White Adipose Tissue Is a Reservoir for Memory T Cells and Promotes Protective Memory Responses to Infection

The immunology of sickness metabolism

Everyone knows that an infection can make you feel sick. Although we perceive infection-induced changes in metabolism as a pathology, they are a part of a carefully regulated process that depends on tissue-specific interactions between the immune system and organs involved in the regulation of systemic homeostasis. Immune-mediated changes in homeostatic parameters lead to altered production and uptake of nutrients in circulation, which modifies the metabolic rate of key organs. This is what we experience as being sick. The purpose of sickness metabolism is to generate a metabolic environment in which the body is optimally able to fight infection while denying vital nutrients for the replication of pathogens. Sickness metabolism depends on tissue-specific immune cells, which mediate responses tailored to the nature and magnitude of the threat. As an infection increases in severity, so do the number and type of immune cells involved and the level to which organs are affected, which dictates the degree to which we feel sick. Interestingly, many alterations associated with metabolic disease appear to overlap with immune-mediated changes observed following infection. Targeting processes involving tissue-specific interactions between activated immune cells and metabolic organs therefore holds great potential for treating both people with severe infection and those with metabolic disease. In this review, we will discuss how the immune system communicates in situ with organs involved in the regulation of homeostasis and how this communication is impacted by infection.

Subcutaneous adipose tissue: Implications in dermatological diseases and beyond

Subcutaneous adipose tissue (SAT) is the deepest component of the three-layered cutaneous integument. While mesenteric adipose tissue-based immune processes have gained recognition in the context of the metabolic syndrome, SAT has been traditionally considered primarily for energy storage, with less attention to its immune functions. SAT harbors a reservoir of immune and stromal cells that significantly impact metabolic and immunologic processes not only in the skin, but even on a systemic level. These processes include wound healing, cutaneous and systemic infections, immunometabolic, and autoimmune diseases, inflammatory skin diseases, as well as neoplastic conditions. A better understanding of SAT immune functions in different processes, could open avenues for novel therapeutic interventions. Targeting SAT may not only address SAT-specific diseases but also offer potential treatments for cutaneous or even systemic conditions. This review aims to provide a comprehensive overview on SAT's structure and functions, highlight recent advancements in understanding its role in both homeostatic and pathological conditions within and beyond the skin, and discuss the main questions for future research in the field.

M6A modification and T cells in adipose tissue inflammation

Adipose tissue in the obese state can lead to low-grade chronic inflammation while inducing or exacerbating obesity-related metabolic diseases and impairing overall health.T cells, which are essential immune cells similar to macrophages, are widely distributed in adipose tissue and perform their immunomodulatory function; they also cross-talk with other cells in the vascular stromal fraction. Based on a large number of studies, it has been found that N6 methyl adenine (m6A) is one of the most representative of epigenetic modifications, which affects the crosstalk between T cells, as well as other immune cells, in several ways and plays an important role in the development of adipose tissue inflammation and related metabolic diseases. In this review, we first provide an overview of the widespread presence of T cells in adipose tissue and summarize the key role of T cells in adipose tissue inflammation. Next, we explored the effects of m6A modifications on T cells in adipose tissue from the perspective of adipose tissue inflammation. Finally, we discuss the impact of m6a-regulated crosstalk between T cells and immune cells on the prospects for improving adipose tissue inflammation research, providing additional new ideas for the treatment of obesity.

Prognostic value of body mass index for first-line chemoimmunotherapy combinations in advanced non-small cell lung cancer in Chinese population

Background

Few studies have examined the correlation between body mass index (BMI) and effectiveness of first-line chemoimmunotherapy in patients with advanced non-small cell lung cancer (NSCLC); moreover, the conclusion remains elusive and no such studies have been conducted in the Chinese population. Our study aimed to validate the predictive significance of BMI in Chinese patients with advanced NSCLC receiving first-line chemoimmunotherapy combinations.

Methods

Data of patients with advanced NSCLC treated with first-line chemoimmunotherapy between June 2018 and February 2022 at three centers were retrieved retrospectively. The association between baseline BMI with progression-free survival (PFS) and overall survival (OS) was evaluated using the Kaplan-Meier method and Cox regression models. BMI was categorized according to the World Health Organization criteria.

Results

Of the included 805 patients, 5.3 % were underweight, 63.4 % had normal weight, 27.8 % were overweight, and 3.5 % were obese. Survival analysis showed that patients in the high BMI group had significantly better PFS (p = 0.012) and OS (p = 0.014) than those in the low BMI group. Further, patients in the overweight subgroup had better PFS (p = 0.036) and OS (p = 0.043) compared to the normal weight population. The results of Cox regression analysis confirmed the correlations between BMI and prognosis of advanced NSCLC patients receiving first-line chemoimmunotherapy combinations.

Conclusions

Baseline BMI affected the clinical outcomes of first-line chemoimmunotherapy combinations in patients with advanced NSCLC, and was especially favorable for the overweight subgroup.

Potential roles of sex-linked differences in obesity and cancer immunotherapy: revisiting the obesity paradox

Obesity, a condition of excess adiposity usually defined by a BMI > 30, can have profound effects on both metabolism and immunity, connecting the condition with a broad range of diseases, including cancer and negative outcomes. Obesity and cancer have been associated with increased incidence, progression, and poorer outcomes of multiple cancer types in part due to the pro-inflammatory state that arises. Surprisingly, obesity has also recently been demonstrated in both preclinical models and clinical outcomes to be associated with improved response to immune checkpoint inhibition (ICI). These observations have laid the foundation for what has been termed the "obesity paradox". The mechanisms underlying these augmented immunotherapy responses are still unclear given the pleiotropic effects obesity exerts on cells and tissues. Other important variables such as age and sex are being examined as further affecting the obesity effect. Sex-linked factors exert significant influences on obesity biology, metabolism as well as differential effects of different immune cell-types. Age can be another confounding factor contributing to the effects on both sex-linked changes, immune status, and obesity. This review aims to revisit the current body of literature describing the immune and metabolic changes mediated by obesity, the role of obesity on cancer immunotherapy, and to highlight questions on how sex-linked differences may influence obesity and immunotherapy outcome.

Association between lipid accumulation product and psoriasis among adults: a nationally representative cross-sectional study

BACKGROUND

Lipid accumulation product (LAP) is an accessible and relatively comprehensive assessment of obesity that represents both anatomical and physiological lipid accumulation. Obesity and psoriasis are potentially related, according to previous research. Investigating the relationship between adult psoriasis and the LAP index was the goal of this study.

METHODS

This is a cross-sectional study based on data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006 and 2009-2014. The association between LAP and psoriasis was examined using multivariate logistic regression and smoothed curve fitting. To verify whether this relationship was stable across populations, subgroup analyses and interaction tests were performed.

RESULTS

The LAP index showed a positive correlation with psoriasis in 9,781 adult participants who were 20 years of age or older. A 27% elevated probability of psoriasis was linked to every unit increase in ln LAP in the fully adjusted model (Model 3: OR 1.27, 95% CI 1.06-1.52). In comparison with participants in the lowest ln LAP quartile, those in the highest quartile had an 83% greater likelihood of psoriasis (Model 3: OR 1.83, 95% CI 1.08-3.11). This positive correlation was more pronounced for young males, participants who had never smoked, non-drinkers, participants who exercised little, as well as non-hypertensive and non-diabetic participants.

CONCLUSIONS

This study found that the LAP index and adult psoriasis were positively correlated, especially in young males without comorbidities. Therefore, it is proposed that LAP may serve as a biomarker for early diagnosis of psoriasis and tracking the effectiveness of treatment.

