein subunit beta-2-like 1, Ig gamma-1 chain C region, macrophage-capping protein, peptidyl-prolyl cis-trans isomerase A, protein S100-A9, and superoxide dismutase [Cu-Zn]) were identified as markers in 10 differential neoplasms. <h3>Conclusions</h3> Although significant limitations were found in the published studies, the results of this systematic review demonstrated a potential biomarkers profile of the SGT.

A series of Polish patients with congenital fibrinogen disorders: 2 new mutations in fibrinogen gamma chain, Fibrinogen Kostrzyn and Fibrinogen Łódź II.

A series of Polish patients with congenital fibrinogen disorders: 2 new mutations in fibrinogen gamma chain, Fibrinogen Kostrzyn and Fibrinogen Łódź II.

A high-quality severe combined immunodeficiency (SCID) rat bioresource.

Immunodeficient animals are valuable models for the engraftment of exogenous tissues; they are widely used in many fields, including the creation of humanized animal models, as well as regenerative medicine and oncology. Compared with mice, laboratory rats have a larger body size and can more easily undergo transplantation of various tissues and organs. Considering the absence of high-quality resources of immunodeficient rats, we used the CRISPR/Cas9 genome editing system to knock out the interleukin-2 receptor gamma chain gene (Il2rg) in F344/Jcl rats-alone or together with recombination activating gene 2 (Rag2)-to create a high-quality bioresource that researchers can freely use: severe combined immunodeficiency (SCID) rats. We selected one founder rat with frame-shift mutations in both Il2rg (5-bp del) and Rag2 ([1-bp del+2-bp ins]/[7-bp del+2-bp ins]), then conducted mating to establish a line of immunodeficient rats. The immunodeficiency phenotype was preliminarily confirmed by the presence of severe thymic hypoplasia in Il2rg-single knockout (sKO) and Il2rg/Rag2-double knockout (dKO) rats. Assessment of blood cell counts in peripheral blood showed that the white blood cell count was significantly decreased in sKO and dKO rats, while the red blood cell count was unaffected. The decrease in white blood cell count was mainly caused by a decrease in lymphocytes. Furthermore, analyses of lymphocyte populations via flow cytometry showed that the numbers of B cells (CD3- CD45+) and natural killer cells (CD3- CD161+) were markedly reduced in both knockout rats. In contrast, T cells were markedly reduced but showed slightly different results between sKO and dKO rats. Notably, our immunodeficient rats do not exhibit growth retardation or gametogenesis defects. This high-quality SCID rat resource is now managed by the National BioResource Project in Japan. Our SCID rat model has been used in various research fields, demonstrating its importance as a bioresource.

Effects of berberine hydrochloride on immune response in the crab Charybdis japonica

Berberine hydrochloride is the main effective component of Coptis spp. used in Chinese herbal medicine and its underlying molecular mechanisms, responsible for inducing effects in crustacean species, are not fully understood. In this study, the molecular response of the crab Charybdis japonica to berberine hydrochloride exposure was studied using transcriptome sequencing. The survival rate, gene expression and activities of several immune enzymes were measured after berberine hydrochloride treatments, with or without injection of the pathogenic bacterium Aeromonas hydrophila. A total of 962 differentially expressed genes (464 up-regulated and 498 down-regulated) were observed during exposure to 100 mg/L of berberine hydrochloride and in the control group after 48 h. Enrichment analysis revealed that these genes are involved in metabolism, cellular processes, signal transduction and immune functions, indicating that exposure to berberine hydrochloride activated the immune complement system. This bioactive compound simultaneously activated fibrinogen beta (FGB), fibrinogen alpha (FGA), alpha-2-macroglobulin (A2M), kininogen (KNG), fibrinogen gamma chain (FGB), alpha-2-HS-glycoprotein (AHSG), caspase-8 (CASP8), cathepsin L (CTSL), adenylate cyclase 3 (Adcy3) and MMP1. Its action could significantly increase the survival rate of the crabs injected with A. hydrophila and promote the activity of LZM, Caspas8, FGA, ACP and AKP in the hepatopancreas. When A. hydrophila was added, the neutralization of 300 mg/L berberine hydrochloride maximized the activities of Caspas8, LZM, ACP and AKP. Our results provide a new understanding of the potential effects of berberine hydrochloride on the immune system mechanisms in crustaceans.

