Sequential polarization and imprinting of type 1 T helper lymphocytes by interferon-gamma and interleukin-12

Comparing Campylobacter jejuni to three other enteric pathogens in OligoMM12 mice reveals pathogen-specific host and microbiota responses

Campylobacter jejuni, non-typhoidal Salmonella spp., Listeria monocytogenes and enteropathogenic/enterohemorrhagic Escherichia coli (EPEC/EHEC) are leading causes of food-borne illness worldwide. Citrobacter rodentium has been used to model EPEC and EHEC infection in mice. The gut microbiome is well-known to affect gut colonization and host responses to many food-borne pathogens. Recent progress has established gnotobiotic mice as valuable models to study how microbiota affect the enteric infections by S. Typhimurium, C. rodentium and L. monocytogenes. However, for C. jejuni, we are still lacking a suitable gnotobiotic mouse model. Moreover, the limited comparability of data across laboratories is often negatively affected by variations between different research facilities or murine microbiotas. In this study, we applied the standardized gnotobiotic OligoMM12 microbiota mouse model and compared the infections in the same facility. We provide evidence of robust colonization and significant pathological changes in OligoMM12 mice following infection with these pathogens. Moreover, we offer insights into pathogen-specific host responses and metabolite signatures, highlighting the advantages of a standardized mouse model for direct comparisons of factors influencing the pathogenesis of major food-borne pathogens. Notably, we reveal for the first time that C. jejuni stably colonizes OligoMM12 mice, triggering inflammation. Additionally, our comparative approach successfully identifies pathogen-specific responses, including the detection of genes uniquely associated with C. jejuni infection in humans. These findings underscore the potential of the OligoMM12 model as a versatile tool for advancing our understanding of food-borne pathogen interactions.

Coordinated Regulation of Extrafollicular B Cell Responses by IL-12 and IFNγ

Upon activation, B cells undergo either the germinal center (GC) or extrafollicular (EF) response. While GC are known to generate high-affinity memory B cells and long-lived plasma cells, the role of the EF response is less well understood. Initially, it was thought to be limited to that of a source of fast but lower-quality antibodies until the GC can form. However, recent evidence strongly supports the EF response as an important component of the humoral response to infection. EF responses are now also recognized as a source of pathogenic B cells in autoimmune diseases. The EF response itself is dynamic and regulated by pathways that are only recently being uncovered. We have identified that the cytokine IL-12 acts as a molecular switch, enhancing the EF response and suppressing GC through multiple mechanisms. These include direct effects on both B cells themselves and the coordinated differentiation of helper CD4 T cells. Here, we explore this pathway in relation to other recent advancements in our understanding of the EF response's role and highlight areas for future research. A better understanding of how the EF response forms and is regulated is essential for advancing treatments for many disease states.

T-cell-derived IFN-γ suppresses T follicular helper cell differentiation and antibody responses

CD4+ T cells play a critical role in antiviral humoral and cellular immune responses. We have previously reported that subcutaneous lymphocytic choriomeningitis virus (s.c. LCMV) infection is characterized by a stark compartmentalization of CD4+ T cells, leading to strong TH1 cell polarization but virtually absent T follicular helper (TFH) cells, key drivers of humoral immunity. Here, we investigate the mechanisms responsible for this impaired TFH differentiation. We show that T-bet+ cells induced by LCMV infection encompass a TH1 cell subset expressing granzyme B (GzmB), and a Tcf-1+ cell subset that retains the potential for TFH differentiation without expressing mature TFH markers. Notably, IFN-γ blockade enables full differentiation of Tcf-1+ cells into TFH cells, formation of germinal centers, and increased antibody production. Suppression of TFH cells by IFN-γ is not directly mediated by CD4+ T cells but rather involves another cell type, likely dendritic cells (DCs). Our study provides novel insights into the mechanisms underlying early CD4+ T-cell polarization and humoral responses to viruses, with the potential to facilitate the development of effective vaccine strategies.

Tissue-Resident Memory T Cells in Tumor Immunity and Immunotherapy of Digestive System Tumors

BACKGROUND

Tissue-resident memory T (TRM) cells possess unique abilities to migrate, establish themselves in tissues, and monitor peripheral tissues without circulating. They are crucial in providing long-lasting and local immune protection against surface infections. TRMs demonstrate distinct phenotypic and functional characteristics compared to central memory T (Tcm) cells and effector memory T (Tem) cells.

METHODS

We reviewed a large number of literature to explore the physiological and functional roles of tissue-resident memory T cells, as well as the link between TRM cells and the development and prognosis of digestive tract tumors. We also investigated the association between TRM cells, intestinal flora, and metabolites.

RESULTS

Recent studies have implicated TRMs in the immune response against tumors, making them a potential target for cancer therapy. However, research specifically focused on gastrointestinal tumors is limited.

CONCLUSION

This review aims to compile and assess the most recent data on the role of TRM cells in gastrointestinal tumor immunity. Additionally, it explores recent advancements in immunotherapy and investigates how TRMs may influence intestinal flora and metabolites.

T cell dysregulation in rheumatoid arthritis: Recent advances and natural product interventions

Autoimmune diseases result from chronic and dysregulated activation of the immune system, culminating in pathological self-tissue damage. These disorders are primarily driven by adaptive immune responses, particularly those mediated by T and B lymphocytes, which mistakenly target self-antigens expressed in host tissues. In rheumatoid arthritis (RA), the pathogenesis is closely associated with the emergence of tissue-invasive effector T cells and the functional impairment of regulatory T cells (Tregs), both of which play pivotal roles in disease progression. Therapeutic interventions targeting these dysregulated T cell populations have emerged as a promising strategy for RA management. Although synthetic immunosuppressants remain the mainstay of RA treatment, their long-term application is often hampered by adverse effects, diminished therapeutic efficacy, and poor patient adherence. These limitations highlight the critical need for the development of novel therapeutic approaches. Natural compounds derived from medicinal plants have been widely utilized in the clinical management of RA, with growing evidence supporting their immunomodulatory potential, particularly in restoring T cell-mediated immune tolerance. This review aims to provide a comprehensive overview of recent advances in understanding T cell dysregulation in RA and to elucidate the mechanisms through which natural compounds regulate immune responses. By integrating current findings, this work seeks to offer a theoretical foundation for the optimized use of natural compounds in the treatment of RA, while exploring their potential in advancing precision medicine and personalized therapeutic strategies.

The Expanding Therapeutic Potential of Deucravacitinib Beyond Psoriasis: A Narrative Review

Deucravacitinib is an allosteric, selective tyrosine kinase 2 (TYK2) inhibitor that has demonstrated significant efficacy in the treatment of psoriasis. TYK2, a member of the Janus kinase (JAK) family, plays a critical role in intracellular signaling pathways for pro-inflammatory cytokines. Unlike traditional JAK inhibitors, which target active domains, deucravacitinib selectively binds to the pseudokinase domain of TYK2. This binding induces a conformational change that locks the enzyme in an inactive state, ensuring superior selectivity for TYK2 over JAK 1/2/3. This unique mechanism specifically inhibits key pro-inflammatory cytokines, including IL-12, IL-23, and type I interferons, critical in the pathogenesis of psoriasis and other immune-mediated diseases. As a result, deucravacitinib represents a promising option for targeted therapy in immune-mediated diseases and may reduce adverse events commonly associated with broader immunosuppressive treatments. Furthermore, its oral administration offers a convenient alternative to injectable biologics, potentially improving patient adherence and treatment satisfaction. This review highlights recent studies suggesting that deucravacitinib may also have therapeutic benefits in psoriatic arthritis, palmoplantar pustulosis, systemic lupus erythematosus, Sjogren's disease, and inflammatory bowel disease. Given its expanding therapeutic potential, deucravacitinib may provide a safer and more effective alternative to current therapies, offering a tailored approach to treatment.