Impaired Remodeling of White Adipose Tissue in Obesity and Aging: From Defective Adipogenesis to Adipose Organ Dysfunction

The adipose organ adapts and responds to internal and environmental stimuli by remodeling both its cellular and extracellular components. Under conditions of energy surplus, the subcutaneous white adipose tissue (WAT) is capable of expanding through the enlargement of existing adipocytes (hypertrophy), followed by de novo adipogenesis (hyperplasia), which is impaired in hypertrophic obesity. However, an impaired hyperplastic response may result from various defects in adipogenesis, leading to different WAT features and metabolic consequences, as discussed here by reviewing the results of the studies in animal models with either overexpression or knockdown of the main molecular regulators of the two steps of the adipogenesis process. Moreover, impaired WAT remodeling with aging has been associated with various age-related conditions and reduced lifespan expectancy. Here, we delve into the latest advancements in comprehending the molecular and cellular processes underlying age-related changes in WAT function, their involvement in common aging pathologies, and their potential as therapeutic targets to influence both the health of elderly people and longevity. Overall, this review aims to encourage research on the mechanisms of WAT maladaptation common to conditions of both excessive and insufficient fat tissue. The goal is to devise adipocyte-targeted therapies that are effective against both obesity- and age-related disorders.

Cytokine production by bovine adipose tissue stromal vascular fraction cells upon Neospora caninum stimulation

In bovines few studies addressed the contribution of adipose tissue to the host immune response to infection. Here we evaluated the in vitro response of bovine adipose tissue stromal vascular fraction (SVF) cells to the protozoan parasite Neospora caninum, using live and freeze-killed tachyzoites. Live N. caninum induced the production of IL-6, IL-1β and IL-10 by SVF cells isolated from subcutaneous adipose tissue (SAT), while in mesenteric adipose tissue (MAT) SVF cell cultures only IL-1β and IL-10 production was increased, showing slight distinct responses between adipose tissue depots. Whereas a clear IL-8 increase was detected in peripheral blood leucocytes (PBL) culture supernatants in response to live N. caninum, no such increase was observed in SAT or MAT SVF cell cultures. Nevertheless, in response to LPS, increased IL-8 levels were detected in all cell cultures. IL-10 levels were always increased in response to stimulation (live, freeze-killed N. caninum and LPS). Overall, our results show that bovine adipose tissue SVF cells produce cytokines in response to N. caninum and can therefore be putative contributors to the host immune response against this parasite.

Nutrients: Signal 4 in T cell immunity

T cells are integral in mediating adaptive immunity to infection, autoimmunity, and cancer. Upon immune challenge, T cells exit from a quiescent state, followed by clonal expansion and effector differentiation. These processes are shaped by three established immune signals, namely antigen stimulation (Signal 1), costimulation (Signal 2), and cytokines (Signal 3). Emerging findings reveal that nutrients, including glucose, amino acids, and lipids, are crucial regulators of T cell responses and interplay with Signals 1-3, highlighting nutrients as Signal 4 to license T cell immunity. Here, we first summarize the functional importance of Signal 4 and the underlying mechanisms of nutrient transport, sensing, and signaling in orchestrating T cell activation and quiescence exit. We also discuss the roles of nutrients in programming T cell differentiation and functional fitness and how nutrients can be targeted to improve disease therapy. Understanding how T cells respond to Signal 4 nutrients in microenvironments will provide insights into context-dependent functions of adaptive immunity and therapeutic interventions.

Transcriptomic Profiling and Cellular Composition of Creeping Fat in Crohn's disease

BACKGROUND AND AIMS

Creeping fat [CF] is a poorly understood feature of Crohn's disease [CD], characterized by the wrapping of mesenteric adipose tissue [MAT] around the inflamed intestine. The aim of this study was to investigate the transcriptional profile and compositional features of CF.

METHODS

We collected 59 MAT samples: 23 paired samples from patients with CD (CF [CD-CF] and MAT around the uninflamed intestine [CD-MAT]) and 13 MAT samples from non-CD patients [Con-MAT]. Differentially expressed gene [DEG], functional pathway, cell deconvolution, and gene co-expression network analyses were performed.

RESULTS

By comparing three different MAT samples, we identified a total of 529 DEGs [|log2FoldChange| > 1.5; false discovery rate < 0.05]. Of these, 323 genes showed an incremental pattern from Con-MAT to CD-MAT, and to CD-CF, while 105 genes displayed a decremental pattern. Genes with an incremental pattern were related to immune cell responses, including B- and T-cell activation, while genes with a decremental pattern were involved in cell trafficking and migration. Cell deconvolution analysis revealed significant changes in cellular composition between the CD-CF and Con-MAT groups, with increased proportions of B-cells/plasma cells [p = 1.16 × 10-4], T-cells [p = 3.66 × 10-3], and mononuclear phagocytes [p = 3.53 × 10-2] in the CD-CF group. In contrast, only the B-cell/plasma cell component showed a significant increase [p = 1.62 × 10-2] in the CD-MAT group compared to Con-MAT.

CONCLUSION

The distinct transcriptional profiles and altered cellular components of each MAT found in our study provide insight into the mechanisms behind CF and highlight its possible role in the pathogenesis of CD.

Adipose Tissue Inflammation: Linking Physiological Stressors to Disease Susceptibility

The study of adipose tissue (AT) is enjoying a renaissance. White, brown, and beige adipocytes are being investigated in adult animals, and the critical roles of small depots like perivascular AT are becoming clear. But the most profound revision of the AT dogma has been its cellular composition and regulation. Single-cell transcriptomic studies revealed that adipocytes comprise well under 50% of the cells in white AT, and a substantial portion of the rest are immune cells. Altering the function of AT resident leukocytes can induce or correct metabolic syndrome and, more surprisingly, alter adaptive immune responses to infection. Although the field is dominated by obesity research, conditions such as rapid lipolysis, infection, and heat stress impact AT immune dynamics as well. Recent findings in rodents lead to critical questions that should be explored in domestic livestock as potential avenues for improved animal resilience to stressors, particularly as animals age.

CD8+ Tissue-Resident Memory T Cells: Versatile Guardians of the Tissue

Tissue-resident memory T (Trm) cells are a subset of T cells maintained throughout life within nonlymphoid tissues without significant contribution from circulating memory T cells. CD8+ Trm cells contribute to both tissue surveillance and direct elimination of pathogens through a variety of mechanisms. Reactivation of these Trm cells during infection drives systematic changes within the tissue, including altering the state of the epithelium, activating local immune cells, and contributing to the permissiveness of the tissue for circulating immune cell entry. Trm cells can be further classified by their functional outputs, which can be either subset- or tissue-specific, and include proliferation, tissue egress, and modulation of tissue physiology. These functional outputs of Trm cells are linked to the heterogeneity and plasticity of this population, and uncovering the unique responses of different Trm cell subsets and their role in immunity will allow us to modulate Trm cell responses for optimal control of disease.

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.

Microbiota configuration determines nutritional immune optimization

Mild or transient dietary restriction (DR) improves many aspects of health and aging. Emerging evidence from us and others has demonstrated that DR also optimizes the development and quality of immune responses. However, the factors and mechanisms involved remain to be elucidated. Here, we propose that DR-induced optimization of immunological memory requires a complex cascade of events involving memory T cells, the intestinal microbiota, and myeloid cells. Our findings suggest that DR enhances the ability of memory T cells to recruit and activate myeloid cells in the context of a secondary infection. Concomitantly, DR promotes the expansion of commensal Bifidobacteria within the large intestine, which produce the short-chain fatty acid acetate. Acetate conditioning of the myeloid compartment during DR enhances the capacity of these cells to kill pathogens. Enhanced host protection during DR is compromised when Bifidobacteria expansion is prevented, indicating that microbiota configuration and function play an important role in determining immune responsiveness to this dietary intervention. Altogether, our study supports the idea that DR induces both memory T cells and the gut microbiota to produce distinct factors that converge on myeloid cells to promote optimal pathogen control. These findings suggest that nutritional cues can promote adaptation and co-operation between multiple immune cells and the gut microbiota, which synergize to optimize immunity and protect the collective metaorganism.

