[Short-term substitution of calcineurin inhibitors (CNI) with recombinant humanized anti-CD25 monoclonal antibody (Basiliximab) as aGVHD prophylaxis in CNI intolerant patients after allogeneic hematopoietic stem cell transplantation].

Objectives: To investigate the efficacy of short-term substitution of recombinant humanized anti-CD25 monoclonal antibody (Basiliximab) as acute GVHD (aGVHD) prophylaxis in calcineurin inhibitors (CNI) intolerant patients following allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: This study included 17 patients with refractory malignant hematological disorders who underwent salvage allo-HSCT at the Bone Marrow Transplantation Department of Shanghai Zhaxin Traditional Chinese and Western Medicine Hospital from August 2021 to August 2022 and were treated with Baliximab to prevent aGVHD due to severe adverse reactions to CNI. There were seven men and ten women, with a median age of 43 years (18-67). Following the discontinuation of CNI, Basiliximab was administered at a dose of 1 mg/kg once weekly until CNI or mTOR inhibitors were resumed. Results: Basiliximab was started at an average of 5 (1-32) days after HSCT. The median duration of substitution was 20 (7-120) days. All had neutrophil engraftment within a median of 12 (10-17) days. Thirteen patients had platelet engraftment after a median of 13 (11-20) days. Four patients did not develop stable platelet engraftment. Eight patients (47.1% ) developed Grade Ⅱ-Ⅳ aGVHD, while four (23.6% ) developed Grade Ⅲ/Ⅳ aGVHD. Only one patient died from aGVHD. Before the end of the followup period, seven of 17 patients died. The longest followup period of the survivors was 347 days, and the median survival rate was not met. The overall survival (OS) rate at six months was 62.6%. Among the 17 patients, 13 (76.4% ) experienced cytomegalovirus reactivation, 7 (41.2% ) experienced EB virus activation, and no cytomegalovirus disease was observed. Conclusions: When CNI intolerance occurs during allo-HSCT, short-term replacement with Baliximab can be used as an alternative to prevent aGVHD.

Depletion of regulatory T cells enhancing the anti-tumor effect of in situ vaccination in solid tumors.

The emergence of immune checkpoint inhibitors (ICIs) has revolutionized the clinical treatment for tumor. However, the low response rate of ICIs remains the major obstacle for curing patients and effective approaches for patients with primary or secondary resistance to ICIs remain lacking. In this study, immune stimulating agent unmethylated CG-enriched (CpG) oligodeoxynucleotide (ODN) was locally injected into the tumor to trigger a robust immune response to eradicate cancer cells, while anti-CD25 antibody was applied to remove immunosuppressive regulatory T cells, which further enhanced the host immune activity to attack tumor systematically. The combination of CpG and anti-CD25 antibody obtained notable regression in mouse melanoma model. Furthermore, rechallenge of tumor cells in the xenograft model has resulted in smaller tumor volume, which demonstrated that the combinational treatment enhanced the activity of memory T cells. Remarkably, this combinational therapy presented significant efficacy on multiple types of tumors as well and was able to prevent relapse of tumor partially. Taken together, our combinational immunotherapy provides a new avenue to enhance the clinical outcomes of patients who are insensitive or resistant to ICIs treatments.

Expression of CD25, mast cell markers and T-cell markers in eosinophilic esophagitis.

While eosinophilic esophagitis (EOE) is defined by histologic presence of eosinophils, a few studies have established the presence of mast cells in EOE and even shown their correlation with symptom persistence despite resolution of eosinophils. Expression of aberrant mast cell markers CD25 and CD2 have not been studied in EOE. This study quantifies the number of hotspot cells per high power field expressing CKIT/CD117, tryptase, CD25, CD2 and CD3 by immunohistochemical stains in endoscopic esophageal biopsies of the following three cohorts: (1) established and histologically confirmed EOE, (2) suspected EOE with biopsies negative for eosinophils, and (3) no history of or suspicion for EOE with histologically unremarkable biopsies. In this study, mast cells were highlighted by CKIT and tryptase in EOE, and not seen in other clinically mimicking cases. There were also significantly higher densities of CD25 and pan-T-cell marker staining in EOE cases. These findings suggest an inflammatory cellular milieu in EOE, beyond just eosinophils, that can be demonstrated by immunohistochemistry, and that invite further study into the role that these cells may play in EOE.