Prognostic significance of cytokine dysregulation in critically ill COVID-19 patients

BACKGROUND

Understanding the immunopathogenesis of COVID-19 has yielded valuable insights into predicting adverse outcomes-particularly mortality. However, significant gaps persist in our comprehension of the complex interplay among the proposed pathophysiological mechanisms. Here, we aim to investigate the immunological factors associated with mortality in critically ill, unvaccinated COVID-19 patients admitted to the intensive care unit (ICU).

METHODS

We conducted a single-center, prospective study involving 56 unvaccinated COVID-19 patients admitted to the ICU. Plasma cytokine levels at admission were quantified using enzyme-linked immunosorbent assay (ELISA). Continuous variables were presented as median (IQR), and categorical variables as frequencies and percentages. Non-parametric tests assessed group differences. Logistic regression and receiver operating characteristic (ROC) curve analyses identified predictors of mortality, with bootstrapping (1000 re-samplings; 95 % BCa CI) applied for model validation.

RESULTS

Deceased patients exhibited significantly higher levels of interleukin (IL)-1β, IL-2, IL-6, transforming growth factor (TGF)-β, and interferon (IFN)-γ compared to survivors. Conversely, IL-10 and IL-27 were associated with favorable outcomes. Logistic regression modeling identified elevated IL-2 and IFN-γ levels as significant predictors of mortality. Notably, individual ROC curve analyses demonstrated that IL-1β and TGF-β had excellent discriminatory ability for mortality, while IFN-γ, IL-2, and IL-27 showed very good to excellent discriminatory capacity.

CONCLUSION

Our results indicate that distinct cytokine profiles differentiate survivors from non-survivors in critically ill, unvaccinated COVID-19 patients. These findings highlight the importance of cytokine dysregulation in severe COVID-19 cases and suggest potential targets for prognostic approaches. Further research is warranted to validate these results and translate them into effective clinical management strategies.

STIM1-mediated NFAT signaling synergizes with STAT1 to control T-bet expression and TH1 differentiation

Stromal interaction molecule 1 (STIM1) is critical for store-operated Ca2+ entry (SOCE) and T cell activation. T helper 1 (TH1) cells, which express T-bet (encoded by TBX21), mediate immunity to intracellular pathogens. Although SOCE is known to regulate other TH lineages, its role in Th1 differentiation remains unclear. Here, we report a patient with an intronic loss-of-function mutation in STIM1, which abolishes SOCE and causes immunodeficiency. We demonstrate that SOCE promotes nuclear factor of activated T cells (NFAT) binding to conserved noncoding sequence (CNS)-12 in the TBX21 enhancer and enables NFAT to synergize with STAT1 to mediate TBX21 expression. While SOCE-deficient CD4+ T cells have reduced expression of TBX21 in the absence of interleukin-12 (IL-12), their expression of IL-12 receptors β1 and β2 is increased, sensitizing them to IL-12 signaling and allowing IL-12 to rescue T-bet expression. Our study reveals that the STIM1-SOCE-NFAT signaling axis is essential for the differentiation of Th1 cells depending on the cytokine milieu.

Interaction between interleukin-12 (IL-12) and its receptor (IL-12Rβ2) mediates CD4+ T cell subsets activation in flounder (Paralichthys olivaceus)

Interleukin-12 (IL-12) regulates the differentiation of CD4+ T lymphocytes into Th1 cells by binding to its receptor, thereby promoting cellular immunity. This study characterized IL-12 and its receptor β2 (IL-12Rβ2) in flounder (Paralichthys olivaceus) and investigated their interaction, effects on T cell proliferation and differentiation, and the adjuvant effects of IL-12. The recombinant IL-12 was successfully expressed, and the IL-12Rβ2 antibody was confirmed to specifically recognize IL-12Rβ2. IL-12 bound to IL-12Rβ2 at the cellular level. IL-12 stimulation increased leukocyte proliferation and the proportion of CD4+/IL-12Rβ2+ cells. Moreover, blocking IL-12Rβ2 with antibody reduced Th1 markers (STAT4, T-bet, IFN-γ) and increased Th2 markers (JAK3, STAT6, GATA3). Immunization with rOmpV+IL-12 significantly upregulated CD4+/IFN-γ+ cells on day seven, peaked the sIgM+ B lymphocyte response in the fourth week, and enhanced survival after Edwardsiella tarda challenge. In conclusion, IL-12 signaling effectively facilitates the differentiation of Th1 cells and negatively impacts the function of Th2 cells in flounder. This study provides new insights into the immune regulation of CD4+ T cells in teleosts and lays the foundation for understanding the cellular immune mechanisms of vaccines in aquaculture.

Immunomodulatory Tissue Factors in the Gallbladder Walls of Pediatric Patients with Chronic Calculous Cholecystitis

BACKGROUND

The rising rates of gallstones and cholecystectomy in pediatric populations underscore the increasing concern regarding chronic cholecystitis. However, the morphopathogenesis of pediatric calculous cholecystitis is still not well understood. This study aimed to determine the expression and distribution of immunomodulatory factors interleukin-12 (IL-12), interleukin-13 (IL-13), interleukin-1β (IL-1β), sonic hedgehog protein (SHH), nuclear factor NF-kappa-B p65 subunit (NFkBp65), and heat shock protein 60 (HSP60) in the gallbladder walls of pediatric patients with chronic calculous cholecystitis.

METHODS

In total, 11 gallbladder samples were collected from pediatric patients with calculous cholecystitis during cholecystectomy, while 5 healthy gallbladder samples served as controls. IL-12, IL-13, IL-1β, SHH, NFkBp65, and HSP60 were detected by immunohistochemistry. The number of positive structures in gallbladder wall epithelium, vasculature, and inflammatory infiltrate was assessed semi-quantitatively by microscopy. A Mann-Whitney U test and Spearman's rank-order correlation coefficient were calculated.

RESULTS

Statistically significant differences were observed between patient and control samples in the expression of IL-1β, SHH, and NFkBp65 in the epithelium, as well as in the expression of IL-12, SHH, and HSP60 in the blood vessels. The expression of IL-1β was stronger in the epithelium of controls, while other markers were more prominent in patient samples.

CONCLUSIONS

An increased number of NFkBp65, IL-12, and HSP60 positive cells in patient gallbladder tissue suggests a significant role of these tissue factors in driving immune modulation and sustaining the inflammation in pediatric chronic calculous cholecystitis. The noticeable expression of SHH in patient gallbladder tissue indicates its part in tissue regeneration and repair processes, as well as in modulating inflammation and vascular responses in calculous cholecystitis. The significant positive correlations between the factors studied highlight the importance of their coordinated interaction and intricate crosstalk in the morphopathogenesis of calculous cholecystitis.

A Snapshot of Cytokine Dynamics: A Fine Balance Between Health and Disease

Health and disease are intricately intertwined and often determined by the delicate balance of biological processes. Cytokines, a family of small signalling molecules, are pivotal in maintaining this balance, ensuring the body's immune system functions optimally. In a healthy condition, cytokines act as potent mediators of immune responses. They orchestrate the activities of immune cells, coordinating their proliferation, differentiation, and migration. This intricate role of cytokine signalling enables the body to effectively combat infections, repair damaged tissues, and regulate inflammation. However, the delicate equilibrium of cytokine production is susceptible to disruption. Excessive or abnormal cytokine levels can lead to a cascade of pathological conditions, including autoimmune diseases, chronic inflammation, infections, allergies, and even cancer. Interestingly, from the bunch of cytokines, few cytokines play an essential role in maintaining the balance between normal physiological status and diseases. In this review, we have appraised key cytokines' potential role and feedback loops in augmenting the imbalances in the body's biological functions, presenting a critical link between inflammation and disease pathology. Moreover, we have also highlighted the significance of cytokines and their molecular interplay, particularly in the recent viral pandemic COVID-19 disease. Hence, understandings regarding the interplay between viral infection and cytokine responses are essential and fascinating for developing effective therapeutic strategies.

