TRM Cells Research Articles

Mitophagy drives maldifferentiation of tissue-resident memory T cells in patients with rheumatoid arthritis

Objective To investigate the function of mitophagy in instructing T-cell differentiation of patients with rheumatoid arthritis (RA). Method The mRNA and protein levels of optic atrophy protein-1 were detected in T cells from 94 RA patients and 37 age- and sex-matched healthy individuals by quantitative polymerase chain reaction and Western blotting. The impact of mitophagy on the differentiation of T cells was determined by flow cytometry. The therapeutic effect of targeting mitophagy was explored in humanized RA chimeras. Results Our study showed that T cells exerted high levels of mitophagy in RA patients. Since multiple T-cell subtypes play crucial roles in RA, we determined that mitophagy had a significant impact on the differentiation of tissue-resident memory T (Trm) cells, but not Th1 or Th17 cells. Importantly, we demonstrated that inhibiting mitophagy significantly reduced the number of Trm cells and downregulated inflammatory responses, as evidenced by diminished levels of T cell receptor β, interferon-γ, and interleukin-17A, in the humanized RA chimeras. Conclusions Mitophagy is elevated in RA T cells, leading to maldifferentiation of Trm cells in RA patients. Since these findings were obtained from clinical patients, mitophagy may be a potential therapeutic target for RA treatment.

Langerhans cells directly interact with resident T cells in the human epidermis

Adult human skin contains nearly twice as many T cells as the peripheral blood, which include tissue-resident memory T (TRM) cells. However, the precise mechanisms maintaining TRM cells in the healthy skin remain unclear. Using normal human skin samples, we find that Langerhans cells (LCs) contact T cells in the epidermis of the elderly. LCs with high human leukocyte antigen (HLA)-II, CD86, and PD-L2 expression directly contacted PD-1+ TRM cells and CTLA-4+ regulatory T cells in the epidermis, indicating an axis of peripheral tolerance in a steady state. Environmental insults, ultraviolet B radiation and hapten, downregulated HLA-II and CD86 on LCs in the epidermis, suggesting that disruption of LC-T cell tolerogenic axis contributes to skin inflammation. Interestingly, immune checkpoint blockade therapy was associated with decreased epidermal LC-T cell contact in the normal skin of cancer patients affected by cutaneous immune-related adverse events. Collectively, our findings indicate that LCs may contribute to T cell tolerance in the epidermis.

Home at last: Mixed signals guide memory T cells to residency

Tissue-resident memory T (TRM) cells adapt to diverse environments, providing local long-term protection. In this issue of Immunity, Obers etal. and Raynor etal. demonstrate how diet, commensals, and host factors determine TRM cell development, maintenance, and function across tissues.

The myocardium of human dilated nonischemic cardiomyopathy harbors unique tissue-resident lymphocyte subsets

Abstract Purpose The etiology of dilated nonischemic cardiomyopathy (NICM) is often unclear, but thought to be multifactorial, involving an interplay between genetic factors and direct myocardial damage caused by infection, autoimmunity, or toxins. Tissue-resident lymphocytes are non-circulating immune cells which are retained within various tissues and play integral roles in maintaining homeostasis, responding to infection, regulating inflammation, and mediating tissue repair. Despite their likely involvement in various cardiac pathologies, the presence of tissue-resident lymphocytes in the human heart has not yet been well-characterized, neither in health nor in disease. Methods Human left ventricular tissue and paired peripheral blood samples were obtained from six adult organ donors with normal heart function who died of noncardiac causes and from the explants of six adult patients with end-stage nonischemic cardiomyopathy. Heart tissue was processed using mechanical and enzymatic digestion. Mononuclear cells were isolated from both heart and paired blood by density centrifugation. Isolated mononuclear cells were surface stained with an antibody cocktail and interrogated using multidimensional flow cytometry. Results The adult human heart contains a diverse immune cell population (Fig 1A). Both healthy and NICM cardiac lymphocytes express distinct phenotypic profiles which resemble those of resident lymphocytes found across various tissues, distinct from those isolated from paired blood. Frequencies of effector memory T (Tem) cells (CD45RA- CCR7-) were higher in heart than in blood among both CD4+ and CD8+ T-cells. In heart compared to blood, significantly more Tem expressed CD69, a canonical marker of tissue-resident memory T (Trm) cells (Fig 1B). Cardiac Trm, especially CD8+ Trm, expressed classical Trm signature markers including integrins CD103 (epithelial binding) and CD49a (collagen binding). NICM Trm expressed more CD49a than healthy heart Trm (Fig 1C). NK-cells also demonstrated higher CD69 expression (trNK) in heart than in blood, with associated expression of CD103, CD49a, and CXCR6 (Fig 1D). Compared to healthy hearts, NICM trNK were predominantly CD56bright/CD16- (Fig 1E and 1F) and expressed less CD57 (Fig 1D), overall indicating a less mature state with lower cytotoxic potential. Confocal imaging of cardiac tissue revealed CD69-expressing tissue-resident lymphocytes within the cardiac interstitium. Conclusions The adult human heart contains diverse populations of lymphocytes which express canonical markers of tissue residency, similar to lymphocytes resident in other tissues. Compared to healthy hearts, NICM hearts have more CD49a+ Trm, perhaps related to greater fibrosis, and also harbor a distinct subset of immature tissue-resident NK cells which may shed light on pathophysiology. Future work is focused on better exploring the functional phenotypes of these resident cells and better localizing them within the myocardium.FA - Figure 1