IL-2/CD25 axis mediates cellular networks promoting the growth of CD25+ acute myeloid leukemia cells.

Although the expression of interleukin-2 receptor α-chain (IL-2Rα, CD25) has been provided prognostic significance independent of known biomarkers in acute myeloid leukemia (AML), the functional role of CD25 molecule remains unknown. Since IL-2 can be trans-presented via CD25 to another cell, CD25+AML cells may deliver environmental IL-2 to surrounding immune cells to produce myeloid growth factors for their proliferation. We hypothesize that cellular interactions via IL-2/CD25 axis in the bone marrow microenvironment contributes to the growth advantage of these AML cells and affects the clinical outcome of those AML patients.

Non-IL-2-blocking anti-CD25 antibody inhibits tumor growth by depleting Tregs and has synergistic effects with anti-CTLA-4 therapy.

CD25, also known as the interleukin-2 receptor α chain (IL-2Rα), is highly expressed on regulatory T cells (Tregs), but relatively lower on effector T cells (Teffs). This makes it a potential target for Treg depletion, which can be used in tumor immunotherapy. However, marketed anti-CD25 antibodies (Basiliximab and Daclizumab) were originally developed as immunosuppressive drugs to prevent graft rejection, because these antibodies can block IL-2 binding to CD25 on Teffs, which in turn destroys the function of Teffs. Recent studies have shown that non-IL-2-blocking anti-CD25 antibodies have displayed exciting antitumor effects. Here, we screened out a non-IL-2-blocking anti-CD25 monoclonal antibody (mAb) 7B7 by hybridoma technology, and confirmed its antitumor activity via depleting Tregs in a CD25 humanized mouse model. Subsequently, we verified that the humanized 7B7, named as h7B7-15S, has comparable activities to 7B7, and that its Treg depletion is further increased when combined with anti-CTLA-4, leading to enhanced remodeling of the tumor immune microenvironment. Moreover, our findings reveal that the Fab form of h7B7-15S has the ability to deplete Tregs, independent of the Fc region. Taken together, our studies expand the application of anti-CD25 in tumor immunotherapy and provide insight into the underlying mechanism.

High IL2RA/CD25 expression is a prognostic stem cell biomarker for pediatric acute myeloid leukemia without a core-binding factor.

CD25 is an aberrant marker expressed on the leukemic stem cell (LSC) surface and an immunotherapy target in acute myeloid leukemia (AML). However, the clinical prevalence and significance of CD25 expression in pediatric AML are unknown. High IL2RA/CD25 expression in pediatric AML showed a stem cell-like phenotype, and elevated CD25 expression was associated with lower overall survival (p < .001) and event-free survival (p < .001) in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study. This finding was reproduced in AML without a core-binding factor in the Children's Oncology Group study cohort. High CD25 expression has prognostic significance in pediatric AML.

The soluble IL-2 receptor α/CD25 as a modulator of IL-2 function.

The pleiotropic cytokine interleukin-2 (IL-2) is an integral regulator of healthy and pathological immune responses, with the most important role in regulating the homeostasis of regulatory T cells. IL-2 signalling involves three distinct receptors: The IL-2 receptor α (IL-2Rα/CD25), IL-2Rß, and IL-2Rγ/γc . While IL-2Rß and γc are essential for signal transduction, IL-2Rα regulates the affinity of the receptor complex towards IL-2. A soluble form of the IL-2Rα (sIL-2Rα) is present in the blood of healthy individuals and increased under various pathological conditions. Although it is known that the sIL-2Rα retains its ability to bind IL-2, it is not fully understood how this molecule affects IL-2 function and thus immune responses. Here, we summarize the current knowledge on the generation and function of the sIL-2Rα. We describe the molecular mechanisms leading to sIL-2Rα generation and discuss the different IL-2 modulating functions that have been attributed to the sIL-2Rα. Finally, we describe attempts to utilize the sIL-2Rα as a therapeutic tool.