Immunoregulation via Cell Density and Quorum Sensing-like Mechanisms: An Underexplored Emerging Field with Potential Translational Implications.

Quorum sensing (QS) was historically described as a mechanism by which bacteria detect and optimize their population density via gene regulation based on dynamic environmental cues. Recently, it was proposed that QS or similar mechanisms may have broader applications across different species and cell types. Indeed, emerging evidence shows that the mammalian immune system can also elicit coordinated responses on a population level to regulate cell density and function, thus suggesting that QS-like mechanisms may also be a beneficial trait of the immune system. In this review, we explore and discuss potential QS-like mechanisms deployed by the immune system to coordinate cellular-level responses, such as T cell responses mediated via the common gamma chain (γc) receptor cytokines and the aryl hydrocarbon receptors (AhRs). We present evidence regarding a novel role of QS as a multifunctional mechanism coordinating CD4+ and CD8+ T cell behavior during steady state and in response to infection, inflammatory diseases, and cancer. Successful clinical therapies such as adoptive cell transfer for cancer treatment may be re-evaluated to harness the effects of the QS mechanism(s) and enhance treatment responsiveness. Moreover, we discuss how signaling threshold perturbations through QS-like mediators may result in disturbances of the complex crosstalk between immune cell populations, undesired T cell responses, and induction of autoimmune pathology. Finally, we discuss the potential therapeutic role of modulating immune-system-related QS as a promising avenue to treat human diseases.

Endophytic bacterium Bacillus aryabhattai induces novel transcriptomic changes to stimulate plant growth.

In nature, plants interact with a wide range of microorganisms, and most of these microorganisms could induce growth through the activation of important molecular pathways. The current study evaluated whether the endophytic bacterium Bacillus aryabhattai encourages plant growth and the transcriptional changes that might be implicated in this effect. The endophytic bacterium promotes the growth of Arabidopsis and tobacco plants. The transcriptional changes in Arabidopsis plants treated with the bacterium were also identified, and the results showed that various genes, such as cinnamyl alcohol dehydrogenase, apyrase, thioredoxin H8, benzaldehyde dehydrogenase, indoleacetaldoxime dehydratase, berberine bridge enzyme-like and gibberellin-regulated protein, were highly expressed. Also, endophytic bacterial genes, such as arginine decarboxylase, D-hydantoinase, ATP synthase gamma chain and 2-hydroxyhexa-2,4-dienoate hydratase, were activated during the interaction. These findings demonstrate that the expression of novel plant growth-related genes is induced by interaction with the endophytic bacterium B. aryabhattai and that these changes may promote plant growth in sustainable agriculture.

Interleukins 4 and 21 Protect Anti-IgM Induced Cell Death in Ramos B Cells: Implication for Autoimmune Diseases.

Interleukins 4 (IL-4) and 21 (IL-21) belong to the common gamma chain cytokine family which are highly involved in the progression of autoimmune diseases. While IL-4 is well known to be involved in the suppression of apoptosis of autoreactive B cells, the role played by IL-21 remains unclear. In the current study, we activated the human Burkitt’s lymphoma Ramos B cells with anti-IgM to mimic B cell hyperactivation observed in patients of autoimmune diseases. Consistent with other reported findings, anti-IgM led to the downregulation of proteins involved in B cell survival and proliferation, as well as the activation of caspase 3 activity and DNA damage, resulting in apoptotic cell death after 48-hour treatment. Although both IL-4 and IL-21 reversed anti-IgM-induced apoptosis and cell cycle arrest, they did so via different mechanisms: while IL-4 could directly suppress anti-IgM-induced caspase 3 activation and marker indicative of DNA damage, IL-21 could induce B cell proliferation in the presence of anti-IgM. Importantly, IL-21 also suppressed activation induced cell death in human primary B cells. Pre-treatment with clinically validated JAK inhibitors completely reversed the effects of IL-4 and IL-21 to rescue anti-IgM induced cell death and DNA damage. The results indicate the underlying mechanisms of how IL-4 and IL-21 differentially promote survival of hyperactivated B cells and provide hints to treat autoimmune diseases.