Characterization of HPV6/11-reactive T-cell subsets in papillomas of patients with juvenile-onset recurrent respiratory papillomatosis and identification of HPV11 E7-specific candidate TCR clonotypes.

Juvenile-onset recurrent respiratory papillomatosis (JORRP) is caused by persistent infection of epithelial cells by low-risk human papillomavirus (HPV) types 6 and 11. While multiple infiltrated immune cells have been reported to mediate disease progress, knowledge of HPV-reactive T-cell subsets in papillomas remains elusive. Through single-cell RNA sequencing and RNA microarray, we found that CD8+ tissue-resident memory T (CD8+ TRM) cells with strong interferon-gamma (IFN-γ) production expanded, and were negatively correlated to the disease severity in the frequency of surgery. These IFN-γ+ CD8+ memory T cells were readily activated and expanded in vitro by autologous dendritic cells loaded with HPV11 E7 peptide pool. Moreover, T cell receptor (TCR) clonal expansion was observed in JORRP papilloma tissues, indicating a biased TCR repertoire toward HPV-specific recognition. Finally, we identified and characterized HPV11 E7-specific candidate TCR clonotypes from IFN-γ+ CD8+ memory T cells, suggesting their potential application in TCR-engineered T cells (TCR-T) therapy for HPV11-related diseases. Our findings provided insights into the specific local immune response to HPV6/11 infection and highlighted the importance of IFN-γ+ CD8+ TRM cells in anti-HPV6/11 T-cell immunity.IMPORTANCEThe persistent recurrence of human papillomavirus (HPV) 6/11 infection in papillomas underscores the failure of local immune responses in patients with juvenile-onset recurrent respiratory papillomatosis (JORRP). Our previous study demonstrated that T cells constitute the predominant immune cell population in JORRP papilloma tissues. Understanding the T-cell-mediated immune responses within JORRP papilloma tissues is crucial for disease control. In the present study, we characterized CD8+ tissue-resident memory T (CD8+ TRM) cells as the primary T-cell subset responsible for local anti-HPV6/11 immunity. Moreover, we identified two HPV11 E7-specific candidate T cell receptor (TCR) clonotypes out of IFN-γ+ CD8+ memory T cells. Overall, our findings provided insights into the local immune responses to HPV6/11 infection and offered information for developing more effective immunotherapeutic strategies against JORRP.

Alarm Functions of PD-1+ Brain-Resident Memory T Cells.