Short-term administration of Qipian®, a mixed bacterial lysate, inhibits airway inflammation in ovalbumin-induced mouse asthma by modulating cellular, humoral and neurogenic immune responses.

AIMS: Qipian® is a commercialized agent composed of extracts of three genera of commensal bacteria, and its mechanism of action on asthma is unclear. This study aimed to examine the impact of Qipian® on airway inflammation and investigate the underlying mechanisms. MATERIALS AND METHODS: Qipian® or dexamethasone (DEX) was administered before OVA challenge in an ovalbumin-induced asthma mouse model, and then asthmatic symptoms were observed and scored. Samples of lung tissues, blood, and bronchoalveolar lavage fluid (BALF) were collected, and eosinophils (Eos), immunoglobins (Igs), and type 1 T helper (Th1)/Th2 cell cytokines were measured. Mucus production in the lung was assessed by periodic acid-Schiff (PAS) staining. The effects of Qipian® on dendritic and T regulatory (Treg) cells were investigated using flow cytometry. KEY FINDINGS: The short-term administration of Qipian® significantly inhibited the cardinal features of allergic asthma, including an elevated asthmatic behaviour score, airway inflammation and immune response. Histological analysis of the lungs showed that Qipian® attenuated airway inflammatory cell infiltration and mucus hyperproduction. Qipian® restored Th1/Th2 imbalance by decreasing interleukin (IL)-4, IL-5, and IL-13 while increasing interferon (IFN)-γ and IL-10. Further investigation revealed that Qipian® treatment induced the upregulation of CD4+CD25+Foxp3+ Treg cells and CD103+ DCs and downregulation of tachykinins neurokinin A (NKA) and NKB in the lung. SIGNIFICANCE: Our findings suggested that short-term treatment with Qipian® could alleviate inflammation in allergic asthma through restoring the Th1/Th2 balance by recruiting Treg cells to airways and inducing the proliferation of CD103+ DCs, which actually provides a new treatment option for asthma.

[Humanized anti-CD25 monoclonal antibody as a salvage therapy for steroid-refractory acute graft-versus-host disease after hematopoietic stem cell transplantation].

Objective: To investigate the efficacy of humanized anti-CD25 monoclonal antibody for steroid-refractory acute graft-versus-host disease (SR-aGVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Methods: A total of 64 patients with SR-aGVHD between June 2019 and October 2020 in Suchow Hopes Hematology Hospital were enrolled in this study. Humanized anti-CD25 monoclonal antibodies 1 mg·kg(-1)·d(-1) were administered on days 1, 3, and 8, and then once per week according to the disease progression. Efficacy was assessed at days 7, 14, and 28 after humanized anti-CD 25 treatment. Results: Of the 64 patients with a median age of 31 (15-63) years, 38 (59.4%) were male and 26 (40.6%) were female. The overall response (OR) rate of the humanized CD25 monoclonal antibody in 64 patients with SR-aGVHD on days 7, 14, and 28 were 48.4% (31/64), 53.1% (34/64), and 79.7% (51/64), respectively. Liver involvement is an independent risk factor for poor efficacy of humanized CD25 monoclonal antibody for SR-aGVHD at day 28 (OR=9.588, 95% CI 0.004-0.291, P=0.002). The median follow-up time for all patients was 17.1 (0.2-50.8) months from the start of humanized CD25 monoclonal antibody therapy. The 1- and 2-year OS rates were 63.2% (95% CI 57.1% -69.3%) and 52.6% (95% CI 46.1% -59.1%), respectively. The 1- and 2-year DFS rates were 58.4% (95% CI 52.1% -64.7%) and 49.8% (95% CI 43.4% -56.2%), respectively. The 1- and 2-year NRM rates were 28.8% (95% CI 23.1% -34.5%) and 32.9% (95% CI 26.8% -39.0%), respectively. The results of the multifactorial analysis showed that liver involvement (OR=0.308, 95% CI 0.108-0.876, P=0.027) and GVHD grade Ⅲ/Ⅳ (OR=9.438, 95% CI 1.211-73.577, P=0.032) were independent risk factors for OS. Conclusion: Humanized CD25 monoclonal antibody has good efficacy and safety for SR-aGVHD. This study shows that SR-aGVHD with pretreatment grade Ⅲ/Ⅳ GVHD and GVHD involving the liver has poor efficacy and prognosis and requires early intervention.