Human adipose tissue as a major reservoir of cytomegalovirus-reactive T cells

Introduction

Cytomegalovirus (CMV) is a common herpesvirus with a high prevalence worldwide. After the acute infection phase, CMV can remain latent in several tissues. CD8 T cells in the lungs and salivary glands mainly control its reactivation control. White adipose tissue (WAT) contains a significant population of memory T cells reactive to viral antigens, but CMV specificity has mainly been studied in mouse WAT. Therefore, we obtained blood, omental WAT (oWAT), subcutaneous WAT (sWAT), and liver samples from 11 obese donors to characterize the human WAT adaptive immune landscape from a phenotypic and immune receptor specificity perspective.

Methods

We performed high-throughput sequencing of the T cell receptor (TCR) locus to analyze tissue and blood TCR repertoires of the 11 donors. The presence of TCRs specific to CMV epitopes was tested through ELISpot assays. Moreover, phenotypic characterization of T cells was carried out through flow cytometry.

Results

High-throughput sequencing analyses revealed that tissue TCR repertoires in oWAT, sWAT, and liver samples were less diverse and dominated by hyperexpanded clones when compared to blood samples. Additionally, we predicted the presence of TCRs specific to viral epitopes, particularly from CMV, which was confirmed by ELISpot assays. Remarkably, we found that oWAT has a higher proportion of CMV-reactive T cells than blood or sWAT. Finally, flow cytometry analyses indicated that most WAT-infiltrated lymphocytes were tissue-resident effector memory CD8 T cells.

Discussion

Overall, these findings postulate human oWAT as a major reservoir of CMV-specific T cells, presumably for latent viral reactivation control. This study enhances our understanding of the adaptive immune response in human WAT and highlights its potential role in antiviral defense.

Metabolic diversity of tumor-infiltrating T cells as target for anti-immune therapeutics

Tumor-infiltrating T cells are promising drug targets to modulate the tumor microenvironment. However, tumor-infiltrating T lymphocytes, as central targets of cancer immunotherapy, show considerable heterogeneity and dynamics across tumor microenvironments and cancer types that may fundamentally influence cancer growth, metastasis, relapse, and response to clinical drugs. The T cell heterogeneity not only refers to the composition of subpopulations but also divergent metabolic states of T cells. Comparing to the diversity of tumor-infiltrating T cell compositions that have been well recognized, the metabolic diversity of T cells deserves more attention for precision immunotherapy. Single-cell sequencing technology enables panoramic stitching of the tumor bulk, partly by showing the metabolic-related gene expression profiles of tumor-infiltrating T cells at a single-cell resolution. Therefore, we here discuss T cell metabolism reprogramming triggered by tumor microenvironment as well as the potential application of metabolic targeting drugs. The tumor-infiltrating T cells metabolic pathway addictions among different cancer types are also addressed in this brief review.

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.

Eurotium cristatum from Fu Brick Tea Promotes Adipose Thermogenesis by Boosting Colonic Akkermansia muciniphila in High-Fat-Fed Obese Mice

This study investigated the potential fat-thermogenic effects of Eurotium cristatum, and elucidated the underlying mechanisms. The 12-week administration of E. cristatum in HFD-fed obese mice reduced body weight and improved glucolipid metabolism disorders. The administration of E. cristatum also efficiently promoted thermogenesis by increasing the expression of UCP1 and PRDM16 in both interscapular brown adipose tissue (iBAT) and inguinal white adipose tissue (iWAT) of HFD-fed mice. Furthermore, E. cristatum shaped the gut microbiome by increasing the abundance of Parabacteroides and Akkermansia muciniphila, and also elevated the levels of cecal short-chain fatty acids, particularly propionate and acetate. Of note, A. muciniphila was highly negatively correlated with body weight gain (r = -0.801, p < 0.05) and the iWAT index (r = -0.977, p < 0.01), suggesting that A. muciniphila may play an important role in the thermogenic mobilization induced by E. cristatum. Continuous supplementation with A. muciniphila suppressed adipose accumulation, improved glucolipid metabolism, and enhanced the thermogenic activity of iWAT and iBAT. Collectively, our results propose that boosted A. muciniphila acts as a key microbe in tea-derived probiotic E. cristatum-mediated fat-thermogenic and anti-obesity effects.

State of CD8+ T cells in progression from nonalcoholic steatohepatitis to hepatocellular carcinoma: From pathogenesis to immunotherapy

With the obesity epidemic, nonalcoholic steatohepatitis (NASH) is emerging as the fastest growing potential cause of hepatocellular carcinoma (HCC). NASH has been demonstrated to establish a tumor-prone liver microenvironment where both innate and adaptive immune systems are involved. As the most typical anti-tumor effector, the cell function of CD8+ T cells is remodeled by chronic inflammation, metabolic alteration, lipid toxicity and oxidative stress in the liver microenvironment along the NASH to HCC transition. Unexpectedly, NASH may blunt the effect of immune checkpoint inhibitor therapy against HCC due to the dysregulated CD8+ T cells. Growing evidence has supported that NASH is likely to facilitate the state transition of CD8+ T cells with changes in cell motility, effector function, metabolic reprogramming and gene transcription according to single-cell sequencing. However, the mechanistic insight of CD8+ T cell states in the NASH-driven HCC is not comprehensive. Herein, we focus on the characterization of state phenotypes of CD8+ T cells with both functional and metabolic signatures in NASH-driven fibrosis and HCC. The NASH-specific CD8+ T cells are speculated to mainly have a dualist effect, where its aberrant activated phenotype sustains chronic inflammation in NASH but subsequently triggers its exhaustion in HCC. As the exploration of CD8+ T cells on the distribution and phenotypic shifts will provide a new direction for the intervention strategies against HCC, we also discuss the implications for targeting different phenotypes of CD8+ T cells, shedding light on the personalized immunotherapy for NASH-driven HCC.

STAT4 increases the phenotypic and functional heterogeneity of intestinal tissue-resident memory T cells

Tissue-resident memory T cells (Trms) are an important subset of lymphocytes that are lodged within non-lymphoid tissues and carry out diverse functions to control local pathogen replication. CD103 has been used to broadly define subsets of Trms within the intestine, with CD103+ and CD103- subsets having unique transcriptional profiles and effector functions. Here we identify signal transducer and activator of transcription 4 (STAT4) as an important regulator of CD103- Trm differentiation. STAT4-deficient cells trafficked to the intestine and localized to areas of infection but displayed impaired Trm differentiation with fewer CD103- Trms. Single-cell RNA-sequencing demonstrated that STAT4-deficiency led to a reduction in CD103- Trm subsets and expansion of a single population of CD103+ cells. Alterations in Trm populations were due, in part, to STAT4-mediated inhibition of transforming growth factor (TGF)-β-driven expression of Trm signature genes. STAT4-dependent Trm populations expressed genes associated with cytokine production and cell migration, and STAT4-deficient Trm cells had altered localization within the tissue and reduced effector function after reactivation in vivo. Overall, our data indicate that STAT4 leads to increased differentiation of CD103- Trms, in part by modulating the expression of TGF-β-regulated genes, and results in increased Trm heterogeneity and function within the intestinal tissue.