Resident memory T cells (TRM cells) have been described in barrier tissues as having a "sensing and alarm" function where, upon sensing cognate Ag, they alarm the surrounding tissue and orchestrate local recruitment and activation of immune cells. In the immunologically unique and tightly restricted CNS, it remains unclear whether and how brain TRM cells, which express the inhibitory receptor programmed cell death protein 1 (PD-1), alarm the surrounding tissue during Ag re-encounter. Using mouse models, we reveal that TRM cells are sufficient to drive the rapid remodeling of the brain immune landscape through activation of microglia, dendritic cells, NK cells, and B cells, expansion of regulatory T cells, and recruitment of macrophages and monocytic dendritic cells. Moreover, we report that although PD-1 restrained granzyme B upregulation in brain TRM cells reactivated via viral peptide, we observed no apparent effect on cytotoxicity invivo, or downstream alarm responses within 48 h of TRM reactivation. We conclude that TRM cells are sufficient to trigger rapid immune activation and recruitment in the CNS and may have an unappreciated role in driving neuroinflammation.

Evolutionary diversity of CXCL16-CXCR6: Convergent substitutions and recurrent gene loss in sauropsids.

The CXCL16-CXCR6 axis is crucial for regulating the persistence of CD8 tissue-resident memory T cells (TRM). CXCR6 deficiency lowers TRM cell numbers in the lungs and depletes ILC3s in the lamina propria, impairing mucosal defence. This axis is linked to diseases like HIV/SIV, cancer, and COVID-19. Together, these highlight that the CXCL16-CXCR6 axis is pivotal in host immunity. Previous studies of the CXCL16-CXCR6 axis found genetic variation among species but were limited to primates and rodents. To understand the evolution and diversity of CXCL16-CXCR6 across vertebrates, we compared approximately 400 1-to-1 CXCR6 orthologs spanning diverse vertebrates. The unique DRF motif of CXCR6 facilitates leukocyte adhesion by interacting with cell surface-expressed CXCL16 and plays a key role in G-protein selectivity during receptor signalling; however, our findings show that this motif is not universal. The DRF motif is restricted to mammals, turtles, and frogs, while the DRY motif, typical in other CKRs, is found in snakes and lizards. Most birds exhibit the DRL motif. These substitutions at the DRF motif affect the receptor-Gi/o protein interaction. We establish recurrent CXCR6 gene loss in 10 out of 36 bird orders, including Galliformes and Passeriformes, Crocodilia, and Elapidae, attributed to segmental deletions and/or frame-disrupting changes. Notably, single-cell RNA sequencing of the lung shows a drop in TRM cells in species with CXCR6 loss, suggesting a possible link. The concurrent loss of ITGAE, CXCL16, and CXCR6 in chickens may have altered CD8 TRM cell abundance, with implications for immunity against viral diseases and vaccines inducing CD8 TRM cells.

Injury-induced myosin-specific tissue-resident memory T cells drive immune checkpoint inhibitor myocarditis

Cardiac myosin-specific (MyHC) T cells drive the disease pathogenesis of immune checkpoint inhibitor-associated myocarditis (ICI-myocarditis). To determine whether MyHC T cells are tissue-resident memory T (TRM) cells, we characterized cardiac TRM cells in naive mice and established that they have a distinct phenotypic and transcriptional profile that can be defined by their upregulation of CD69, PD-1, and CXCR6. We then investigated the effects of cardiac injury through a modified experimental autoimmune myocarditis mouse model and an ischemia-reperfusion injury mouse model and determined that cardiac inflammation induces the recruitment of autoreactive MyHC TRM cells, which coexpress PD-1 and CD69. To investigate whether the recruited MyHC TRM cells could increase susceptibility to ICI-myocarditis, we developed a two-hit ICI-myocarditis mouse model where cardiac injury was induced, mice were allowed to recover, and then were treated with anti-PD-1 antibodies. We determined that mice who recover from cardiac injury are more susceptible to ICI-myocarditis development. We found that murine and human TRM cells share a similar location in the heart and aggregate along the perimyocardium. We phenotyped cells obtained from pericardial fluid from patients diagnosed with dilated cardiomyopathy and ischemic cardiomyopathy and established that pericardial T cells are predominantly CD69+ TRM cells that up-regulate PD-1. Finally, we determined that human pericardial macrophages produce IL-15, which supports and maintains pericardial TRM cells.

A Prime-Boost Vaccination Approach Induces Lung Resident Memory CD8+ T Cells Derived from Central Memory T Cells That Prevent Tumor Lung Metastasis.

