The potential of CD4 T-cell memory

CD4+TEM cells drive the progression from acute myocarditis to dilated cardiomyopathy in CVB3-induced BALB/c mice

Acute viral myocarditis can progress to chronic myocarditis leading to dilated cardiomyopathy (DCM). Persistent CD4+ T-cell-mediated autoimmunity triggered by infection plays a critical role in this progression. Increasing evidence demonstrates that effector memory CD4+T (CD4+TEM) cells, a subset of memory CD4+ T cells, are crucial pathogenic mediators of many autoimmune diseases. However, the role of CD4+TEM cells during the progression from acute viral myocarditis to DCM remains unknown. In this study, we observed an increase in CD4+TEM cells both in the periphery and the heart, and memory CD4+ T cells were the predominant sources of IL-17A and IFN-γ among inflamed heart-infiltrating CD4+ T cells during the progression from acute myocarditis to chronic myocarditis and DCM in CVB3-induced BALB/c mice. Moreover, splenic CD4+TEM cells sorted from DCM mice induced by CVB3 were found to respond to cardiac self-antigens ex vivo. Additionally, adoptive transfer experiments substantiated their pathogenic impact, inducing sustained myocardial inflammation, tissue fibrosis, cardiac injury, and impairment of cardiac systolic function in vivo. Our findings illustrate that long-lived CD4+TEM cells are important contributors to the progression from acute viral myocarditis into DCM.

Human endogenous retroviruses of the HERV-K (HML-2) family are expressed in the brain of healthy individuals and modify the composition of the brain-infiltrating immune cells

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections in the human genome. RNA expression of individual HERVs has frequently been observed in various pathologic conditions, but some activity can also be seen in healthy individuals, e.g. in the blood. To quantitate the basal expression levels of HERVs in the brain, we now used high-throughput sequencing-based metagenomic analysis to characterize the expression profiles of the HERV-K (HML-2) family proviruses in different brain regions of healthy brain tissue. To this end, RNA-seq data from the Genotype-Tissue Expression (GTEx) project was used. The GTEx project is a public resource to study tissue-specific gene expression and regulation, consisting of a large selection of sequenced samples from different tissues. The GTEx data used in this study consisted of 378 samples taken from 13 brain regions from 55 individuals. The data demonstrated that out of 99 intact proviruses in the family 58 were expressed, but the expression profiles were highly divergent and there were no significant differences in the expression profiles between the various anatomic regions of the brain. It is known that the brain contains a variety of infiltrating immune cells, which are probably of great importance both in the normal defense mechanisms as well as in the various pathogenic processes. Digital cytometry (CIBERSORTx) was used to quantify the proportions of the infiltrating immune cells in the same brain samples. Six most abundant (>5 % of the total population) cell types were observed to be CD4 memory resting T cells, M0 macrophages, plasma cells, CD8 T cells, CD4 memory activated T cells, and monocytes. Analysis of the correlations between the individual HERVs and infiltrating cell types indicated that a cluster of 6 HERVs had a notable correlation signature between T cell type infiltrating cell proportions and HERV RNA expression intensity. The correlations between inflammatory type infiltrating cells were negative or weak. Taken together, these data indicate that the expression of HERVs is associated with a T cell type immunity.

Immune-Related Genes can Serve as Potential Biomarkers for Predicting Severe Acute Pancreatitis

We aimed to investigate immune-related candidate genes for predicting the severity of acute pancreatitis (AP). RNA sequencing profile GSE194331 was downloaded, and differentially expressed genes (DEGs) were investigated. Meanwhile, the infiltration of immune cells in AP were assessed using CIBERSORT. Genes related with the infiltration of immune cells were investigated using weighted gene co-expression network analysis (WGCNA). Furthermore, immune subtypes, micro-environment, and DEGs between immune subtypes were explored. Immune-related genes, protein-protein interaction (PPI) network, and functional enrichment analysis were further performed. Overall, 2533 DEGs between AP and healthy controls were obtained. After trend cluster analysis, 411 upregulated and 604 downregulated genes were identified. Genes involved in two modules were significantly positively related to neutrophils and negatively associated with T cells CD4 memory resting, with correlation coefficient more than 0.7. Then, 39 common immune-related genes were obtained, and 56 GO BP were enriched these genes, including inflammatory response, immune response, and innate immune response; 10 KEGG pathways were enriched, including cytokine-cytokine receptor interaction, Th1 and Th2 cell differentiation, and IL-17 signaling pathway. Genes, including S100A12, MMP9, IL18, S100A8, HCK, S100A9, RETN, OSM, FGR, CAMP, were selected as genes with top 10 degree in PPI, and the expression levels of these genes increased gradually in subjects of healthy, mild, moderately severe, and severe AP. Our findings indicate a central role of immune-related genes in predicting the severity of AP, and the hub genes involved in PPI represent logical candidates for further study.

Novel approaches to preventing phagosomal infections: timing is key

Prophylactic vaccination strategies designed to prevent diseases caused by pathogens using the phagolysosome of innate immune cells as a site of intracellular replication and survival have been largely ineffective. These include Mycobacterium tuberculosis (Mtb), Leishmania spp., and Cryptococcus spp. These failed strategies have traditionally targeted CD4⁺ T helper (Th) 1 cell-mediated immune memory, deeming it crucial for vaccine efficacy. This failure warrants an investigation of alternative mediators of protection. Here, we suggest three novel approaches to activate phagocytic cells prior to or at the time of infection. We hypothesize that preventing the formation of the pathogen niche within the phagolysosome is essential for preventing disease, and a greater emphasis on the timing of phagocyte activation should generate more effective prophylactic treatment options.

Cuproptosis-Related MiR-21-5p/FDX1 Axis in Clear Cell Renal Cell Carcinoma and Its Potential Impact on Tumor Microenvironment

As a newly identified type of programmed cell death, cuproptosis may have an impact on cancer development, including clear cell renal cell carcinoma (ccRCC). Herein, we first noticed that the expression levels of cuproptosis regulators exhibited a tight correlation with the clinicopathological characteristics of ccRCC. The cuproptosis-sensitive sub-type (CSS), classified via consensus clustering analysis, harbored a higher overall survival rate compared to the cuproptosis-resistant sub-type (CRS), which may have resulted from the differential infiltration of immune cells. FDX1, the cuproptosis master regulator, was experimentally determined as a tumor suppressor in ccRCC cells by suppressing the cell growth and cell invasion of ACHN and OSRC-2 cells in a cuproptosis-dependent and -independent manner. The results from IHC staining also demonstrated that FDX1 expression was negatively correlated with ccRCC tumor initiation and progression. Furthermore, we identified the miR-21-5p/FDX1 axis in ccRCC and experimentally verified that miR-21-5p directly binds the 3'-UTR of FDX1 to mediate its degradation. Consequently, a miR-21-5p inhibitor suppressed the cell growth and cell invasion of ACHN and OSRC-2 cells, which could be compensated by FDX1 knockdown, reinforcing the functional linkage between miR-21-5p and FDX1 in ccRCC. Finally, we evaluated the ccRCC tumor microenvironment under the miR-21-5p/FDX1 axis and noted that this axis was strongly associated with the infiltration of immune cells such as CD4⁺ T cells, Treg cells, and macrophages, suggesting that this signaling axis may alter microenvironmental components to drive ccRCC progression. Overall, this study constructed the miR-21-5p/FDX1 axis in ccRCC and analyzed its potential impact on the tumor microenvironment, providing valuable insights to improve current ccRCC management.

