T cell responses: naive to memory and everything in between

Perspectives on label-free microscopy of heterogeneous and dynamic biological systems

Significance

Advancements in label-free microscopy could provide real-time, non-invasive imaging with unique sources of contrast and automated standardized analysis to characterize heterogeneous and dynamic biological processes. These tools would overcome challenges with widely used methods that are destructive (e.g., histology, flow cytometry) or lack cellular resolution (e.g., plate-based assays, whole animal bioluminescence imaging).

Aim

This perspective aims to (1) justify the need for label-free microscopy to track heterogeneous cellular functions over time and space within unperturbed systems and (2) recommend improvements regarding instrumentation, image analysis, and image interpretation to address these needs.

Approach

Three key research areas (cancer research, autoimmune disease, and tissue and cell engineering) are considered to support the need for label-free microscopy to characterize heterogeneity and dynamics within biological systems. Based on the strengths (e.g., multiple sources of molecular contrast, non-invasive monitoring) and weaknesses (e.g., imaging depth, image interpretation) of several label-free microscopy modalities, improvements for future imaging systems are recommended.

Conclusion

Improvements in instrumentation including strategies that increase resolution and imaging speed, standardization and centralization of image analysis tools, and robust data validation and interpretation will expand the applications of label-free microscopy to study heterogeneous and dynamic biological systems.

DNA methylation differences between cord and adult white blood cells reflect postnatal immune cell maturation

Epigenetic modifications such as DNA methylation are both cell type and developmental age specific. Here, we show that the immunological maturation of blood cell types influences DNA methylation changes from naive cord blood to fully functional adult blood. Lymphoid cells in adult blood showed more variability than in cord blood suggesting an antigen-dependent maturation of DNA methylation in lymphoid cells throughout the lifespan. Fewer DNA methylation changes between cord and adult blood were observed in myeloid cells, particularly in monocytes, which demonstrated the least number of DNA methylation changes between cord and adult blood. We also noted differences in epigenetic ages by immune cell types within the same individuals, specifically in cord blood where monocytes were epigenetically oldest compared to the other cell types. In addition, we provide a publicly available resource to the community as an R Shiny web application to interactively explore epigenetic patterns between naive cord white blood cells and fully functional adult white blood cells for six immune cell types.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

Immune responses of cattle vaccinated by various routes with Mycobacterium bovis Bacillus Calmette-Guérin (BCG)

BACKGROUND

Mycobacterium bovis BCG is the human tuberculosis vaccine and is the oldest vaccine still in use today with over 4 billion people vaccinated since 1921. The BCG vaccine has also been investigated experimentally in cattle and wildlife by various routes including oral and parenteral. Thus far, oral vaccination studies of cattle have involved liquid BCG or liquid BCG incorporated into a lipid matrix. Lyophilization is an established technique used for stabilizing bioproducts such as vaccines.

METHODS

In the current study, cattle were vaccinated in two phases. In each phase, cattle were divided into three groups. Group 1 received BCG injected SQ, Group 2 received liquid BCG delivered to the posterior oral cavity, Group 3 orally consumed lyophilized BCG contained within a gelatin capsule placed within a small amount of a commercial alfalfa product.

RESULTS

No vaccinated cattle were positive by an interferon gamma release assay. All but 4 animals were negative by tuberculin skin testing prior to vaccination: the 4 non-negative animals being categorized as suspects. Sixteen weeks post-vaccination all but 1 animal was negative, it being categorized as a suspect. An in vitro antigen stimulation assay and flow cytometry were used to detect antigen-specific CD4, CD8 and γδ T cell responses following vaccination. Oral vaccination of animals with lyophilized BCG did not result in any increases in the frequency of CD4, CD8 or γδ T cell proliferative or IFN-γ responses at any of the time points analyzed in either phase 1 or 2. In contrast, vaccination with BCG SQ and liquid BCG delivered to the posterior pharynx, resulted in an increase in the frequency of proliferating and IFN-γ-producing CD4 T cells with peak responses at 9-12 weeks post-vaccination. Similar to oral lyophilized BCG vaccinated animals, we did not observe any significant increases in the frequency of CD8 and γδ T cell proliferative and IFN-γ responses following SQ or oral liquid vaccinated animals.

CONCLUSIONS

These data would suggest that vaccination with oral lyophilized BCG does not induce a measurable, antigen-specific cell mediated responses in the periphery, when compared to BCG administered SQ or liquid BCG administered via the oral route. However, vaccination with either SQ or liquid BCG delivered to the posterior pharynx does induce measurable CD4 T cell responses in the periphery.

Sex-specific transcriptomic effects of low-dose inorganic arsenic exposure on bone marrow-derived macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. There are numerous diseases caused by iAs exposure in which macrophages are involved, including cardiovascular disease, cancer, and increased risk of (respiratory) infectious diseases. Notably, prenatal iAs exposure is also associated with negative birth outcomes and developmental immunotoxicity (DIT) contributing to long-term adverse outcomes of these immune-related diseases. Therefore, understanding the effects of iAs exposure on macrophages, particularly during immune development or tissue injury and inflammation, can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In contrast to prior published studies which often only focused on the effect of iAs on mature macrophages after development, in this study, we analyzed the transcriptome of M0-, M1- and M2-polarized male and female murine bone marrow-derived macrophages (BMDMs) which were exposed to iAs during the differentiation phase, as a model to study iAs (developmental) immunotoxicity. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure during differentiation. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding the role of (early-life) arsenic exposure in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

Unlocking cancer vaccine potential: What are the key factors?

Cancer is a global health challenge, with changing demographics and lifestyle factors producing an increasing burden worldwide. Screening advancements are enabling earlier diagnoses, but current cancer immunotherapies only induce remission in a small proportion of patients and come at a high cost. Cancer vaccines may offer a solution to these challenges, but they have been mired by poor results in past decades. Greater understanding of tumor biology, coupled with the success of vaccine technologies during the COVID-19 pandemic, has reinvigorated cancer vaccine development. With the first signs of efficacy being reported, cancer vaccines may be beginning to fulfill their potential. Solid tumors, however, present different hurdles than infectious diseases. Combining insights from previous cancer vaccine clinical development and contemporary knowledge of tumor immunology, we ask: who are the 'right' patients, what are the 'right' targets, and which are the 'right' modalities to maximize the chances of cancer vaccine success?

Environmental Low-Dose Radiation Activates Th1 Immunity through the Mitochondria-STING Pathway

The presence of low-dose radiation (LDR) in the environment has become more prevalent. However, the effect of LDR exposure on the immune system remains elusive. Here, we interestingly found that LDR specifically elevated the percentage of CD4+IFNγ+ Th1 splenocytes, both in vitro and in vivo, without affecting the percentage of CD8+IFNγ+ Tc1 cells and regulatory T cells. A similar phenomenon was found in T cells from peripheral blood. Mechanistically, we found that LDR can induce mitochondrial damage, which stimulated the STING signaling pathway, leading to the enhanced expression of T-bet, the master transcriptional factor of Th1-cell differentiation. The specific STING signal inhibitor can abrogate the effect of LDR on Th1 differentiation, confirming the central role of the STING pathway. To further validate the immunoregulatory role of LDR, we exposed mice with whole body LDR and evaluated if LDR could protect mice against triple-negative breast cancer through enhanced antitumor immunity. As expected, LDR significantly delayed tumor development and promoted cell death. Meanwhile, LDR resulted in increased tumor-infiltrating Th1 cells, while the proportion of Tc1 and Treg cells remained unchanged. Furthermore, the infiltration of antitumor macrophages was also increased. In summary, we revealed that environmental LDR could specifically regulate Th1 T-cell activities, providing critical information for the potential application of LDR in both clinical and nonclinical settings.