Obesity intensifies sex-specific interferon signaling to selectively worsen central nervous system autoimmunity in females

Obesity has been implicated in the rise of autoimmunity in women. We report that obesity induces a serum protein signature that is associated with T helper 1 (Th1), interleukin (IL)-17, and multiple sclerosis (MS) signaling pathways selectively in human females. Females, but not male mice, subjected to diet-induced overweightness/obesity (DIO) exhibited upregulated Th1/IL-17 inflammation in the central nervous system during experimental autoimmune encephalomyelitis, a model of MS. This was associated with worsened disability and a heightened expansion of myelin-specific Th1 cells in the peripheral lymphoid organs. Moreover, at steady state, DIO increased serum levels of interferon (IFN)-α and potentiated STAT1 expression and IFN-γ production by naive CD4+ T cells uniquely in female mice. This T cell phenotype was driven by increased adiposity and was prevented by the removal of ovaries or knockdown of the type I IFN receptor in T cells. Our findings offer a mechanistic explanation of how obesity enhances autoimmunity.

A review of CD4+ T cell differentiation and diversity in dogs

CD4+ T cells are an integral component of the adaptive immune response, carrying out many functions to combat a diverse range of pathogenic challenges. These cells exhibit remarkable plasticity, differentiating into specialized subsets such as T helper type 1 (TH1), TH2, TH9, TH17, TH22, regulatory T cells (Tregs), and follicular T helper (TFH) cells. Each subset is capable of addressing a distinct immunological need ranging from pathogen eradication to regulation of immune homeostasis. As the immune response subsides, CD4+ T cells rest down into long-lived memory phenotypes-including central memory (TCM), effector memory (TEM), resident memory (TRM), and terminally differentiated effector memory cells (TEMRA) that are localized to facilitate a swift and potent response upon antigen re-encounter. This capacity for long-term immunological memory and rapid reactivation upon secondary exposure highlights the role CD4+ T cells play in sustaining both adaptive defense mechanisms and maintenance. Decades of mouse, human, and to a lesser extent, pig T cell research has provided the framework for understanding the role of CD4+ T cells in immune responses, but these model systems do not always mimic each other. Although our understanding of pig immunology is not as extensive as mouse or human research, we have gained valuable insight by studying this model. More akin to pigs, our understanding of CD4+ T cells in dogs is much less complete. This disparity exists in part because canine immunologists depend on paradigms from mouse and human studies to characterize CD4+ T cells in dogs, with a fraction of available lineage-defining antibody markers. Despite this, every major CD4+ T cell subset has been described to some extent in dogs. These subsets have been studied in various contexts, including in vitro stimulation, homeostatic conditions, and across a range of disease states. Canine CD4+ T cells have been categorized according to lineage-defining characteristics, trafficking patterns, and what cytokines they produce upon stimulation. This review addresses our current understanding of canine CD4+ T cells from a comparative perspective by highlighting both the similarities and differences from mouse, human, and pig CD4+ T cell biology. We also discuss knowledge gaps in our current understanding of CD4+ T cells in dogs that could provide direction for future studies in the field.

IL-12 induces a B cell-intrinsic IL-12/IFNγ feed-forward loop promoting extrafollicular B cell responses

While some infections elicit germinal centers, others produce only extrafollicular responses. The mechanisms controlling these dichotomous fates are poorly understood. We identify IL-12 as a cytokine switch, acting directly on B cells to promote extrafollicular and suppress germinal center responses. IL-12 initiates a B cell-intrinsic feed-forward loop between IL-12 and IFNγ, amplifying IFNγ production, which promotes proliferation and plasmablast differentiation from mouse and human B cells, in synergy with IL-12. IL-12 sustains the expression of a portion of IFNγ-inducible genes. Together, they also induce unique gene changes, reflecting both IFNγ amplification and cooperative effects between both cytokines. In vivo, cells lacking both IL-12 and IFNγ receptors are more impaired in plasmablast production than those lacking either receptor alone. Further, B cell-derived IL-12 enhances both plasmablast responses and T helper 1 cell commitment. Thus, B cell-derived IL-12, acting on T and B cells, determines the immune response mode, with implications for vaccines, pathogen protection and autoimmunity.

The role of CD4+ T cells in visceral leishmaniasis; new and emerging roles for NKG7 and TGFβ

Visceral leishmaniasis is a potentially devastating neglected tropical disease caused by the protozoan parasites Leishmania donovani and L. infantum (chagasi). These parasites reside in tissue macrophages and survive by deploying a number of mechanisms aimed at subverting the host immune response. CD4+ T cells play an important role in controlling Leishmania parasites by providing help in the form of pro-inflammatory cytokines to activate microbiocidal pathways in infected macrophages. However, because these cytokines can also cause tissue damage if over-produced, regulatory immune responses develop, and the balance between pro-inflammatory and regulatory CD4+ T cells responses determines the outcomes of infection. Past studies have identified important roles for pro-inflammatory cytokines such as IFNγ and TNF, as well as regulatory co-inhibitory receptors and the potent anti-inflammatory cytokine IL-10. More recently, other immunoregulatory molecules have been identified that play important roles in CD4+ T cell responses during VL. In this review, we will discuss recent findings about two of these molecules; the NK cell granule protein Nkg7 and the anti-inflammatory cytokine TGFβ, and describe how they impact CD4+ T cell functions and immune responses during visceral leishmaniasis.

Network switches and their role in circadian clocks

Circadian rhythms are generated by complex interactions among genes and proteins. Self-sustained ∼24 h oscillations require negative feedback loops and sufficiently strong nonlinearities that are the product of molecular and network switches. Here, we review common mechanisms to obtain switch-like behavior, including cooperativity, antagonistic enzymes, multisite phosphorylation, positive feedback, and sequestration. We discuss how network switches play a crucial role as essential components in cellular circadian clocks, serving as integral parts of transcription-translation feedback loops that form the basis of circadian rhythm generation. The design principles of network switches and circadian clocks are illustrated by representative mathematical models that include bistable systems and negative feedback loops combined with Hill functions. This work underscores the importance of negative feedback loops and network switches as essential design principles for biological oscillations, emphasizing how an understanding of theoretical concepts can provide insights into the mechanisms generating biological rhythms.

Deciphering the developmental trajectory of tissue-resident Foxp3+ regulatory T cells

Foxp3+ TREG cells have been at the focus of intense investigation for their recognized roles in preventing autoimmunity, facilitating tissue recuperation following injury, and orchestrating a tolerance to innocuous non-self-antigens. To perform these critical tasks, TREG cells undergo deep epigenetic, transcriptional, and post-transcriptional changes that allow them to adapt to conditions found in tissues both at steady-state and during inflammation. The path leading TREG cells to express these tissue-specialized phenotypes begins during thymic development, and is further driven by epigenetic and transcriptional modifications following TCR engagement and polarizing signals in the periphery. However, this process is highly regulated and requires TREG cells to adopt strategies to avoid losing their regulatory program altogether. Here, we review the origins of tissue-resident TREG cells, from their thymic and peripheral development to the transcriptional regulators involved in their tissue residency program. In addition, we discuss the distinct signalling pathways that engage the inflammatory adaptation of tissue-resident TREG cells, and how they relate to their ability to recognize tissue and pathogen-derived danger signals.

The novel small molecule TPN10518 alleviates EAE pathogenesis by inhibiting AP1 to depress Th1/Th17 cell differentiation

Multiple sclerosis (MS) is one of the most common autoimmune diseases of central nervous system (CNS) demyelination. Experimental autoimmune encephalomyelitis (EAE) is the most classic animal model for simulating the onset of clinical symptoms in MS. Previous research has reported the anti-inflammatory effects of artemisinin on autoimmune diseases. In our study, we identified a novel small molecule, TPN10518, an artemisinin derivative, which plays a protective role on the EAE model. We found that TPN10518 reduced CNS inflammatory cell infiltration and alleviated clinical symptoms of EAE. In addition, TPN10518 downregulated the production of Th1 and Th17 cells in vivo and in vitro, and decrease the levels of related chemokines. RNA-seq assay combined with the experimental results demonstrated that TPN10518 lowered the mRNA and protein levels of the AP1 subunits c-Fos and c-Jun in EAE mice. It was further confirmed that TPN10518 was dependent on AP1 to inhibit the differentiation of Th1 and Th17 cells. The results suggest that TPN10518 reduces the production of Th1 and Th17 cells through inhibition of AP1 to alleviate the severity of EAE disease. It is expected to be a potential drug for the treatment of MS.