Identification of TRP-Related Subtypes, Development of a Prognostic Model, and Characterization of Tumor Microenvironment Infiltration in Lung Adenocarcinoma

The TRP (transient receptor potential) superfamily, as cation channels, is a critical chemosensor for potentially harmful irritants. Their activation is closely related not only to tumor progression and prognosis but also to tumor therapy response. Nevertheless, the TRP-related immune gene (TRIG) expression of the tumor microenvironment (TME) and the associations with prognosis remain unclear. First, we represented the transcriptional and genetic variations in TRIGs in 535 lung adenocarcinoma (LUAD) samples as well as their expression patterns. LUAD samples were divided into two distinct subtypes based on the TRIG variations. Significant differences had been found in prognosis, clinical features, and TME cell-infiltration features between the two subtypes of patients. Second, we framed a TRIG score for predicting overall survival (OS) and validated the predictive capability of the TRIG score in LUAD patients. Accordingly, to enhance the clinical applicability of TRIG score, we developed a considerable nomogram. A low TRIG score, characterized by increased immunity activation, indicated favorable advantages of OS compared with a high TRIG score. Furthermore, the TRIG score was found to have a significant connection with the TME cell-infiltration and immune checkpoint expressions. Our analysis of TRIGs in LUAD showed their potential roles in prognosis, clinical features, and tumor-immune microenvironments. These results may advance our knowledge of TRP genes in LUAD and show a new light on prognosis estimation and the improvement of immunotherapy strategies.

Computational Analysis Reveals the Characteristics of Immune Cells in Glomerular and Tubulointerstitial Compartments in IgA Nephropathy Patients

Objective: The commonalities and differences regarding immune states between glomerular and tubulointerstitial compartments of IgA nephropathy (IgAN) remains largely undetermined. We aim to perform bioinformatic analysis for providing a comprehensive insight into the characteristics of immune cells and associated molecular mechanisms in IgAN.

Materials and Methods: We performed integrated bioinformatic analyses by using IgAN-related datasets from the Gene Expression Omnibus database. First, the differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Then, CIBERSORT was employed to determine the landscape of infiltrating immune cells in both glomerular and tubulointerstitial compartments of IgAN patients, followed by Pearson’s correlation analysis and principal component analysis (PCA). Finally, commonly shared DEGs between glomerular and tubulointerstitial entities were recognized, followed by correlation analyses to identify the dominant commonly shared DEGs associated with immune cell infiltration in IgAN.

Results: GO and KEGG enrichment analyses showed apparently distinct biological processes in the glomerular and tubulointerstitial compartments of IgAN. In addition, CIBERSORT analyses revealed a clear trend of increasing proportions of M1 macrophage and M2 macrophage in the glomerular compartment while noticeably higher proportions of resting CD4⁺ memory T cells and M2 macrophages in the tubulointerstitial compartments. The PCA analyses showed that the varying composition of immune cells in both glomerular and tubulointerstitial entities was compelling to distinguish IgAN patients from healthy living controls. In addition, 21 commonly shared DEGs between glomerular and tubulointerstitial entities were recognized as key regulators in the pathogenesis of IgAN, among which the enhanced hemoglobin subunit beta (HBB) gene expression was found to be positively associated with M2 macrophage in the glomerular compartment and resting CD4⁺ memory T cells in the tubulointerstitial compartment. Most importantly, FBJ murine osteosarcoma viral oncogene homolog B (FOSB) gene deficiency was recognized as the dominant alteration in promoting M2 macrophage infiltration in the glomerular compartment of IgAN.

Conclusion: The findings from our current study for the first time reveal commonalities and differences regarding immune states between glomerular and tubulointerstitial compartments, as well as decode the essential role of M2 macrophages and associated molecular patterns within the microenvironments of IgAN.

Computational Modeling of T Cell Hypersensitivity during Coronavirus Infections Leading to Autoimmunity and Lethality

The human angiotensin-converting enzyme 2 (hACE2) receptor is the primary receptor for SARS-CoV-2 infection. However, the presence of alternative receptors such as the transmembrane glycoprotein CD147 has been proposed as a potential route for SARS-CoV-2 infection. The outcomes of SARS-CoV-2 spike protein binding to receptors have been shown to vary among individuals. Additionally, some patients infected with SARS-CoV-2 develop autoimmune responses. Given that CD147 is involved in the hyperactivation of memory T cells resulting in autoimmunity, we investigated the interaction of the SARS-CoV-2 viral spike protein with CD147 receptor and retinal specific CD147 Ig0 domain in silico using molecular docking and molecular dynamics (MD) simulations. The results indicated that binding involves two critical residues Lys63 and Asp65 in a ubiquitous CD147 isoform, potentially leading to the hyperactivation of T cells for only SARS-CoV-2, but not for SARS-CoV or MERS-CoV. Overall binding was confirmed by docking simulations. Next, MD analyses were completed to verify the docking poses. Polar interactions suggested that the interaction via Lys63 and Asp65 might be one of the determinants associated with severe COVID-19 outcomes. Neither did SARS-CoV nor MERS-CoV bind to these two critical residues when molecular docking analyses were performed. Interestingly, SARS-CoV was able to bind to CD147 with a lower affinity (-4.5 kcal/mol) than SARS-CoV-2 (-5.6 kcal/mol). Furthermore, Delta and Omicron variants of SARS-CoV-2 did not affect the polar interactions with Lys63 and Asp65 in CD147. This study further strengthens the link between SARS-CoV-2 infection and autoimmune responses and provides novel insights for prudent antiviral drug designs for COVID-19 treatment that have implications in the prevention of T cell hyperactivation.

Interactions between the breast tissue microbiota and host gene regulation in nonpuerperal mastitis

BACKGROUND

Nonpuerperal mastitis (NPM) causes considerable psychological distress in females, since it is difficult to diagnose and treat. A spectrum of etiological factors can lead to NPM. However, the pathogenesis of NPM remains unclear. Here, we aimed to dissect the role of host gene-microbe interactions in NPM.

METHODS

We compared the breast tissue microbiome between NPM patients and controls using 16S rRNA sequencing. We also compared the gut microbiome between NPM patients and healthy controls. Moreover, we investigated whether the breast tissue microbiome was associated with an altered gut microbiome in patients with NPM. We analyzed differentially expressed genes in inflammatory tissues of mammary gland from patients with NPM and normal mammary gland tissues from patients with benign and non-infectious breast disease by RNA-sequencing (RNA-seq). Lastly, we explored the association of specific bacterial taxa with differential expression of immune-related genes and differences in infiltrating immune cells.

RESULTS

The breast tissue microbiome from NPM and controls showed significant differences in community composition. The breast tissue shared a relatively small proportion of bacterial communities with the gut in patients with NPM. Ruminococcus (family Ruminococcaceae) of breast tissue was positively correlated with the differentially expression of immune-related genes between NPM patients and controls, including antigen processing and presentation genes (ICAM1, LGMN, THBS1, TAP1, HSPA1B and HSPA1A), cytokine receptor gene IL15RA, and chemokine gene CCN1. Rhizobium of breast tissue was negatively correlated with the differentially expression of the antigen processing and presentation gene HSPA6 between NPM patients and controls. We also found that Ruminococcus (family Ruminococcaceae), Coprococcus, and Clostridium of breast tissue positively correlated with the difference of CD8⁺ T cells between NPM patients and controls.

CONCLUSIONS

We preliminarily explored the potential role of host-microbe interactions in NPM. We demonstrate cross-talk between the breast tissue microbiome and the gut microbiome in patients with NPM. We suggest that NPM microbiome composition influences the immune microenvironment of the disease by affecting the transcriptome. This is an exploratory study and further investigation of host-microbe interactions and its potential mechanism in NPM development are warranted.