Humoral and cellular immune response to AZD1222 /Covishield and BV152/Covaxin COVID-19 vaccines among adults in India

Several COVID-19 vaccines were developed using different approaches to prevent both symptomatic COVID-19 cases and fatalities. The adults were vaccinated with two doses of AZD1222/Covishield (n = 77) [manufactured by Serum Institute of India Pvt Ltd] vaccine and BV152/Covaxin (n = 99) [manufactured by Bharat Biotech] vaccine. They were assessed for immune response at pre-vaccination, 1 month post first and 6 months post second dose for anti-SARS-CoV-2 IgG antibody, surrogate neutralizing antibody (NAbs), immune phenotypes, antigen specific NK, B and T cell response, their effector functionality by ELISPOT and plasma cytokine profile. Both vaccines elicited enhanced IgG antibody and Nab levels compared to the baseline. BV152/Covaxin, the whole virus inactivated vaccine exhibited higher IgG (70% vs 100%), Nab (90% vs 100%), and robust T cell (31% vs 96%) responses at 6 months post second dose compared to 1 month post first dose justifying the utility of the second dose. Detection of SARS-CoV-2 WV and S1 specific CD4+ central T cell memory response in AZD1222/Covishield vaccinee at 6 months post second dose and higher CD4+ and CD8+ naïve and central memory T cell response in BV152/Covaxin vaccinee at 1 month post first dose indicated the involvement of memory T cells. Persistent IgG and NAb responses along with IgG+B and IgG+memory B cells in AZD1222/Covishield recipients at 6 months post second dose indicated sustained immune memory response. Continued heightened IFN-γ secreting T cell response (ELISPOT) displayed by both the vaccine platforms could serve as a co correlate of protection, further to evaluation in follow up studies. Overall, our data suggest that coordinated functions of humoral and cellular branches of adaptive immunity may pave ways toward protective immunity against COVID-19.

Differential Immunological Responses of Adult Domestic and Bighorn Sheep to Inoculation with Mycoplasma ovipneumoniae Type Strain Y98

Bighorn sheep (BHS) populations have been reported to experience high levels of morbidity and mortality following infection with Mycoplasma ovipneumoniae. This contrasts with the subclinical presentation in domestic sheep (DS). Understanding this difference requires baseline knowledge of pre- and post-infection immune responses of both species. The present study identifies differences in leukocyte phenotypes between adult BHS and DS before and after intranasal inoculation with 1 × 108Mycoplasma ovipneumoniae. Prior to inoculation, BHS were confirmed to have a higher abundance of leukocyte CD14 and serum concentrations of IL-36RA. In contrast, DS had a higher leukocyte abundance of CD16 in addition to previously observed integrin markers and CD172a, as well as greater serum TNF-α concentrations. Within 15 days of inoculation, BHS displayed signs of mild respiratory disease and M. ovipneumoniae DNA was detected on nasal swabs using a quantitative PCR; meanwhile, DS exhibited few to no clinical signs and had levels of M. ovipneumoniae DNA below the standard curve threshold. Immunologic markers remained relatively consistent pre- and post-inoculation in DS, while BHS demonstrated changes in the peripheral leukocyte expression of CD172a and CD14. Circulating serum IL-36RA decreased and CXCL10 increased within BHS. These findings highlight significant differences in cellular immunity between BHS and DS, raised and housed under similar conditions, prior to and following inoculation with M. ovipneumoniae.

The development and maintenance of immunity against visceral leishmaniasis

Understanding the development and maintenance of immunological memory is important for efforts to eliminate parasitic diseases like leishmaniasis. Leishmaniasis encompasses a range of pathologies, resulting from infection with protozoan parasites belonging to the subgenera Leishmania and Viannia of the genus Leishmania. A striking feature of these infections is that natural or drug-mediated cure of infection generally confers life-long protection against disease. The generation of protective T cell responses are necessary to control Leishmania infections. CD4+ T helper (Th) cells orchestrate immune responses in leishmaniasis and IFNγ+ Tbet+ CD4+ T (Th1) cells are required for the activation of phagocytes to kill captured or resident parasites, while other Th cell subset, including FoxP3+ natural regulatory T cells and Th2 cells can promote disease progression by suppressing the activities of Th1 cells. Upon resolution of a primary Leishmania infection, different subsets of CD4+ T cells, including tissue-resident memory T cells, effector memory T cells, central memory T cells, and short-lived effector T cells, help to confer resistance against reinfection. To maintain long-term protective Leishmania-specific CD4+ T cells responses, it is believed that persistent parasites or re-exposure to parasites at regular intervals is required (concomitant immunity). Despite the advances in our understanding about the immune responses during leishmaniasis, the generation of long-lasting protective immunity via vaccination has yet to be achieved. In this review, we summarize our current understanding about the formation and maintenance of immunological memory and control of leishmaniasis at the individual and population level. We will focus on Indian visceral leishmaniasis and discuss T cell responses that contribute to susceptibility to leishmaniasis, parasite persistence in populations and the environment, as well as describing advances in the development of leishmaniasis vaccines aimed at inducing protective CD4+ T cell responses.

Perspectives on Microbiome Therapeutics in Infectious Diseases: A Comprehensive Approach Beyond Immunology and Microbiology

Although global life expectancy has increased over the past 20 years due to advancements in managing infectious diseases, one-fifth of people still die from infections. In response to this ongoing threat, significant efforts are underway to develop vaccines and antimicrobial agents. However, pathogens evolve resistance mechanisms, complicating their control. The COVID-19 pandemic has underscored the limitations of focusing solely on the pathogen-killing strategies of immunology and microbiology to address complex, multisystemic infectious diseases. This highlights the urgent need for practical advancements, such as microbiome therapeutics, that address these limitations while complementing traditional approaches. Our review emphasizes key outcomes in the field, including evidence of probiotics reducing disease severity and insights into host-microbiome crosstalk that have informed novel therapeutic strategies. These findings underscore the potential of microbiome-based interventions to promote physiological function alongside existing strategies aimed at enhancing host immune responses and pathogen destruction. This narrative review explores microbiome therapeutics as next-generation treatments for infectious diseases, focusing on the application of probiotics and their role in host-microbiome interactions. While offering a novel perspective grounded in a cooperative defense system, this review also addresses the practical challenges and limitations in translating these advancements into clinical settings.

Induction of CD4 T cell memory responses following BCG vaccination in cattle

Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), is a zoonotic pathogen that contributes to economic losses in the cattle industry and poses a public health risk worldwide. Bacillus Calmette-Guerin, or BCG, is a live attenuated strain of M. bovis that is used for human vaccination against tuberculosis and is considered a potential vaccine candidate against bTB. However, BCG affords widely variable levels of protection against challenge and interferes with current diagnostic methods, and as such, it is not currently approved for use as a livestock or wildlife vaccine in the United States. Many efforts have been made to develop bTB vaccines that are reliable and do not interfere with diagnostic testing, but BCG continues to be the most effective option. Previous work has shown that a T helper 1 immune response is essential for protection against virulent M. bovis infection, characterized by CD4+ central and effector memory T cells. In an effort to identify an efficacious bTB intervention strategy, the study presented here used an in vitro recall response assay and concurrent evaluation of CD4+ T cell proliferation and cytokine production to characterize the surface and functional phenotypes of memory responses to BCG vaccination in cattle. Our findings enhance understanding of the bovine immune response to BCG and provide insights into the development of improved vaccines for the control of bTB.

Rab8a restores diverse innate functions in CD11c+CD11b+ dendritic cells from aged mice

Age-related alterations of the immune system compromise the host's ability to respond to pathogens, but how immune aging is regulated is still poorly understood. Here, we identify via transcriptomic analysis of splenic DCs and bone marrow derived dendritic cells (BMDC) of young and aged mice, the small GTPase Rab8a as a regulator of dendritic cell (DC) functions in mice. CD11c+CD11b+ DCs of aged in comparison to young host exhibit a diminished type I IFN response upon viral stimulation and inefficiently present exogenous antigens to CD8+ T cells in vitro and in vivo. Rab8a overexpression, which is accompanied by the upregulation of Rab11, restores the functionality of these aged DCs, whereas knockdown of Rab8a reduces functionality of DCs from young mice. Mechanistically, Rab8a and Rab11 cooperate to induce efficient trafficking of peptide loaded class I MHC molecules from the ER to the cell surface. We propose that targeting Rab8a might serve as a strategy to restore DC functionality in the context of immune aging.