Identification, expression pattern and functional characterization of IFN-γ involved in activating JAK-STAT pathway in Sebastes schlegeli

IFN-γ (interferon gamma) is a critical cytokine in the immune system involved both directly and indirectly in antiviral activity, stimulation of bactericidal activity, antigen presentation and activation of macrophages via the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway. The IFN-γ function is best described in cell defense against intracellular pathogens in mammals, but IFN-γ cytokine-induced metabolic change and its role in anti-infection remain unknown in teleost fish. In this study, a novel IFN-γ (SsIFN-γ) was identified from black rockfish (Sebastes schlegeli) by rapid amplification of cDNA ends (RACE). The open reading frame (ORF) of SsIFN-γ encoded a putative protein of 215 amino acids and shares 60.2%-93.5% overall sequence identities with other teleost IFN-γ. SsIFN-γ was distributed ubiquitously in all the detected tissues and immune cells, which was highly expressed in the spleen, gills, head kidney by quantitative real-time PCR. The mRNA expression of SsIFN-γ was significantly upregulated in the spleen, head kidney, head kidney (HK) macrophages and peripheral blood lymphocytes (PBLs) during pathogen infection. Meanwhile, the recombinant protein (rSsIFN-γ) exhibited an immunomodulatory function to enhance respiratory burst activity and nitric oxide response of HK macrophages. Furthermore, rSsIFN-γ could effectively upregulate the expression of macrophage proinflammatory cytokine, the expression of JAK-STAT signaling pathway related genes and interferon-related downstream genes in the head kidney and spleen. Luciferase assays showed ISRE and GAS activity were obviously enhanced after rSsIFN-γ treatment. These results indicated that SsIFN-γ possessed apparent immunoregulatory properties and played a role in fighting pathogen infection which will be helpful to further understanding of the immunologic mechanism of teleosts IFN-γ in innate immunity.

Non-Classical HLA Class 1b and Hepatocellular Carcinoma

A number of studies are underway to gain a better understanding of the role of immunity in the pathogenesis of hepatocellular carcinoma and to identify subgroups of individuals who may benefit the most from systemic therapy according to the etiology of their tumor. Human leukocyte antigens play a key role in antigen presentation to T cells. This is fundamental to the host's defense against pathogens and tumor cells. In addition, HLA-specific interactions with innate lymphoid cell receptors, such those present on natural killer cells and innate lymphoid cell type 2, have been shown to be important activators of immune function in the context of several liver diseases. More recent studies have highlighted the key role of members of the non-classical HLA-Ib and the transcript adjacent to the HLA-F locus, FAT10, in hepatocarcinoma. The present review analyzes the major contribution of these molecules to hepatic viral infection and hepatocellular prognosis. Particular attention has been paid to the association of natural killer and Vδ2 T-cell activation, mediated by specific HLA class Ib molecules, with risk assessment and novel treatment strategies to improve immunotherapy in HCC.

A single-cell RNA sequencing atlas of circulating leukocytes from healthy and osteosarcoma affected dogs

Translationally relevant animal models are essential for the successful translation of basic science findings into clinical medicine. While rodent models are widely accessible, there are numerous limitations that prevent the extrapolation of findings to human medicine. One approach to overcome these limitations is to use animal models that are genetically diverse and naturally develop disease. For example, pet dogs spontaneously develop diseases that recapitulate the natural progression seen in humans and live in similar environments alongside humans. Thus, dogs represent a useful animal model for many areas of research. Despite the value of the canine model, species specific reagent limitations have hampered in depth characterization of canine immune cells, which constrains the conclusions that can be drawn from canine immunotherapy studies. To address this need, we used single-cell RNA sequencing to characterize the heterogeneity of circulating leukocytes in healthy dogs (n = 7) and osteosarcoma (OS) affected dogs (n = 10). We present a cellular atlas of leukocytes in healthy dogs, then employ the dataset to investigate the impact of primary OS tumors on the transcriptome of circulating leukocytes. We identified 36 unique cell populations amongst dog circulating leukocytes, with a remarkable amount of heterogeneity in CD4 T cell subtypes. In our comparison of healthy dogs and dogs with OS, we identified relative increases in the abundances of polymorphonuclear (PMN-) and monocytic (M-) myeloid-derived suppressor cells (MDSCs), as well as aberrations in gene expression within myeloid cells. Overall, this study provides a detailed atlas of canine leukocytes and investigates how the presence of osteosarcoma alters the transcriptional profiles of circulating immune cells.

Toward a general model of CD4+ T cell subset specification and memory cell formation

In the past few decades, a number of transformative discoveries have been made regarding memory CD8+ T cell biology; meanwhile, the CD4+ T cell field has lagged behind this progress. This perspective focuses on CD4+ helper T (Th) cell subset specification and memory cell formation. Here, we argue that the sheer number of Th effector and memory cell subsets and a focus on their differences have been a barrier to a general model of CD4+ memory T cell formation that applies to all immune responses. We highlight a bifurcation model that relies on an IL-2 signal-dependent switch as an explanation for the balanced production of diverse Th memory cells that participate in cell-mediated or humoral immunity in most contexts.

Cancer-specific tissue-resident memory T-cells express ZNF683 in colorectal cancer

BACKGROUND

Tissue-resident memory T (Trm) cells are associated with cytotoxicity not only in viral infection and autoimmune disease pathologies but also in many cancers. Tumour-infiltrating CD103⁺ Trm cells predominantly comprise CD8 T cells that express cytotoxic activation and immune checkpoint molecules called exhausted markers. This study aimed to investigate the role of Trm in colorectal cancer (CRC) and characterise the cancer-specific Trm.

METHODS

Immunochemical staining with anti-CD8 and anti-CD103 antibodies for resected CRC tissues was used to identify the tumour-infiltrating Trm cells. The Kaplan-Meier estimator was used to evaluate the prognostic significance. Cells immune to CRC were targeted for single-cell RNA-seq analysis to characterise cancer-specific Trm cells in CRC.

RESULTS

The number of CD103⁺/CD8⁺ tumour-infiltrating lymphocytes (TILs) was a favourable prognostic and predictive factor of the overall survival and recurrence-free survival in patients with CRC. Single-cell RNA-seq analysis of 17,257 CRC-infiltrating immune cells revealed a more increased zinc finger protein 683 (ZNF683) expression in cancer Trm cells than in noncancer Trm cells and in high-infiltrating Trm cells than low-infiltrating Trm in cancer, with an upregulated T-cell receptor (TCR)- and interferon-γ (IFN-γ) signalling-related gene expression in ZNF683⁺ Trm cells.

CONCLUSIONS

The number of CD103⁺/CD8⁺ TILs is a prognostic predictive factor in CRC. In addition, we identified the ZNF683 expression as one of the candidate markers of cancer-specific Trm cells. IFN-γ and TCR signalling and ZNF683 expression are involved in Trm cell activation in tumours and are promising targets for cancer immunity regulation.

Early T-bet promotes LFA1 upregulation required for CD8+ effector and memory T cell development

The T-box transcription factor T-bet is regarded as a "master regulator" of CD4+ Th1 differentiation and IFN-γ production. However, in multiple models of infection, T-bet appears less critical for CD8+ T cell expansion and effector function. Here, we show that following vaccination with a replication-deficient strain of Toxoplasma gondii, CD8+ T cell expression of T-bet is required for optimal expansion of parasite-specific effector CD8+ T cells. Analysis of the early events associated with T cell activation reveals that the α chain of LFA1, CD11a, is a target of T-bet, and T-bet is necessary for CD8+ T cell upregulation of this integrin, which influences the initial priming of CD8+ effector T cells. We propose that the early expression of T-bet represents a T cell-intrinsic factor that optimizes T-DC interactions necessary to generate effector responses.

