Specific Cell Subsets Research Articles

Physiopathological Aspects of Synovial Fluid and Membrane in Psoriatic Arthritis

Background: Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy characterized by a variety of clinical manifestations, mainly affecting joints and entheses, but also skin, nails, the eye, and the intestine. Objectives: In this review, we describe the essential characteristics of both synovial membranes and synovial fluid (SF) in PsA. Similarly to other inflammatory arthritis, the histological peculiarities in PsA synovitis are lining hyperplasia, neoangiogenesis, and sublining infiltration by immune cells and inflammatory mediators. Synovial effusions are frequent in PsA patients and SF analysis allows us to determine the pathological process occurring in the joint. Routine examinations help clinicians in defining the inflammatory status and possibly the detection of specific cell subsets. In addition, pathogenic crystals including monosodium urate and calcium pyrophosphate may be found in PsA SF. Conclusions: SF represents a potential substrate to identify the biomarkers that are useful to predict disease progression and response to medications in PsA patients, thus guiding the choice of appropriate and tailored pharmacological treatment.

Nuclear receptor corepressor 1 controls regulatory T cell subset differentiation and effector function.

FOXP3+ regulatory T cells (Treg cells) are key for immune homeostasis. Here, we reveal that nuclear receptor corepressor 1 (NCOR1) controls naïve and effector Treg cell states. Upon NCOR1 deletion in T cells, effector Treg cell frequencies were elevated in mice and in in vitro-generated human Treg cells. NCOR1-deficient Treg cells failed to protect mice from severe weight loss and intestinal inflammation associated with CD4+ T cell transfer colitis, indicating impaired suppressive function. NCOR1 controls the transcriptional integrity of Treg cells, since effector gene signatures were already upregulated in naïve NCOR1-deficient Treg cells while effector NCOR1-deficient Treg cells failed to repress genes associated with naïve Treg cells. Moreover, genes related to cholesterol homeostasis including targets of liver X receptor (LXR) were dysregulated in NCOR1-deficient Treg cells. However, genetic ablation of LXRβ in T cells did not revert the effects of NCOR1 deficiency, indicating that NCOR1 controls naïve and effector Treg cell subset composition independent from its ability to repress LXRβ-induced gene expression. Thus, our study reveals that NCOR1 maintains naïve and effector Treg cell states via regulating their transcriptional integrity. We also reveal a critical role for this epigenetic regulator in supporting the suppressive functions of Treg cells in vivo.

OMIP-109: 45-color full spectrum flow cytometry panel for deep immunophenotyping of the major lineages present in human peripheral blood mononuclear cells with emphasis on the T cell memory compartment.

The need for more in-depth exploration of the human immune system has moved the flow cytometry field forward with advances in instrumentation, reagent development and availability, and user-friendly implementation of data analysis methods. We developed a high-quality human 45-color panel, for comprehensive characterization of major cell lineages present in circulation including T cells, γδ T cells, NKT-like cells, B cells, NK cells, monocytes, basophils, dendritic cells, and ILCs. Assay optimization steps are described in detail to ensure that each marker in the panel was optimally resolved. In addition, we highlight the outstanding discernment of cell activation, exhaustion, memory, and differentiation states of CD4+ and CD8+ T cells using this 45-color panel. The panel enabled an in-depth description of very distinct phenotypes associated with the complexity of the T cell memory response. Furthermore, we present how this panel can be effectively used for cell sorting on instruments with a similar optical layout to achieve the same level of resolution. Functional evaluation of sorted specific rare cell subsets demonstrated significantly different patterns of immunological responses to stimulation, supporting functional and phenotypic differences within the T cell memory subsets. In summary, the combination of full spectrum profiling technology and careful assay design and optimization results in a high resolution multiparametric 45-color assay. This panel offers the opportunity to fully characterize immunological profiles present in peripheral blood in the context of infectious diseases, autoimmunity, neurodegeneration, immunotherapy, and biomarker discovery.

Chromatin remodelling drives immune cell-fibroblast communication in heart failure.