Therapeutic potential of natural coumarins in autoimmune diseases with underlying mechanisms

Autoimmune diseases encompass a wide range of disorders characterized by disturbed immunoregulation leading to the development of specific autoantibodies, which cause inflammation and multiple organ involvement. However, its pathogenesis remains unelucidated. Furthermore, the cumulative medical and economic burden of autoimmune diseases is on the rise, making these diseases a ubiquitous global phenomenon that is predicted to further increase in the coming decades. Coumarins, a class of aromatic natural products with benzene and alpha-pyrone as their basic structures, has good therapeutic effects on autoimmune diseases. In this review, we systematically highlighted the latest evidence on coumarins and autoimmune diseases data from clinical and animal studies. Coumarin acts on immune cells and cytokines and plays a role in the treatment of autoimmune diseases by regulating NF-κB, Keap1/Nrf2, MAPKs, JAK/STAT, Wnt/β-catenin, PI3K/AKT, Notch and TGF-β/Smad signaling pathways. This systematic review will provide insight into the interaction of coumarin and autoimmune diseases, and will lay a groundwork for the development of new drugs for autoimmune diseases.

Development and optimization of a diluted whole blood ELISpot assay to test immune function

Sepsis remains a leading cause of death worldwide with no proven immunomodulatory therapies. Stratifying Patient Immune Endotypes in Sepsis ('SPIES') is a prospective, multicenter observational study testing the utility of ELISpot as a functional bioassay specifically measuring cytokine-producing cells after stimulation to identify the immunosuppressed endotype, predict clinical outcomes in septic patients, and test potential immune stimulants for clinical development. Most ELISpot protocols call for the isolation of PBMC prior to their inclusion in the assay. In contrast, we developed a diluted whole blood (DWB) ELISpot protocol that has been validated across multiple laboratories. Heparinized whole blood was collected from healthy donors and septic patients and tested under different stimulation conditions to evaluate the impact of blood dilution, stimulant concentration, blood storage, and length of stimulation on ex vivo IFNγ and TNFα production as measured by ELISpot. We demonstrate a dynamic range of whole blood dilutions that give a robust ex vivo cytokine response to stimuli. Additionally, a wide range of stimulant concentrations can be utilized to induce cytokine production. Further modifications demonstrate anticoagulated whole blood can be stored up to 24 h at room temperature without losing significant functionality. Finally, we show ex vivo stimulation can be as brief as 4 h allowing for a substantial decrease in processing time. The data demonstrate the feasibility of using ELISpot to measure the functional capacity of cells within DWB under a variety of stimulation conditions to inform clinicians on the extent of immune dysregulation in septic patients.

PLGA-PEI nanoparticle covered with poly(I:C) for personalised cancer immunotherapy

Melanoma is the main cause of death among skin cancers and its incidence worldwide has been experiencing an appalling increase. However, traditional treatments lack effectiveness in advanced or metastatic patients. Immunotherapy, meanwhile, has been shown to be an effective treatment option, but the rate of cancers responding remains far from ideal. Here we have developed a personalized neoantigen peptide-based cancer vaccine by encapsulating patient derived melanoma neoantigens in polyethylenimine (PEI)-functionalised poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and coating them with polyinosinic:polycytidylic acid (poly(I:C)). We found that PLGA NPs can be effectively modified to be coated with the immunoadjuvant poly(I:C), as well as to encapsulate neoantigens. In addition, we found that both dendritic cells (DCs) and lymphocytes were effectively stimulated. Moreover, the developed NP was found to have a better immune activation profile than NP without poly(I:C) or without antigen. Our results demonstrate that the developed vaccine has a high capacity to activate the immune system, efficiently maturing DCs to present the antigen of choice and promoting the activity of lymphocytes to exert their cytotoxic function. Therefore, the immune response generated is optimal and specific for the elimination of melanoma tumour cells.

Synthesis and evaluation of anti-PD-L1-B11 antibody fragments for PET imaging of PD-L1 in breast cancer and melanoma tumor models

There is a critical need to non-invasively assess the PD-L1 expression in tumors as a predictive biomarker for determining the efficacy of anti-PD-1/PD-L1 immunotherapies. Non-invasive imaging modality like positron emission tomography (PET) can be a powerful tool to assess the PD-L1 expression in the whole body including multiple metastases as a patient selection criterion for the anti-PD-1/PD-L1 immunotherapy. In this study, we synthesized B11-nanobody, B11-scFv and B11-diabody fragments from the full-length anti-PD-L1 B11 IgG. Out of the three antibody fragments, B11-diabody showed higher nM affinity towards PD-L1 antigen as compared to B11-scFv and B11-nanobody. All three antibody fragments were successfully radiolabeled with 64Cu, a PET radioisotope. For radiolabeling, the antibody fragments were first conjugated with p-SCN-Bn-NOTA followed by chelation with 64Cu. All three radiolabeled antibody fragments were found to be stable in mouse and human sera for up to 24 h. Additionally, all three [64Cu]Cu-NOTA-B11-antibody fragments were evaluated in PD-L1 negative and human PD-L1 expressing cancer cells and subcutaneous tumor models. Based on the results, [64Cu]Cu-NOTA-B11-diabody has potential to be used as a PET imaging probe for assessing PD-L1 expression in tumors as early as 4 h post-injection, allowing faster assessment compared to the full length IgG based PET imaging probe.

Differentiation and regulation of CD4+ T cell subsets in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, and its hallmark pathological features are the loss of dopaminergic (DA) neurons in the midbrain substantia nigra pars compacta (SNpc) and the accumulation of alpha-synuclein (α-syn). It has been shown that the integrity of the blood-brain barrier (BBB) is damaged in PD patients, and a large number of infiltrating T cells and inflammatory cytokines have been detected in the cerebrospinal fluid (CSF) and brain parenchyma of PD patients and PD animal models, including significant change in the number and proportion of different CD4+ T cell subsets. This suggests that the neuroinflammatory response caused by CD4+ T cells is an important risk factor for the development of PD. Here, we systematically review the differentiation of CD4+ T cell subsets, and focus on describing the functions and mechanisms of different CD4+ T cell subsets and their secreted cytokines in PD. We also summarize the current immunotherapy targeting CD4+ T cells with a view to providing assistance in the diagnosis and treatment of PD.

Vaccine Platform Comparison: Protective Efficacy against Lethal Marburg Virus Challenge in the Hamster Model

Marburg virus (MARV), a filovirus, was first identified in 1967 in Marburg, Germany, and Belgrade, former Yugoslavia. Since then, MARV has caused sporadic outbreaks of human disease with high case fatality rates in parts of Africa, with the largest outbreak occurring in 2004/05 in Angola. From 2021 to 2023, MARV outbreaks occurred in Guinea, Ghana, New Guinea, and Tanzania, emphasizing the expansion of its endemic area into new geographical regions. There are currently no approved vaccines or therapeutics targeting MARV, but several vaccine candidates have shown promise in preclinical studies. We compared three vaccine platforms simultaneously by vaccinating hamsters with either a single dose of an adenovirus-based (ChAdOx-1 MARV) vaccine, an alphavirus replicon-based RNA (LION-MARV) vaccine, or a recombinant vesicular stomatitis virus-based (VSV-MARV) vaccine, all expressing the MARV glycoprotein as the antigen. Lethal challenge with hamster-adapted MARV 4 weeks after vaccination resulted in uniform protection of the VSV-MARV and LION-MARV groups and 83% of the ChAdOx-1 MARV group. Assessment of the antigen-specific humoral response and its functionality revealed vaccine-platform-dependent differences, particularly in the Fc effector functions.