Phosphorylated signal transducer and activator of transcription proteins 1 in salivary glandular tissue: an important histological marker for diagnosis of primary Sjögren's syndrome

OBJECTIVES

The pathological diagnostic criteria for primary Sjögren's syndrome (SjS) have certain limitations. We first explored the key pathogenic pathways of SjS through a bioinformatics approach, and then evaluated the diagnostic value of the important biomarker in SjS.

METHODS

Transcriptome data from non-SjS controls and patients with SjS were analysed using integrated bioinformatics methods. In a case-control study, phosphorylated signal transducer and activator of transcription proteins 1 (p-STAT1), a key biomarker for the activation of interferon (IFN) pathway, was selected to evaluate its diagnostic value by immunohistochemical analyses in salivary gland (SG) tissues.

RESULTS

The IFN-related pathways were aberrantly activated in patients with SjS. Positive staining of p-STAT1 was detected in the SjS group, but not in non-SjS control group. There was a significant difference in the integrated optical density values of p-STAT1 expressions between the controls and the SjS groups, as well as between the controls and the SjS lymphatic foci-negative groups (p<0.05). The area under the curve of the receiver operating characteristic curve for p-STAT1 was 0.990 (95% CI 0.969 to 1.000). There was a significant difference in both accuracy and sensitivity of p-STAT1 compared with the Focus Score (p<0.05). The Jorden index for p-STAT1 was 0.968 (95% CI 0.586 to 0.999).

CONCLUSIONS

The IFN pathway is the key pathogenic pathway in SjS. p-STAT1 may serve as an important biomarker, in addition to lymphocytic infiltration, to diagnose SjS. Particularly in SG samples with negative lymphatic foci, p-STAT1 confers pathological diagnostic value.

IFN-γR/STAT1 signaling in recipient hematopoietic antigen-presenting cells suppresses graft-versus-host disease

The absence of IFN-γ receptor (IFN-γR) or STAT1 signaling in donor cells has been shown to result in reduced induction of acute graft-versus-host disease (GVHD). In this study, we unexpectedly observed increased activation and expansion of donor lymphocytes in both lymphohematopoietic organs and GVHD target tissues of IFN-γR/STAT1-deficient recipient mice, leading to rapid mortality following the induction of GVHD. LPS-matured, BM-derived Ifngr1-/- Stat1-/- DCs (BMDCs) were more potent allogeneic stimulators and expressed increased levels of MHC II and costimulatory molecules. Similar effects were observed in human antigen-presenting cells (APCs) with knockdown of Stat1 by CRISPR/Cas9 and treatment with a JAK1/2 inhibitor. Furthermore, we demonstrated that the absence of IFN-γR/STAT1 signaling in hematopoietic APCs impaired the presentation of exogenous antigens, while promoting the presentation of endogenous antigens. Thus, the indirect presentation of host antigens to donor lymphocytes was defective in IFN-γR/STAT1-deficient, donor-derived APCs in fully donor chimeric mice. The differential effects of IFN-γR/STAT1 signaling on endogenous and exogenous antigen presentation could provide further insight into the roles of the IFN-γ/STAT1 signaling pathway in the pathogenesis of GVHD, organ rejection, and autoimmune diseases.

DSP-0509, a systemically available TLR7 agonist, exhibits combination effect with immune checkpoint blockade by activating anti-tumor immune effects

TLR7 is an innate immune receptor that recognizes single-stranded RNAs, and its activation leads to anti-tumor immune effects. Although it is the only approved TLR7 agonist in cancer therapy, imiquimod is allowed to be administered with topical formulation. Thus, systemic administrative TLR7 agonist is expected in terms of expanding applicable cancer types. Here, we demonstrated the identification and characterization of DSP-0509 as a novel small-molecule TLR7 agonist. DSP-0509 is designed to have unique physicochemical features that could be administered systemically with a short half-life. DSP-0509 activated bone marrow-derived dendritic cells (BMDCs) and induced inflammatory cytokines including type I interferons. In the LM8 tumor-bearing mouse model, DSP-0509 reduced tumor growth not only in subcutaneous primary lesions but also in lung metastatic lesions. DSP-0509 inhibited tumor growth in several syngeneic tumor-bearing mouse models. We found that the CD8⁺ T cell infiltration of tumor before treatment tended to be positively correlated with anti-tumor efficacy in several mouse tumor models. The combination of DSP-0509 with anti-PD-1 antibody significantly enhanced the tumor growth inhibition compared to each monotherapy in CT26 model mice. In addition, the effector memory T cells were expanded in both the peripheral blood and tumor, and rejection of tumor re-challenge occurred in the combination group. Moreover, synergistic anti-tumor efficacy and effector memory T cell upregulation were also observed for the combination with anti-CTLA-4 antibody. The analysis of the tumor-immune microenvironment by using the nCounter assay revealed that the combination of DSP-0509 with anti-PD-1 antibody enhanced infiltration by multiple immune cells including cytotoxic T cells. In addition, the T cell function pathway and antigen presentation pathway were activated in the combination group. We confirmed that DSP-0509 enhanced the anti-tumor immune effects of anti-PD-1 antibody by inducing type I interferons via activation of dendritic cells and even CTLs. In conclusion, we expect that DSP-0509, a new TLR7 agonist that synergistically induces anti-tumor effector memory T cells with immune checkpoint blockers (ICBs) and can be administered systemically, will be used in the treatment of multiple cancers.

Differential regulation of lineage-determining transcription factor expression in innate lymphoid cell and adaptive T helper cell subsets

CD4 T helper (Th) cell subsets, including Th1, Th2 and Th17 cells, and their innate counterparts innate lymphoid cell (ILC) subsets consisting of ILC1s, ILC2s and ILC3s, display similar effector cytokine-producing capabilities during pro-inflammatory immune responses. These lymphoid cell subsets utilize the same set of lineage-determining transcription factors (LDTFs) for their differentiation, development and functions. The distinct ontogeny and developmental niches between Th cells and ILCs indicate that they may adopt different external signals for the induction of LDTF during lineage commitment. Increasing evidence demonstrates that many conserved cis-regulatory elements at the gene loci of LDTFs are often preferentially utilized for the induction of LDTF expression during Th cell differentiation and ILC development at different stages. In this review, we discuss the functions of lineage-related cis-regulatory elements in inducing T-bet, GATA3 or RORγt expression based on the genetic evidence provided in recent publications. We also review and compare the upstream signals involved in LDTF induction in Th cells and ILCs both in vitro and in vivo. Finally, we discuss the possible mechanisms and physiological importance of regulating LDTF dynamic expression during ILC development and activation.

Dendritic cell-natural killer cell cross-talk modulates T cell activation in response to influenza A viral infection

Influenza viruses lead to substantial morbidity and mortality including ~3-5 million cases of severe illness and ~290,000-650,000 deaths annually. One of the major hurdles regarding influenza vaccine efficacy is generating a durable, robust cellular immune response. Appropriate stimulation of the innate immune system is key to generating cellular immunity. Cross-talk between innate dendritic cells (DC) and natural killer (NK) cells plays a key role in activating virus-specific T cells, yet the mechanisms used by influenza A viruses (IAV) to govern this process remain incompletely understood. Here, we used an ex vivo autologous human primary immune cell culture system to evaluate the impact of DC-NK cell cross-talk and subsequent naïve T cell activation at steady-state and after exposure to genetically distinct IAV strains-A/California/07/2009 (H1N1) and A/Victoria/361/2011 (H3N2). Using flow cytometry, we found that exposure of DCs to IAV in co-culture with NK cells led to a decreased frequency of CD83⁺ and CD86⁺ cells on DCs and an increased frequency of HLA-DR⁺ on both DCs and NK cells. We then assessed the outcome of DC-NK cell cross-talk on T cell activation. At steady-state, DC-NK cell cross-talk increased pan T cell CD69 and CD25 expression while exposure to either IAV strain reduced pan T cell CD25 expression and suppressed CD4⁺ and CD8⁺ T cell IFN-γ and TNF production, following chemical stimulation with PMA/Ionomycin. Moreover, exposure to A/Victoria/361/2011 elicited lower IFN-γ production by CD4⁺ and CD8⁺ T cells compared with A/California/07/2009. Overall, our results indicate a role for DC-NK cell cross-talk in T cell priming in the context of influenza infection, informing the immunological mechanisms that could be manipulated for the next generation of influenza vaccines or immunotherapeutics.