Chronic inflammation and tissue fibrosis are common responses that worsen organ function, yet the molecular mechanisms governing their cross-talk are poorly understood. In diseased organs, stress-induced gene expression changes fuel maladaptive cell state transitions1 and pathological interaction between cellular compartments. Although chronic fibroblast activation worsens dysfunction in the lungs, liver, kidneys and heart, and exacerbates many cancers2, the stress-sensing mechanisms initiating transcriptional activation of fibroblasts are poorly understood. Here we show that conditional deletion of the transcriptional co-activator Brd4 in infiltrating Cx3cr1+ macrophages ameliorates heart failure in mice and significantly reduces fibroblast activation. Analysis of single-cell chromatin accessibility and BRD4 occupancy in vivo in Cx3cr1+ cells identified a large enhancer proximal to interleukin-1β (IL-1β, encoded by Il1b), and a series of CRISPR-based deletions revealed the precise stress-dependent regulatory element that controls Il1b expression. Secreted IL-1β activated a fibroblast RELA-dependent (also known as p65) enhancer near the transcription factor MEOX1, resulting in a profibrotic response in human cardiac fibroblasts. In vivo, antibody-mediated IL-1β neutralization improved cardiac function and tissue fibrosis in heart failure. Systemic IL-1β inhibition or targeted Il1b deletion in Cx3cr1+ cells prevented stress-induced Meox1 expression and fibroblast activation. The elucidation of BRD4-dependent cross-talk between a specific immune cell subset and fibroblasts through IL-1β reveals how inflammation drives profibrotic cell states and supports strategies that modulate this process in heart disease and other chronic inflammatory disorders featuring tissue remodelling.

Label-free ghost cytometry for manufacturing of cell therapy products

Automation and quality control (QC) are critical in manufacturing safe and effective cell and gene therapy products. However, current QC methods, reliant on molecular staining, pose difficulty in in-line testing and can increase manufacturing costs. Here we demonstrate the potential of using label-free ghost cytometry (LF-GC), a machine learning-driven, multidimensional, high-content, and high-throughput flow cytometry approach, in various stages of the cell therapy manufacturing processes. LF-GC accurately quantified cell count and viability of human peripheral blood mononuclear cells (PBMCs) and identified non-apoptotic live cells and early apoptotic/dead cells in PBMCs (ROC-AUC: area under receiver operating characteristic curve = 0.975), T cells and non-T cells in white blood cells (ROC-AUC = 0.969), activated T cells and quiescent T cells in PBMCs (ROC-AUC = 0.990), and particulate impurities in PBMCs (ROC-AUC ≧ 0.998). The results support that LF-GC is a non-destructive label-free cell analytical method that can be used to monitor cell numbers, assess viability, identify specific cell subsets or phenotypic states, and remove impurities during cell therapy manufacturing. Thus, LF-GC holds the potential to enable full automation in the manufacturing of cell therapy products with reduced cost and increased efficiency.

A Paradigm Shift in Tumor Immunology: Th17 Cells and TGF-β in Intestinal Cancer Initiation.

Cancer remains one of the most complex challenges in modern medicine, with intricate relationships between immune responses and tumor development. This article examines a groundbreaking study by Fesneau, Thevin and colleagues, published in Nature Immunology. This elegant body of work explores the link between chronic inflammation and cancer, particularly focusing on Th17 cells involved in intestinal cancer initiation. Th17 cells, known for their dual roles in immunity, can promote or inhibit tumor growth depending on their environment. This study reveals that a specific subset of Th17 cells, derived from IL-17-producing cells, can transition to a tumorigenic state when TGF-β signaling is impaired. Surprisingly, TGF-β acts as a crucial regulatory factor, maintaining the balance between immune tolerance and tumorigenesis by preventing Th17 cells from becoming tumorigenic. This research highlights the potential for therapeutic interventions targeting TGF-β signaling to prevent cancer initiation in chronic inflammatory conditions. The findings have clinical implications for improving cancer immunotherapies, including immune checkpoint inhibitors and adoptive T cell therapies, by enhancing the efficacy of treatments and mitigating the risk of tumorigenic transformations. Overall, this study provides insights into the mechanisms linking inflammation and cancer, paving the way for innovative strategies to harness the immunity in cancer treatment.