Memory T cells play a key role in immune protection against cancer. Vaccine-induced tissue-resident memory T (TRM) cells in the lung have been shown to protect against lung metastasis. Identifying the source of lung TRM cells can help to improve strategies, preventing tumor metastasis. Here, we found that a prime-boost vaccination approach using intramuscular DNA vaccine priming, followed by intranasal live-attenuated influenza-vectored vaccine (LAIV) boosting induced higher frequencies of lung CD8+ TRM cells compared with other vaccination regimens. Vaccine-induced lung CD8+ TRM cells, but not circulating memory T cells, conferred significant protection against metastatic melanoma and mesothelioma. Central memory T (TCM) cells induced by the DNA vaccination were major precursors of lung TRM cells established after the intranasal LAIV boost. Single-cell RNA sequencing analysis indicated that transcriptional reprogramming of TCM cells for differentiation into TRM cells in the lungs started as early as day 2 post the LAIV boost. Intranasal LAIV altered the mucosal microenvironment to recruit TCM cells via CXCR3-dependent chemotaxis and induced CD8+ TRM-associated transcriptional programs. These results identified TCM cells as the source of vaccine-induced CD8+ TRM cells that protect against lung metastasis. Significance: Prime-boost vaccination shapes the mucosal microenvironment and reprograms central memory T cells to generate lung resident memory T cells that protect against lung metastasis, providing insights for the optimization of vaccine strategies.

Retinoic acid and TGF-β orchestrate organ-specific programs of tissue residency

Tissue-resident memory T (TRM) cells are integral to tissue immunity, persisting in diverse anatomical sites where they adhere to a common transcriptional framework. How these cells integrate distinct local cues to adopt the common TRM cell fate remains poorly understood. Here, we show that whereas skin TRM cells strictly require transforming growth factor β (TGF-β) for tissue residency, those in other locations utilize the metabolite retinoic acid (RA) to drive an alternative differentiation pathway, directing a TGF-β-independent tissue residency program in the liver and synergizing with TGF-β to drive TRM cells in the small intestine. We found that RA was required for the long-term maintenance of intestinal TRM populations, in part by impeding their retrograde migration. Moreover, enhanced RA signaling modulated TRM cell phenotype and function, a phenomenon mirrored in mice with increased microbial diversity. Together, our findings reveal RA as a fundamental component of the host-environment interaction that directs immunosurveillance in tissues.

CRISPR screens unveil nutrient-dependent lysosomal and mitochondrial nodes impacting intestinal tissue-resident memory CD8+ T cell formation

Nutrient availability and organelle biology direct tissue homeostasis and cell fate, but how these processes orchestrate tissue immunity remains poorly defined. Here, using invivo CRISPR-Cas9 screens, we uncovered organelle signaling and metabolic processes shaping CD8+ tissue-resident memory T (TRM) cell development. TRM cells depended on mitochondrial translation and respiration. Conversely, three nutrient-dependent lysosomal signaling nodes-Flcn, Ragulator, and Rag GTPases-inhibited intestinal TRM cell formation. Depleting these molecules or amino acids activated the transcription factor Tfeb, thereby linking nutrient stress to TRM programming. Further, Flcn deficiency promoted protective TRM cell responses in the small intestine. Mechanistically, the Flcn-Tfeb axis restrained retinoic acid-induced CCR9 expression for migration and transforming growth factor β (TGF-β)-mediated programming for lineage differentiation. Genetic interaction screening revealed that the mitochondrial protein Mrpl52 enabled early TRM cell formation, while Acss1 controlled TRM cell development under Flcn deficiency-associated lysosomal dysregulation. Thus, the interplay between nutrients, organelle signaling, and metabolic adaptation dictates tissue immunity.

CD8+ tissue-resident memory T cells are expanded in primary Sjögren’s disease and can be therapeutically targeted by CD103 blockade

ObjectiveTissue-resident memory cells (Trm) are a subset of T cells residing persistently and long-term within specific tissues that contribute to persistent inflammation and tissue damage. We characterised the phenotype and...

Higher frequency of peripheral blood CD103+CD8+ T cells with lower levels of PD-1 and TIGIT expression related to favorable outcomes in leukemia patients.