Endothelial Immunosuppression in Atherosclerosis : Translational Control by Elavl1/HuR

Atherosclerotic plaques are defined by the accumulation of lipids and immune cells beneath the endothelium of the arterial intima. CD8 T cells are among the most abundant immune cell types in plaque, and conditions linked to their activation correlate with increased levels of cardiovascular disease. As lethal effectors of the immune response, CD8 T cell activation is suppressed at multiple levels. These checkpoints are critical in dampening autoimmune responses, and limiting damage in cardiovascular disease. Endothelial cells are well known for their role in recruiting CD8 T and other hematopoietic cells to low and disturbed flow (LDF) arterial regions that develop plaque, but whether they locally influence CD8 effector functions is unclear. Here, we show that endothelial cells can actively suppress CD8 T cell responses in settings of chronic plaque inflammation, but that this behavior is governed by expression of the RNA-binding protein Embryonic Lethal, Abnormal Vision-Like 1 (Elavl1). In response to immune cell recruitment in plaque, the endothelium dynamically shifts splicing of pre-mRNA and their translation to enhance expression of immune-regulatory proteins including C1q and CD27. This program is immuno-suppressive, and limited by Elavl1. We show this by Cdh5(PAC)-CreERT2-mediated deletion of Elavl1 (ECKO), and analysis of changes in translation by Translating Ribosome Affinity Purification (TRAP). In ECKO mice, the translational shift in chronic inflammation is enhanced, leading to increased ribosomal association of C1q components and other critical regulators of immune response and resulting in a ~70% reduction in plaque CD8 T cells. CITE-seq analysis of the remaining plaque T cells shows that they exhibit lower levels of markers associated with T cell receptor (TCR) signaling, survival, and activation. To understand whether the immunosuppressive mechanism occurred through failed CD8 recruitment or local modulation of T cell responses, we used a novel in vitro co-culture system to show that ECKO endothelial cells suppress CD8 T cell expansion-even in the presence of wild-type myeloid antigen-presenting cells, antigen-specific CD8 T cells, and antigen. Despite the induction of C1q mRNA by T cell co-culture in both wild-type and ECKO endothelial cells, we find C1q protein abundantly expressed only in co-culture with ECKO cells. Together, our data define a novel immune-suppressive transition in the endothelium, reminiscent of the transition of T cells to T-regs, and demonstrate the regulation of this process by Elavl1.

Tissue-resident memory T cells in immunotherapy and immune-related adverse events by immune checkpoint inhibitor

Tissue-resident memory T cells (TRM) are a specialized subset of T cells that reside in tissues and provide long-term protective immunity against pathogens that enter the body through that specific tissue. TRM cells have specific phenotype and reside preferentially in barrier tissues. Recent studies have revealed that TRM cells are the main target of immune checkpoint inhibitor immunotherapy since their role in cancer immunosurveillance. Furthermore, TRM cells also play a crucial part in pathogenesis of immune-related adverse events (irAEs). Here, we provide a concise review of biological characteristics of TRM cells, and the major advances and recent findings regarding their involvement in immune checkpoint inhibitor immunotherapy and the corresponding irAEs.

The role of CD8 PET imaging in guiding cancer immunotherapy

Currently, immunotherapy is being widely used for treating cancers. However, the significant heterogeneity in patient responses is a major challenge for its successful application. CD8-positive T cells (CD8+ T cells) play a critical role in immunotherapy. Both their infiltration and functional status in tumors contribute to treatment outcomes. Therefore, accurate monitoring of CD8+ T cells, a potential biomarker, may improve therapeutic strategy. Positron emission tomography (PET) is an optimal option which can provide molecular imaging with enhanced specificity. This review summarizes the mechanism of action of CD8+ T cells in immunotherapy, and highlights the recent advancements in PET-based tracers that can visualize CD8+ T cells and discusses their clinical applications to elucidate their potential role in cancer immunotherapy.

Bergenin potentiates BCG efficacy by enriching mycobacteria-specific adaptive memory responses via the Akt-Foxo-Stat4 axis

The extensive inability of the BCG vaccine to produce long-term immune protection has not only accelerated the disease burden but also progressed towards the onset of drug resistance. In our previous study, we have reported the promising effects of Bergenin (Berg) in imparting significant protection as an adjunct immunomodulator against tuberculosis (TB). In congruence with our investigations, we delineated the impact of Berg on T cells, wherein it enhanced adaptive memory responses by modulating key transcription factors, STAT4 and Akt. We translated this finding into the vaccine model of TB and observed a notable reduction in the burden of Mycobacterium tuberculosis (M.tb) in BCG-Berg co-immunized mice as compared to BCG vaccination. Moreover, Berg, along with BCG, also aided in a heightened proinflammatory response milieu that corroborates the host protective immune response against TB. Furthermore, this response aligns with the escalated central and resident memory responses by modulating the Akt-Foxo-Stat4 axis, which plays a crucial role in enhancing the vaccine efficacy of BCG. These findings showcase the utilization of immunomodulator Berg as an immunoprophylactic agent to upgrade immunological memory, making it a more effective defender against TB.

In vitro effect of diazoxon on cell signaling and second messengers in Nile tilapia (Oreochromis niloticus) leukocytes

The physiological and molecular responses of leukocytes are altered by organophosphate pesticides. Some reports have shown that diazinon causes immunotoxic effects; diazoxon, the oxon metabolite of diazinon, is attributed to influence the immune response by affecting the leukocyte cholinergic system. In this study, the in vitro effects of diazoxon on molecules involved in cell signaling (cAMP, IP3, DAG, JAK1, and STAT3), which play a crucial role in the activation, differentiation, and survival of leukocytes, were evaluated. Data indicate that diazoxon leads to a decrease in cAMP concentration and an increase in basal IP3 levels. However, diazoxon does not affect basal levels of JAK1 and STAT3 phosphorylation. Instead, diazoxon inhibits leukocyte responsiveness to phorbol myristate acetate and ionomycin, substances that, under normal conditions, enhance JAK/STAT signaling. These findings demonstrate that diazoxon significantly affects key molecular parameters related to cell signaling.

Effective and Successful Quantification of Leukemia-Specific Immune Cells in AML Patients' Blood or Culture, Focusing on Intracellular Cytokine and Degranulation Assays

Novel (immune) therapies are needed to stabilize remissions or the disease in AML. Leukemia derived dendritic cells (DCleu) can be generated ex vivo from AML patients' blasts in whole blood using approved drugs (GM-CSF and PGE-1 (Kit M)). After T cell enriched, mixed lymphocyte culture (MLC) with Kit M pretreated (vs. untreated WB), anti-leukemically directed immune cells of the adaptive and innate immune systems were already shown to be significantly increased. We evaluated (1) the use of leukemia-specific assays [intracellular cytokine production of INFy, TNFa (INCYT), and degranulation detected by CD107a (DEG)] for a detailed quantification of leukemia-specific cells and (2), in addition, the correlation with functional cytotoxicity and patients' clinical data in Kit M-treated vs. not pretreated settings. We collected whole blood (WB) samples from 26 AML patients at first diagnosis, during persisting disease, or at relapse after allogeneic stem cell transplantation (SCT), and from 18 healthy volunteers. WB samples were treated with or without Kit M to generate DC/DCleu. After MLC with Kit M-treated vs. untreated WB antigen-specific/anti-leukemic effects were assessed through INCYT, DEG, and a cytotoxicity fluorolysis assay. The quantification of cell subtypes was performed via flow cytometry. Our study showed: (1) low frequencies of leukemia-specific cells (subtypes) detectable in AML patients' blood. (2) Significantly higher frequencies of (mature) DCleu generable without induction of blast proliferation in Kit M-treated vs. untreated samples. (3) Significant increase in frequencies of immunoreactive cells (e.g., non-naive T cells, Tprol) as well as in INCYT/DEG ASSAYS leukemia-specific adaptive-(e.g., B, T(memory)) or innate immune cells (e.g., NK, CIK) after MLC with Kit M-treated vs. untreated WB. The results of the intracellular production of INFy and TNFa were comparable. The cytotoxicity fluorolysis assay revealed significantly enhanced blast lysis in Kit M-treated vs. untreated WB. Significant correlations could be shown between induced leukemia-specific cells from several lines and improved blast lysis. We successfully detected and quantified immunoreactive cells at a single-cell level using the functional assays (DEG, INCYT, and CTX). We could quantify leukemia-specific subtypes in uncultured WB as well as after MLC and evaluate the impact of Kit M pretreated (DC/DCleu-containing) WB on the provision of leukemia-specific immune cells. Kit M pretreatment (vs. no pretreatment) was shown to significantly increase leukemia-specific IFNy and TNFa producing, degranulating cells and to improve blast-cytotoxicity after MLC. In vivo treatment of AML patients with Kit M may lead to anti-leukemic effects and contribute to stabilizing the disease or remissions. INCYT and DEG assays qualify to quantify potentially leukemia-specific cells on a single cell level and to predict the clinical course of patients under treatment.