Activation of circulating TFH17 cells associated with activated naive and double negative 2 B cell expansion, and disease activity in systemic lupus erythematosus patients

BackgroundSystemic lupus erythematosus (SLE) is the quintessential autoimmune disease, as it is characterized by hyperactivity of CD4+ T cells and subsequently drives lupus pathology. Follicular helper T (TFH) cells play an important role in B cell maturation and antibody production. However, which specific subset of cTFH cells drives B cell function and contributes to the development of anti-dsDNA antibodies and SLE pathogenesis remains unclear.MethodsPeripheral blood mononuclear cells from SLE patients with inactive (n = 11) and active (n = 21) were used to determine and detect frequencies and phenotypes of circulating TFH cells (cTFH), memory cTFH, and B cell subsets. The correlations among cTFH cell subsets and phenotypes, B cell subsets, anti-dsDNA autoantibodies, and clinical parameters were analyzed.ResultsIn subjects with active SLE, cTFH1 and cTFH17 cells were significantly expanded and activated. These expanded cTFH cells expressed memory phenotypes; cTFH1 cells were predominantly central memory (CM) type, while cTFH17 cells were largely effector memory (EM) type. Phenotyping B cell subsets in these patients showed increased frequencies of aNAV and DN2 B cells. Clinically, ICOS+ cTFH1, ICOS+ cTFH17 cells, and SLEDAI-2k scores were found to be correlated. Analysis of cTFH-B cell relationship revealed positive correlations among ICOS+ cTFH1 cells, aNAV B cells, and anti-dsDNA antibodies. Activation of ICOS+ cTFH17 cells was significantly related to the expansion of aNAV and DN2 B cells. The presence of CM cells in cTFH1 and cTFH17 subsets was correlated with aNAV and DN2 B cell frequencies.ConclusionSLE cTFH cells were found to be polarized toward cTFH1 and cTFH17 cells; activation of these cTFH subsets was significantly associated with disease activity score, aNAV, DN2 B cell expansion, and anti-dsDNA antibody level. Thus, the interactions among cTFH1, cTFH17, and B cells likely contribute to the development of autoantibodies and the pathogenesis in SLE.

Immunoregulation of Liver Fibrosis: New Opportunities for Antifibrotic Therapy.

Liver fibrosis develops in response to chronic liver injury and is characterized by a sustained inflammatory response that leads to excessive collagen deposition by myofibroblasts. The fibrogenic response is governed by the release of inflammatory mediators from innate, adaptive, and innate-like lymphoid cells and from nonprofessional immune cells (i.e., epithelial cells, hepatic myofibroblasts, and liver sinusoidal endothelial cells). Upon removal of the underlying cause, liver fibrosis can resolve via activation of specific immune cell subsets. Despite major advances in the understanding of fibrosis pathogenesis, there is still no approved antifibrotic therapy. This review summarizes our current knowledge of the immune cell landscape and the inflammatory mechanisms underlying liver fibrosis progression and regression. We discuss how reprogramming immune cell phenotype, in particular through targeting selective inflammatory pathways or modulating cell-intrinsic metabolism, may be translated into antifibrogenic therapies.

Effect of Cyclin-Dependent Kinase 4/6 Inhibitors on Circulating Cells in Patients with Metastatic Breast Cancer.

The combination of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) with endocrine therapy (ET) is the standard-of-care for estrogen receptor (ER)-positive, HER2-negative (ER+/HER2- advanced/metastatic breast cancer (mBC). However, the impact of CDK4/6i on circulating immune cells and circulating tumor cells (CTCs) in patients receiving CDK4/6i and ET (CDK4/6i+ET) remains poorly understood. This was a prospective cohort study including 44 patients with ER+/HER2- mBC treated with CDK4/6i+ET in either first or second line. Peripheral blood samples were collected before (baseline) and 3 months (t2) after therapy. Immune cell's subsets were quantified by flow cytometry, and microfluidic-captured CTCs were counted and classified according to the expression of cytokeratin and/or vimentin. Patients were categorized according to response as responders (progression-free survival [PFS] ≥ 6.0 months; 79.1%) and non-responders (PFS < 6.0 months; 20.9%). CDK4/6i+ET resulted in significant changes in the hematological parameters, including decreased hemoglobin levels and increased mean corpuscular volume, as well as reductions in neutrophil, eosinophil, and basophil counts. Specific immune cell subsets, such as early-stage myeloid-derived suppressor cells, central memory CD4+ T cells, and Vδ2+ T cells expressing NKG2D, decreased 3 months after CDK4/6i+ET. Additionally, correlations between the presence of CTCs and immune cell populations were observed, highlighting the interplay between immune dysfunction and tumor dissemination. This study provides insights into the immunomodulatory effects of CDK4/6i+ET, underscoring the importance of considering immune dynamics in the management of ER+/HER2- mBC.