Leukemia is a prevalent pediatric life-threatening hematologic malignancy with a poor prognosis. Targeting immune checkpoints (ICs) to reverse T cell exhaustion is a potentially effective treatment for leukemia. Tissue resident memory T (TRM) cells have been found to predict the efficacy of programmed death receptor-1 inhibitor (anti-PD-1) therapy in solid tumors. However, the IC characteristics of TRM cells in leukemia and their relationship with prognosis remain unclear. We employed multi-color flow cytometry to evaluate the frequencies of CD103+CD4+ and CD103+CD8+ T cells in the peripheral blood (PB) of patients with acute myeloid leukemia and B-cell acute lymphoblastic leukemia compared to healthy individuals. We examined the expression patterns of PD-1 and T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) within the circulating CD103+ T cell subsets affected by leukemia. To further elucidate the immunological landscape, we assessed the differentiation status of CD103+ T cells across various disease states in patients with leukemia. Our findings showed a significant increase in the frequency of CD103+CD8+ T cells in the PB of patients with leukemia who had achieved complete remission (CR) compared to those in the de novo (DN) and relapsed/refractory (RR) stages. This increase was accompanied by a notable decrease in the expression levels of PD-1 and TIGIT in CD103+CD8+ T cells in the CR stage. Additionally, our analysis revealed a higher proportion of CD103+CD8+ T cells in the central memory (TCM) and effector memory (TEM) subsets of the immune profile. Notably, the proportions of CD103+ naïve T cells, CD103+ TEM, and CD103+ terminally differentiated T cells within the CD8+ T cell population were significantly elevated in patients with CR compared to those in the DN/RR stages. The data indicate that circulating higher frequency of CD103+CD8+ T cells with lower expression of PD-1 and TIGIT are associated with favorable outcomes in patients with leukemia. This suggests a potential role of TRM cells in leukemia prognosis and provides a foundation for developing targeted immunotherapies.

Tissue-resident memory T cells: Harnessing their properties against infection for cancer treatment.

We have rapidly gained insights into the presence and function of T lymphocytes in non-lymphoid tissues, the tissue-resident memory T (TRM) cells. The central pillar of adaptive immunity has been expanded from classic central memory T cells giving rise to progeny upon reinfection and effector memory cells circulating through the blood and patrolling the tissues to include TRM cells that reside and migrate inside solid organs and tissues. Their development and maintenance have been studied in detail, providing exciting clues on how their unique properties used to fight infections may benefit therapies against solid tumors. We provide an overview of CD8 TRM cells and the properties that make them of interest for vaccination and cancer therapies.

CD8+ tissue-resident memory T cells are essential in bleomycin-induced pulmonary fibrosis.

Human tissue-resident memory T (TRM) cells play a crucial role in protecting the body from infections and cancers. Recent research observed increased numbers of TRM cells in the lung tissues of idiopathic pulmonary fibrosis patients. However, the functional consequences of TRM cells in pulmonary fibrosis remain unclear. Here, we found that the numbers of TRM cells, especially the CD8+ subset, were increased in the mouse lung with bleomycin-induced pulmonary fibrosis. Increasing or decreasing CD8+ TRM cells in mouse lungs accordingly altered the severity of fibrosis. In addition, the adoptive transfer of CD8+ T cells containing a large number of CD8+ TRM cells from fibrotic lungs was sufficient to induce pulmonary fibrosis in control mice. Treatment with chemokine CC-motif ligand (CCL18) induced CD8+ TRM cell expansion and exacerbated fibrosis, whereas blocking C-C chemokine receptor 8 (CCR8) prevented CD8+ TRM recruitment and inhibited pulmonary fibrosis. In conclusion, CD8+ TRM cells are essential for bleomycin-induced pulmonary fibrosis, and targeting CCL18/CCR8/CD8+ TRM cells may be a potential therapeutic approach. NEW & NOTEWORTHY The role of CD8+ TRM cells in the development of pulmonary fibrosis was validated and studied in the classic model of pulmonary fibrosis. It was proposed for the first time that CCL18 has a chemotactic effect on CD8+ TRM cells, thereby exacerbating pulmonary fibrosis.

The NSCLC immunotherapy response predicted by tumor-infiltrating T cells via a non-invasive radiomic approach.