Regulation of CD4 T Cell Responses by the Transcription Factor Eomesodermin

Central to the impacts of CD4 T cells, both positive in settings of infectious disease and cancer and negative in the settings of autoimmunity and allergy, is their ability to differentiate into distinct effector subsets with specialized functions. The programming required to support such responses is largely dictated by lineage-specifying transcription factors, often called ‘master regulators’. However, it is increasingly clear that many aspects of CD4 T cell immunobiology that can determine the outcomes of disease states involve a broader transcriptional network. Eomesodermin (Eomes) is emerging as an important member of this class of transcription factors. While best studied in CD8 T cells and NK cells, an increasing body of work has focused on impacts of Eomes expression in CD4 T cell responses in an array of different settings. Here, we focus on the varied impacts reported in these studies that, together, indicate the potential of targeting Eomes expression in CD4 T cells as a strategy to improve a variety of clinical outcomes.

The FoxO4/DKK3 axis represses IFN-γ expression by Th1 cells and limits antimicrobial immunity

Forkhead box O transcriptional factors, especially FoxO1 and FoxO3a, play critical roles in physiologic and pathologic immune responses. However, the function of FoxO4, another main member of the FoxO family, in lymphoid cells is still poorly understood. Here, we showed that loss of FoxO4 in T cells augmented IFN-γ production of Th1 cells in vitro. Correspondingly, conditional deletion of FoxO4 in CD4⁺ T cells enhanced T cell–specific responses to Listeria monocytogenes infection in vivo. Genome-wide occupancy and transcriptomic analyses identified Dkk3 (encoding the Dickkopf-3 protein) as a direct transcriptional target of FoxO4. Consistent with the FoxO4-DKK3 relationship, recombinant DKK3 protein restored normal levels of IFN-γ production in FoxO4-deficient Th1 cells through the downregulation of lymphoid enhancer–binding factor 1 (Lef1) expression. Together, our data suggest a potential FoxO4/DKK3 axis in Th1 cell differentiation, providing what we believe to be an important insight and supplement for FoxO family proteins in T lymphocyte biology and revealing a promising target for the treatment of immune-related diseases.

Dissecting the dynamic transcriptional landscape of early T helper cell differentiation into Th1, Th2, and Th1/2 hybrid cells

Selective differentiation of CD4+ T helper (Th) cells into specialized subsets such as Th1 and Th2 cells is a key element of the adaptive immune system driving appropriate immune responses. Besides those canonical Th-cell lineages, hybrid phenotypes such as Th1/2 cells arise in vivo, and their generation could be reproduced in vitro. While master-regulator transcription factors like T-bet for Th1 and GATA-3 for Th2 cells drive and maintain differentiation into the canonical lineages, the transcriptional architecture of hybrid phenotypes is less well understood. In particular, it has remained unclear whether a hybrid phenotype implies a mixture of the effects of several canonical lineages for each gene, or rather a bimodal behavior across genes. Th-cell differentiation is a dynamic process in which the regulatory factors are modulated over time, but longitudinal studies of Th-cell differentiation are sparse. Here, we present a dynamic transcriptome analysis following Th-cell differentiation into Th1, Th2, and Th1/2 hybrid cells at 3-h time intervals in the first hours after stimulation. We identified an early bifurcation point in gene expression programs, and we found that only a minority of ~20% of Th cell-specific genes showed mixed effects from both Th1 and Th2 cells on Th1/2 hybrid cells. While most genes followed either Th1- or Th2-cell gene expression, another fraction of ~20% of genes followed a Th1 and Th2 cell-independent transcriptional program associated with the transcription factors STAT1 and STAT4. Overall, our results emphasize the key role of high-resolution longitudinal data for the characterization of cellular phenotypes.

The association between diabetes and obesity with Dengue infections

Dengue, an arboviral disease is a global threat to public health as the number of Dengue cases increases through the decades and this trend is predicted to continue. Non-communicable diseases such as diabetes and obesity are also on an upward trend. Moreover, past clinical studies have shown comorbidities worsen the clinical manifestation of especially Severe Dengue. However, discussion regarding the underlying mechanisms regarding the association between these comorbidities and dengue are lacking. The hallmark of Severe Dengue is plasma leakage which is due to several factors including presence of pro-inflammatory cytokines and dysregulation of endothelial barrier protein expression. The key factors of diabetes affecting endothelial functions are Th1 skewed responses and junctional-related proteins expression. Additionally, obesity alters the lipid metabolism and immune response causing increased viral replication and inflammation. The similarity between diabetes and obesity individuals is in having chronic inflammation resulting in endothelial dysfunction. This review outlines the roles of diabetes and obesity in severe dengue and gives some insights into the plausible mechanisms of comorbidities in Severe Dengue.

Role of Glycogen Synthase Kinase-3 in Interferon-γ-Mediated Immune Hepatitis

Glycogen synthase kinase-3 (GSK-3), a serine/threonine kinase, is a vital glycogen synthase regulator controlling glycogen synthesis, glucose metabolism, and insulin signaling. GSK-3 is widely expressed in different types of cells, and its abundant roles in cellular bioregulation have been speculated. Abnormal GSK-3 activation and inactivation may affect its original bioactivity. Moreover, active and inactive GSK-3 can regulate several cytosolic factors and modulate their diverse cellular functional roles. Studies in experimental liver disease models have illustrated the possible pathological role of GSK-3 in facilitating acute hepatic injury. Pharmacologically targeting GSK-3 is therefore suggested as a therapeutic strategy for liver protection. Furthermore, while the signaling transduction of GSK-3 facilitates proinflammatory interferon (IFN)-γ in vitro and in vivo, the blockade of GSK-3 can be protective, as shown by an IFN-γ-induced immune hepatitis model. In this study, we explored the possible regulation of GSK-3 and the potential relevance of GSK-3 blockade in IFN-γ-mediated immune hepatitis.

STING and TLR7/8 agonists-based nanovaccines for synergistic antitumor immune activation

Immunostimulatory therapies based on pattern recognition receptors (PRRs) have emerged as an effective approach in the fight against cancer, with the ability to recruit tumor-specific lymphocytes in a low-immunogenicity tumor environment. The agonist cyclic dinucleotides (CDNs) of the stimulator of interferon gene (STING) are a group of very promising anticancer molecules that increase tumor immunogenicity by activating innate immunity. However, the tumor immune efficacy of CDNs is limited by several factors, including relatively narrow cytokine production, inefficient delivery to STING, and rapid clearance. In addition, a single adjuvant molecule is unable to elicit a broad cytokine response and thus cannot further amplify the anticancer effect. To address this problem, two or more agonist molecules are often used together to synergistically enhance immune efficacy. In this work, we found that a combination of the STING agonist CDG^SF and the Toll-like receptor 7/8 (TLR7/8) agonist 522 produced a broader cytokine response. Subsequently, we developed multicomponent nanovaccines (MCNVs) consisting of a PC7A polymer as a nanocarrier encapsulating the antigen OVA and adjuvant molecules. These MCNVs activate bone marrow-derived dendritic cells (BMDCs) to produce multiple proinflammatory factors that promote antigen cross-presentation to stimulate specific antitumor T-cell responses. In in vivo experiments, we observed that MCNVs triggered a strong T-cell response in tumor-infiltrating lymphocytes, resulting in significant tumor regression and, notably, a 100% survival rate in mice through 25 days without other partnering therapies. These data suggest that our nanovaccines have great potential to advance cancer immunotherapy with increased durability and potency.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (synthesis of CDG^SF, 522, PC7A and OVA; preparation of MCNVs; representative gating strategies for flow cytometry) is available in the online version of this article at 10.1007/s12274-022-4282-x.