Novel strategies for cancer immunotherapy: counter-immunoediting therapy

The advent of immunotherapy has made an indelible mark on the field of cancer therapy, especially the application of immune checkpoint inhibitors in clinical practice. Although immunotherapy has proven its efficacy and safety in some tumors, many patients still have innate or acquired resistance to immunotherapy. The emergence of this phenomenon is closely related to the highly heterogeneous immune microenvironment formed by tumor cells after undergoing cancer immunoediting. The process of cancer immunoediting refers to the cooperative interaction between tumor cells and the immune system that involves three phases: elimination, equilibrium, and escape. During these phases, conflicting interactions between the immune system and tumor cells result in the formation of a complex immune microenvironment, which contributes to the acquisition of different levels of immunotherapy resistance in tumor cells. In this review, we summarize the characteristics of different phases of cancer immunoediting and the corresponding therapeutic tools, and we propose normalized therapeutic strategies based on immunophenotyping. The process of cancer immunoediting is retrograded through targeted interventions in different phases of cancer immunoediting, making immunotherapy in the context of precision therapy the most promising therapy to cure cancer.

Nivolumab or Atezolizumab in the Second-Line Treatment of Advanced Non-Small Cell Lung Cancer? A Prognostic Index Based on Data from Daily Practice

BACKGROUND

The efficacy of nivolumab and atezolizumab in advanced pre-treated NSCLC was documented in prospective trials. We aim to confirm the benefits and indicate predictive factors for immunotherapy in daily practice.

METHODS

This study was a retrospective analysis. The median PFS and OS were estimated using the Kaplan-Meier method. The log-rank test was used for comparisons. Multivariate analyses were performed using the Cox regression method.

RESULTS

A total of 260 patients (ECOG 0-1) with advanced NSCLC (CS III-IV) were eligible to receive nivolumab or atezolizumab as second-line treatment. Median PFS and OS were three months (95% confidence interval [CI] 2.57-3.42) and 10 months (95% CI 8.03-11.96), respectively, for the overall population. The median OS for the atezolizumab arm was eight months (95% CI 5.89-10.1), while for the nivolumab group, it was 14 months (95% CI 10.02-17.97) (p = 0.018). The sum of all measurable changes >100.5 mm (p = 0.007; HR = 1.003, 95% CI 1.001-1.005), PLT > 281.5 G/l (p < 0.001; HR = 1.003, 95% CI 1.001-1.003) and bone metastases (p < 0.004; HR = 1.58, 95% CI 1.04-2.38) were independent negative prognostic factors for OS in multivariate analysis. Based on preliminary analyses, a prognostic index was constructed to obtain three prognostic groups. Median OS in the subgroups was 16 months (95% CI 13.3-18.7), seven months (95% CI 4.83-9.17) and four months (95% CI 2.88-5.13), respectively (p < 0.001).

CONCLUSIONS

Nivolumab and atezolizumab provided clinical benefit in real life. Clinical and laboratory factors may help to identify subgroups likely to benefit. The use of prognostic indices may be valuable in clinical practice.

Yersinia enterocolitica in Crohn’s disease

Increasing attention is being paid to the unique roles gut microbes play in both physiological and pathological processes. Crohn’s disease (CD) is a chronic, relapsing, inflammatory disease of the gastrointestinal tract with unknown etiology. Currently, gastrointestinal infection has been proposed as one initiating factor of CD. Yersinia enterocolitica, a zoonotic pathogen that exists widely in nature, is one of the most common bacteria causing acute infectious gastroenteritis, which displays clinical manifestations similar to CD. However, the specific role of Y. enterocolitica in CD is controversial. In this Review, we discuss the current knowledge on how Y. enterocolitica and derived microbial compounds may link to the pathogenesis of CD. We highlight examples of Y. enterocolitica-targeted interventions in the diagnosis and treatment of CD, and provide perspectives for future basic and translational investigations on this topic.

Obesity and immune-checkpoint inhibitors in advanced melanoma: A meta-analysis of survival outcomes from clinical studies

Obesity is a chronic inflammatory condition that has been associated with different types of cancer. However, its role in melanoma incidence, progression, and response to immune-checkpoint-inhibitors (ICI) is still controversial. On the one hand, increased levels of lipids and adipokines can promote tumor proliferation and several genes associated with fatty acid metabolism have been found to be upregulated in melanomas. On the other hand, immunotherapy seems to be more effective in obese animal models, presumably due to an increase in CD8 + and subsequent decrease in PD-1 + T-cells in the tumor microenvironment. In humans, several studies have investigated the role of BMI (body mass index) and other adiposity-related parameters as potential prognostic markers of survival in advanced melanoma patients treated with ICI. The aim of this research has been to systematically review the scientific literature on studies evaluating the relationship between overweight/obesity and survival outcomes in patients with advanced melanoma treated with ICI and to perform a meta-analysis on those sharing common characteristics. After screening 1070 records identified through a literature search, 18 articles assessing the role of BMI-related exposure in relation to survival outcomes in ICI-treated patients with advanced melanoma were included in our review. In the meta-analysis of the association between overweight (defined as BMI>25 or BMI 25-30), overall survival (OS), and progression free survival (PFS), 7 studies were included, yielding a summary HR of 0.87 (95% CI: 0.74-1.03) and 0.96 (95% CI: 0.86-1.08), respectively. Our results show that, despite few suggestive findings, the use of BMI as a valuable predictor of melanoma patients' survival in terms of PFS and OS should not be currently recommended, due to the limited evidence available.

Beyond energy balance regulation: The underestimated role of adipose tissues in host defense against pathogens

Although the adipose tissue (AT) is a central metabolic organ in the regulation of whole-body energy homeostasis, it is also an important endocrine and immunological organ. As an endocrine organ, AT secretes a variety of bioactive peptides known as adipokines - some of which have inflammatory and immunoregulatory properties. As an immunological organ, AT contains a broad spectrum of innate and adaptive immune cells that have mostly been studied in the context of obesity. However, overwhelming evidence supports the notion that AT is a genuine immunological effector site, which contains all cell subsets required to induce and generate specific and effective immune responses against pathogens. Indeed, AT was reported to be an immune reservoir in the host's response to infection, and a site of parasitic, bacterial and viral infections. In addition, besides AT's immune cells, preadipocytes and adipocytes were shown to express innate immune receptors, and adipocytes were reported as antigen-presenting cells to regulate T-cell-mediated adaptive immunity. Here we review the current knowledge on the role of AT and AT's immune system in host defense against pathogens. First, we will summarize the main characteristics of AT: type, distribution, function, and extraordinary plasticity. Second, we will describe the intimate contact AT has with lymph nodes and vessels, and AT immune cell composition. Finally, we will present a comprehensive and up-to-date overview of the current research on the contribution of AT to host defense against pathogens, including the respiratory viruses influenza and SARS-CoV-2.

Regional immunity of chicken adipose tissue responds to secondary immunity induced by Newcastle disease vaccine via promoting immune activation and weakening lipid metabolism

Adipose tissue (AT) is considered as a regional immune organ and plays an important role in the anti-infection immune response. However, the function and mechanism of chicken AT in response to secondary immune response remain poorly understood. Here, we used mRNA and microRNA (miRNA) sequencing technology to survey the transcriptomic landscape of chicken abdominal adipose tissue (AAT) during the first and second immunization with Newcastle disease virus (NDV) vaccine, and carried out bioinformatics analysis, such as Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis, protein-protein interaction (PPI) analysis, and miRNA-mRNA integrated analysis. The results indicated that chicken AAT actively responded to the secondary immune response. DNA replication and cytoskeleton regulation as the regulatory functions of immune activation changed significantly, and weakened lipid metabolism was an effective strategy for the secondary immunity. Mechanically, the regulatory network between the differentially expressed miRNAs (DEMs) and their targeted differentially expressed genes (DEGs), such as miR-206/miR-499-5p-nuclear receptor subfamily 4 group A member 3 (NR4A3)/methylsterol monooxygenase 1 (MSMO1) pathway, was one of the potential key mechanisms by which AAT responded to the secondary immune response. In conclusion, regional immunity of chicken AT responds to secondary immunity by promoting immune activation and weakening lipid metabolism, and this study can instruct future research on antiviral strategy.