19 Phase II Trial of Ubamatamab in MUC16-Expressing SMARCB1-Deficient Renal Medullary Carcinoma and Epithelioid Sarcoma

Abstract Background Mucin 16 (MUC16) is a large integral membrane glycoprotein that is highly expressed in malignancies such as ovarian cancer but only at low abundance in epithelial cells of normal tissues. Proteolytic cleavage of cell surface MUC16 results in the shedding of its extracellular portion, known as cancer antigen 125 (CA-125), into the bloodstream and a short, membrane-associated C-terminal MUC16 domain that remains on the cell surface. Renal medullary carcinoma (RMC) and epithelioid sarcoma (ES) are aggressive SMARCB1-deficient malignancies found to have elevated serum CA-125 levels in 70-80% of cases. Our preclinical studies suggest that upregulation of MUC16 upon SMARCB1 loss is a viable and attractive tumor target for SMARCB1-deficient malignancies such as ES and RMC. Ubamatamab is a human IgG4-based anti-MUC16 x anti-CD3 bispecific antibody that specifically targets the cell surface bound C-terminal MUC16 domain and can thus induce T cell–redirected killing of tumor cells even in the presence of high concentrations of CA-125. It would thus be a rationale therapy to use in SMARCB1-deficient malignancies expressing MUC16, including those such as RMC known to downregulate MHC Class I as a resistance mechanism to conventional immunotherapy. This is because CD3-targeting bispecific antibodies such as ubamatamab replace conventional signal 1 by engaging T cells regardless of MHC class I expression. As proof of concept, a 20-year-old patient with metastatic SMARCB1-negative ES expressing high levels of serum CA-125 achieved a durable (12+ months) partial response to ubamatamab after progressing on multiple prior therapies, including EZH2 inhibition with tazemetostat as well as anti-PD1/CTLA4 immune checkpoint inhibition with nivolumab plus ipilimumab. The patient reported Grade 2 CRS, pleural effusion, and pericardial effusion, all of which resolved without intervention1. This serves as proof-of-concept for the ability of CD3-targeted bispecifics to overcome resistance to immune checkpoint inhibition. Given this strong preclinical and clinical evidence, we have developed a phase II clinical trial of ubamatamab alone or in combination with the anti-PD1 immune-checkpoint inhibitor cemiplimab in patients with MUC16-expressing RMC and ES who have progressed on at least one line of prior therapy. Up to 20 patients will be enrolled from each disease cohort (ES and RMC) for a total of up to 40 patients. Patients enrolled in Stage I of the trial will receive ubamatamab monotherapy. Patients with disease progression on ubamatamab monotherapy during Stage I can proceed to stage II, which will evaluate the combination of ubamatamab with cemiplimab combination. The co-primary endpoints will be objective response rate (ORR) at any time during the trial and disease control rate (DCR) through 18 weeks. Secondary endpoints will include overall survival, progression-free survival, duration of response, and safety. All endpoints will be analyzed and reported separately for each disease cohort (RMC and ES), and for each Stage (ubamatamab monotherapy and combination ubamatamab with cemiplimab). The trial will utilize the time-to-event Bayesian Optimal Phase II (TOP) design, which maximizes statistical power with well-controlled type I errors. For patients with ES, the joint null hypotheses are that the objective response rate (ORR) is 15% and the disease control rate (DCR) is 26%. The regimen will be promising if either ORR is greater than 15% or DCR is greater than 26% with 69.6% power to declare this an interesting regimen if ORR is 30% and the DCR is 43%. For patients with RMC, the joint null hypotheses are that the objective response rate (ORR) is 15% and the disease control rate (DCR) is 15%. The regimen will be promising if either ORR is greater than 15% or DCR is greater than 15% with 71.4% power to declare this an interesting regimen if ORR is 30% and the DCR is 30%. Pre- and post-treatment correlative analyses will be performed in blood and tumor biopsy tissues to identify changes in specific immune cell subsets and elucidate the dynamic evolution of tumor and immune cell compartments as well as their spatial relationships following ubamatamab alone or in combination with cemiplimab. References 1 Revon-Riviere G, Chami R, Mills D, et al. Mucin 16 (cancer antigen 125) Expression in Epithelioid Sarcoma leads to Single-Patient Study with Bispecific T-Cell Engager Ubamatamab (Mucin16xCD3): A Bench-To-Bedside Experience. Connective Tissue Oncology Society, Nov 16–19, 2022, Vancouver, Canada.