CD4+ Memory T-Cell Formation during Type 1 Immune Responses

Naive CD4+ T cells become memory cells after proliferating in response to their cognate major histocompatibility complex class II (MHCII)-bound peptide and passing through an effector cell stage. The process by which CD4+ memory T cells emerge from the effector cell pool, however, is less well understood than in the case of CD8+ T cells. During certain acute infections, naive CD4+ T cells proliferate and differentiate into various forms of type 1 (Th1) and follicular helper (Tfh) effector cells. We review the evidence that about 10% of the cells in each of these subsets survive to become memory cells that resemble their effector cell precursors. The roles that asymmetric cell division, the TCF-1 transcription factor, metabolic activity, reactive oxygen species, and the IL-7 receptor play in the effector to memory cell transition are discussed. We propose a speculative model in which the metabolic activity needed for rapid clonal expansion also generates toxic products that induce apoptosis in most effector cells. Memory cells then arise from the effector cells in each subset that are at the low end of the metabolic activity spectrum.

REV-ERB agonist suppresses IL-17 production in γδT cells and improves psoriatic dermatitis in a mouse model

Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperplasia and cellular infiltration. Studies have shown that disease development depends on proinflammatory cytokines, such as interleukin (IL)-23 and IL-17. It has been suggested that IL-23 produced by innate immune cells, such as macrophages, stimulates a subset of helper T cells to release IL-17, promoting neutrophil recruitment and keratinocyte proliferation. However, recent studies have revealed the crucial role of γδT cells in psoriasis pathogenesis as the primary source of dermal IL-17. The nuclear receptors REV-ERBs are ligand-dependent transcription factors recognized as circadian rhythm regulators. REV-ERBs negatively regulate IL-17-producing helper T cells, whereas the involvement of REV-ERBs in regulating IL-17-producing γδT (γδT17) cells remains unclear. Here we revealed the regulatory mechanism involving γδT17 cells through REV-ERBs. γδT17 cell levels were remarkably elevated in the secondary lymphoid organs of mice that lacked an isoform of REV-ERBs. A synthetic REV-ERB agonist, SR9009, suppressed γδT17 cells in vitro and in vivo. Topical application of SR9009 to the skin reduced the inflammatory symptoms of psoriasiform dermatitis in mice. The results of this study provide a novel therapeutic approach for psoriasis targeting REV-ERBs in γδT17 cells.

Expression Regulation and Function of T-Bet in NK Cells

Natural killer (NK) cells are cytotoxic innate lymphocytes that play an important role in immune surveillance. The development, maturation and effector functions of NK cells are orchestrated by the T-box transcription factor T-bet, whose expression is induced by cytokines such as IFN-γ, IL-12, IL-15 and IL-21 through the respective cytokine receptors and downstream JAK/STATs or PI3K-AKT-mTORC1 signaling pathways. In this review, we aim to discuss the expression and regulation of T-bet in NK cells, the role of T-bet in mouse NK cell development, maturation, and function, as well as the role of T-bet in acute, chronic infection, inflammation, autoimmune diseases and tumors.

Diversity of T Helper and Regulatory T Cells and Their Contribution to the Pathogenesis of Allergic Diseases

T helper (Th) and regulatory T (Treg) cells represent important effectors of adaptive immunity. They mediate communication between the immune system and tissue sites and thereby coordinate effective defense against environmental threats or maintain tolerance, respectively. Since the discovery of two prototypic T helper cells, Th1 and Th2, additional phenotypic and functional distinct subsets have been described ranging from Th17, Th22, Th9, and T follicular helper cells. The same holds true for regulatory T cells that represent a family with functionally distinct subsets characterized by co-expression of the transcription factors T-bet, Gata3, or RORγt. Here, we summarize the current knowledge on differentiation and function of T helper and regulatory T cell subsets and discuss their lineage stability versus plasticity towards other subsets. In addition, we highlight the direct and indirect contribution of each subset to the pathology of allergies and indicate novel therapies for specific targeting the effector functions of T helper and regulatory T cells.

Junctional adhesion molecule-A on dendritic cells regulates Th1 differentiation

The junctional adhesion molecule-A (JAM-A) is an adhesion molecule present in the surface of several cell types, such as endothelial cells and leukocytes as well as Dendritic Cells (DC). Given the potential relevance of JAM-A in diverse pathological conditions such as inflammatory diseases and cancer, we investigated the role of JAM-A in CD4+ T cell priming. We demonstrate that JAM-A is present in the immunological synapse formed between T cells and DC during priming. Furthermore, an antagonistic anti-JAM-A mAb could disrupt the interaction between CD4+ T cell and DC. Antagonism of JAM-A also attenuated T cell activation and proliferation with a decrease in T-bet expression and increased IL-6 and IL-17 secretion. These findings demonstrate a functional role for JAM-A in interactions between CD4+ T cells and DCs during T cell priming as a positive regulator of Th1 differentiation.

Oral Administration of Lactococcus lactis Producing Interferon Type II, Enhances the Immune Response Against Bacterial Pathogens in Rainbow Trout

Lactic acid bacteria are a powerful vehicle for releasing of cytokines and immunostimulant peptides at the gastrointestinal level after oral administration. However, its therapeutic application against pathogens that affect rainbow trout and Atlantic salmon has been little explored. Type II interferon in Atlantic salmon activates the antiviral response, protecting against viral infection, but its role against bacterial infection has not been tested in vivo. In this work, through the design of a recombinant lactic acid bacterium capable of producing Interferon gamma from Atlantic salmon, we explore its role against bacterial infection and the ability to stimulate systemic immune response after oral administration of the recombinant probiotic. Recombinant interferon was active in vitro, mainly stimulating IL-6 expression in SHK-1 cells. In vivo, oral administration of the recombinant probiotic produced an increase in IL-6, IFNγ and IL-12 in the spleen and kidney, in addition to stimulating the activity of lysozyme in serum. The challenge trials indicated that the administration of the IFNγ-producing probiotic doubled the survival in fish infected with F. psychrophilum. In conclusion, our results showed that the oral administration of lactic acid bacteria producing IFNγ managed to stimulate the immune response at a systemic level, conferring protection against pathogens, showing a biotechnological potential for its application in aquaculture.

The Preliminary Study for Postoperative Radiotherapy Survival Associated with RUNX3 and TLR9 Expression in Lung Cancer

Background

Many studies have reported that the inflammatory immune response related to TLR9 signaling activation participates in tumor development and affects the treatment outcome. RUNX3 functions as a tumor suppressor by regulating DNA methylation. RUNX3 protein plays an important role in TGF-β signaling pathway that is involved in tumor growth inhibition and apoptosis. At present, radiotherapy is still an important treatment in lung cancer, which induces immune response and affects the therapeutic outcome. The role of TLR9 signaling activation and RUNX3 in this process is not clear.

Methods

In this study, we investigated the expression of TLR9 in tumor and RUNX3 in surrounding tissues by immunohistochemical methods and analyzed the relationship on postoperative survival in lung cancer.

Results

We found that the high expression of TLR9 was the risk factor in postoperative survival of lung cancer with no difference in lifetime. The high expression of RUNX3 in lung cancer with TLR9 signaling activation was in favor of progression-free survival and overall survival in postoperative radiotherapy. It suggested that RUNX3 played an important role in lung cancer radiotherapy. In order to determine the effect of RUNX3 in lung cancer radiation with TLR9 signaling activation, we introduced 5-Aza-2ʹ-deoxycytidine (5-Aza-CdR) and exposed lung cancer A459 cells repeatedly. The high expression of RUNX3 especially RUNX3-B in cells treated with 5-Aza-CdR was observed. We examined that 5-Aza-CdR induced more cell blocking in G2/M phase in combining irradiation.

Conclusion

The result implied that it was feasible to improve radiosensitivity of lung cancer with TLR9 signaling activation by increasing RUNX3 expression, and 5-Aza-CdR was an option in this process.