Mass spectrometry applied to diagnosis, prognosis, and therapeutic targets identification for the novel coronavirus SARS-CoV-2: A review

Mass spectrometry (MS) has found numerous applications in medicine and has been widely used in the detection and characterization of biomolecules associated with viral infections such as COVID-19. COVID-19 is a multisystem disease and, therefore, the need arises to carry out a careful and conclusive assessment of the pathophysiological parameters involved in the infection, to develop an effective therapeutic approach, assess the prognosis of the disease, and especially the early diagnosis of the infected population. Thus, the urgent need for highly accurate methods of diagnosis and prognosis of this infection presents new challenges for the development of laboratory medicine, whose methods require sensitivity, speed, and accuracy of the techniques for analyzing the biological markers involved in the infection. In this context, MS stands out as a robust analytical tool, with high sensitivity and selectivity, accuracy, low turnaround time, and versatility for the analysis of biological samples. However, it has not yet been adopted as a frontline clinical laboratory technique. Therefore, this review explores the potential and trends of current MS methods and their contribution to the development of new strategies to COVID-19 diagnosis and prognosis and how this tool can assist in the discovery of new therapeutic targets, in addition, to comment what could be the future of MS in medicine.

Circulating activated immune cells as a potential blood biomarkers of non-small cell lung cancer occurrence and progression

BACKGROUND

Treatment for non-small cell lung cancer (NSCLC) has greatly improved in recent years. However, noninvasive early screening for carcinogenesis and progression unclear. The aim of this study was to explore the predictive value of peripheral blood immune cells in untreated NSCLC patients.

METHODS

We retrospectively enrolled 305 untreated NSCLC patients and 132 healthy participants from February 2016 to August 2019 in Peking Union Medical College Hospital. Immune cell levels were determined by flow cytometry and routine blood tests.

RESULTS

NSCLC patients had lower levels of T lymphocytes, NK cells, CD8+ T cells, naïve CD4+/CD4+, naïve CD4+ T cells and higher levels of CD4+ T cells, memory CD4+/CD4+ T cells, memory CD4+ T cells, CD4+CD28+/CD4+ T cells, CD4+CD28+ T cells, CD8+CD28+/CD8+ T cells, CD8+HLA-DR+/CD8+ T cells, CD8+HLA-DR+ T cells T cells, CD8+CD38+/CD8+ T cells, CD8+CD38+ T cells and CD4+/CD8+ T cells than those in controls. The percentages of specific lymphocyte subtypes were significantly different in cancer patients versus healthy individuals. For instance, cancer patients had lower levels of B cells, CD4+ T cells, naïve CD4+/CD4+ T cells, naïve CD4+ T cells, CD4+CD28+ T cells, CD8+CD28+ T cells and higher levels of NK cells, white blood cells (WBC), monocytes, neutrophils, eosinophils, basophils, monocytes to lymphocyte ratio (MLR), neutrophils to lymphocyte ratio (NLR), eosinophil to lymphocyte ratio (ELR), basophil to lymphocyte ratio (BLR), and blood platelet to lymphocyte ratio (PLR).

CONCLUSIONS

Abnormal T cell levels can be used as an independent predictive biomarker for noninvasive early screening in NSCLC occurrence and progression.

Evasion of the Host Immune Response by Betaherpesviruses

The human immune system boasts a diverse array of strategies for recognizing and eradicating invading pathogens. Human betaherpesviruses, a highly prevalent subfamily of viruses, include human cytomegalovirus (HCMV), human herpesvirus (HHV) 6A, HHV-6B, and HHV-7. These viruses have evolved numerous mechanisms for evading the host response. In this review, we will highlight the complex interplay between betaherpesviruses and the human immune response, focusing on protein function. We will explore methods by which the immune system first responds to betaherpesvirus infection as well as mechanisms by which viruses subvert normal cellular functions to evade the immune system and facilitate viral latency, persistence, and reactivation. Lastly, we will briefly discuss recent advances in vaccine technology targeting betaherpesviruses. This review aims to further elucidate the dynamic interactions between betaherpesviruses and the human immune system.

Monocyte-Derived Dendritic Cells (moDCs) Differentiate into Bcl6+ Mature moDCs to Promote Cyclic di-GMP Vaccine Adjuvant-Induced Memory TH Cells in the Lung

Induction of lung mucosal immune responses is highly desirable for vaccines against respiratory infections. We recently showed that monocyte-derived dendritic cells (moDCs) are responsible for lung IgA induction. However, the dendritic cell subset inducing lung memory T_H cells is unknown. In this study, using conditional knockout mice and adoptive cell transfer, we found that moDCs are essential for lung mucosal responses but are dispensable for systemic vaccine responses. Next, we showed that mucosal adjuvant cyclic di-GMP differentiated lung moDCs into Bcl6⁺ mature moDCs promoting lung memory T_H cells, but they are dispensable for lung IgA production. Mechanistically, soluble TNF mediates the induction of lung Bcl6⁺ moDCs. Our study reveals the functional heterogeneity of lung moDCs during vaccination and paves the way for an moDC-targeting vaccine strategy to enhance immune responses on lung mucosa.

Gene co-expression modules integrated with immunoscore predicts survival of non-small cell lung cancer

BACKGROUND

This study aimed to deconvolve the levels of infiltrating immune cells in non-small cell lung cancer (NSCLC) and to identify specific gene co-expression modules associated with prognosis of NSCLC.

MATERIALS AND METHODS

CIBERSORT algorithm was employed to infer the relative abundance of 22 immune cell subtypes in 1751 NSCLC subjects. The patterns of immune infiltration were identified for NSCLC with different clinical and genomic features and were used to construct an immunoscore by LASSO regression associated with NSCLC survival. Weighted gene co-expression network analysis (WGCNA) was employed to identify specific modules related to immunoscore and NSCLC survival. An integrated prognostic model was constructed with immunoscore combined with the available clinical variables and the selected gene modules to predict the prognosis of NSCLC.

RESULTS

We found distinct immune infiltration patterns for NSCLC with different genotype. EGFR-mutant NSCLC was characterized by enriched resting memory CD4+ T cell. An immunoscore was established based on the infiltration abundance of 17 selected immune cell subtypes. Patients with a low immunoscore had a prolonged survival and higher abundance of CD4+ T cell, resting dendritic cells and resting mast cells. The WGCNA analysis identified the gene modules significantly associated with immunoscore and the prognosis of NSCLC. The immunoscore was further incorporated with clinical parameters and selected gene modules to fit a predictive model which stratified patients into subgroups with significantly different survival.

CONCLUSION

The distinct immune profiles are associated with differential overall survival of NSCLC and the integrated model can robustly predict the prognosis of NSCLC.

Multiple developmental pathways lead to the generation of CD4 T-cell memory

Long-term immunological memory mediated by CD4 T cells provides a rapid protection against previously encountered pathogens or antigens. However, it is still controversial how memory CD4 T cells are generated and maintained. Unclear definitions of T-cell memory may be partially responsible for this controversy. It is becoming clear that diverse pathways are responsible for the differentiation and long-term persistence of memory T cells. We herein discuss the diversity of memory cell generation, describing a novel population of resting memory CD4 T cells and their precursors.