Targeted protein degradation combined with PET imaging reveals the role of host PD-L1 in determining anti-PD-1 therapy efficacy.

Immunohistochemical staining of programmed death-ligand 1 (PD-L1) in tumor biopsies acquired through invasive procedures is routinely employed in clinical practice to identify patients who are most likely to benefit from anti-programmed cell death protein 1 (PD-1) therapy. Nevertheless, PD-L1 expression is observed in various cellular subsets within tumors and their microenvironments, including tumor cells, dendritic cells, and macrophages. The impact of PD-L1 expression across these different cell types on the responsiveness to anti-PD-1 treatment is yet to be fully understood. We synthesized polymer-based lysosome-targeting chimeras (LYTACs) that incorporate both PD-L1-targeting motifs and liver cell-specific asialoglycoprotein receptor (ASGPR) recognition elements. Small-animal positron emission tomography (PET) imaging of PD-L1 expression was also conducted using a PD-L1-specific radiotracer 89Zr-αPD-L1/Fab. The PD-L1 LYTAC platform was capable of specifically degrading PD-L1 expressed on liver cancer cells through the lysosomal degradation pathway via ASGPR without impacting the PD-L1 expression on host cells. When coupled with whole-body PD-L1 PET imaging, our studies revealed that host cell PD-L1, rather than tumor cell PD-L1, is pivotal in the antitumor response to anti-PD-1 therapy in a mouse model of liver cancer. The LYTAC strategy, enhanced by PET imaging, has the potential to surmount the limitations of knockout mouse models and to provide a versatile approach for the selective degradation of target proteins in vivo. This could significantly aid in the investigation of the roles and mechanisms of protein functions associated with specific cell subsets in living subjects.

TLR9-Dependent Activation by Inactivated Parapoxvirus Ovis in Murine Bone Marrow-Derived Dendritic Cells Is Associated with Specific Strain-Dependent Dendritic Cell Subsets

Introduction: Inactivated parapoxvirus ovis (iPPVO) exerts strong immunomodulatory effects on innate immune cells, making it an attractive therapeutic candidate. However, little is known about the signaling pathways that are involved in iPPVO-induced immune responses. Methods: In this study, we systematically analyzed how different types of dendritic cells (DCs) react to iPPVO (Zylexis, strain D1701) in both BALB/c and C57BL/6 mice by flow cytometry and ELISAs, and investigated which signaling pathway is related to DC activation by Western blotting and protein profiling. Results: We demonstrated that bone marrow-derived conventional DCs (BM-cDCs) and bone marrow-derived plasmacytoid DCs (BM-pDCs) matured and secreted type I interferons in response to Zylexis stimulation in both mouse strains. Similarly, Zylexis promoted the secretion of IL-12/23p40 and TNF by pDCs. However, IL-12/23p40 and TNF secretion by cDCs were induced in BALB/c mice but not in C57BL/6 mice. Analyzing the underlying signaling pathways revealed that iPPVO-induced maturation of cDCs was Toll-like receptor 9 (TLR9) independent, while the maturation of pDCs partially depended on the TLR9 pathway. Moreover, the production of proinflammatory cytokines by cDCs and the secretion of IFN-α/β by pDCs partially depended on the TLR9 pathway in both mouse strains. Therefore, other signaling pathways seem to participate in the response of DCs to iPPVO, supported by protein profiling. Conclusion: Our data provide useful insights into the diversity of iPPVO sensors and their varying effects across different strains and species.

Peripheral endotoxin exposure in mice activates crosstalk between phagocytes in the brain and periphery.

Inflammation is a central process of many neurological diseases, and a growing number of studies suggest that non-brain-resident immune cells may contribute to this neuroinflammation. However, the unique contributions of specific immune cell subsets to neuroinflammation are presently unknown, and it is unclear how communication between brain-resident and non-resident immune cells underlies peripheral immune cell involvement in neuroinflammation. In this study, we employed the well-established model of lipopolysaccharide (LPS)-induced neuroinflammation and captured brain-resident and non-resident immune cells from the brain and its vasculature by magnetically enriching cell suspensions from the non-perfused brain for CD45 + cells. Then, we identified immune subtype-specific neuroinflammatory processes using single-cell genomics and predicted the crosstalk between immune cell subtypes by analyzing the simultaneous expression of ligands and receptors. We observed a greater abundance of peripheral phagocytes associated with the brain in this model of neuroinflammation, and report that these professional phagocytes activated similar transcriptional profiles to microglia during LPS-induced neuroinflammation. And, we observed that the probable crosstalk between microglia and peripheral phagocytes was activated in this model while homotypic microglial communication was likely to be decreased. Our novel findings reveal that microglia signaling to non-brain-resident peripheral phagocytes is preferentially triggered by peripheral inflammation, which is associated with brain infiltration of peripheral cells. Overall, our study supports the involvement of peripheral immune cells in neuroinflammation and suggests several possible molecular signaling pathways between microglia and peripheral cells that may facilitate central-peripheral crosstalk during inflammation. Examining these molecular mediators in human disease and other rodent models may reveal novel targets that modify brain health, especially in comorbidities characterized by peripheral inflammation.