Thrombosis in patients with hereditary fibrinogen deficiency

Introduction. In most cases, in patients with hereditary fibrinogen deficiency, clinical manifestations are represented by bleeding of varying intensity and localization. However, the clinical picture of hereditary fibrinogen deficiency can also be represented by thrombosis.Aim — to characterize the detected mutations in fibrinogen genes and to analyze prothrombotic factors in patients with hereditary hypofibrinogenemia and thrombosis.Materials and methods. Forty-nine patients with hereditary hypofibrinogenemia were observed, of which 46 patients had no history of thrombosis and 3 patients had a confirmed history of thrombosis. These 3 patients made up the study group.Results. Heterozygous mutations were found in all 3 patients in the fibrinogen gamma chain gene (FGG), one of them had a previously undescribed deletion g.2653_2684+211del, p.(Asp167Glufs*2), which removes 32 terminal nucleotides of the fifth exon of the FGG gene and leads to the formation of a stop codon in place of amino acid 168. In two other patients, there were missense mutations c.1140T&gt;A, p.(Cys365Ser) and c.1114A&gt;T, p.(Asp356Val), which can determine the thrombogenic properties of the altered protein structure of fibrinogen. Other prothrombotic factors were also identified: genetic polymorphisms of low thrombotic risk, surgery, taking combined oral contraceptives.Conclusion. Hereditary fibrinogen deficiency does not play a protective role in relation to the development of thrombosis and may cause the development of thrombosis, which is associated with its multifunctional role in the hemostasis system. The pathogenesis of thrombosis in patients with hereditary hypofibrinogenemia is multifactorial and may be associated with the characteristics of the main protein defect and the coexistence of hereditary and acquired thrombotic risk factors (surgical interventions, taking combined oral contraceptives, etc.).

Phosphorylation on Syk Y342 is important for both ITAM and hemITAM signaling in platelets

Immune cells express receptors bearing an immune tyrosine activation motif (ITAM) containing two YXXL motifs or hemITAMs containing only one YXXL motif. Phosphorylation of the ITAM/hemITAM is mediated by Src family kinases allowing for the binding and activation of spleen tyrosine kinase (Syk). It is believed that Syk must be phosphorylated on tyrosine residues for activation, and Tyr342, а conserved tyrosine in the interdomain B region, has been shown to be critical for regulating Syk in FcεR1-activated mast cells. Syk is a key mediator of signaling pathways downstream of several platelet pathways including the ITAM bearing glycoprotein VI (GPVI)/Fc receptor gamma chain collagen receptor and the hemITAM containing C-type lectin-like receptor-2 (CLEC-2). Since platelet activation is a crucial step in both hemostasis and thrombosis, we evaluated the importance of Syk Y342 in these processes by producing an Syk Y342F knock-in mouse. When using a CLEC-2 antibody as an agonist, reduced aggregation and secretion were observed in Syk Y342F mouse platelets when compared with control mouse platelets. Platelet reactivity was also reduced in response to the GPVI agonist collagen-related peptide. Signaling initiated by either GPVI or CLEC-2 was also greatly inhibited, including Syk Y519/520 phosphorylation. Hemostasis, as measured by tail bleeding time, was not altered in Syk Y342F mice, but thrombus formation in response to FeCl3 injury was prolonged in Syk Y342F mice. These data demonstrate that phosphorylation of Y342 on Syk following stimulation of either GPVI or CLEC-2 receptors is important for the ability of Syk to transduce a signal.