Tumor Inflammatory Microenvironment of the Thyroid Cancer: Relationship between Regulatory T-Cell Imbalance, and p-NFΚB (p65) Expression-A Preliminary Study.

BACKGROUND: Inflammatory microenvironment is an essential component of all tumors, including thyroid cancer. Autoimmune thyroid diseases are often associated with thyroid cancer. CD25, expressed in Treg cells and B cells, has been found to be associated with autoimmune thyroid diseases and the NFkB pathway is critical to tumor formation, regulating immune-related genes, and pro-inflammatory cytokine. METHODS: Protein expression of CD25 and NFkB and its phosphorylated form was analyzed by immunohistochemistry in 80 patients with thyroid cancer (10 cases of cancers with Hashimoto's thyroiditis and 70 cases without). RESULTS: CD25 was mainly detected in the nucleus of the inflammatory cells such as in the thyrocytes and neoplastic cells. Protein staining was detected in the T-lymphocytes of the outermost zone of the lymphoid follicles. Moreover, in all cancer alterations, there were a higher level of p-NFkB than in the surrounding tissues. Again, p-NFkB staining was evident in neoplastic cells but not evident in inflammatory cells. CONCLUSIONS: Strong inflammatory infiltrate in the tumor microenvironment is correlated with an invasive phenotype. CD25 and p-NFkB levels were statistically significantly overexpressed in cancer cells.

The Impact of Basiliximab on Clinical Treg Detection through the Interference with CD25 Binding Site.

OBJECTIVE: Basiliximab (BXM) is commercial monoclonal antibody inhibitor of interleukin 2 receptor, which is widely used in the transplantation therapy for preventing acute rejection. However, we found BXM would interfere with the detection of Treg through flow cytometry in clinical practice. This study aimed to explore the interference caused by BXM in the clinical detection of Treg. METHODS: We compared the effects of BXM on two CD25 antibodies with different clone site, which are commonly used for Treg measurement. RESULTS: The result suggested CD25 (2A3) was inhibited by BXM, while CD25 (M-A251) was not affected. Moreover, we found 2A3/M-A251 Treg Ratio could reflect Treg cell activity and BXM blood concentration to some extent. CONCLUSION: BXM can effectively inhibit the binding of CD25 (2A3) antibody to its receptor on T cells membrane, which should be noted during Treg clinical detection.

Role of the CD40-CD40L expression level pathway in the diagnosis of unexplained recurrent pregnancy loss.

BACKGROUND: Unexplained recurrent spontaneous pregnancy loss (URPL) lacks effective treatment and reliable early diagnosis and prediction. Immunologic dysfunction can be an underlying cause of recurrent pregnancy loss (RPL). Considering the regulatory role of CD40-CD40L in immune responses, we explored its clinical significance in URPL. METHODS: The 108 women with URPL who were treated in Hebei Yanda Hospital from January 2020 to December 2022 were selected as study subjects, and another 108 healthy women who were not pregnant and matched with the age and body mass index of the study group were selected as the control group. CD40 and CD4 + CD25 + Treg cells in peripheral blood mononuclear cells (PBMCs) and CD40L in peripheral blood platelets were measured by flow cytometry. The predictive value of CD40-CD40L in URPL for the risk of RPL was determined by receiver operating characteristic (ROC) curves. The correlations of CD40-CD40L with CD4 + CD25 + Treg cells and serum pro-inflammatory factors were assessed by Pearson's analysis. RESULTS: CD40 on the surface of PBMCs and CD40L on the surface of platelets were up-regulated in URPL patients. CD40 in combination with CD40L had high predictive value for the risk of RPL in URPL patients. Peripheral blood CD40-CD40L was positively linked to IL-17 and IL-23, and negatively to CD4 + CD25 + Treg cells and IL-10 in URPL patients. CONCLUSIONS: The CD40-CD40L pathway expression in peripheral blood can help predict the risk of RPL in URPL patients.