Mitochondrial Oxidative Stress Regulates FOXP3+ T-Cell Activity and CD4-Mediated Inflammation in Older Adults with Frailty.

In healthy older adults, the immune system generally preserves its response and contributes to a long, healthy lifespan. However, rapid deterioration in immune regulation can lead to chronic inflammation, termed inflammaging, which accelerates pathological aging and diminishes the quality of life in older adults with frailty. A significant limitation in current aging research is the predominant focus on comparisons between young and older populations, often overlooking the differences between healthy older adults and those experiencing pathological aging. Our study elucidates the intricate immunological dynamics of the CD4/Treg axis in frail older adults compared to comparable age-matched healthy older adults. By utilizing publicly available RNA sequencing and single-cell RNA sequencing (scRNAseq) data from peripheral blood mononuclear cells (PBMCs), we identified a specific Treg cell subset and transcriptional landscape contributing to the dysregulation of CD4+ T-cell responses. We explored the molecular mechanisms underpinning Treg dysfunction, revealing that Tregs from frail older adults exhibit reduced mitochondrial protein levels, impairing mitochondrial oxidative phosphorylation. This impairment is driven by the TNF/NF-kappa B pathway, leading to cumulative inflammation. Further, we gained a deeper understanding of the CD4/Treg axis by predicting the effects of gene perturbations on cellular signaling networks. Collectively, these findings highlight the age-related relationship between mitochondrial dysfunction in the CD4/Treg axis and its role in accelerating aging and frailty in older adults. Targeting Treg dysfunction offers a critical basis for developing tailored therapeutic strategies aimed at improving the quality of life in older adults.

GM-CSF-dependent CD301b+ lung dendritic cells confer tolerance to inhaled allergens.

The severity of allergic asthma is driven by the balance between allergen-specific T regulatory (Treg) and T helper (Th)2 cells. However, it is unclear whether specific subsets of conventional dendritic cells (cDCs) promote the differentiation of these two T cell lineaeges. We have identified a subset of lung resident type 2 cDCs (cDC2s) that display high levels of CD301b and have potent Treg-inducing activity ex vivo. Single cell RNA sequencing and adoptive transfer experiments show that during allergic sensitization, many CD301b+ cDC2s transition in a stepwise manner to CD200+ cDC2s that selectively promote Th2 differentiation. GM-CSF augments the development and maintenance of CD301b+ cDC2s in vivo, and also selectively expands Treg-inducing CD301b+ cDC2s derived from bone marrow. Upon their adoptive transfer to recipient mice, lung-derived CD301b+ cDC2s confer immunological tolerance to inhaled allergens. Thus, GM-CSF maintains lung homeostasis by increasing numbers of Treg-inducing CD301b+ cDC2s.

Immunotherapy with genetically engineered T cells holds promise for the treatment of nonmalignant diseases in the dog.

The ability to genetically redirect the antigenic specificity of T cells using chimeric antigen receptors (CAR) has led to unprecedented durable clinical remissions in human patients with relapsed/refractory hematological malignancies. This remarkable advance in successful immune cell engineering has now led to investigations into the application of CAR-T-cell technology to treat nonmalignant diseases. The use of CAR-T cells to target and eliminate specific cell subsets involved in the pathogenesis of autoimmunity, fibrosis, senescence, and infectious disease represents a new direction for adoptive cell therapies. While the use of CAR-T cells for nonmalignant disease is still in its infancy, early reports of dramatic clinical responses to CAR-T cells targeting CD19+ B cells in patients with severe autoimmune disease raise the possibility that this approach could lead to durable remissions, eliminating the need for ongoing conventional immunosuppressive therapies. Excitingly, nonmalignant disease processes that may be addressed by CAR-T-cell therapy in humans also occur in our canine populations. Given that technologies for developing canine CAR constructs are now available, robust protocols have been described for generating canine CAR-T cells, and experience is being gathered with their clinical use in oncology, it is anticipated that CAR-T cells will soon enter the veterinary clinics for the treatment of debilitating nonmalignant diseases. Here, we provide a broad overview of CAR-T-cell therapies for nonmalignant diseases and extrapolate these advances into the veterinary space, highlighting areas in which canine CAR-T cells are poised to enter the clinics for the treatment of nonmalignant disease.