P800: BLOCKADE OF COMMON GAMMA CHAIN CYTOKINE SIGNALING WITH REGN7257, AN INTERLEUKIN 2 RECEPTOR GAMMA (IL2RG) MONOCLONAL ANTIBODY, PROTECTED MICE FROM GRAFT-VERSUS-HOST DISEASE AND IMMUNE APLASTIC ANEMIA

Background: Pathogenic T-cell responses in T cell-mediated diseases can be driven by cytokines of the common gamma chain (γc) cytokine family (IL2, IL4, IL7, IL9, IL15, and IL21). γc cytokines signal through their corresponding receptors, expressed primarily on immune cells (including T cells), that share a common coreceptor, interleukin 2 receptor subunit gamma (IL2RG) that is required for signaling. Aims: To understand the roles of γc cytokines in driving graft-versus-host disease (GVHD) and bone marrow failure disorders such as immune aplastic anemia (AA), we generated REGN7257, a fully human IL2RG monoclonal antibody that inhibits γc cytokine-induced signaling, and we tested its ability to suppress pathogenic T-cell responses in mouse models of T cell-mediated disease. Methods: We evaluated the efficacy of REGN7257 in a xenogeneic mouse model of GVHD, where immunodeficient NOD-scid-IL2RGnull mice were engrafted with human peripheral blood mononuclear cells (huPBMC). Mice were treated with REGN7257 either prophylactically or therapeutically, and monitored for weight loss and survival, peripheral human T-cell engraftment as well as serum pro-inflammatory cytokine levels over time. In a separate experiment, mice were sacrificed at day 49 post-huPBMC injection (after 4 weeks of antibody treatment) for tissue analysis (liver, lung, skin and bone marrow) of immune cell infiltration (T cells and macrophages), inflammation and/or fibrosis. Results: In a xenogeneic model of GVHD, both prophylactic and therapeutic γc cytokine signaling blockade with REGN7257 effectively protected mice from weight loss and resulted in improved survival, by reducing T-cell expansion in blood and production of pro-inflammatory cytokines in serum. Consistent with the classic pathology of GVHD, lungs, liver and skin of control mice were highly infiltrated by T cells, while γc cytokine signaling blockade strongly reduced T-cell infiltration, with reduced tissue levels of pro-inflammatory cytokines. Importantly, therapeutic γc cytokine signaling blockade in established GVHD (i.e. when mice already showed weight loss) provided similar benefit. Blockade of γc cytokine signaling also led to a reduction in the severity of chronic GVHD, with decreased macrophage infiltration in liver and associated hepatic fibrosis. In this xenogeneic model of GVHD, hemoglobin levels and platelet numbers in blood were both reduced, indicating anemia and thrombocytopenia, respectively, which are two complications associated with aplastic anemia. In addition to peripheral pancytopenia, recipient mice that were engrafted with huPBMC also showed severe marrow aplasia. Importantly, this phenotype of aplastic anemia was prevented by blockade of γc cytokine signaling. Summary/Conclusion: Blockade of γc cytokine signaling with REGN7257 protected against T cell-mediated pathology in a xenogeneic GVHD mouse model that uniquely presents hallmarks of both acute and chronic GVHD, with T-cell expansion/infiltration into tissues and liver fibrosis, as well as hallmarks of immune aplastic anemia, with bone marrow aplasia and peripheral cytopenia. These data provide evidence of γc cytokines as key drivers of T cell-mediated responses, offering a potentially novel strategy for the management of T cell-mediated diseases, such as GVHD and immune AA.

Abstract LB006: In vivo programming of myeloid cells by mRNA mediated delivery of novel Fc alpha fusion receptor activates anti-tumor immunity