An Aggregation-Induced Emission-Based Dual Emitting Nanoprobe for Detecting Intracellular pH and Unravelling Metabolic Variations in Differentiating Lymphocytes

Monitoring T lymphocyte differentiation is essential for understanding T cell fate regulation and advancing adoptive T cell immunotherapy. However, current biomarker analysis methods necessitate cell lysis, leading to source depletion. Intracellular pH (pHi) can be affected by the presence of lactic acid (LA), a metabolic mediator of T cell activity such as glycolysis during T cell activation; therefore, it is a potentially a good biomarker of T cell state. In this work, a dual emitting enhancement-based nanoprobe, namely, AIEgen@F127-AptCD8, was developed to accurately detect the pHi of T cells to "read" the T cell differentiation process. The nanocore of this probe comprises a pair of AIE dyes, TPE-AMC (pH-sensitive moiety) and TPE-TCF, that form a donor-acceptor pair for sensitive detection of pHi by dual emitting enhancement analysis. The nanoprobe exhibits a distinctly sensitive narrow range of pHi values (from 6.0 to 7.4) that can precisely distinguish the differentiated lymphocytes from naïve ones based on their distinct pHi profiles. Activated CD8+ T cells demonstrate lower pHi (6.49 ± 0.09) than the naïve cells (7.26 ± 0.11); Jurkat cells exhibit lower pHi (6.43 ± 0.06) compared to that of nonactivated ones (7.29 ± 0.09) on 7 days post-activation. The glycolytic product profiles in T cells strongly correlate with their pHi profiles, ascertaining the reliability of probing pHi for predicting T cell states. The specificity and dynamic detection capabilities of this nanoprobe make it a promising tool for indirectly and noninvasively monitoring T cell activation and differentiation states.

Neoadjuvant immunotherapy for head and neck squamous cell carcinoma

The neoadjuvant immunotherapy approach marks a significant shift in the treatment paradigm of potentially curable HNSCC. Here, current therapies, despite being highly individualized and advanced, often fall short in achieving satisfactory long-term survival rates and are frequently associated with substantial morbidity.The primary advantage of this approach lies in its potential to intensify and enhance treatment regimens, offering a distinct modality that complements the existing triad of surgery, radiotherapy, and chemotherapy. Checkpoint inhibitors have been at the forefront of this evolution. Demonstrating moderate yet significant survival benefits in the recurrent-metastatic setting with a relatively better safety profile compared to conventional treatments, these agents hold promise when considered for earlier stages of HNSCC.On the other hand, a significant potential benefit of introducing immunotherapy in the neoadjuvant phase is the possibility of treatment de-escalation. By reducing the tumor burden before surgery, this strategy could lead to less invasive surgical interventions. The prospect of organ-sparing protocols becomes a realistic and highly valued goal in this context. Further, the early application of immunotherapy might catalyze a more effective and durable immune response. The induction of an immune memory may potentially lead to a more effective surveillance of residual disease, decreasing the rates of local, regional, and distant recurrences, thereby enhancing overall and recurrence-free survival.However, neoadjuvant immunotherapy is not without its challenges. One of the primary concerns is the safety and adverse events profile. While data suggest that adverse events are relatively rare and manageable, the long-term safety profile in the neoadjuvant setting, especially in the context of curative intent, remains a subject for ongoing research. Another unsolved issue lies in the accurate assessment of treatment response. The discrepancy between radiographic assessment using RECIST criteria and histological findings has been noted, indicating a gap in current imaging techniques' ability to accurately reflect the true efficacy of immunotherapy. This gap underscores the necessity for improved imaging methodologies and the development of new radiologic and pathologic criteria tailored to evaluate the response to immunotherapy accurately.Treatment combinations and timing represent another layer of complexity. There is a vast array of possibilities in combining immunotherapy agents with conventional chemotherapy, targeted therapy, radiation, and other experimental treatments. Determining the optimal treatment regimen for individual patients becomes an intricate task, especially when comparing small, single-arm, non-randomized trials with varying regimens and outcome measures.Moreover, one needs to consider the importance of pre- and intraoperative decision-making in the context of neoadjuvant immunotherapy. As experience with this treatment paradigm grows, there is potential for more tailored surgical approaches based on the patient's remaining disease post-neoadjuvant treatment. This consideration is particularly relevant in extensive surgeries, where organ-sparing protocols could be evaluated.In practical terms, the multi-modal nature of this treatment strategy introduces complexities, especially outside clinical trial settings. Patients face challenges in navigating the treatment landscape, which involves coordination across multiple medical disciplines, highlighting the necessity for streamlined care pathways at specialized centers to facilitate effective treatment management if the neoadjuvant approach is introduced to the real-world.These potential harms and open questions underscore the critical need for meticulously designed clinical trials and correlational studies to ensure patient safety and efficacy. Only these can ensure that this new treatment approach is introduced in a safe way and fulfils the promise it theoretically holds.

Immunoprotection of cellular transplants for autoimmune type 1 diabetes through local drug delivery

Type 1 diabetes mellitus (T1DM) is an autoimmune condition that results in the destruction of insulin-secreting β cells of the islets of Langerhans. Allogeneic islet transplantation could be a successful treatment for T1DM; however, it is limited by the need for effective, permanent immunosuppression to prevent graft rejection. Upon transplantation, islets are rejected through non-specific, alloantigen specific, and recurring autoimmune pathways. Immunosuppressive agents used for islet transplantation are generally successful in inhibiting alloantigen rejection, but they are suboptimal in hindering non-specific and autoimmune pathways. In this review, we summarize the challenges with cellular immunological rejection and therapeutics used for islet transplantation. We highlight agents that target these three immune rejection pathways and how to package them for controlled, local delivery via biomaterials. Exploring macro-, micro-, and nano-scale immunomodulatory biomaterial platforms, we summarize their advantages, challenges, and future directions. We hypothesize that understanding their key features will help identify effective platforms to prevent islet graft rejection. Outcomes can further be translated to other cellular therapies beyond T1DM.

AMPK Alchemy: Therapeutic Potentials in Allergy, Aging, and Cancer

All cells are equipped with intricate signaling networks to meet the energy demands and respond to the nutrient availability in the body. AMP-activated protein kinase (AMPK) is among the most potent regulators of cellular energy balance. Under ATP -deprived conditions, AMPK phosphorylates substrates and affects various biological processes, such as lipid/glucose metabolism and protein synthesis. These actions further affect the cell growth, death, and functions, altering the cellular outcomes in energy-restricted environments. AMPK plays vital roles in maintaining good health. AMPK dysfunction is observed in various chronic diseases, making it a promising target for preventing and alleviating such diseases. Herein, we highlight the different AMPK functions, especially in allergy, aging, and cancer, to facilitate the development of new therapeutic approaches in the future.