Identifying patients with non-small cell lung cancer (NSCLC) who are optimal candidates for immunotherapy is a cornerstone in clinical decision-making. The tumor immune microenvironment (TIME) is intricately linked with both the prognosis of the malignancy and the efficacy of immunotherapeutic interventions. CD8+ T cells, and more specifically, tissue-resident memory CD8+ T cells [CD8+ tissue-resident memory T (TRM) cells] are postulated to be pivotal in orchestrating the immune system's assault on tumor cells. Nevertheless, the accurate quantification of immune cell infiltration-and by extension, the prediction of immunotherapeutic efficacy-remains a significant scientific frontier. In this study, we introduce a cutting-edge non-invasive radiomic model, grounded in TIME markers (CD3+ T, CD8+ T, and CD8+ TRM cells), to infer the levels of immune cell infiltration in NSCLC patients receiving immune checkpoint inhibitors and ultimately predict their response to immunotherapy. Data from patients who had surgical resections (cohort 1) were employed to construct a radiomic model capable of predicting the TIME. This model was then applied to forecast the TIME for patients under immunotherapy (cohort 2). Conclusively, the study delved into the association between the predicted TIME from the radiomic model and the immunotherapeutic outcomes of the patients. For the immune cell infiltration radiomic prediction models in cohort 1, the AUC values achieved 0.765, 0.763, and 0.675 in the test set of CD3+ T, CD8+ T, and CD8+ TRM, respectively. While the AUC values for the TIME-immunotherapy predictive value were 0.651, 0.763, and 0.829 in the CD3-immunotherapy response model, CD8-immunotherapy response model, and CD8+ TRM-immunotherapy response model in cohort 2, respectively. The CD8+ TRM-immunotherapy model exhibited the highest predictive value and was significantly better than the CD3-immunotherapy model in predicting the immunotherapy response. The progression-free survival (PFS) analysis based on the predicted levels of CD3+ T, CD8+ T, and CD8+ TRM immune cell infiltration showed that the CD8+ T cell infiltration level was an independent factor (P=0.014, HR=0.218) with an AUC value of 0.938. Our empirical evidence reveals that patients with substantial CD8+ T cell infiltration experience a markedly improved PFS compared with those with minimal infiltration, asserting the status of the CD8+ T cell as an independent prognosticator of PFS in the context of immunotherapy. Although CD8+ TRM cells demonstrated the greatest predictive accuracy for immunotherapy response, their predictive strength for PFS was marginally surpassed by that of CD8+ T cells. These insights advocate for the application of the proposed non-invasive radiomic model, which utilizes TIME analysis, as a reliable predictor for immunotherapy outcomes and PFS in NSCLC patients.

Intranasal Immunization with a Recombinant Adenovirus Encoding Multi-Stage Antigens of Mycobacterium tuberculosis Preferentially Elicited CD8+ T Cell Immunity and Conferred a Superior Protection in the Lungs of Mice than Bacillus Calmette-Guerin.

The development of a tuberculosis (TB) vaccine is imperative. Employing multi-stage Mycobacterium tuberculosis (Mtb) antigens as targeted antigens represents a critical strategy in establishing an effective novel TB vaccine. In this investigation, we evaluated the immunogenicity and protective efficacy of a recombinant adenovirus vaccine expressing two fusion proteins, Ag85B-ESAT6 (AE) and Rv2031c-Rv2626c (R2), derived from multi-stage antigens of Mtb via intranasal administration in mice. Intranasal delivery of Ad-AE-R2 induced both long-lasting mucosal and systemic immunities, with a preferential elicitation of CD8+ T cell immunity demonstrated by the accumulation and retention of CD8+ T cells in BALF, lung, and spleen, as well as the generation of CD8+ TRM cells in BALF and lung tissues. Compared to subcutaneous immunization with Bacillus Calmette-Guerin (BCG), Ad-AE-R2 provided superior protection against high-dose intratracheal BCG challenge, specifically within the lungs of mice. Our findings support the notion that empowering T cells within the respiratory mucosa is crucial for TB vaccine development while highlighting targeting CD8+ T cell immunity as an effective strategy for optimizing TB vaccines and emphasizing that eliciting systemic memory immunity is also vital for the successful development of a TB mucosal vaccine. Furthermore, our results demonstrate that the BCG challenge serves as a convenient and efficient method to evaluate candidate vaccine efficacy.