Infection-elicited microbiota promotes host adaptation to nutrient restriction

The microbiota performs multiple functions vital to host fitness, including defense against pathogens and adaptation to dietary changes. Yet, how environmental challenges shape microbiota resilience to nutrient fluctuation remains largely unexplored. Here, we show that transient gut infection can optimize host metabolism toward the usage of carbohydrates. Following acute infection and clearance of the pathogen, mice gained more weight as a result of white adipose tissue expansion. Concomitantly, previously infected mice exhibited enhanced carbohydrate (glucose) disposal and insulin sensitivity. This metabolic remodeling depended on alterations to the gut microbiota, with infection-elicited Betaproteobacteria being sufficient to enhance host carbohydrate metabolism. Further, infection-induced metabolic alteration protected mice against stunting in the context of limited nutrient availability. Together, these results propose that alterations to the microbiota imposed by acute infection may enhance host fitness and survival in the face of nutrient restriction, a phenomenon that may be adaptive in settings where both infection burden and food precarity are prevalent.

Coexpression of PD-L1/PD-1 with CXCR3/CD36 and IL-19 Increase in Extranodal Lymphoma

Many studies have demonstrated that PD-L1/PD-1 signaling is an immune evasion mechanism in tumors. PD-L1/PD-1 coexpression with CXCR3/CD36 in peripheral lymphocytes in lymphoma still needs to be clarified. The current study investigated PD-L1/PD-1 coexpression with CXCR3/CD36 in circulating lymphocytes, serum IL-19 levels, and their correlation with clinical outcome and extranodal involvement in lymphoma. Subjects and Methods. The coexpression of PD-L1/PD-1 with CXCR3/CD36 on circulating lymphocytes was analyzed by flow cytometry in 78 lymphoma patients before and after therapy and in 50 healthy controls. The concentration levels of IL-19 in serum were assessed by an ELISA. Results. PD-L1 and PD-1 were expressed on circulating CXCR3+ and CD36+ lymphocytes in lymphoma and were significantly higher in patients with extranodal involvement than in lymphoma patients without extranodal involvement (P < 0.001). Elevated IL-19 levels were observed in lymphoma patients and increased significantly in extranodal involvement (P < 0.001). High percentages of PD-L1+CXCR3+ and PD-1+CXCR3+ lymphocytes were associated with high LDH levels, hepatomegaly, lymphedema, advanced tumor stage, and recurrence. Furthermore, patients with splenomegaly and generalized lymphadenopathy had high percentages of PD-L1+CXCR3+ lymphocytes. In addition, levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 were significantly associated with bone marrow, lung, and lymph vessel involvement. Further analysis revealed that high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes were associated with lung and bone marrow involvement. Patients with high levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 had inferior event-free survival (EFS) compared with that in lymphoma patients with low levels. EFS was decreased in patients with high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes. When using the receiver operating characteristic (ROC) curve, the superiority of IL-19 (area under the curve (AUC): 0.993) and PD-L1+CXCR3+% (AUC: 0.961) to PD-1+CXCR3+% (AUC: 0.805), PD-L1+CD36+% (AUC: 0.694), and PD-1+CD36+% (AUC 0.769) was evident in the diagnosis of extranodal involvement, identifying lymphoma patients with extranodal involvement from patients without extranodal involvement. Conclusions. Coexpression of PD-L1/PD-1 with CXCR3/CD36 in circulating lymphocytes and serum IL-19 levels contributes to poor prognosis and might be potential markers for extranodal involvement in lymphoma.

The role of Th17 cells in endocrine organs: Involvement of the gut, adipose tissue, liver and bone

T Helper 17 (Th17) cells are adaptive immune cells that play myriad roles in the body. Immune-endocrine interactions are vital in endocrine organs during pathological states. Th17 cells are known to take part in multiple autoimmune diseases over the years. Current evidence has moved from minimal to substantial that Th17 cells are closely related to endocrine organs. Diverse tissue Th17 cells have been discovered within endocrine organs, including gut, adipose tissue, liver and bone, and these cells are modulated by various secretions from endocrine organs. Th17 cells in these endocrine organs are key players in the process of an array of metabolic disorders and inflammatory conditions, including obesity, insulin resistance, nonalcoholic fatty liver disease (NAFLD), primary sclerosing cholangitis (PSC), osteoporosis and inflammatory bowel disease (IBD). We reviewed the pathogenetic or protective functions played by Th17 cells in various endocrine tissues and identified potential regulators for plasticity of it. Furthermore, we discussed the roles of Th17 cells in crosstalk of gut-organs axis.

Drastic transformation of visceral adipose tissue and peripheral CD4 T cells in obesity

Obesity has a pronounced effect on the immune response in systemic organs that results in not only insulin resistance but also altered immune responses to infectious diseases and malignant tumors. Obesity-associated microenvironmental changes alter transcriptional expression and metabolism in T cells, leading to alterations in T-cell differentiation, proliferation, function, and survival. Adipokines, cytokines, and lipids derived from obese visceral adipose tissue (VAT) may also contribute to the systemic T-cell phenotype, resulting in obesity-specific pathogenesis. VAT T cells, which have multiple roles in regulating homeostasis and energy utilization and defending against pathogens, are most susceptible to obesity. In particular, many studies have shown that CD4 T cells are deeply involved in the homeostasis of VAT endocrine and metabolic functions and in obesity-related chronic inflammation. In obesity, macrophages and adipocytes in VAT function as antigen-presenting cells and contribute to the obesity-specific CD4 T-cell response by inducing CD4 T-cell proliferation and differentiation into inflammatory effectors via interactions between major histocompatibility complex class II and T-cell receptors. When obesity persists, prolonged stimulation by leptin and circulating free fatty acids, repetitive antigen stimulation, activating stress responses, and hypoxia induce exhaustion of CD4 T cells in VAT. T-cell exhaustion is characterized by restricted effector function, persistent expression of inhibitory receptors, and a transcriptional state distinct from functional effector and memory T cells. Moreover, obesity causes thymic regression, which may result in homeostatic proliferation of obesity-specific T-cell subsets due to changes in T-cell metabolism and gene expression in VAT. In addition to causing T-cell exhaustion, obesity also accelerates cellular senescence of CD4 T cells. Senescent CD4 T cells secrete osteopontin, which causes further VAT inflammation. The obesity-associated transformation of CD4 T cells remains a negative legacy even after weight loss, causing treatment resistance of obesity-related conditions. This review discusses the marked transformation of CD4 T cells in VAT and systemic organs as a consequence of obesity-related microenvironmental changes.

Immune-related adverse events correlate with the efficacy of PD-1 inhibitors combination therapy in advanced cholangiocarcinoma patients: A retrospective cohort study

Background

Whether irAEs can predict the efficacy of PD-1 inhibitors in cholangiocarcinoma (CCA) has not been assessed. Therefore, this study aims to investigate the correlation between irAEs and the therapeutic effect of PD-1 inhibitors combination therapy in patients with advanced CCA.

Methods

All patients with CCA who were consecutively admitted to the inpatient unit of our hospital and received PD-1 inhibitors combination therapy between September 2020 and April 2022 were screened. In total, 106 patients with CCA were screened out. We then followed up these patients until October 2022. Due to perioperative use (n=28), less than 2 cycles of PD-1 inhibitor therapy (n=9), incomplete data (n=8) and no pathological report (n=2), 59 patients were included in the final analysis. The patients were divided into the irAEs cohort and the non-irAEs cohort according to whether they experienced irAEs or not. The Log-Rank test was performed to compare the difference in survival time between these two cohorts. We then applied multivariate COX regression analysis to investigate whether irAEs were independent prognostic factors for survival in patients with advanced CCA.