Elucidating the role of T-Reg related cytokines: serum transforming growth factor beta and interleukin-35 in alopecia areata.

Previous studies demonstrated that Th1 cytokines like IL-2, IL-12 and IFN-γ have initiatory role in alopecia areata (AA) and positive correlation with disease severity. They informed that serum levels of Th17 cytokines, IL-17, IL-22, IL-23 increased in active AA patients and corelated, particularly IL-17, with disease severity. In recent reports it was showed the balance between Th17 and Treg cells is crucial for maintaining tolerance to self-antigens, and an imbalance towards Th17 may contribute to the development of autoimmune diseases like AA. But research on serum Treg markers in AA is limited. It was aimed to investigate whether the Treg cells have a role in the pathogenesis of AA analyzing the serum levels of Treg cytokines IL-35 and TGF-β in the patients with AA. 42 AA patients and 38 healthy controls were enrolled. Patient demographics, clinical data, disease severity assessed by Severity of Alopecia Tool (SALT) scores were recorded. Serum samples were collected and analyzed for TGF-β and IL-35 levels using ELISA kits. The cytokine levels in both groups were statistically compared. Their relation with parameters of demographic and severity of disease was evaluated. The patient and control groups had no statistically significant difference, there was 71.4% males and 28.6% females in patient group, while the control group had 63.2% males and 36.8% females, Severity analysis classified 18 patients with mild AA, 19 with moderate AA, and 5 with alopecia totalis/areata universalis. While TGF-β levels exhibited no significant difference between groups, IL-35 levels were significantly elevated in AA patients (p = 0.002). Logistic regression identified IL-35 as a significant parameter influencing disease status (OR = 1.055). Correlation analysis revealed a weak positive correlation between patient age and IL-35 levels (r = 0.436; p = 0.004). Notably, IL-35 levels displayed a significant decrease in individuals with antinuclear antibody (ANA) positivity. No correlations were identified between cytokine levels and disease severity, prognosis, or disease activity. Elevated IL-35 levels suggest that IL-35 and specific Treg cell subsets can play a role in AA pathogenesis. The nuanced roles of TGF-β and IL-35 highlight the need for comprehensive studies to interpret their implications in the complex immunopathogenesis of AA. These findings open avenues for further research, positioning IL-35 as a prospective target for investigating and potentially intervening in AA pathogenesis.

One‐Component Cationic Lipids for Systemic mRNA Delivery to Splenic T Cells

AbstractUnlocking the full potential of mRNA immunotherapy necessitates targeted delivery to specific cell subsets in the spleen. Four‐component lipid nanoparticles (LNPs) utilized in numerous clinical trials are primarily limited in hepatocyte and muscular targeting, highlighting the imperative demand for targeted and simplified non‐liver mRNA delivery systems. Herein, we report the rational design of one‐component ionizable cationic lipids to selectively deliver mRNA to the spleen and T cells with high efficacy. Unlike the tertiary amine‐based ionizable lipids involved in LNPs, the proposed cationic lipids rich in secondary amines can efficiently deliver mRNA both in vitro and in vivo as the standalone carriers. Furthermore, these vectors facilitate efficacious mRNA delivery to the T cell subsets following intravenous administration, demonstrating substantial potential for advancing immunotherapy applications. This straightforward strategy extends the utility of lipid family for extrahepatic mRNA delivery, offering new insights into vector development beyond LNPs to further the field of precise mRNA therapy.

One-Component Cationic Lipids for Systemic mRNA Delivery to Splenic T Cells.