Distinct profiles of proliferating CD8+/TCF1+ T cells and CD163+/PD-L1+ macrophages predict risk of relapse differently among treatment-naïve breast cancer subtypes

Immunophenotypic analysis of breast cancer microenvironment is gaining attraction as a clinical tool improving breast cancer patient stratification. The aim of this study is to evaluate proliferating CD8 + including CD8 + TCF1 + Τ cells along with PD-L1 expressing tissue-associated macrophages among different breast cancer subtypes. A well-characterized cohort of 791 treatment-naïve breast cancer patients was included. The analysis demonstrated a distinct expression pattern among breast cancer subtypes characterized by increased CD8 + , CD163 + and CD163 + PD-L1 + cells along with high PD-L1 status and decreased fraction of CD8 + Ki67 + T cells in triple negative (TNBC) and HER2 + compared to luminal tumors. Kaplan-Meier and Cox univariate survival analysis revealed that breast cancer patients with high CD8 + , CD8 + Ki67 + , CD8 + TCF1 + cells, PD-L1 score and CD163 + PD-L1 + cells are likely to have a prolonged relapse free survival, while patients with high CD163 + cells have a worse prognosis. A differential impact of high CD8 + , CD8 + Ki67 + , CD8 + TCF1 + T cells, CD163 + PD-L1 + macrophages and PD-L1 status on prognosis was identified among the various breast cancer subtypes since only TNBC patients experience an improved prognosis compared to patients with luminal A tumors. Conversely, high infiltration by CD163 + cells is associated with worse prognosis only in patients with luminal A but not in TNBC tumors. Multivariate Cox regression analysis in TNBC patients revealed that increased CD8 + [hazard ratio (HR) = 0.542; 95% confidence interval (CI) 0.309-0.950; p = 0.032), CD8 + TCF1 + (HR = 0.280; 95% CI 0.101-0.779; p = 0.015), CD163 + PD-L1 + (HR: 0.312; 95% CI 0.112-0.870; p = 0.026) cells along with PD-L1 status employing two different scoring methods (HR: 0.362; 95% CI 0.162-0.812; p = 0.014 and HR: 0.395; 95% CI 0.176-0.884; p = 0.024) were independently linked with a lower relapse rate. Multivariate analysis in Luminal type A patients revealed that increased CD163 + was independently associated with a higher relapse rate (HR = 2.360; 95% CI 1.077-5.170; p = 0.032). This study demonstrates that the evaluation of the functional status of CD8 + T cells in combination with the analysis of immunosuppressive elements could provide clinically relevant information in different breast cancer subtypes.

p21 Prevents the Exhaustion of CD4+ T Cells Within the Antitumor Immune Response Against Colorectal Cancer

BACKGROUND & AIMS

T cells are crucial for the antitumor response against colorectal cancer (CRC). T-cell reactivity to CRC is nevertheless limited by T-cell exhaustion. However, molecular mechanisms regulating T-cell exhaustion are only poorly understood.

METHODS

We investigated the functional role of cyclin-dependent kinase 1a (Cdkn1a or p21) in cluster of differentiation (CD) 4+ T cells using murine CRC models. Furthermore, we evaluated the expression of p21 in patients with stage I to IV CRC. In vitro coculture models were used to understand the effector function of p21-deficient CD4+ T cells.

RESULTS

We observed that the activation of cell cycle regulator p21 is crucial for CD4+ T-cell cytotoxic function and that p21 deficiency in type 1 helper T cells (Th1) leads to increased tumor growth in murine CRC. Similarly, low p21 expression in CD4+ T cells infiltrated into tumors of CRC patients is associated with reduced cancer-related survival. In mouse models of CRC, p21-deficient Th1 cells show signs of exhaustion, where an accumulation of effector/effector memory T cells and CD27/CD28 loss are predominant. Immune reconstitution of tumor-bearing Rag1-/- mice using ex vivo-treated p21-deficient T cells with palbociclib, an inhibitor of cyclin-dependent kinase 4/6, restored cytotoxic function and prevented exhaustion of p21-deficient CD4+ T cells as a possible concept for future immunotherapy of human disease.

CONCLUSIONS

Our data reveal the importance of p21 in controlling the cell cycle and preventing exhaustion of Th1 cells. Furthermore, we unveil the therapeutic potential of cyclin-dependent kinase inhibitors such as palbociclib to reduce T-cell exhaustion for future treatment of patients with colorectal cancer.

To be remembered: B cell memory response against SARS-CoV-2 and its variants in vaccinated and unvaccinated individuals

COVID-19 disease has plagued the world economy and affected the overall well-being and life of most of the people. Natural infection as well as vaccination leads to the development of an immune response against the pathogen. This involves the production of antibodies, which can neutralize the virus during future challenges. In addition, the development of cellular immune memory with memory B and T cells provides long-lasting protection. The longevity of the immune response has been a subject of intensive research in this field. The extent of immunity conferred by different forms of vaccination or natural infections remained debatable for long. Hence, understanding the effectiveness of these responses among different groups of people can assist government organizations in making informed policy decisions. In this article, based on the publicly available data, we have reviewed the memory response generated by some of the vaccines against SARS-CoV-2 and its variants, particularly B cell memory in different groups of individuals.

CHOIR improves significance-based detection of cell types and states from single-cell data

Clustering is a critical step in the analysis of single-cell data, as it enables the discovery and characterization of putative cell types and states. However, most popular clustering tools do not subject clustering results to statistical inference testing, leading to risks of overclustering or underclustering data and often resulting in ineffective identification of cell types with widely differing prevalence. To address these challenges, we present CHOIR (clustering hierarchy optimization by iterative random forests), which applies a framework of random forest classifiers and permutation tests across a hierarchical clustering tree to statistically determine which clusters represent distinct populations. We demonstrate the enhanced performance of CHOIR through extensive benchmarking against 14 existing clustering methods across 100 simulated and 4 real single-cell RNA-seq, ATAC-seq, spatial transcriptomic, and multi-omic datasets. CHOIR can be applied to any single-cell data type and provides a flexible, scalable, and robust solution to the important challenge of identifying biologically relevant cell groupings within heterogeneous single-cell data.

Identification of T cell and linear B cell epitopes on African horse sickness virus serotype 4 proteins VP1-1, VP2, VP4, VP7 and NS3

The viral proteins VP1-1, VP2, VP4, VP7 and NS3, of African horse sickness virus serotype 4 (AHSV4), have previously been identified to contain CD8+ T cell epitopes. In this study, overlapping peptides spanning the entire sequences of these AHSV4 proteins were synthesized and used to map epitopes. Peripheral blood mononuclear cells (PBMC) isolated from five horses immunized with an attenuated AHSV4 were stimulated in vitro with the synthesized peptides. Various memory immune assays were used to identify the individual peptides that contain CD8+ T cell epitopes, CD4+ T cell epitopes and linear B cell epitopes. The newly discovered individual peptides of AHSV4 proteins VP1-1, VP4, VP7 and/or NS3 that contain CD8+ T cell, CD4+ T cell or linear B cell epitopes could contribute to the design and development of new generation AHS peptide-based vaccines and therapeutics.

Posttranscriptional Events Orchestrate Immune Homeostasis of CD8+ T Cells

Maintaining immune homeostasis is instrumental for host health. Immune cells, such as T cells, are instrumental for the eradication of pathogenic bacteria, fungi and viruses. Furthermore, T cells also play a major role in the fight against cancer. Through the formation of immunological memory, a pool of antigen-experienced T cells remains in the body to rapidly protect the host upon reinfection or retransformation. In order to perform their protective function, T cells produce cytolytic molecules, such as granzymes and perforin, and cytokines such as interferon γ and tumor necrosis factor α. Recently, it has become evident that posttranscriptional regulatory events dictate the kinetics and magnitude of cytokine production by murine and human CD8+ T cells. Here, the recent literature regarding the role posttranscriptional regulation plays in maintaining immune homeostasis of antigen-experienced CD8+ T cells is reviewed.

Assessing Antigen-Specific T Cell Responses Through IFN-γ Enzyme-Linked Immune Absorbent Spot (ELISpot)

T cells are instrumental in protecting the host against invading pathogens and the development of cancer. To do so, they produce effector molecules such as granzymes, interleukins, interferons, and perforin. For the development and immunomonitoring of therapeutic applications such as cell-based therapies and vaccines, assessing T cell effector function is paramount. This can be achieved through various methods, such as 51Cr release assays, flow cytometry, and enzyme-linked immune absorbent spot (ELISpot) assays. For T cell ELISpots, plates are coated with antibodies directed against the effector molecule of interest (e.g., IFN-g). Subsequently, peripheral blood mononuclear cells (PBMCs) or isolated T cells are cultured on the plate together with stimuli of choice, and the production of effector molecules is visualized via labeled detection antibodies. For clinical studies, ELISpot is currently the gold standard to determine antigen-specific T cell frequencies. In contrast to 51Cr release assays, ELISpot allows for the exact enumeration of responding T cells, and compared to flow cytometry, ELISpot is more cost-effective and high throughput. Here, we optimize and describe, in a step-by-step fashion, how to perform a controlled IFN-γ ELISpot experiment to determine the frequency of responding or antigen-specific T cells in healthy human volunteers. Of note, this protocol can also be employed to assess the frequency of antigen-specific T cells induced in, e.g., vaccination studies or present in cellular products.