Results

Finally, 32 patients were included in the irAEs cohort and 27 patients in the non-irAEs cohort. A total of 32 patients (54.2%) had any-grade irAEs, of which 4 patients (6.8%) had grade 3-4 irAEs. The most common irAEs were thyroid toxicity (30.5%) and dermatologic toxicity (30.5%). There were no notable differences in demographics and clinical characteristics between the irAEs and non-irAEs cohorts, except for total bilirubin level (P=0.026) and relapse (P=0.016). The disease control rate (DCR) in the irAEs cohort was higher than in the non-irAEs cohort (90.6% vs 70.4%, P=0.047). Median overall survival (OS) and median progression-free survival (PFS) were better in the irAEs cohort than in the non-irAEs cohort (OS: 21.2 vs 10.0 months, P<0.001; PFS: 9.0 vs 4.4 months, P=0.003). Multivariate COX regression analysis showed that irAEs were independent prognostic factors for OS and PFS (OS: HR=0.133, 95% CI: 0.039-0.452, P=0.001; PFS: HR=0.435, 95% CI: 0.202-0.934, P=0.033).

Conclusion

IrAEs correlated with improved DCR, OS, and PFS in advanced CCA patients receiving PD-1 inhibitors combination therapy.

Heimao tea polysaccharides ameliorate obesity by enhancing gut microbiota-dependent adipocytes thermogenesis in mice fed with high fat diet

Heimao tea (HMT) is a kind of fermented dark tea that has various health benefits. However, the available information regarding the anti-obesity effect of HMT and its active ingredients is still limited. Herein, we extracted the polysaccharides from Heimao tea (HMTP) and evaluated the anti-obesity effect and the underlying mechanism of HMTP. 12-Week administration of HMTP ameliorated lipid accumulation in the adipose tissue and improved glucolipid metabolism in high-fat diet (HFD)-fed mice. HMTP also induced browning of inguinal white adipose tissue (iWAT) and enhanced the thermogenic activity of interscapular brown adipose tissue (iBAT) by upregulating the expression of a series of thermogenic genes, such as Ucp1, Prdm16, and Pgc1α. Interestingly, the anti-obesity effect of HMTP was closely associated with altered relative abundance of the gut microbes, especially Dubosiella and Romboutsia, with significant increases, in which the abundance of Dubosiella and Romboutsia was negatively correlated with the body weight (r = -0.567, p < 0.05; r = -0.407, p < 0.05) and positively correlated with the iBAT index (r = 0.520, p < 0.05; r = 0.315, p < 0.05). Our data suggest that the alteration of the gut microbiota may play a critical role in HMTP-induced iWAT browning and iBAT activation, and our findings may provide a promising way for preventing obesity.

Neuroimmune regulation of white adipose tissues

The white adipose tissues (WAT) are located in distinct depots throughout the body. They serve as an energy reserve, providing fatty acids for other tissues via lipolysis when needed, and function as an endocrine organ to regulate systemic metabolism. Their activities are coordinated through intercellular communications among adipocytes and other cell types such as residential and infiltrating immune cells, which are collectively under neuronal control. The adipocytes and immune subtypes including macrophages/monocytes, eosinophils, neutrophils, group 2 innate lymphoid cells (ILC2s), T and B cells, dendritic cells (DCs), and natural killer (NK) cells display cellular and functional diversity in response to the energy states and contribute to metabolic homeostasis and pathological conditions. Accumulating evidence reveals that neuronal innervations control lipid deposition and mobilization via regulating lipolysis, adipocyte size, and cellularity. Vice versa, the neuronal innervations and activity are influenced by cellular factors in the WAT. Though the literature describing adipose tissue cells is too extensive to cover in detail, we strive to highlight a selected list of neuronal and immune components in this review. The cell-to-cell communications and the perspective of neuroimmune regulation are emphasized to enlighten the potential therapeutic opportunities for treating metabolic disorders.

MPYS Modulates Fatty Acid Metabolism and Immune Tolerance at Homeostasis Independent of Type I IFNs

MPYS/STING (stimulator of IFN genes) senses cyclic dinucleotides (CDNs), generates type I IFNs, and plays a critical role in infection, inflammation, and cancer. In this study, analyzing genotype and haplotype data from the 1000 Genomes Project, we found that the R71H-G230A-R293Q (HAQ) MPYS allele frequency increased 57-fold in East Asians compared with sub-Saharan Africans. Meanwhile, the G230A-R293Q (AQ) allele frequency decreased by 98% in East Asians compared with sub-Saharan Africans. We propose that the HAQ and AQ alleles underwent a natural selection during the out-of-Africa migration. We used mouse models of HAQ and AQ to investigate the underlying mechanism. We found that the mice carrying the AQ allele, which disappeared in East Asians, had normal CDN-type I IFN responses. Adult AQ mice, however, had less fat mass than did HAQ or wild-type mice on a chow diet. AQ epididymal adipose tissue had increased regulatory T cells and M2 macrophages with protein expression associated with enhanced fatty acid oxidation. Conditional knockout mice and adoptive cell transfer indicate a macrophage and regulatory T cell-intrinsic role of MPYS in fatty acid metabolism. Mechanistically, AQ/IFNAR1-/- mice had a similar lean phenotype as for the AQ mice. MPYS intrinsic tryptophan fluorescence revealed that the R71H change increased MPYS hydrophilicity. Lastly, we found that the second transmembrane (TM) and the TM2-TM3 linker region of MPYS interact with activated fatty acid, fatty acyl-CoA. In summary, studying the evolution of the human MPYS gene revealed an MPYS function in modulating fatty acid metabolism that may be critical during the out-of-Africa migration.

Keeping T cell memories in mind

The mammalian central nervous system (CNS) contains a vibrant community of resident adaptive immune cells at homeostasis. Among these are memory CD8+ and CD4+ T cells, which reside in the CNS in the settings of health, aging, and neurological disease. These T cells commonly exhibit a tissue-resident memory (TRM) phenotype, suggesting that they are antigen-experienced and remain separate from the circulation. Despite these characterizations, T cell surveillance of the CNS has only recently been studied through the lens of TRM immunology. In this Review, we outline emerging concepts of CNS TRM generation, localization, maintenance, function, and specificity. In this way, we hope to highlight roles of CNS TRM in health and disease to inform future studies of adaptive neuroimmunity.

CD103 fate mapping reveals that intestinal CD103- tissue-resident memory T cells are the primary responders to secondary infection

Tissue-resident memory T (T_RM) cells remain poised in the tissue and mediate robust protection from secondary infection. T_RM cells within the intestine and other tissues are heterogeneous in their phenotype and function; however, the contributions of these T_RM subsets to secondary infection remain poorly defined. To address the plasticity of intestinal T_RM subsets and their role in local and systemic immunity, we generated mice to fate map intestinal CD103⁺ T_RM cells and track their location and function during secondary infection with Yersinia pseudotuberculosis. We found that CD103⁺ T_RM cells remained lodged in the tissue and were poorly reactivated during secondary challenge. CD103^- T_RM cells were the primary responders to secondary infection and expanded within the tissue, with limited contribution from circulating memory T cells. The transcriptional profile of CD103^- T_RM cells demonstrated maintenance of a gene signature similar to circulating T cells along with increased cytokine production and migratory potential. CD103^- T_RM cells also expressed genes associated with T cell receptor (TCR) activation and displayed enhanced TCR-mediated reactivation both in vitro and in vivo compared with their CD103⁺ counterparts. These studies reveal the limited recall potential of CD103⁺ T_RM subsets and the role of CD103^- T_RM cells as central memory-like T cells within peripheral tissues.