This study discovered significant increases in the blood levels of two transmembrane glycoproteins, CD40 and CD40L, in patients with two or more consecutive unexplained recurrent spontaneous pregnancy loss, compared to healthy women. The elevated levels of CD40 and CD40L indicated an increased risk of recurrent pregnancy loss in these patients, which could help early and timely management of these patients.

Deciphering Potential Molecular Signatures to Differentiate Acute Myeloid Leukemia (AML) with BCR::ABL1 from Chronic Myeloid Leukemia (CML) in Blast Crisis.

Acute myeloid leukemia (AML) with BCR::ABL1 has recently been recognized as a distinct subtype in international classifications. Distinguishing it from myeloid blast crisis chronic myeloid leukemia (BC-CML) without evidence of a chronic phase (CP), remains challenging. We aimed to better characterize this entity by integrating clonal architecture analysis, mutational landscape assessment, and gene expression profiling. We analyzed a large retrospective cohort study including CML and AML patients. Two AML patients harboring a BCR::ABL1 fusion were included in the study. We identified BCR::ABL1 fusion as a primary event in one patient and a secondary one in the other. AML-specific variants were identified in both. Real-time RT-PCR experiments demonstrated that CD25 mRNA is overexpressed in advanced-phase CML compared to AML. Unsupervised principal component analysis showed that AML harboring a BCR::ABL1 fusion was clustered within AML. An AML vs. myeloid BC-CML differential expression signature was highlighted, and while ID4 (inhibitor of DNA binding 4) mRNA appears undetectable in most myeloid BC-CML samples, low levels are detected in AML samples. Therefore, CD25 and ID4 mRNA expression might differentiate AML with BCR::ABL1 from BC-CML and assign it to the AML group. A method for identifying this new WHO entity is then proposed. Finally, the hypothesis of AML with BCR::ABL1 arising from driver mutations on a BCR::ABL1 background behaving as a clonal hematopoiesis mutation is discussed. Validation of our data in larger cohorts and basic research are needed to better understand the molecular and cellular aspects of AML with a BCR::ABL1 entity.

Permafrost viremia and immune tweening.

The immune system, an exquisitely regulated physiological system, utilizes a wide spectrum of soluble factors and multiple cell populations and subpopulations at diverse states of maturation to monitor and protect the organism against foreign organisms. Immune surveillance is ensured by distinguishing self-antigens from self-associated with non-self (e.g., viral) peptides presented by major histocompatibility complexes (MHC). Pathology is often identified as unregulated inflammatory responses (e.g., cytokine storm), or recognizing self as a non-self entity (i.e., auto-immunity). Artificial intelligence (AI), and in particular specific machine learning (ML) paradigms (e.g., Deep Learning [DL]) proffer powerful algorithms to better understand and more accurately predict immune responses, immune regulation and homeostasis, and immune reactivity to challenges (i.e., immune allostasis) by their intrinsic ability to interpret immune parameters, pathways and events by analyzing large amounts of complex data and drawing predictive inferences (i.e., immune tweening). We propose here that DL models play an increasingly significant role in better defining and characterizing immunological surveillance to ancient and novel virus species released by thawing permafrost.

Investigating the T regulatory cells and Sirtuin-I serum level in immunotherapy treated house dust mite allergic asthma patients.