Abstract Immunotherapy has revolutionized cancer treatment. However, for the majority of patients with advanced solid tumors, sustained clinical benefit has yet to be achieved. Myeloid cells such as monocytes and macrophages readily accumulate in tumors, in some cases contributing up to 75% of the tumor mass. Reprogramming circulating and tumor associated myeloid cells to activate their ability to elicit anti-tumor adaptive immunity by phagocytosis, cytokine secretion and antigen presentation is an attractive approach to harness and orchestrate systemic anti-tumor immunity. It remains challenging to specifically target and activate myeloid cells in vivo. To overcome this hurdle, we have developed a novel in vivo myeloid cell engineering platform: Fc-alpha Receptor Fusion Constructs. Unlike other chimeric antigen receptors (CARs) the construct was engineered by fusing a tumor recognition scFv with the alpha chain of human Fc receptors. The stable expression and function of these receptors requires endogenously expressed Fc receptor gamma chain, a protein with limited expression to immune cells, mostly myeloid cells. Here, we present that intravenous infusion of lipid-nanoparticle (LNP) encapsulating the Fc-alpha Receptor Fusion Construct mRNA results in the uptake and expression of the construct by myeloid cells. In immunodeficient xenograft models of hepatocellular carcinoma and triple negative breast cancer, delivery of LNP mRNA encoding for GPC3 or TROP2 targeted Fc-alpha Receptor Fusion Constructs resulted in tumor killing, confirming the ability of this approach to program myeloid cells. Furthermore, in the B16 syngeneic melanoma model, treatment with the melanoma antigen GP75 targeted Fc-alpha Receptor Fusion Constructs was also associated with the initiation of broad systemic immune responses, characterized by tumoral accumulation of activated CD8+ T cells, reduced tumor associated Tregs and activation of antigen presenting cells in spleen. Together these studies highlight the potential of Fc-alpha Receptor Fusion Construct delivered directly in vivo to program myeloid cells to recognize and kill cancer. Citation Format: Hongyun Zhao, Inna Shcherbakova, Thomas Prod’homme, Bruce McCreedy, Yuxiao Wang, Daniel Getts. In vivo programming of myeloid cells by mRNA mediated delivery of novel Fc alpha fusion receptor activates anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB006.

Abstract 1528: Molecular mechanisms of TSLP as a therapy for CRLF2 B-Cell acute lymphoblastic leukemia

Abstract B-cell acute lymphoblastic leukemia (B-ALL) is the most common type of leukemia in children. B-ALL characterized by cytokine receptor-like factor 2 (CRLF2) overexpression (CRLF2 B-ALL) has a survival rate of &amp;lt;30% and is the highest risk sub-group of B-ALL in both adults and children. CRLF2 is a receptor component for the cytokine thymic stromal lymphopoietin (TSLP). TSLP plays a role in the survival and proliferation of B-cell precursors, thus explaining the oncogenic role of increased CRLF2 signaling in CRLF2 B-ALL. To our surprise, we found that high-levels of TSLP eliminated leukemia cells in patient-derived xenograft (PDX) models of CRLF2 B-ALL. CRLF2 and IL-7 receptor-alpha (IL-7Ra) form the heterodimer type-I cytokine receptor for TSLP cytokine. Binding of TSLP to its CRLF2 receptor complex induces JAK-STAT5 and PI3K-AKT pathway signals. TSLP shares the IL-7Ra with Interleukin 7 (IL-7) which has a heterodimer receptor consisting of IL-7Ra and the common gamma chain. High-levels of IL-7 (50 ng/ml) have been shown to induce IL-7Ra internalization and degradation in T-cells. We hypothesize that high-level TSLP induces internalization and degradation of IL-7Ra leading to CRLF2 signal inhibition, death of CRLF2 B-ALL cells and the anti-leukemia effects that we have observed in PDX mice. To test this hypothesis, we treated CRLF2 B-ALL cell lines with different TSLP concentrations to observe the effect of TSLP on its receptor and CRLF2 signaling. Flow cytometry data showed that continuous or a pulse of high-dose TSLP induced a loss of surface IL-7Ra expression for up to 24 hours. Phosphorylation assays showed that cells cultured with high-dose TSLP were unresponsive to subsequent TSLP-induced phosphorylation events (pSTAT5 and pRPS6), indicating CRLF2 signal inhibition. In conclusion, high-dose TSLP induces loss of (IL-7Ra) and inhibition of CRLF2 signaling. These results suggest that TSLP exerts its anti-leukemia effects by shutting down CRLF2-mediated signals possibly via the loss of the IL-7Ra receptor component. Citation Format: Hossam Alkashgari, Cornelia Stoian, Caleb Ruiz-Jimenez, Jacqueline Coats, Carlos A. Casiano, Sinisa Dovat, Kimberly J. Payne. Molecular mechanisms of TSLP as a therapy for CRLF2 B-Cell acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1528.