Employing CRISPR-Cas9 to Enhance T Cell Effector Function

As part of the adaptive immune system, T cells are critical to maintain immune homeostasis. T cells provide protective immunity by killing infected cells and combatting cancerous cells. To do so, T cells produce and secrete effector molecules, such as granzymes, perforin, and cytokines such as tumor necrosis factor α and interferon γ. However, in immune suppressive environments, such as tumors, T cells gradually lose the capacity to perform their effector function. One way T cell effector function can be enhanced is through genetic engineering with tools such as clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9). This protocol explains in a step-by-step fashion how to perform a controlled electroporation-based CRISPR experiment to enhance human T cell effector function. Of note, these steps are suitable for CRISPR-mediated genome editing in T cells in general and can thus also be used to study proteins of interest that do not influence T cell effector function.

Revolutionizing Skin Cancer Treatment: The Rise of PD-1/PDL-1 and CTLA-4 as Key Therapeutic Targets

Skin cancer is a significant health concern, affecting millions of individuals globally on an annual basis. According to data from the World Health Organization, it stands as the most prevalent form of cancer within the white population. Current treatments for skin cancer typically involve a combination of chemotherapy, radiation therapy, and surgery. However, these methods often come with drawbacks, such as side effects and potential scarring. Therefore, there is a growing need for alternative treatments that can offer effective results with fewer adverse effects, driving ongoing research in skin cancer therapy. The advancement of immune checkpoint inhibitors has been facilitated by a more profound comprehension of the interplay between tumors and the immune system, along with the regulatory mechanisms governing T-cells. As cancer treatment continues to evolve, immunotherapy is emerging as a powerful strategy, leading to a growing interest in the role of immunological checkpoints in skin cancer. Various types of immune checkpoints and their expression, including PD-1, PDL-1, CTLA-4, lymphocyte activation gene 3, and B7-H3, along with their blockers and monoclonal antibodies, have been established for various cancers. PD-1, PDL-1, and CTLA-4 are crucial immune system regulators, acting as brakes to prevent T-- cell overactivation and potential autoimmunity. However, tumors can exploit these checkpoints to evade immune detection. Inhibiting these immune checkpoints can enhance the body's ability to recognize and attack cancer cells. This review focuses on the characteristics of PD-1, PDL-1, and CTLA-4 immune checkpoints, their mechanism of action, and their role in skin cancer. Additionally, it summarizes the ongoing clinical trials sponsored or conducted by various pharmaceutical companies and provides insights into the latest patent data.

Macrophage and T cell networks in adipose tissue

The signals and structure of the tissues in which leukocytes reside critically mould leukocyte function and development and have challenged our fundamental understanding of how to define and categorize tissue-resident immune cells. One specialized tissue niche that has a powerful effect on immune cell function is adipose tissue. The field of adipose tissue leukocyte biology has expanded dramatically and has revealed how tissue niches can shape immune cell function and reshape them in a setting of metabolic stress, such as obesity. Most notably, adipose tissue macrophages and T cells are under intense investigation due to their contributions to adipose tissue in the lean and obese states. Both adipose tissue macrophages and T cells have features associated with the metabolic function of adipose tissue that are distinct from features of macrophages and T cells that are classically characterized in other tissues. This Review provides state-of-the-art understanding of adipose tissue macrophages and T cells and discusses how their unique niche can help us to better understand diversity in leukocyte responses.

Circulating cytotoxic immune cell composition, activation status and toxins expression associate with white matter microstructure in bipolar disorder

Patients with bipolar disorder (BD) show higher immuno-inflammatory setpoints, with in vivo alterations in white matter (WM) microstructure and post-mortem infiltration of T cells in the brain. Cytotoxic CD8+ T cells can enter and damage the brain in inflammatory disorders, but little is known in BD. Our study aimed to investigate the relationship between cytotoxic T cells and WM alterations in BD. In a sample of 83 inpatients with BD in an active phase of illness (68 depressive, 15 manic), we performed flow cytometry immunophenotyping to investigate frequencies, activation status, and expression of cytotoxic markers in CD8+ and tested for their association with diffusion tensor imaging (DTI) measures of WM microstructure. Frequencies of naïve and activated CD8+ cell populations expressing Perforin, or both Perforin and Granzyme, negatively associated with WM microstructure. CD8+ Naïve cells negative for Granzyme and Perforin positively associates with indexes of WM integrity, while the frequency of CD8+ memory cells negatively associates with index of WM microstructure, irrespective of toxins expression. The resulting associations involve measures representative of orientational coherence and myelination of the fibers (FA and RD), suggesting disrupted oligodendrocyte-mediated myelination. These findings seems to support the hypothesis that immunosenescence (less naïve, more memory T cells) can detrimentally influence WM microstructure in BD and that peripheral CD8+ T cells may participate in inducing an immune-related WM damage in BD mediated by killer proteins.

A forskolin-mediated increase in cAMP promotes T helper cell differentiation into the Th1 and Th2 subsets rather than into the Th17 subset

The adenylyl cyclase (AC) signaling pathway is suggested to be a key regulator of immune system functions. However, specific effects of cyclic adenosine monophosphate (cAMP) on T helper (Th) cell differentiation and functions are unclear. The involvement of cAMP in the Th cell differentiation program, in particular the development of Th1, Th2, and Th17 subsets, was evaluated employing forskolin (FSK), a labdane diterpene well known as an AC activator. FSK mediated an elevation in Th1-specific markers reinforcing the Th1 cell phenotype. The Th2 differentiation was supported by FSK, though cell metabolism was negatively affected. In contrast, the Th17 immunophenotype was severely suppressed leading to the highly specific upregulation of CXCL13. The causality between FSK-elicited cAMP production and the observed reinforcement of Th2 differentiation was established by using AC inhibitor 2',5'-dideoxyadenosine, which reverted the FSK effects. Overall, an FSK-mediated cAMP increase affects Th1, Th2 and Th17 differentiation and can contribute to the identification of novel therapeutic targets for the treatment of Th cell-related pathological processes.

Advancing the frontiers of adaptive cell therapy: A transformative mechanistic journey from preclinical to clinical settings

Although the concept of using the patient's immune system to combat cancer has been around for a while, it is only in recent times that substantial progress has been achieved in this field. Over the last ten years, there has been a significant advancement in the treatment of cancer through immune checkpoint blockade. This treatment has been approved for multiple types of tumors. Another approach to modifying the immune system to detect tumor cells and fight them off is adaptive cell therapy (ACT). This therapy involves using T cells that have been modified with either T cell receptors (TCR) or chimeric antigen receptors (CAR) to target the tumor cells. ACT has demonstrated encouraging outcomes in different types of tumors, and clinical trials are currently underway worldwide to enhance this form of treatment. This review focuses on the advancements that have been made in ACT from preclinical to clinical settings till now.

ACE configurator for ELISpot: optimizing combinatorial design of pooled ELISpot assays with an epitope similarity model

The enzyme-linked immunosorbent spot (ELISpot) assay is a powerful in vitro immunoassay that enables cost-effective quantification of antigen-specific T-cell reactivity. It is used widely in the context of cancer and infectious diseases to validate the immunogenicity of predicted epitopes. While technological advances have kept pace with the demand for increased throughput, efforts to increase scale are bottlenecked by current assay design and deconvolution methods, which have remained largely unchanged. Current methods for designing pooled ELISpot experiments offer limited flexibility of assay parameters, lack support for high-throughput scenarios and do not consider peptide identity during pool assignment. We introduce the ACE Configurator for ELISpot (ACE) to address these gaps. ACE generates optimized peptide-pool assignments from highly customizable user inputs and handles the deconvolution of positive peptides using assay readouts. In this study, we present a novel sequence-aware pooling strategy, powered by a fine-tuned ESM-2 model that groups immunologically similar peptides, reducing the number of false positives and subsequent confirmatory assays compared to existing combinatorial approaches. To validate ACE's performance on real-world datasets, we conducted a comprehensive benchmark study, contextualizing design choices with their impact on prediction quality. Our results demonstrate ACE's capacity to further increase precision of identified immunogenic peptides, directly optimizing experimental efficiency. ACE is freely available as an executable with a graphical user interface and command-line interfaces at https://github.com/pirl-unc/ace.