TCR Affinity Controls the Dynamics but Not the Functional Specification of the Antimycobacterial CD4+ T Cell Response

The quality of T cell responses depends on the lymphocytes' ability to undergo clonal expansion, acquire effector functions, and traffic to the site of infection. Although TCR signal strength is thought to dominantly shape the T cell response, by using TCR transgenic CD4⁺ T cells with different peptide:MHC binding affinity, we reveal that TCR affinity does not control Th1 effector function acquisition or the functional output of individual effectors following mycobacterial infection in mice. Rather, TCR affinity calibrates the rate of cell division to synchronize the distinct processes of T cell proliferation, differentiation, and trafficking. By timing cell division-dependent IL-12R expression, TCR affinity controls when T cells become receptive to Th1-imprinting IL-12 signals, determining the emergence and magnitude of the Th1 effector pool. These findings reveal a distinct yet cooperative role for IL-12 and TCR binding affinity in Th1 differentiation and suggest that the temporal activation of clones with different TCR affinity is a major strategy to coordinate immune surveillance against persistent pathogens.

Two sequential activation modules control the differentiation of protective T helper-1 (Th1) cells

Interferon-γ (IFN-γ)-producing CD4+ T helper-1 (Th1) cells are critical for protection from microbes that infect the phagosomes of myeloid cells. Current understanding of Th1 cell differentiation is based largely on reductionist cell culture experiments. We assessed Th1 cell generation in vivo by studying antigen-specific CD4+ T cells during infection with the phagosomal pathogen Salmonella enterica (Se), or influenza A virus (IAV), for which CD4+ T cells are less important. Both microbes induced T follicular helper (Tfh) and interleukin-12 (IL-12)-independent Th1 cells. During Se infection, however, the Th1 cells subsequently outgrew the Tfh cells via an IL-12-dependent process and formed subsets with increased IFN-γ production, ZEB2-transcription factor-dependent cytotoxicity, and capacity to control Se infection. Our results indicate that many infections induce a module that generates Tfh and poorly differentiated Th1 cells, which is followed in phagosomal infections by an IL-12-dependent Th1 cell amplification module that is critical for pathogen control.

IFNγ Is Critical for CAR T Cell-Mediated Myeloid Activation and Induction of Endogenous Immunity

Chimeric antigen receptor (CAR) T cells mediate potent antigen-specific antitumor activity; however, their indirect effects on the endogenous immune system are not well characterized. Remarkably, we demonstrate that CAR T-cell treatment of mouse syngeneic glioblastoma (GBM) activates intratumoral myeloid cells and induces endogenous T-cell memory responses coupled with feed-forward propagation of CAR T-cell responses. IFNγ production by CAR T cells and IFNγ responsiveness of host immune cells are critical for tumor immune landscape remodeling to promote a more activated and less suppressive tumor microenvironment. The clinical relevance of these observations is supported by studies showing that human IL13Rα2-CAR T cells activate patient-derived endogenous T cells and monocytes/macrophages through IFNγ signaling and induce the generation of tumor-specific T-cell responses in a responding patient with GBM. These studies establish that CAR T-cell therapy has the potential to shape the tumor microenvironment, creating a context permissible for eliciting endogenous antitumor immunity. SIGNIFICANCE: Our findings highlight the critical role of IFNγ signaling for a productive CAR T-cell therapy in GBM. We establish that CAR T cells can activate resident myeloid populations and promote endogenous T-cell immunity, emphasizing the importance of host innate and adaptive immunity for CAR T-cell therapy of solid tumors.This article is highlighted in the In This Issue feature, p. 2113.

Immunological memory in rheumatic inflammation - a roadblock to tolerance induction

Why do we still have no cure for chronic inflammatory diseases? One reason could be that current therapies are based on the assumption that chronic inflammation is driven by persistent 'acute' immune reactions. Here we discuss a paradigm shift by suggesting that beyond these reactions, chronic inflammation is driven by imprinted, pathogenic 'memory' cells of the immune system. This rationale is based on the observation that in patients with chronic inflammatory rheumatic diseases refractory to conventional immunosuppressive therapies, therapy-free remission can be achieved by resetting the immune system; that is, by ablating immune cells and regenerating the immune system from stem cells. The success of this approach identifies antigen-experienced and imprinted immune cells as essential and sufficient drivers of inflammation. The 'dark side' of immunological memory primarily involves memory plasma cells secreting pathogenic antibodies and memory T lymphocytes secreting pathogenic cytokines and chemokines, but can also involve cells of innate immunity. New therapeutic strategies should address the persistence of these memory cells. Selective targeting of pathogenic immune memory cells could be based on their specificity, which is challenging, or on their lifestyle, which differs from that of protective immune memory cells, in particular for pathogenic T lymphocytes. The adaptations of such pathogenic memory cells to chronic inflammation offers entirely new therapeutic options for their selective ablation and the regeneration of immunological tolerance.

Type I and II Interferons in the Anti-Tumor Immune Response

The interferons (IFNs) are essential components of the immune response against infections and malignancies. IFNs are potent promoters of the anti-tumor response, but there is also evidence that feedback mechanisms regulated by IFNs negatively control immune responses to avoid hyper-activation and limit inflammation. This balance of responses plays an important role in cancer surveillance, immunoediting and response to anticancer therapeutic approaches. Here we review the roles of both type I and type II IFNs on the control of the immune response against malignancies in the context of effects on both malignant cells and cells of the immune system in the tumor microenvironment.

The Role of Interferons in the Pathogenesis of Sjögren's Syndrome and Future Therapeutic Perspectives

There is a great deal of evidence pointing to interferons (IFNs) as being key cytokines in the pathogenesis of different systemic autoimmune diseases, including primary Sjögren’s syndrome (pSS). In this disease, a large number of studies have shown that an overexpression of type I IFN, the ‘so-called’ type I IFN signature, is present in peripheral blood mononuclear cells, and that this finding is associated with the development of systemic extra-glandular manifestations, and a substantial production of autoantibodies and inflammatory cytokines. In contrast, the absence or a milder expression of type I IFN signature and low level of inflammatory cytokines characterizes patients with a different clinical phenotype, where the disease is limited to glandular involvement and often marked by the presence of widespread pain and depression. The role of type II (IFNγ) in this subset of pSS patients, together with the potentially related activation of completely different immunological and metabolic pathways, are emerging issues. Expression of both types of IFNs has also been shown in target tissues, namely in minor salivary glands where a predominance of type II IFN signature appeared to have a certain association with the development of lymphoma. In view of the role played by IFN overexpression in the development and progression of pSS, inhibition or modulation of IFN signaling has been regarded as a potential target for the therapeutic approach. A number of therapeutic compounds with variable mechanisms of action have been tested or are under consideration for the treatment of patients with pSS.

STAT4 Is Largely Dispensable for Systemic Lupus Erythematosus-like Autoimmune- and Foreign Antigen-Driven Antibody-Forming Cell, Germinal Center, and Follicular Th Cell Responses

Genome-wide association studies identified variants in the transcription factor STAT4 gene and several other genes in the STAT4 signaling pathway, such as IL12A, IL12B, JAK2, and TYK2, which are associated with an increased risk of developing systemic lupus erythematosus (SLE) and other autoimmune diseases. Consistent with the genome-wide association studies data, STAT4 was shown to play an important role in autoimmune responses and autoimmunity development in SLE mouse models. Despite such important role for STAT4 in SLE development in mice and humans, little is known whether and how STAT4 may regulate extrafollicular Ab-forming cell (AFC) and follicular germinal center (GC) responses, two major pathways of autoreactive B cell development and autoantibody production. To our surprise, we found STAT4 to be largely dispensable for promoting autoimmune AFC and GC responses in various autoimmune- and SLE-prone mouse models, which strongly correlated with autoantibody production, and immune complex deposition and immune cell infiltration in the kidney. We further observed that STAT4 deficiency had no effects on AFC, GC, and Ag-specific Ab responses during protein Ag immunization or influenza virus infection. Additionally, CD4+ effector and follicular Th cell responses in autoimmune- and SLE-prone mice and protein Ag-immunized and influenza virus-infected mice were intact in the absence of STAT4. Together, our data demonstrate a largely dispensable role for STAT4 in AFC, GC, and Ab responses in SLE mouse models and in certain foreign Ag-driven responses.