Regulatory T cells as metabolic sensors

Compelling experimental evidence links immunity and metabolism. In this perspective, we propose forkhead-box-P3 (FoxP3)⁺CD4⁺CD25⁺ regulatory T (Treg) cells as key metabolic sensors controlling the immunological state in response to their intrinsic capacity to perceive nutritional changes. Treg cell high anabolic state in vivo, residency in metabolically crucial districts, and recirculation between lymphoid and non-lymphoid sites enable them to recognize the metabolic cues and adapt their intracellular metabolism and anti-inflammatory function at the paracrine and systemic levels. As privileged regulators at the interface between neuroendocrine and immune systems, the role of Treg cells in maintaining metabolic homeostasis makes these cells promising targets of therapeutic strategies aimed at restoring organismal homeostasis not only in autoimmune but also metabolic disorders.

Resident TH2 cells orchestrate adipose tissue remodeling at a site adjacent to infection

Type 2 immunity is associated with adipose tissue (AT) homeostasis and infection with parasitic helminths, but whether AT participates in immunity to these parasites is unknown. We found that the fat content of mesenteric AT (mAT) declined in mice during infection with a gut-restricted helminth. This was associated with the accumulation of metabolically activated, interleukin-33 (IL-33), thymic stromal lymphopoietin (TSLP), and extracellular matrix (ECM)-producing stromal cells. These cells shared transcriptional features, including the expression of Dpp4 and Pi16, with multipotent progenitor cells (MPC) that have been identified in numerous tissues and are reported to be capable of differentiating into fibroblasts and adipocytes. Concomitantly, mAT became infiltrated with resident T helper 2 (T_H2) cells that responded to TSLP and IL-33 by producing stromal cell-stimulating cytokines, including transforming growth factor β1 (TGFβ₁) and amphiregulin. These T_H2 cells expressed genes previously associated with type 2 innate lymphoid cells (ILC2), including Nmur1, Calca, Klrg1, and Arg1, and persisted in mAT for at least 11 months after anthelmintic drug-mediated clearance of infection. We found that MPC and T_H2 cells localized to ECM-rich interstitial spaces that appeared shared between mesenteric lymph node, mAT, and intestine. Stromal cell expression of epidermal growth factor receptor (EGFR), the receptor for amphiregulin, was required for immunity to infection. Our findings point to the importance of MPC and T_H2 cell interactions within the interstitium in orchestrating AT remodeling and immunity to an intestinal infection.

The multifunctional nature of CD103 (αEβ7 integrin) signaling in tissue-resident lymphocytes

Intestinal tissue-resident lymphocytes are critical for maintenance of the mucosal barrier and to prevent enteric infections. The activation of these lymphocytes must be tightly regulated to prevent aberrant inflammation and epithelial damage observed in autoimmune diseases, yet also ensure that antimicrobial host defense remains uncompromised. Tissue-resident lymphocytes express CD103, or αE integrin, which dimerizes with the β7 subunit to bind to E-cadherin expressed on epithelial cells. Although the role of CD103 in homing and retention of lymphocytes to and within peripheral tissues has been well characterized, the molecular signals activated following CD103 engagement remain understudied. Here, we highlight recent studies that elucidate the functional contribution of CD103 in various lymphocyte subpopulations, either as an independent signaling molecule or in the context of TCR co-stimulation. Finally, we will discuss the gaps in our understanding of CD103 biology and the therapeutic potential of targeting CD103 on tissue-resident lymphocytes.

cDC1 coordinate innate and adaptive responses in the omentum required for T cell priming and memory

In the peritoneal cavity, the omentum contains fat-associated lymphoid clusters (FALCs) whose role in response to infection is poorly understood. After intraperitoneal immunization with Toxoplasma gondii, conventional type 1 dendritic cells (cDC1s) were critical to induce innate sources of IFN-γ and cellular changes in the FALCs. Unexpectedly, infected peritoneal macrophages that migrated into the FALCs primed CD8+ T cells. Although T cell priming was cDC1 independent, these DCs were required for maximal CD8+ T cell expansion. An agent-based computational model and experimental data highlighted that cDC1s affected the magnitude of the proliferative burst and promoted CD8+ T cell expression of nutrient uptake receptors and cell survival. Thus, although FALCs lack the organization of secondary lymphoid organs, cDC1s resident in this tissue coordinate innate responses to microbial challenge and provide secondary signals required for T cell expansion and memory formation.

A novel fatty acid metabolism-related gene signature predicts the prognosis, tumor immune properties, and immunotherapy response of colon adenocarcinoma patients

Colon adenocarcinoma (COAD) has a high incidence and death rate. Despite the fact that change in fatty acid metabolism promotes tumor growth and metastasis to the greatest degree among metabolite profiles, a thorough investigation on the involvement of fatty acid metabolism-related genes (FAMRGs) in COAD has yet not been conducted. Here, the clinical data as well as the gene expression profiles were extracted from The Cancer Genome Atlas (TCGA) database. Based on the FAMRG expression data and clinical information, a FAMRG risk signature was developed using LASSO as well as multivariate and univariate Cox regression analyses. Then, the nomogram was used to create a customized prognostic prediction model, and the calibration and receiver operating characteristic curves were used to evaluate the nomogram's prediction performance and discriminative capability. Lastly, a number of studies were conducted to assess the influence of independent FAMRGs on COAD, including unsupervised cluster analysis, functional analysis, and drug sensitivity analysis. Three hundred and sixty-seven patients were included in this study, and a 12-FAMRG risk signature was discovered in the training cohort based on a detailed examination of the FAMRGs expression data and clinical information. After that, risk scores were computed to classify patients into low or high-risk groups, and the Kaplan-Meier curve analysis revealed that patients in the low-risk group exhibited an elevated overall survival (OS) rate. The FAMRG was shown to be substantially correlated with prognosis in multivariate Cox regression analysis and was validated using the validation dataset. Then, using the clinical variables and risk signature, we developed and validated a prediction nomogram for OS. Functional characterization showed a strong correlation between this signature and immune cell infiltration and immune modulation. Additionally, by evaluating the GDSC database, it was determined that the high-risk group exhibited medication resistance to many chemotherapeutic and targeted medicines, including VX.680, gemcitabine, doxorubicin, and paclitaxel. Overall, we have revealed the significance of a FAMRG risk signature for predicting the prognosis and response to immunotherapy in COAD, and our findings might contribute to an enhanced comprehension of metabolic pathways and the future development of innovative COAD therapeutic methods.

Importance of the Microenvironment and Mechanosensing in Adipose Tissue Biology

The expansion of adipose tissue is an adaptive mechanism that increases nutrient buffering capacity in response to an overall positive energy balance. Over the course of expansion, the adipose microenvironment undergoes continual remodeling to maintain its structural and functional integrity. However, in the long run, adipose tissue remodeling, typically characterized by adipocyte hypertrophy, immune cells infiltration, fibrosis and changes in vascular architecture, generates mechanical stress on adipose cells. This mechanical stimulus is then transduced into a biochemical signal that alters adipose function through mechanotransduction. In this review, we describe the physical changes occurring during adipose tissue remodeling, and how they regulate adipose cell physiology and promote obesity-associated dysfunction in adipose tissue.

Mechanisms of Post-critical Illness Cardiovascular Disease

Prolonged critical care stays commonly follow trauma, severe burn injury, sepsis, ARDS, and complications of major surgery. Although patients leave critical care following homeostatic recovery, significant additional diseases affect these patients during and beyond the convalescent phase. New cardiovascular and renal disease is commonly seen and roughly one third of all deaths in the year following discharge from critical care may come from this cluster of diseases. During prolonged critical care stays, the immunometabolic, inflammatory and neurohumoral response to severe illness in conjunction with resuscitative treatments primes the immune system and parenchymal tissues to develop a long-lived pro-inflammatory and immunosenescent state. This state is perpetuated by persistent Toll-like receptor signaling, free radical mediated isolevuglandin protein adduct formation and presentation by antigen presenting cells, abnormal circulating HDL and LDL isoforms, redox and metabolite mediated epigenetic reprogramming of the innate immune arm (trained immunity), and the development of immunosenescence through T-cell exhaustion/anergy through epigenetic modification of the T-cell genome. Under this state, tissue remodeling in the vascular, cardiac, and renal parenchymal beds occurs through the activation of pro-fibrotic cellular signaling pathways, causing vascular dysfunction and atherosclerosis, adverse cardiac remodeling and dysfunction, and proteinuria and accelerated chronic kidney disease.