Circulating activated lymphocyte subsets as potential blood biomarkers of cancer progression

The objective of this study was to predict the value of lymphocyte subsets in cancer progression. Peripheral blood was obtained from 327 untreated patients with cancer and 158 healthy volunteers. Levels of lymphocyte subsets were determined by flow cytometry. There were decreased levels of natural killer (NK) cells, CD8⁺ T cells, and naïve CD4⁺/CD4⁺ T cells in untreated patients with cancer compared to those in healthy controls. Inversely, there were elevated levels of the following T‐cell percentages in cancer patients compared to those in healthy controls: memory CD4⁺/CD4⁺, CD8⁺ T cells, HLA‐DR/CD8⁺, CD8⁺ CD38⁺/CD8⁺, and CD4⁺/CD8⁺. In addition, there are a decreasing trend in terms of CD4⁺ T‐cell counts and an increase CD8⁺ HLA‐DR/CD8⁺ T‐cell and CD8⁺ CD38⁺/CD8⁺ T‐cell percentages in the advanced stage. An increasing trend with advanced tumor stage and the percentages of CD8⁺ HLA‐DR/CD8⁺ T cells and CD8⁺ CD38⁺/CD8⁺ T cells was shown in this study. There are a negative correlation for CD4⁺ T‐cell counts and positive correlation for percentages of CD8⁺ HLA‐DR/CD8⁺ T cell and CD8⁺ CD38⁺/CD8⁺ T cells with the lymph node metastasis. In the presence of distant metastatic spread, we observed higher NK‐cell counts, CD8⁺ HLA‐DR/CD8⁺ T‐cell percentages, CD8⁺ CD38⁺/CD8⁺ T‐cell percentages, as well as lower CD4⁺ T‐cell counts than those in the absence of distant metastases spread. Abnormal levels of NK cell, CD8⁺ T cells, memory CD4⁺/CD4⁺, naïve CD4⁺/ CD4⁺, CD8⁺ HLA‐DR/CD8⁺, CD8⁺ CD38⁺/CD8⁺, and CD4⁺/CD8⁺ can be a potential blood biomarkers of cancer development. CD4+ T‐cell counts and percentages of CD8⁺ HLA‐DR/ CD8⁺ and CD8⁺ CD38⁺/ CD8⁺ can predict the cancer progression.

Integrated analysis of immunocyte infiltration and differential gene expression in tricuspid aortic valve-associated thoracic aortic aneurysms

Background

Progressive dilatation is responsible for significant mortality and morbidity in patients with thoracic aortic aneurysms (TAAs). Studies have shown that the development and progression of TAAs are closely related to immune regulatory pathways and genes. Therefore, it is important to understand the immune regulatory mechanisms and biomarkers of TAA dilatation.

Methods

Systematic bioinformatics analysis was applied, including linear models for microarray data (LIMMA) differential expression analyses, principal component analysis (PCA), immunocyte identification, and genetic function enrichment analysis.

Results

Our results showed that both aortic intima-media (AMed) and outer aortic adventitia (AAdv) tissues were closely associated with T cell activation during the process of tricuspid aortic valve (TAV)-associated TAA dilation. Additionally, the degree of infiltration of resting memory CD4+ T cells was linked to both AAdv and AMed vascular dilation. The core regulators PPTRC, IL1B, CD4, CD3G, and IL2RA were also identified and are closely related to resting memory CD4+ T cell infiltration in this pathological process.

Conclusions

The candidate genes PPTRC, IL1B, CD4, CD3G, and IL2RA were involved in the regulation of resting memory CD4 T cell tissue infiltration, which is closely related to the process of AAdv and AMed vascular dilation in TAV patients.

Chlamydia muridarum infection induces CD4+ T cells apoptosis via PI3K/AKT signal pathway

Apoptosis is essential for the homeostatic control of the lymphocytes number during the development of an immune response to an invasive microorganism. CD4+ T cells play a major role in homeostasis of the immune system and are sufficient to confer protection against Chlamydia muridarum (Cm) infection in mice. The present study demonstrated that phosphatidylinositol 3-kinase (PI3K) p110δ mRNA and phosphorylation of protein kinase B (p-AKT) level were significantly increased in lung cells and spleen cells at day 3 and day 7 post-infection, p-AKT level was inhibited when adding PI3K inhibitor LY294002. Moreover, Cm infection induced high levels of IL-2/IL-2Rα in CD4+ T cells, which may relate to PI3K/AKT signal pathway activation. We observed that Cm infection significantly induced apoptosis of CD4+ T cells. The related apoptosis proteins Bcl-2 and Mcl-1 uneven expression levels were induced in CD4+ T cells by Cm infection. These findings provided in vivo and in vitro evidence that Cm infection induces CD4+ T cells apoptosis possibly via PI3K/AKT signal pathway.

Striking a Balance-Cellular and Molecular Drivers of Memory T Cell Development and Responses to Chronic Stimulation

Effective adaptive immune responses are characterized by stages of development and maturation of T and B cell populations that respond to disturbances in the host homeostasis in cases of both infections and cancer. For the T cell compartment, this begins with recognition of specific peptides by naïve, antigen-inexperienced T cells that results in their activation, proliferation, and differentiation, which generates an effector population that clears the antigen. Loss of stimulation eventually returns the host to a homeostatic state, with a heterogeneous memory T cell population that persists in the absence of antigen and is primed for rapid responses to a repeat antigen exposure. However, in chronic infections and cancers, continued antigen persistence impedes a successful adaptive immune response and the formation of a stereotypical memory population of T cells is compromised. With repeated antigen stimulation, responding T cells proceed down an altered path of differentiation that allows for antigen persistence, but much less is known regarding the heterogeneity of these cells and the extent to which they can become “memory-like,” with a capacity for self-renewal and recall responses that are characteristic of bona fide memory cells. This review focuses on the differentiation of CD4⁺ and CD8⁺ T cells in the context of chronic antigen stimulation, highlighting the central observations in both human and mouse studies regarding the differentiation of memory or “memory-like” T cells. The importance of both the cellular and molecular drivers of memory T cell development are emphasized to better understand the consequences of persisting antigen on T cell fates. Integrating what is known and is common across model systems and patients can instruct future studies aimed at further understanding T cell differentiation and development, with the goal of developing novel methods to direct T cells toward the generation of effective memory populations.

An immune infiltration signature to predict the overall survival of patients with colon cancer

Immune infiltration of tumors has been increasingly accepted as a prognostic factor in colon cancer. Here, we aim to develop a novel immune signature, based on estimated immune landscape from tumor transcriptomes, to predict the overall survival of patients with colon cancer. The compositions of 22 immune cell subtypes from three microarray datasets were characterized with the CIBERSORT deconvolution algorithm. A prognostic immunoscore (PIS) model for overall survival prediction was established by using least absolute shrinkage and selection operator (LASSO) penalized regression analysis. A total of 17 immune cell markers were screened out in the LASSO model and were then aggregated to generate the PIS. In the training cohort (n = 490), patients with high PIS exhibited a remarkably poorer overall survival than those with low PIS. Similar results were obtained in patients with different TNM stages and in patients receiving adjunctive chemotherapy or not. Multivariate Cox regression indicated that the PIS was an independent predictor for overall survival in colon cancer (hazard ratio: 2.734, 95% confidence interval: 2.052-3.643, p < .001). The prognostic capability of PIS was also confirmed in the testing cohort (n = 245) and the entire cohort (n = 735). As for biological implications, the PIS was significantly associated with some immune checkpoints, inflammatory factors, epithelial-mesenchymal transformation regulators, and many known signaling pathways in cancer. The results of our study provide a novel and promising immune signature for overall survival prediction of patients with colon cancer.