OBJECTIVES: House dust mite aeroallergens are predominant triggers of frequent asthma attacks among adults and children. The intensity of asthma and immune reaction necessitates treatment alternatives based on adjusting chosen immunity biomarkers to control the exacerbation of symptoms and establish long-term immune tolerance. In this study, we selected CD4+CD25+Foxp3+ regulatory T cells (Tregs), FOXP3, and Sirtuin-1 as they are known to have a potential role in the immune reaction in different allergic diseases. We investigated their interplay during HDM allergic asthma and its respective immunotherapy. METHODS: Eighty-four subjects were divided into 3 groups; healthy controls (CT), HDM asthma patients without immunotherapy (WOIT), and HDM asthma patients treated with subcutaneous immunotherapy for 6 months before recruitment (WIT). They were enrolled according to the pulmonary function, skin prick tests, and HDM-specific IgE. CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cells Cell percentages, FOXP3 gene expression, and Sirtuin-1 (Sirt1) serum level were analyzed. RESULTS: We found that there is a significant difference between WOIT and WIT groups in the CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cell percentages. While there is no statistically significant difference between WOIT and WIT groups in FOXP3 level. On the controversy, the SIRT1 level in the CT group (4.53 ± 3.880) significantly decreased in the WOIT and WIT groups. CONCLUSION: This study revealed that both CD4 CD25 and CD4 CD25 high FOXP3 cell percentages increased in the WIT group and declined in the WOIT group. While, FOXP3 gene expression increased in both groups. In addition, the Sirt1 serum level showed some improvement in WIT group after a serious drop in the WOIT group comparing with the CT group. The modulation of these biomarkers for the remission and control of allergic asthma can be a prognostic outcome of immunotherapy which needs to be confirmed by larger scale studies.

CD4+TGFß+ cells infiltrated the bursa of Fabricius following IBDV infection, and correlated with a delayed viral clearance, but did not correlate with disease severity, or immunosuppression.

Introduction: Infectious Bursal Disease Virus (IBDV) causes immunosuppression in chickens. While B-cell destruction is the main cause of humoral immunosuppression, bursal T cells from IBDV-infected birds have been reported to inhibit the mitogenic response of splenocytes, indicating that some T cell subsets in the infected bursa have immunomodulatory activities. CD4+CD25+TGFß+ cells have been recently described in chickens that have immunoregulatory properties and play a role in the pathogenesis of Marek's Disease Virus. Methods: To evaluate if CD4+CD25+TGFß+ cells infiltrated the bursa of Fabricius (BF) following IBDV infection, and influenced the outcome of infection, birds were inoculated at either 2 days or 2 weeks of age with vaccine strain (228E), classic field strain (F52/70), or PBS (mock), and bursal cell populations were quantified by flow cytometry. Results: Both 228E and F52/70 led to atrophy of the BF, a significant reduction of Bu1+-B cells, and a significant increase in CD4+ and CD8α+ T cells in the BF, but only F52/70 caused suppression of immune responses to a test antigen in younger birds, and clinical signs in older birds. Virus was cleared from the BF more rapidly in younger birds than older birds. An infiltration of CD4+CD25+T cells into the BF, and elevated expression of bursal TGFß-1+ mRNA was observed at all time points following infection, irrespective of the strain or age of the birds, but CD4+TGFß+cells and CD4+CD25+TGFß+ cells only appeared in the BF at 28 dpi in younger birds. In older birds, CD4+TGFß+ cells and CD4+CD25+TGFß+ cells were present at earlier time points, from 7dpi following 228E infection, and from 14 and 28 dpi following F52/70 infection, respectively. Discussion: Our data suggest that an earlier infiltration of CD4+TGFß+ cells into the BF correlated with a delayed clearance of virus. However, the influx of CD4+TGFß+ cells and CD4+CD25+TGFß+ into the BF did not correlate with increased pathogenicity, or immunosuppression.

Causal relationships between CD25 on immune cells and hip osteoarthritis.