Unlocking the full potential of mRNA immunotherapy necessitates targeted delivery to specific cell subsets in the spleen. Four-component lipid nanoparticles (LNPs) utilized in numerous clinical trials are primarily limited in hepatocyte and muscular targeting, highlighting the imperative demand for targeted and simplified non-liver mRNA delivery systems. Herein, we report the rational design of one-component ionizable cationic lipids to selectively deliver mRNA to the spleen and T cells with high efficacy. Unlike the tertiary amine-based ionizable lipids involved in LNPs, the proposed cationic lipids rich in secondary amines can efficiently deliver mRNA both in vitro and in vivo as the standalone carriers. Furthermore, these vectors facilitate efficacious mRNA delivery to the T cell subsets following intravenous administration, demonstrating substantial potential for advancing immunotherapy applications. This straightforward strategy extends the utility of lipid family for extrahepatic mRNA delivery, offering new insights into vector development beyond LNPs to further the field of precise mRNA therapy.

Abstract PO1-14-07: Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial)

Abstract Background: Immune checkpoint inhibitors (ICIs) have heralded a new era in breast cancer treatment; however, response rates remain limited, making precision immune-oncology a major unmet need. In addition to T cells, effective immune responses to ICIs rely on coordinated interactions between innate and adaptive immune cells. Mast cells are evolutionarily conserved, tissue-resident cells of importance to human health. Specific subsets of mast cells might be endowed with opposite roles in cancer treatment, yet the extent of mast cell heterogeneity and its clinical merit in immunotherapy remain undefined. Objective: We sought to comprehensively characterize mast cells in breast cancer, investigate their association with immunotherapy response with in-depth mechanistic insights, and identify actionable strategies to modulate mast cell functional states, thereby optimizing immunotherapy efficacy. Methods: We employed single-cell profiling on longitudinal breast cancer samples from three independent clinical trials (NCT04613674, NCT03197389 and GSE169246) to delineate mast cell heterogeneity in anti-PD-(L)1 therapy. By integrating multi-omic analyses, tissue characterization, preclinical experiments, transgenic mice, and high-throughput drug screening, we outlined the molecular features, underlying mechanisms, and clinical relevance of distinct mast cells to elicit ICI-responsive microenvironments. Subsequently, we launched RENAISSANCE (NCT05076682), a proof-of-concept, Bayesian adaptive, phase 2 platform trial, to evaluate the efficacy and safety of combining mast cell therapeutics with anti-PD-1 backbone therapy in metastatic triple-negative breast cancer (TNBC) patients who progressed after immunotherapy. The primary endpoint was the objective response rate (ORR) assessed using RECIST v1.1 criteria. Results: We identified a distinct population of mast cells termed antigen-presenting mast cells (APMCs), constituting approximately 30% of intratumoral mast cells and correlating with improved clinical benefit of anti-PD-(L)1 therapy in TNBC. APMCs displayed MHC-II and costimulatory molecules, and indicated the presence of tumor-reactive T cells and tertiary lymphoid structures. Using three immunocompetent mouse models, we confirmed the immunomodulatory capacity of APMCs in immunotherapy. Mechanistically, by employing Cpa3CreERT2Cd74fl/fl mice, we demonstrated that APMCs potentiate anti-PD-1 efficacy and antitumor T cell immunity through their antigen-presentation machinery. Interestingly, we identified cromolyn, an FDA-approved drug for allergy, as a potential therapeutic agent that elicited APMC-dependent CD8+ T cell cytotoxicity to synergize with anti-PD-1 therapy. Between February 2022 and March 2023, 10 patients with immunotherapy-refractory metastatic TNBC were enrolled to receive cromolyn plus camrelizumab backbone treatment. Given Bayesian predictive probability, this arm was “graduated” due to meeting the pre-specified efficacy boundary, with an ORR of 40.0% (4/10). The treatment was well tolerated with similar safety profiles of relevant drugs. Conclusions: Our findings provide crucial insights into the impact of mast cell heterogeneity on the clinical response to ICIs at a single-cell level, and pave the way for APMC-directed therapeutic interventions in cancer treatment. To our knowledge, this is the first prospective study in breast cancer of cromolyn plus anti-PD-1 backbone regimen after anti-PD-(L)1 immunotherapy failure, demonstrating significant antitumor activity and commendable tolerability. Consequently, we suggest a phase 3 randomized study to consolidate this finding, which might be an effective treatment in patients for whom there are few effective treatment options. Citation Format: Song-Yang Wu, Xi Jin, Yin Liu, Wen-Jia Zuo, Li Chen, Xiyu Liu, Lei Fan, Zhong-Hua Wang, Yan-Fei Liu, Yi-Zhou Jiang, Zhi-Ming Shao. Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-14-07.