Subversion of host immune responses by otopathogens during otitis media

Otitis media (OM) is one of the most common ear diseases affecting humans. Children are at greater risk and suffer most frequently from OM, which can cause serious deterioration in the quality of life. OM is generally classified into two main types: acute and chronic OM (AOM and COM). AOM is characterized by tympanic membrane swelling or otorrhea and is accompanied by signs or symptoms of ear infection. In COM, there is a tympanic membrane perforation and purulent discharge. The most common pathogens that cause AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis whereas Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with COM. Innate and adaptive immune responses provide protection against OM. However, pathogens employ a wide arsenal of weapons to evade potent immune responses and these mechanisms likely contribute to AOM and COM. Immunologic evasion is multifactorial, and involves damage to host mucociliary tract, genetic polymorphisms within otopathogens, the number and variety of different otopathogens in the nasopharynx as well as the interaction between the host's innate and adaptive immune responses. Otopathogens utilize host mucin production, phase variation, biofilm production, glycans, as well as neutrophil and eosinophilic extracellular traps to induce OM. The objective of this review article is to discuss our current understanding about the mechanisms through which otopathogens escape host immunity to induce OM. A better knowledge about the molecular mechanisms leading to subversion of host immune responses will provide novel clues to develop effective treatment modalities for OM.

Origins of CD4+ circulating and tissue-resident memory T-cells

In response to infection, naive CD4+ T-cells proliferate and differentiate into several possible effector subsets, including conventional T helper effector cells (TH 1, TH 2, TH 17), T regulatory cells (Treg ) and T follicular helper cells (TFH ). Once infection is cleared, a small population of long-lived memory cells remains that mediate immune defenses against reinfection. Memory T lymphocytes have classically been categorized into central memory cell (TCM ) and effector memory cell (TEM ) subsets, both of which circulate between blood, secondary lymphoid organs and in some cases non-lymphoid tissues. A third subset of memory cells, referred to as tissue-resident memory cells (TRM ), resides in tissues without recirculation, serving as 'first line' of defense at barrier sites, such as skin, lung and intestinal mucosa, and augmenting innate immunity in the earliest phases of reinfection and recruiting circulating CD4+ and CD8+ T-cells. The presence of multiple CD4+ T helper subsets has complicated studies of CD4+ memory T-cell differentiation, and the mediators required to support their function. In this review, we summarize recent investigations into the origins of CD4+ memory T-cell populations and discuss studies addressing CD4+  TRM differentiation in barrier tissues.

Th1-type immune responses to Porphyromonas gingivalis antigens exacerbate angiotensin II-dependent hypertension and vascular dysfunction

Background and Purpose

Emerging evidence indicates that hypertension is mediated by immune mechanisms. We hypothesized that exposure to Porphyromonas gingivalis antigens, commonly encountered in periodontal disease, can enhance immune activation in hypertension and exacerbate the elevation in BP, vascular inflammation and vascular dysfunction.

Experimental Approach

Th1 immune responses were elicited through immunizations using P. gingivalis lysate antigens (10 μg) conjugated with aluminium oxide (50 μg) and IL‐12 (1 μg). The hypertension and vascular endothelial dysfunction evoked by subpressor doses of angiotensin II (0.25 mg·kg⁻¹·day⁻¹) were studied, and vascular inflammation was quantified by flow cytometry and real‐time PCR.

Key Results

Systemic T‐cell activation, a characteristic of hypertension, was exacerbated by P. gingivalis antigen stimulation. This translated into increased aortic vascular inflammation with enhanced leukocyte, in particular, T‐cell and macrophage infiltration. The expression of the Th1 cytokines, IFN‐γ and TNF‐α, and the transcription factor, TBX21, was increased in aortas of P. gingivalis/IL‐12/aluminium oxide‐immunized mice, while IL‐4 and TGF‐β were unchanged. These immune changes in mice with induced T‐helper‐type 1 immune responses were associated with an enhanced elevation of BP and endothelial dysfunction compared with control mice in response to 2 week infusion of a subpressor dose of angiotensin II.

Conclusions and Implications

These results support the concept that Th1 immune responses induced by bacterial antigens such as P. gingivalis can increase sensitivity to subpressor pro‐hypertensive insults such as low‐dose angiotensin II, thus providing a mechanistic link between chronic infection, such as periodontitis, and hypertension.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Advax augments B and T cell responses upon influenza vaccination via the respiratory tract and enables complete protection of mice against lethal influenza virus challenge

Administration of influenza vaccines via the respiratory tract has potential benefits over conventional parenteral administration, inducing immunity directly at the site of influenza exposure as well as being needle free. In this study, we investigated the suitability of Advax™, a stable particulate polymorph of inulin, also referred to as delta inulin, as a mucosal adjuvant for whole inactivated influenza vaccine (WIV) administered either as a liquid or dry powder formulation. Spray freeze-drying produced Advax-adjuvanted WIV powder particles in a size range (1-5 μm) suitable for inhalation. The physical and biological characteristics of both WIV and Advax remained unaltered both by admixing WIV with Advax and by spray freeze drying. Upon intranasal or pulmonary immunization, both liquid and dry powder formulations containing Advax induced significantly higher systemic, mucosal and cellular immune responses than non-adjuvanted WIV formulations. Furthermore, pulmonary immunization with Advax-adjuvanted WIV led to robust memory B cell responses along with an increase of lung localization factors i.e. CXCR3, CD69, and CD103. A less pronounced but still positive effect of Advax was seen on memory T cell responses. In contrast to animals immunized with WIV alone, all animals pulmonary immunized with a single dose of Advax-adjuvanted WIV were fully protected with no visible clinical symptoms against a lethal dose of influenza virus. These data confirm that Advax is a potent mucosal adjuvant that boosts vaccine-induced humoral and cellular immune responses both in the lung and systemically with major positive effects on B-cell memory and complete protection against live virus. Hence, respiratory tract immunization, particularly via the lungs, with Advax-adjuvanted WIV formulation as a liquid or dry powder is a promising alternative to parenteral influenza vaccination.

Phase II study of ERC1671 plus bevacizumab versus bevacizumab plus placebo in recurrent glioblastoma: interim results and correlations with CD4+ T-lymphocyte counts

Aim:

ERC1671 is an allogeneic/autologous therapeutic glioblastoma (GBM) vaccine – composed of whole, inactivated tumor cells mixed with tumor cell lysates derived from the patient and three GBM donors.

Methods:

In this double-blinded, randomized, Phase II study bevacizumab-naive patients with recurrent GBM were randomized to receive either ERC1671 in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF) (Leukine^® or sargramostim) and cyclophosphamide plus bevacizumab, or placebo plus bevacizumab.

Interim results:

Median overall survival (OS) of patients treated with ERC1671 plus bevacizumab was 12 months. In the placebo plus bevacizumab group, median OS was 7.5 months. The maximal CD4⁺ T-lymphocyte count correlated with OS in the ERC1671 but not in the placebo group.

Conclusion:

The addition of ERC1671/GM-CSF/cyclophosphamide to bevacizumab resulted in a clinically meaningful survival benefit with minimal additional toxicity.

A temporally dynamic Foxp3 autoregulatory transcriptional circuit controls the effector Treg programme

Regulatory T cells (Treg) are negative regulators of the immune response; however, it is poorly understood whether and how Foxp3 transcription is induced and regulated in the periphery during T‐cell responses. Using Foxp3‐Timer of cell kinetics and activity (Tocky) mice, which report real‐time Foxp3 expression, we show that the flux of new Foxp3 expressors and the rate of Foxp3 transcription are increased during inflammation. These persistent dynamics of Foxp3 transcription determine the effector Treg programme and are dependent on a Foxp3 autoregulatory transcriptional circuit. Persistent Foxp3 transcriptional activity controls the expression of coinhibitory molecules, including CTLA‐4 and effector Treg signature genes. Using RNA‐seq, we identify two groups of surface proteins based on their relationship to the temporal dynamics of Foxp3 transcription, and we show proof of principle for the manipulation of Foxp3 dynamics by immunotherapy: new Foxp3 flux is promoted by anti‐TNFRII antibody, and high‐frequency Foxp3 expressors are targeted by anti‐OX40 antibody. Collectively, our study dissects time‐dependent mechanisms behind Foxp3‐driven T‐cell regulation and establishes the Foxp3‐Tocky system as a tool to investigate the mechanisms behind T‐cell immunotherapies.