Retinal Proteomic Analysis in a Mouse Model of Endotoxin-Induced Uveitis Using Data-Independent Acquisition-Based Mass Spectrometry

Uveitis is a group of sight-threatening ocular inflammatory diseases, potentially leading to permanent vision loss in patients. However, it remains largely unknown how uveitis causes retinal malfunction and vision loss. Endotoxin-induced uveitis (EIU) in rodents is a good animal model to study uveitis and associated acute retinal inflammation. To understand the pathogenic mechanism of uveitis and screen potential targets for treatment, we analyzed the retinal proteomic profile of the EIU mouse model using a data-independent acquisition-based mass spectrometry (SWATH-MS). After systemic LPS administration, we observed activation of microglial cells accompanied with the elevation of pro-inflammatory mediators and visual function declines. In total, we observed 79 upregulated and 90 downregulated differentially expressed proteins (DEPs). Among the DEPs, we found that histone family members (histone H1, H2A, H2B) and blood proteins including haptoglobin (HP), hemopexin (HPX), and fibrinogen gamma chain (FGG) were dramatically increased in EIU groups relative to those in control groups. We identified phototransduction and synaptic vesicle cycle as the top two significant KEGG pathways. Moreover, canonical pathway analysis on DEPs using Ingenuity Pathway Analysis revealed top three most significant enriched pathways related to acute phase response signaling, synaptogenesis signaling, and eif2 signaling. We further confirmed upregulation of several DEPs associated with the acute phase response signaling including HP, HPX, and FGG in LPS-treated retinas by qPCR and Western blot. In summary, this study serves as the first report to detect retinal proteome changes in the EIU model. The study provides several potential candidates for exploring the mechanism and novel therapeutic targets for uveitis and other retinal inflammatory diseases.

Whole-exome sequencing of 14 389 individuals from the ESP and CHARGE consortia identifies novel rare variation associated with hemostatic factors.

Plasma levels of fibrinogen, coagulation factors VII and VIII and von Willebrand factor (vWF) are four intermediate phenotypes that are heritable and have been associated with the risk of clinical thrombotic events. To identify rare and low-frequency variants associated with these hemostatic factors, we conducted whole-exome sequencing in 10 860 individuals of European ancestry (EA) and 3529 African Americans (AAs) from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium and the National Heart, Lung and Blood Institute's Exome Sequencing Project. Gene-based tests demonstrated significant associations with rare variation (minor allele frequency < 5%) in fibrinogen gamma chain (FGG) (with fibrinogen, P = 9.1×10-13), coagulation factor VII (F7) (with factor VII, P = 1.3×10-72; seven novel variants) and VWF (with factor VIII and vWF; P = 3.2×10-14; one novel variant). These eight novel rare variant associations were independent of the known common variants at these loci and tended to have much larger effect sizes. In addition, one of the rare novel variants in F7 was significantly associated with an increased risk of venous thromboembolism in AAs (Ile200Ser; rs141219108; P = 4.2×10-5). After restricting gene-based analyses to only loss-of-function variants, a novel significant association was detected and replicated between factor VIII levels and a stop-gain mutation exclusive to AAs (rs3211938) in CD36 molecule (CD36). This variant has previously been linked to dyslipidemia but not with the levels of a hemostatic factor. These efforts represent the largest integration of whole-exome sequence data from two national projects to identify genetic variation associated with plasma hemostatic factors.