Preexisting Skin-Resident CD8 and γδ T-cell Circuits Mediate Immune Response in Merkel Cell Carcinoma and Predict Immunotherapy Efficacy.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with a ∼50% response rate to immune checkpoint blockade (ICB) therapy. To identify predictive biomarkers, we integrated bulk and single-cell RNA sequencing (RNA-seq) with spatial transcriptomics from a cohort of 186 samples from 116 patients, including bulk RNA-seq from 14 matched pairs pre- and post-ICB. In nonresponders, tumors show evidence of increased tumor proliferation, neuronal stem cell markers, and IL1. Responders have increased type I/II interferons and preexisting tissue resident (Trm) CD8 or Vδ1 γδ T cells that functionally converge with overlapping antigen-specific transcriptional programs and clonal expansion of public T-cell receptors. Spatial transcriptomics demonstrated colocalization of T cells with B and dendritic cells, which supply chemokines and costimulation. Lastly, ICB significantly increased clonal expansion or recruitment of Trm and Vδ1 cells in tumors specifically in responders, underscoring their therapeutic importance. These data identify potential clinically actionable biomarkers and therapeutic targets for MCC. Significance: MCC serves as a model of ICB response. We utilized the largest-to-date, multimodal MCC dataset (n = 116 patients) to uncover unique tumor-intrinsic properties and immune circuits that predict response. We identified CD8 Trm and Vδ1 T cells as clinically actionable mediators of ICB response in major histocompatibility complex-high and -low MCCs, respectively.

Generation of antigen-specific memory CD4 T cells by heterologous immunization enhances the magnitude of the germinal center response upon influenza infection.

Current influenza vaccine strategies have yet to overcome significant obstacles, including rapid antigenic drift of seasonal influenza viruses, in generating efficacious long-term humoral immunity. Due to the necessity of germinal center formation in generating long-lived high affinity antibodies, the germinal center has increasingly become a target for the development of novel or improvement of less-efficacious vaccines. However, there remains a major gap in current influenza research to effectively target T follicular helper cells during vaccination to alter the germinal center reaction. In this study, we used a heterologous infection or immunization priming strategy to seed an antigen-specific memory CD4+ T cell pool prior to influenza infection in mice to evaluate the effect of recalled memory T follicular helper cells in increased help to influenza-specific primary B cells and enhanced generation of neutralizing antibodies. We found that heterologous priming with intranasal infection with acute lymphocytic choriomeningitis virus (LCMV) or intramuscular immunization with adjuvanted recombinant LCMV glycoprotein induced increased antigen-specific effector CD4+ T and B cellular responses following infection with a recombinant influenza strain that expresses LCMV glycoprotein. Heterologously primed mice had increased expansion of secondary Th1 and Tfh cell subsets, including increased CD4+ TRM cells in the lung. However, the early enhancement of the germinal center cellular response following influenza infection did not impact influenza-specific antibody generation or B cell repertoires compared to primary influenza infection. Overall, our study suggests that while heterologous infection or immunization priming of CD4+ T cells is able to enhance the early germinal center reaction, further studies to understand how to target the germinal center and CD4+ T cells specifically to increase long-lived antiviral humoral immunity are needed.

Tissue-resident memory T cells in epicardial adipose tissue comprise transcriptionally distinct subsets that are modulated in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and carries an increased risk of stroke and heart failure. Here we investigated how the immune infiltrate of human epicardial adipose tissue (EAT), which directly overlies the myocardium, contributes to AF. Flow cytometry analysis revealed an enrichment of tissue-resident memory T (TRM) cells in patients with AF. Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) and single-cell T cell receptor (TCR) sequencing identified two transcriptionally distinct CD8+ TRM cells that are modulated in AF. Spatial transcriptomic analysis of EAT and atrial tissue identified the border region between the tissues to be a region of intense inflammatory and fibrotic activity, and the addition of TRM populations to atrial cardiomyocytes demonstrated their ability to differentially alter calcium flux as well as activate inflammatory and apoptotic signaling pathways. This study identified EAT as a reservoir of TRM cells that can directly modulate vulnerability to cardiac arrhythmia.