Th1-like Plasmodium-Specific Memory CD4+ T Cells Support Humoral Immunity

Effector T cells exhibiting features of either T helper 1 (Th1) or T follicular helper (Tfh) populations are essential to control experimental Plasmodium infection and are believed to be critical for resistance to clinical malaria. To determine whether Plasmodium-specific Th1- and Tfh-like effector cells generate memory populations that contribute to protection, we developed transgenic parasites that enable high-resolution study of anti-malarial memory CD4 T cells in experimental models. We found that populations of both Th1- and Tfh-like Plasmodium-specific memory CD4 T cells persist. Unexpectedly, Th1-like memory cells exhibit phenotypic and functional features of Tfh cells during recall and provide potent B cell help and protection following transfer, characteristics that are enhanced following ligation of the T cell co-stimulatory receptor OX40. Our findings delineate critical functional attributes of Plasmodium-specific memory CD4 T cells and identify a host-specific factor that can be targeted to improve resolution of acute malaria and provide durable, long-term protection against Plasmodium parasite re-exposure.

Comparative study of the immunoprotective effect of two DNA vaccines against grass carp reovirus

Grass carp reovirus II (GCRV II) causes severe hemorrhagic disease with high mortality in grass carp, Cyenopharyngodon idellus. DNA vaccination has been proven to be a very effective method in conferring protection against fish viruses. However, DNA vaccines for GCRV II have not yet been conducted on grass carp. In the current work, we vaccinated grass carp with a DNA vaccine consisting of the segment 6 (pC-S6; encoding VP4) or 10 (pC-S10; encoding NS38) of GCRV II and comparatively analyzed the immune responses induced by these two vaccines. The protective efficacy of pC-S6 and pC-S10, in terms of relative percentage survival (RPS), was 59.9% and 23.1% respectively. This suggests that pC-S6 and pC-S10 DNA vaccines could increase the survival rate of grass carp against GCRV, albeit with variations in immunoprotective effect. Immunological analyses indicated the following. First, post-vaccination (pv), both pC-S6 and pC-S10 up-regulated the expression of interferon (IFN-1), Mx1, IL-1β, and TNF-α. However, CD4 and CD8α were up-regulated in the case of pC-S6 but not pC-S10. Second, comparing non-vaccinated and pC-S10-vaccinated fish, the T cell response related genes, such as CD4, CD8α, and GATA3, were elevated in pC-S6-vaccinated fish at 48 h post-challenge (pc). Third, pC-S6 and pC-S10 induced similar patterns of specific antibody response pv. However, only anti-VP4 IgM in the sera of surviving fish infected with GCRV was significantly increased pc compared with that pre-challenge. Taken together, these results indicate that pC-S6 promotes both innate (IFN-1 and Mx1 induction) and adaptive (T cell and specific antibody response) immunity pv and that the induction of a memory state promptly primes the immune response upon later encounters with the virus, whereas pC-S10 only induces the type I IFN-related response pv and a lower inflammatory response pc.

A critical epitope in CD147 facilitates memory CD4+ T-cell hyper-activation in rheumatoid arthritis

The abnormal activation of CD4⁺CD45RO⁺ memory T (Tm) cells plays an important role in the pathogenesis of rheumatoid arthritis (RA). Previous studies have shown that CD147 participates in T-cell activation. However, it remains unclear whether CD147 is involved in abnormal Tm-cell activation in RA patients. In this study, we demonstrated that CD147 was predominantly upregulated in Tm cells derived from RA patients. The anti-CD147 mAb 5A12 specifically inhibited Tm-cell activation and proliferation and further restrained osteoclastogenesis. Using a structural-functional approach, we depicted the interface between 5A12 and CD147. This allowed us to identify two critical residues, Lys63 and Asp65, as potential targets for RA treatment, as the double mutation K63A/D65A inhibited Tm-cell activation, mimicking the neutralization by 5A12. This study provides not only a theoretical basis for a "CD147-Tm/Osteoclast-RA chain" for the potential prevention and treatment of RA or other T-cell-mediated autoimmune diseases but also a new target for related drug design and development.

Mixed Th1 and Th2 Mycobacterium tuberculosis-specific CD4 T cell responses in patients with active pulmonary tuberculosis from Tanzania

Mycobacterium tuberculosis (Mtb) and helminth infections elicit antagonistic immune effector functions and are co-endemic in several regions of the world. We therefore hypothesized that helminth infection may influence Mtb-specific T-cell immune responses. We evaluated the cytokine profile of Mtb-specific T cells in 72 individuals with pulmonary TB disease recruited from two Sub-Saharan regions with high and moderate helminth burden i.e. 55 from Tanzania (TZ) and 17 from South Africa (SA), respectively. We showed that Mtb-specific CD4 T-cell functional profile of TB patients from Tanzania are primarily composed of polyfunctional Th1 and Th2 cells, associated with increased expression of Gata-3 and reduced expression of T-bet in memory CD4 T cells. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by single IFN-γ and dual IFN-γ/TNF-α and associated with TB-induced systemic inflammation and elevated serum levels of type I IFNs. Of note, the proportion of patients with Mtb-specific CD8 T cells was significantly reduced in Mtb/helminth co-infected patients from TZ. It is likely that the underlying helminth infection and possibly genetic and other unknown environmental factors may have caused the induction of mixed Th1/Th2 Mtb-specific CD4 T cell responses in patients from TZ. Taken together, these results indicate that the generation of Mtb-specific CD4 and CD8 T cell responses may be substantially influenced by environmental factors in vivo. These observations may have major impact in the identification of immune biomarkers of disease status and correlates of protection.

Mycobacterium tuberculosis (Mtb) and helminth infections are co-endemic in several regions of the world and their immune responses may be mutually antagonistic. We therefore hypothesized that helminth infection would impact and potentially shape Mtb-specific T-cell responses and systemic inflammation in patients suffering from active pulmonary tuberculosis (TB) enrolled from two helminth endemic regions i.e. Tanzania (TZ) and South Africa (SA). In this study, we demonstrate for the first time that TB patients from SA and TZ harbor distinct immune responses to Mtb antigens. Indeed, we showed that Mtb-specific CD4 T-cell responses of TB patients from TZ were composed by a mixed T helper type 1 (Th1) and Th2 responses. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by Th1 cells and associated with TB-induced systemic inflammation and elevated serum levels of type I IFN. Taken together, these data indicate that Mtb-specific T-cell responses are diverse in human populations and can be strongly influenced by host and pathogen genetic background, co-infections and yet unknown environmental factors. Identification of correlates of risk and protection from TB disease will help in the rational development of protective T-cell based vaccines against TB, early monitoring TB treatment outcomes and focused follow up of high risk populations.

Selective pre-priming of HA-specific CD4 T cells restores immunological reactivity to HA on heterosubtypic influenza infection

A hallmark of the immune response to influenza is repeated encounters with proteins containing both genetically conserved and variable components. Therefore, the B and T cell repertoire is continually being remodeled, with competition between memory and naïve lymphocytes. Our previous work using a mouse model of secondary heterosubtypic influenza infection has shown that this competition results in a focusing of CD4 T cell response specificity towards internal virion proteins with a selective decrease in CD4 T cell reactivity to the novel HA epitopes. Strikingly, this shift in CD4 T cell specificity was associated with a diminished anti-HA antibody response. Here, we sought to determine whether the loss in HA-specific reactivity that occurs as a consequence of immunological memory could be reversed by selectively priming HA-specific CD4 T cells prior to secondary infection. Using a peptide-based priming strategy, we found that selective expansion of the anti-HA CD4 T cell memory repertoire enhanced HA-specific antibody production upon heterosubtypic infection. These results suggest that the potentially deleterious consequences of repeated exposure to conserved influenza internal virion proteins could be reversed by vaccination strategies that selectively arm the HA-specific CD4 T cell compartment. This could be a potentially useful pre-pandemic vaccination strategy to promote accelerated neutralizing antibody production on challenge with a pandemic influenza strain that contains few conserved HA epitopes.