Common gamma chain-dependent cytokines drive antigen-independent proliferation of circulating and resident memory CD8+ T cells

Abstract Memory CD8+ T cells are found throughout the body and can locally control reinfection at barrier sites. Vaccines often fail to elicit durable tissue-resident memory (TRM) CD8+ T cells, likely contributing to unsuccessful efforts to vaccinate against several important pathogens. TRMs locally self-renew by poorly understood mechanisms; a better understanding of this process could help to enhance TRM immunity. We propose that proliferating TRMs flexibly use available members of the common gamma chain-(γC)-dependent cytokine family to persist and as bystanders during other immune responses. We have found that γC-dependent cytokines can mediate cell-intrinsic signaling to drive proliferation of both circulating and resident memory CD8+ T cells, in contrast to naïve T cells. Using adoptive transfer as well as tetramer staining of endogenous populations, we have confirmed that cytokine-stimulated proliferation of memory T cells of known antigen specificities elicited by different pathogens can occur without cognate antigen. Via bulk and single-cell RNA-Seq of resting and in vivo cytokine-stimulated memory CD8+ T cells, we are elucidating the downstream signature of cytokine-driven TRM proliferation. We have also found that memory CD8+ T cells proliferate comparably in response to exogenous cytokines or unrelated pathogens, consistent with pathogen-elicited γC-dependent cytokine signals driving memory CD8+ T cell proliferation. These data support a conserved ability of TRM and circulating memory T cells to use infection-elicited γC-dependent cytokines for enhanced proliferation, likely to promote maintenance, and that treatment with γC-dependent cytokines can drive rapid proliferation without a need to identify antigens. N. N. J. Damon Runyon Cancer Research Foundation Fellow DRG-2427-21 K. M. W. NCI F30 H. B. d. S. CRI/Paul Shiverick Fellow; NIAID K99/R00 AI139381 S. C. J. NIAID R01 AI038903

A tumor-targeted cytokine/antibody fusion protein to stimulate anti-cancer immunity

Abstract Interleukin-2 (IL-2) is a pleiotropic cytokine that has clinical utility in stimulating anti-cancer immunity. However, the clinical efficacy of IL-2 is limited by its short serum half-life, systemic toxicity, and concurrent activation of immunostimulatory natural killer (NK) and effector T (Teff) cells and immunosuppressive regulatory T (Treg) cells. IL-2 can signal down an intermediate-affinity receptor consisting of IL-2 receptor beta (IL-2Rβ) and common gamma chain (γc) or a high-affinity receptor that also includes IL-2Rα. Tregs express high levels of IL-2Rα, making them much more responsive to IL-2 than naïve NK and Teff cells. To extend the serum half-life and selectively bias the immunostimulatory functions of IL-2 in a stable unimolecular format, we created a single-chain fusion protein, denoted F10 immunocytokine (F10 IC), that intramolecularly fuses human IL-2 to an anti-IL-2 antibody that sterically blocks the IL-2/IL-2Rα interaction and allosterically enhances the IL-2/IL-2Rβ interaction. To exploit the abundance and accessibility of collagen in the tumor microenvironment for targeting, we fused collagen binding domains to F10 IC in various topographies. These novel fusion proteins occlude IL-2Rα binding and enhance IL-2Rβ binding, thereby eliminating the Treg advantage conferred by IL-2Rα and preferentially activating immune effector cells. Furthermore, these proteins selectively bind purified collagen and are capable of homing to, and being retained in, the tumor in vivo. Building on these promising results, we are assessing the in vivo therapeutic efficacy of these fusion proteins in various murine tumor models to illustrate the potential of collagen binding F10 IC as a powerful anti-cancer therapeutic. Supported by a Sanofi Innovation Award and NIH grants (R01 EB029341, T32 AI007417)

Novel IL2RG Gene Mutation in One of Dizygotic Twins Causing Profound Changes of Receptor Structure.

In this study, we report a 4-month-old boy with T−B+NK− severe combined immunodeficiency (SCID) due to a novel mutation in exon 2 of IL2RG, the gene encoding the interleukin (IL) common gamma chain (γc) of the cytokine receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. The patient was born from a twin pregnancy. He manifested recurrent infections of the gastrointestinal tract, whereas his twin brother was asymptomatic with no immune defects. In order to evaluate the effect of this unreported variant on the protein structure, a structural modeling process was performed showing prominent biochemical alterations of the protein features, including molecular weight, isoelectric charge, and possible changes to its secondary and tertiary structure.