CD4+ T cell metabolism, gut microbiota, and autoimmune diseases: Implication in precision medicine of autoimmune diseases

CD4⁺ T cells are critical to the development of autoimmune disorders. Glucose, fatty acids, and glutamine metabolisms are the primary metabolic pathways in immune cells, including CD4⁺ T cells. The distinct metabolic programs in CD4⁺ T cell subsets are recognized to reflect the bioenergetic requirements, which are compatible with their functional demands. Gut microbiota affects T cell responses by providing a series of antigens and metabolites. Accumulating data indicate that CD4⁺ T cell metabolic pathways underlie aberrant T cell functions, thereby regulating the pathogenesis of autoimmune disorders, including inflammatory bowel diseases, systemic lupus erythematosus, and rheumatoid arthritis. Here, we summarize the current progress of CD4⁺ T cell metabolic programs, gut microbiota regulation of T cell metabolism, and T cell metabolic adaptions to autoimmune disorders to shed light on potential metabolic therapeutics for autoimmune diseases.

Tissue-resident memory CD8+ T cells possess unique transcriptional, epigenetic and functional adaptations to different tissue environments

Tissue-resident memory T cells (T_RM cells) provide protective immunity, but the contributions of specific tissue environments to T_RM cell differentiation and homeostasis are not well understood. In the present study, the diversity of gene expression and genome accessibility by mouse CD8⁺ T_RM cells from distinct organs that responded to viral infection revealed both shared and tissue-specific transcriptional and epigenetic signatures. T_RM cells in the intestine and salivary glands expressed transforming growth factor (TGF)-β-induced genes and were maintained by ongoing TGF-β signaling, whereas those in the fat, kidney and liver were not. Constructing transcriptional-regulatory networks identified the transcriptional repressor Hic1 as a critical regulator of T_RM cell differentiation in the small intestine and showed that Hic1 overexpression enhanced T_RM cell differentiation and protection from infection. Provision of a framework for understanding how CD8⁺ T_RM cells adapt to distinct tissue environments, and identification of tissue-specific transcriptional regulators mediating these adaptations, inform strategies to boost protective memory responses at sites most vulnerable to infection.

Detection of SARS-CoV-2 in subcutaneous fat but not visceral fat, and the disruption of fat lymphocyte homeostasis in both fat tissues in the macaque

The well documented association between obesity and the severity of SARS-CoV-2 infection raises the question of whether adipose tissue (AT) is impacted during this infection. Using a model of SARS-CoV-2 infection in cynomolgus macaques, we detected the virus within subcutaneous AT (SCAT) but not in visceral AT (VAT) or epicardial AT on day 7 post-infection. We sought to determine the mechanisms responsible for this selective detection and observed higher levels of angiotensin-converting-enzyme-2 mRNA expression in SCAT than in VAT. Lastly, we evaluated the immunological consequences of SARS-CoV-2 infection on AT: both SCAT and VAT T cells showed a drastic reduction in CD69 expression, a standard marker of resident memory T cell in tissue, that is also involved in the migratory and metabolic properties of T cells. Our results demonstrate that in a model of mild infection, SCAT is selectively infected by SARS-CoV-2 although changes in the immune properties of AT are observed in both SCAT and VAT.

Subcutaneous fat tissue expresses higher angiotensin-converting-enzyme 2 mRNA than visceral fat tissue and is selectively infected by SARS-Cov-2, while both fat tissues show drastic reduction in CD69 expression in T cells.

Immune and non-immune functions of adipose tissue leukocytes

Adipose tissue is a complex dynamic organ with whole-body immunometabolic influence. Much of the work into understanding the role of immune cells in adipose tissue has been in the context of obesity. These investigations have also uncovered a range of typical (immune) and non-typical functions exerted by adipose tissue leukocytes. Here we provide an overview of the adipose tissue immune system, including its role as an immune reservoir in the whole-body response to infection and as a site of parasitic and viral infections. We also describe the functional roles of specialized immunological structures found within adipose tissue. However, our main focus is on the recently discovered 'non-immune' functions of adipose tissue immune cells, which include the regulation of adipocyte homeostasis, as well as responses to changing nutrient status and body temperature. In doing so, we outline the therapeutic potential of the adipose tissue immune system in health and disease.

Autologous Human Immunocompetent White Adipose Tissue-on-Chip

Obesity and associated diseases, such as diabetes, have reached epidemic proportions globally. In this era of "diabesity", white adipose tissue (WAT) has become a target of high interest for therapeutic strategies. To gain insights into mechanisms of adipose (patho-)physiology, researchers traditionally relied on animal models. Leveraging Organ-on-Chip technology, a microphysiological in vitro model of human WAT is introduced: a tailored microfluidic platform featuring vasculature-like perfusion that integrates 3D tissues comprising all major WAT-associated cellular components (mature adipocytes, organotypic endothelial barriers, stromovascular cells including adipose tissue macrophages) in an autologous manner and recapitulates pivotal WAT functions, such as energy storage and mobilization as well as endocrine and immunomodulatory activities. A precisely controllable bottom-up approach enables the generation of a multitude of replicates per donor circumventing inter-donor variability issues and paving the way for personalized medicine. Moreover, it allows to adjust the model's degree of complexity via a flexible mix-and-match approach. This WAT-on-Chip system constitutes the first human-based, autologous, and immunocompetent in vitro adipose tissue model that recapitulates almost full tissue heterogeneity and can become a powerful tool for human-relevant research in the field of metabolism and its associated diseases as well as for compound testing and personalized- and precision medicine applications.

The Gut Microbiota Metabolite Succinate Promotes Adipose Tissue Browning in Crohn's Disease

BACKGROUND AND AIMS

Crohn's disease [CD] is associated with complex microbe-host interactions, involving changes in microbial communities, and gut barrier defects, leading to the translocation of microorganisms to surrounding adipose tissue [AT]. We evaluated the presence of beige AT depots in CD and questioned whether succinate and/or bacterial translocation promotes white-to-beige transition in adipocytes.

METHODS

Visceral [VAT] and subcutaneous [SAT] AT biopsies, serum and plasma were obtained from patients with active [n = 21] or inactive [n = 12] CD, and from healthy controls [n = 15]. Adipose-derived stem cells [ASCs] and AT macrophages [ATMs] were isolated from VAT biopsies.

RESULTS

Plasma succinate levels were significantly higher in patients with active CD than in controls and were intermediate in those with inactive disease. Plasma succinate correlated with the inflammatory marker high-sensitivity C-reactive protein. Expression of the succinate receptor SUCNR1 was higher in VAT, ASCs and ATMs from the active CD group than from the inactive or control groups. Succinate treatment of ASCs elevated the expression of several beige AT markers from controls and from patients with inactive disease, including uncoupling protein-1 [UCP1]. Notably, beige AT markers were prominent in ASCs from patients with active CD. Secretome profiling revealed that ASCs from patients with active disease secrete beige AT-related proteins, and co-culture assays showed that bacteria also trigger the white-to-beige switch of ASCs from patients with CD. Finally, AT depots from patients with CD exhibited a conversion from white to beige AT together with high UCP1 expression, which was corroborated by in situ thermal imaging analysis.

CONCLUSIONS

Succinate and bacteria trigger white-to-beige AT transition in CD. Understanding the role of beige AT in CD might aid in the development of therapeutic or diagnostic interventions.