Using Data from Macaques To Predict Gamma Interferon Responses after Mycobacterium bovis BCG Vaccination in Humans: a Proof-of-Concept Study of Immunostimulation/Immunodynamic Modeling Methods

Macaques play a central role in the development of human tuberculosis (TB) vaccines. Immune and challenge responses differ across macaque and human subpopulations. We used novel immunostimulation/immunodynamic modeling methods in a proof-of-concept study to determine which macaque subpopulations best predicted immune responses in different human subpopulations. Data on gamma interferon (IFN-γ)-secreting CD4⁺ T cells over time after recent Mycobacterium bovis BCG vaccination were available for 55 humans and 81 macaques. Human population covariates were baseline BCG vaccination status, time since BCG vaccination, gender, and the monocyte/lymphocyte cell count ratio. The macaque population covariate was the colony of origin. A two-compartment mathematical model describing the dynamics of the IFN-γ T cell response after BCG vaccination was calibrated to these data using nonlinear mixed-effects methods. The model was calibrated to macaque and human data separately. The association between subpopulations and the BCG immune response in each species was assessed. The macaque subpopulations that best predicted immune responses in different human subpopulations were identified using Bayesian information criteria. We found that the macaque colony and the human baseline BCG status were significantly (P < 0.05) associated with the BCG-induced immune response. For humans who were BCG naïve at baseline, Indonesian cynomolgus macaques and Indian rhesus macaques best predicted the immune response. For humans who had already been BCG vaccinated at baseline, Mauritian cynomolgus macaques best predicted the immune response. This work suggests that the immune responses of different human populations may be best modeled by different macaque colonies, and it demonstrates the potential utility of immunostimulation/immunodynamic modeling to accelerate TB vaccine development.

Toll-Like Receptor 2 Ligation Enhances HIV-1 Replication in Activated CCR6+ CD4+ T Cells by Increasing Virus Entry and Establishing a More Permissive Environment to Infection

In this study, we investigated the effect of Toll-like receptor 2 (TLR2) ligation on the permissiveness of activated CD4⁺ T cells to HIV-1 infection by focusing our experiments on the relative susceptibility of cell subsets based on their expression of CCR6. Purified primary human CD4⁺ T cells were first subjected to a CD3/CD28 costimulation before treatment with the TLR2 agonist Pam3CSK4. Finally, cells were inoculated with R5-tropic HIV-1 particles that permit us to study the effect of TLR2 triggering on virus production at both population and single-cell levels. We report here that HIV-1 replication is augmented in CD3/CD28-costimulated CCR6⁺ CD4⁺ T cells upon engagement of the cell surface TLR2. Additional studies indicate that a higher virus entry and polymerization of the cortical actin are seen in this cell subset following TLR2 stimulation. A TLR2-mediated increase in the level of phosphorylated NF-κB p65 subunit was also detected in CD3/CD28-costimulated CCR6⁺ CD4⁺ T cells. We propose that, upon antigenic presentation, an engagement of TLR2 acts specifically on CCR6⁺ CD4⁺ T cells by promoting virus entry in an intracellular milieu more favorable for productive HIV-1 infection.

IMPORTANCE

Following primary infection, HIV-1 induces an immunological and structural disruption of the gut mucosa, leading to bacterial translocation and release of microbial components in the bloodstream. These pathogen-derived constituents include several agonists of Toll-like receptors that may affect gut-homing CD4⁺ T cells, such as those expressing the chemokine receptor CCR6, which are highly permissive to HIV-1 infection. We demonstrate that TLR2 ligation in CD3/CD28-costimulated CCR6⁺ CD4⁺ T cells leads to enhanced virus production. Our results highlight the potential impact of bacterial translocation on the overall permissiveness of CCR6⁺ CD4⁺ T cells to productive HIV-1 infection.

Current views on HIV-1 latency, persistence, and cure

HIV-1 infection cannot be cured as it persists in latently infected cells that are targeted neither by the immune system nor by available therapeutic approaches. Consequently, a lifelong therapy suppressing only the actively replicating virus is necessary. The latent reservoir has been defined and characterized in various experimental models and in human patients, allowing research and development of approaches targeting individual steps critical for HIV-1 latency establishment, maintenance, and reactivation. However, additional mechanisms and processes driving the remaining low-level HIV-1 replication in the presence of the suppressive therapy still remain to be identified and targeted. Current approaches toward HIV-1 cure involve namely attempts to reactivate and purge HIV latently infected cells (so-called "shock and kill" strategy), as well as approaches involving gene therapy and/or gene editing and stem cell transplantation aiming at generation of cells resistant to HIV-1. This review summarizes current views and concepts underlying different approaches aiming at functional or sterilizing cure of HIV-1 infection.

Immunization with Protein D from Non-Typeable Haemophilus influenzae (NTHi) Induced Cytokine Responses and Bioactive Antibody Production

Background

Outer membrane protein D (PD) is a highly conserved and stable protein in the outer membrane of both encapsulated (typeable) and non-capsulated (non-typeable) strains of Haemophilus influenzae. As an immunogen, PD is a potential candidate vaccine against non-typeable H. influenzae (NTHi) strains.

Objectives

The aim of this study was to determine the cytokine pattern and the opsonic antibody response in a BALB/c mouse model versus PD from NTHi as a vaccine candidate.

Methods

Protein D was formulated with Freund’s and outer membrane vesicle (OMV) adjuvants and injected into experimental mice. Sera from all groups were collected. The bioactivity of the anti-PD antibody was determined by opsonophagocytic killing test. To evaluate the cytokine responses, the spleens were assembled, suspension of splenocytes was recalled with antigen, and culture supernatants were analyzed by ELISA for IL-4, IL-10, and IFN-γ cytokines.

Results

Anti-PD antibodies promoted phagocytosis of NTHi in both immunized mice groups (those administered PD + Freund’s and those administered PD + OMV adjuvants, 92.8% and 83.5%, respectively, compared to the control group). In addition, the concentrations of three cytokines were increased markedly in immunized mice.

Conclusions

We conclude that immunization with PD protects mice against NTHi. It is associated with improvements in both cellular and humoral immune responses and opsonic antibody activity.

HLA-DRB1 Alleles Are Associated With Different Magnitudes of Dengue Virus-Specific CD4+ T-Cell Responses

BACKGROUND

Each year dengue virus (DENV) infects 400 million human but causes symptomatic disease in only a subset of patients, suggesting that host genetic factors may play a role. HLA molecules that restrict T-cell responses are one of the most polymorphic host factors in humans.

METHODS

Here we map HLA DRB1-restricted DENV-specific epitopes in individuals previously exposed to DENV, to identify the breadth and specificity of CD4(+) T-cell responses. To investigate whether HLA-specific variations in the magnitude of response might predict associations between dengue outcomes and HLA-DRB1 alleles, we assembled samples from hospitalized patients with known severity of disease.

RESULTS

The capsid protein followed by nonstructural protein 3 (NS3), NS2A, and NS5 were the most targeted proteins. We further noticed a wide variation in magnitude of T-cell responses as a function of the restricting DRB1 allele and found several HLA alleles that showed trends toward a lower risk of hospitalized disease were associated with a higher magnitude of T-cell responses.