Adjuvantation of whole-killed Leishmania vaccine with anti-CD200 and anti-CD300a antibodies potentiates its efficacy and provides protection against wild-type parasites

One of the major reasons behind the limited success of vaccine candidates against all forms of leishmaniasis is the inability of parasitic antigens to induce robust cell-mediated immunity and immunological memory. Here we find, for the first time, that the adjuvantation of whole-killed Leishmania vaccine (Leishvacc) with anti-CD200 and anti-CD300a antibodies enhances CD4+ T cells mediated immunity in vaccinated mice and provides protection against wild-type parasites. The antibody adjuvantation, either alone or with a TLR4 agonist monophosphoryl A (MPL-A), induced the production of pro-inflammatory cytokines viz., IFN-γ, TNF-α, and IL-2 by antigen experienced CD4+ T cells, and also enhanced their rate of conversion into their memory phenotypes against Leishvacc antigens. The antibody adjuvanted vaccine also promoted the generation of IgG2a-mediated protective humoral immunity in vaccinated mice. Further, the mice vaccinated with antibodies adjuvanted vaccine showed strong resilience against metacyclic forms of L. donovani parasites as we observed reduced clinical features such as splenomegaly, hepatomegaly, granulomatous tissues in the liver, and parasitic load in their spleen. The findings of this study demonstrate that the anti-CD200 and anti-CD300a antibodies have potential to increase the protective efficacy of the whole-killed Leishmania vaccine, and opens up a new gateway to diversify the roles of immune checkpoints in vaccine development against leishmaniasis.

T Lymphocyte Metabolic Features and Techniques to Modulate Them

T cells demonstrate high degree of complexity and broad range of functions, which distinguish them from other immune cells. Throughout their lifetime, T lymphocytes experience several functional states: quiescence, activation, proliferation, differentiation, performance of effector and regulatory functions, memory formation, and apoptosis. Metabolism supports all functions of T cells, providing lymphocytes with energy, biosynthetic substrates, and signaling molecules. Therefore, T cells usually restructure their metabolism as they transition from one functional state to another. Strong association between the metabolism and T cell functions implies that the immune response can be controlled by manipulating metabolic processes within T lymphocytes. This review aims to highlight the main metabolic adaptations necessary for the T cell function, as well as the recent progress in techniques to modulate metabolic features of lymphocytes.

The Role and Therapeutic Implications of Inflammation in the Pathogenesis of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are focal vascular lesions composed of abnormal vascular channels without an intervening capillary network. As a result, high-pressure arterial blood shunts directly into the venous outflow system. These high-flow, low-resistance shunts are composed of dilated, tortuous, and fragile vessels, which are prone to rupture. BAVMs are a leading cause of hemorrhagic stroke in children and young adults. Current treatments for bAVMs are limited to surgery, embolization, and radiosurgery, although even these options are not viable for ~20% of AVM patients due to excessive risk. Critically, inflammation has been suggested to contribute to lesion progression. Here we summarize the current literature discussing the role of the immune system in bAVM pathogenesis and lesion progression, as well as the potential for targeting inflammation to prevent bAVM rupture and intracranial hemorrhage. We conclude by proposing that a dysfunctional endothelium, which harbors the somatic mutations that have been shown to give rise to sporadic bAVMs, may drive disease development and progression by altering the immune status of the brain.

Dysregulated metal ion homeostasis underscores non-canonical function of CD8+ T cell during COVID-19

Introduction

Several efforts have been made to describe the complexity of T cell heterogeneity during the COVID-19 disease; however, there remain gaps in our understanding in terms of the granularity within.

Methods

For this attempt, we performed a single-cell transcriptomic analysis of 33 individuals (4 healthy, 16 COVID-19 positive patients, and 13 COVID-19 recovered individuals).

Results

We found CD8+ T cell-biased lymphopenia in COVID-19 patients compared to healthy and recovered individuals. We also found an optimal Th1/Th2 ratio, indicating an effective immune response during COVID-19. Expansion of activated CD4+ T and NK T was detected in the COVID-19-positive individuals. Surprisingly, we found cellular and metal ion homeostasis pathways enriched in the COVID-19-positive individuals compared to the healthy and recovered in the CD8+ T cell populations (CD8+ TCM and CD8+ TEM) as well as activated CD4+ T cells.

Discussion

In summary, the COVID-19-positive individuals exhibit a dynamic T cell mediated response. This response may have a possible association with the dysregulation of non-canonical pathways, including housekeeping functions in addition to the conventional antiviral immune response mediated by the T cell subpopulation. These findings considerably extend our insights into the heterogeneity of T cell response during and post-SARS-CoV-2 infection.

Impact of senolytic treatment on immunity, aging, and disease

Cellular senescence has been implicated in the pathophysiology of many age-related diseases. However, it also plays an important protective role in the context of tumor suppression and wound healing. Reducing senescence burden through treatment with senolytic drugs or the use of genetically targeted models of senescent cell elimination in animals has shown positive results in the context of mitigating disease and age-associated inflammation. Despite positive, albeit heterogenous, outcomes in clinical trials, very little is known about the short-term and long-term immunological consequences of using senolytics as a treatment for age-related conditions. Further, many studies examining cellular senescence and senolytic treatment have been demonstrated in non-infectious disease models. Several recent reports suggest that senescent cell elimination may have benefits in COVID-19 and influenza resolution and disease prognosis. In this review, we discuss the current clinical trials and pre-clinical studies that are exploring the impact of senolytics on cellular immunity. We propose that while eliminating senescent cells may have an acute beneficial impact on primary immune responses, immunological memory may be negatively impacted. Closer investigation of senolytics on immune function and memory generation would provide insight as to whether senolytics could be used to enhance the aging immune system and have potential to be used as therapeutics or prophylactics in populations that are severely and disproportionately affected by infections such as the elderly and immunocompromised.

Bcl-3 regulates T cell function through energy metabolism

BACKGROUND

Bcl-3 is a member of the IκB protein family and an essential modulator of NF-κB activity. It is well established that Bcl-3 is critical for the normal development, survival and differentiation of adaptive immune cells, especially T cells. However, the regulation of immune cell function by Bcl-3 through metabolic pathways has rarely been studied.

RESULTS

In this study, we explored the role of Bcl-3 in the metabolism and function of T cells via the mTOR pathway. We verified that the proliferation of Bcl-3-deficient Jurkat T cells was inhibited, but their activation was promoted, and Bcl-3 depletion regulated cellular energy metabolism by reducing intracellular ATP and ROS production levels and mitochondrial membrane potential. Bcl-3 also regulates cellular energy metabolism in naive CD4+ T cells. In addition, the knockout of Bcl-3 altered the expression of mTOR, Akt, and Raptor, which are metabolism-related genes, in Jurkat cells.

CONCLUSIONS

This finding indicates that Bcl-3 may mediate the energy metabolism of T cells through the mTOR pathway, thereby affecting their function. Overall, we provide novel insights into the regulatory role of Bcl-3 in T-cell energy metabolism for the prevention and treatment of immune diseases.

Unraveling Immunological Dynamics: HPV Infection in Women-Insights from Pregnancy

During pregnancy, hormonal and immune adaptations are vital for supporting the genetically distinct fetus during elevated infection risks. The global prevalence of HPV necessitates its consideration during pregnancy. Despite a seemingly mild immune response, historical gestational viral infections underscore its significance. Acknowledging the established HPV infection risks during pregnancy, our review explores the unfolding immunological changes in pregnant women with HPV. Our analysis aims to uncover strategies for safely modulating the immune system, mitigating adverse pregnancy consequences, and enhancing maternal and child health. This comprehensive narrative review delves into the existing knowledge and studies on this topic.