Objectives: Previous research has indicated a potential association between immune factors and osteoarthritis (OA), but the causal relationship between CD25 expression on immune cells and hip OA remains enigmatic. To shed light on this relationship, this study utilized the two-sample Mendelian Randomization (MR) method. Methods: Leveraging genome-wide association studies (GWAS) data from the UK Biobank and arcOGEN, the investigation encompasses a substantial European cohort comprising 15,704 hip OA cases and 378,169 controls. Genetic insights into CD25 stem from a subgroup of 3,757 individuals with European ancestry, encompassing 77 CD25-related traits. Several MR methods were applied, and robustness was assessed through heterogeneity and sensitivity analysis. Results: Among the 77 traits examined, 66 shared the same single nucleotide polymorphisms (SNPs) with hip OA. Of these, 7 CD25-related traits were found to be causally associated with hip OA (adjusted P><0.05), with F-statistics ranging from 33 to 122. These traits are specifically related to CD4+CD25+ T cells, exhibiting odds ratios (OR) and 95% confidence intervals (CI) less than 1. Notably, no causal link was discerned with the CD8+CD25+ T cell subset. Within absolute count (AC) and relative count (RC) trait types, a significant causal relationship was observed solely between CD4+CD25+ T cells and hip OA, without subtype localization. A more intricate examination of CD25 expression levels within the CD4+CD25+ T cell subset revealed a correlation with the CD39+ regulatory T (Treg) subset and hip OA, particularly within the CD39+ activated Treg subset. Furthermore, a notable causal relationship emerged between CD25 expression levels in the CD45RA- not Treg subset and hip OA. However, no significant causal link was established with any subsets of B cells. Conclusion: The genetic prediction suggests that CD25, particularly within the realm of CD4+CD25+ T cells, may exert a protective influence against the development of hip OA. These findings provide a novel therapeutic approach for the prevention and treatment of hip OA.

IL-2 can signal via chemokine receptors to promote regulatory T cells' suppressive function.

Canonical interleukin-2 (IL-2) signaling via the high-affinity CD25-containing IL-2 receptor-Janus kinase (JAK)1,3-signal transducer and activator of transcription 5 (STAT5) pathway is essential for development and maintenance of CD4+CD25HiFoxp3+ regulatory T cells (Tregs) that support immune homeostasis. Here, we report that IL-2 signaling via an alternative CD25-chemokine receptor pathway promotes the suppressive function of Tregs. Using an antibody against CD25 that biases IL-2 signaling toward this alternative pathway, we establish that this pathway increases the suppressive activity of Tregs and ameliorates murine experimental autoimmune encephalomyelitis (EAE). Furthermore, heparan sulfate, an IL-2-binding element of cell surfaces and extracellular matrix, or an engineered IL-2 immunocytokine can also direct IL-2 signaling toward this alternative pathway. Overall, these data reveal a non-canonical mechanism for IL-2 signaling that promotes suppressive functions of Tregs, further elucidates how IL-2 supports immune homeostasis, and suggests approaches to promote or suppress Treg functions.

Autoimmune Limbic Encephalitis in Patients with Hematologic Malignancies after Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplant Cyclophosphamide.

Autoimmune limbic encephalitis (LE) is a rare, but devastating complication of allogeneic hematopoietic stem cell transplantation (HSCT). There is currently limited evidence describing the risk factors, laboratory features, and underlying mechanisms of this neurologic adverse event. We retrospectively reviewed available clinical, imaging, and laboratory data from adult patients with hematological malignancies who underwent haploidentical HSCT with post-transplant cyclophosphamide (PTCy) at Chungnam National University Hospital from June 2016 to May 2020. Patients who developed LE were compared to those who did not based on clinical assessment, serum inflammatory biomarkers, and reconstitution of various T cell populations. Of 35 patients, 4 developed LE. There were no differences in patient demographics, donor demographics, or treatment conditions between patients that did and did not develop LE. Overall, patients with LE had worse clinical outcomes and overall survival than those without. In addition, they tended to have higher markers of systemic inflammation in the early post-transplant period, including fever, C-reactive protein (CRP), and cytokines. Remarkably, baseline interleukin-6 levels before HSCT were found to be higher in patients who developed LE than those who did not. In addition, analysis of T cell subsets showed impaired expansion of CD25+FOXP3+ regulatory T (Treg) cells in LE compared to non-LE patients despite appropriate reconstitution of the total CD4+ T cell population. Patients that developed LE within the first 30 days of HSCT were likely to have high serum IL-6 among other inflammatory cytokines coupled with suppression of regulatory T cell differentiation. Further work is needed on the mechanisms underlying impaired Treg expansion following HSCT and potential therapies.