CONCLUSIONS

Comprehensive identification of unique CD4(+) T-cell epitopes across the 4 DENV serotypes allows the testing of T-cell responses by use of a simple, approachable technique and points to important implications for vaccine design.

Promoter H3K4 methylation dynamically reinforces activation-induced pathways in human CD4 T cells

The epigenetic determinants driving the responses of CD4 T cells to antigen are currently an area of active research. Much has been done to characterize helper T-cell subsets and their associated genome-wide epigenetic patterns. In contrast, little is known about the dynamics of histone modifications during CD4 T-cell activation and the differential kinetics of these epigenetic marks between naive and memory T cells. In this study, we have detailed the dynamics of genome-wide promoter H3K4me2 and H3K4me3 over a time course during activation of human naive and memory CD4 T cells. Our results demonstrate that changes to H3K4 methylation occur relatively late after activation (5 days) and reinforce activation-induced upregulation of gene expression, affecting multiple pathways important to T-cell activation, differentiation and function. The dynamics and mapped pathways of H3K4 methylation are distinctly different in memory cells, which have substantially more promoters marked by H3K4me3 alone, reinforcing their more differentiated state. Our study provides the first data examining genome-wide histone modification dynamics during CD4 T-cell activation, providing insight into the cross talk between H3K4 methylation and gene expression, and underscoring the impact of these marks upon key pathways integral to CD4 T-cell activation and function.

The Role of CD4 T Cell Memory in Generating Protective Immunity to Novel and Potentially Pandemic Strains of Influenza

Recent events have made it clear that potentially pandemic strains of influenza regularly pose a threat to human populations. Therefore, it is essential that we develop better strategies to enhance vaccine design and evaluation to predict those that will be poor responders to vaccination and to identify those that are at particular risk of disease-associated complications following infection. Animal models have revealed the discrete functions that CD4 T cells play in developing immune response and to influenza immunity. However, humans have a complex immunological history with influenza through periodic infection and vaccination with seasonal variants, leading to the establishment of heterogeneous memory populations of CD4 T cells that participate in subsequent responses. The continual evolution of the influenza-specific CD4 T cell repertoire involves both specificity and function and overlays other restrictions on CD4 T cell activity derived from viral antigen handling and MHC class II:peptide epitope display. Together, these complexities in the influenza-specific CD4 T cell repertoire constitute a formidable obstacle to predicting protective immune response to potentially pandemic strains of influenza and in devising optimal vaccine strategies to potentiate these responses. We suggest that more precise efforts to identify and enumerate both the positive and negative contributors within the CD4 T cell compartment will aid significantly in the achievement of these goals.

CD4 memory T cells develop and acquire functional competence by sequential cognate interactions and stepwise gene regulation

Memory CD4(+) T cells promote protective humoral immunity; however, how memory T cells acquire this activity remains unclear. This study demonstrates that CD4(+) T cells develop into antigen-specific memory T cells that can promote the terminal differentiation of memory B cells far more effectively than their naive T-cell counterparts. Memory T cell development requires the transcription factor B-cell lymphoma 6 (Bcl6), which is known to direct T-follicular helper (Tfh) cell differentiation. However, unlike Tfh cells, memory T cell development did not require germinal center B cells. Curiously, memory T cells that develop in the absence of cognate B cells cannot promote memory B-cell recall responses and this defect was accompanied by down-regulation of genes associated with homeostasis and activation and up-regulation of genes inhibitory for T-cell responses. Although memory T cells display phenotypic and genetic signatures distinct from Tfh cells, both had in common the expression of a group of genes associated with metabolic pathways. This gene expression profile was not shared to any great extent with naive T cells and was not influenced by the absence of cognate B cells during memory T cell development. These results suggest that memory T cell development is programmed by stepwise expression of gatekeeper genes through serial interactions with different types of antigen-presenting cells, first licensing the memory lineage pathway and subsequently facilitating the functional development of memory T cells. Finally, we identified Gdpd3 as a candidate genetic marker for memory T cells.

IFN-γ Priming Effects on the Maintenance of Effector Memory CD4(+) T Cells and on Phagocyte Function: Evidences from Infectious Diseases

Although it has been established that effector memory CD4⁺ T cells play an important role in the protective immunity against chronic infections, little is known about the exact mechanisms responsible for their functioning and maintenance, as well as their effects on innate immune cells. Here we review recent data on the role of IFN-γ priming as a mechanism affecting both innate immune cells and effector memory CD4⁺ T cells. Suboptimal concentrations of IFN-γ are seemingly crucial for the optimization of innate immune cell functions (including phagocytosis and destruction of reminiscent pathogens), as well as for the survival and functioning of effector memory CD4⁺ T cells. Thus, IFN-γ priming can thus be considered an important bridge between innate and adaptive immunity.

Epigenetic control of HIV-1 post integration latency: implications for therapy

With the development of effective combined anti-retroviral therapy (cART), there is significant reduction in deaths associated with human immunodeficiency virus type 1 (HIV-1) infection. However, the complete cure of HIV-1 infection is difficult to achieve without the elimination of latent reservoirs which exist in the infected individuals even under cART regimen. These latent reservoirs established during early infection have long life span, include resting CD4⁺ T cells, macrophages, central nervous system (CNS) resident macrophage/microglia, and gut-associated lymphoid tissue/macrophages, and can actively produce virus upon interruption of the cART. Several epigenetic and non-epigenetic mechanisms have been implicated in the regulation of viral latency. Epigenetic mechanisms such as histone post translational modifications (e.g., acetylation and methylation) and DNA methylation of the proviral DNA and microRNAs are involved in the establishment of HIV-1 latency. The better understanding of epigenetic mechanisms modulating HIV-1 latency could give clues for the complete eradication of these latent reservoirs. Several latency-reversing agents (LRA) have been found effective in reactivating HIV-1 reservoirs in vitro, ex vivo, and in vivo. Some of these agents target epigenetic modifications to elicit viral expression in order to kill latently infected cells through viral cytopathic effect or host immune response. These therapeutic approaches aimed at achieving a sterilizing cure (elimination of HIV-1 from the human body). In the present review, we will discuss our current understanding of HIV-1 epigenomics and how this information can be moved from the laboratory bench to the patient’s bedside.

Matrix M(TM) adjuvanted virosomal H5N1 vaccine induces balanced Th1/Th2 CD4(+) T cell responses in man

T cellular responses play a significant role in mediating protective immune responses against influenza in humans. In the current study, we evaluated the ability of a candidate virosomal H5N1 vaccine adjuvanted with Matrix M(TM) to induce CD4(+) and CD8(+) T cell responses in a phase 1 clinical trial. We vaccinated 60 healthy adult volunteers (at days 0 and 21) with 30 μg haemagglutinin (HA) alone or 1.5, 7.5, or 30 μg HA formulated with Matrix M(TM). To evaluate the T cellular responses, lymphocytes were stimulated in vitro with homologous (A/Vietnam/1194/2004 [H5N1]) and heterologous H5N1 (A/Anhui/1/05 or A/Bar-headed Goose/Qinghai/1A/05) antigens. The antigen-specific cytokine responses were measured by intracellular cytokine staining and by multiplex (Luminex) assays. An increase in CD4(+) Th1 and Th2 cytokines was detected 21 days after the first vaccine dose. No increase in Th cytokine responses was observed after the second dose, although it is possible that the cytokine levels peaked earlier than sampling point at day 42. Formulation with the Matrix M(TM) adjuvant augmented both the homologous and cross-reactive cytokine response. Antigen-specific CD8(+) T cell responses were detected only in a few vaccinated individuals. The concentrations of Th1 and to a lesser extent, Th2 cytokines at 21 days post-vaccination correlated moderately with subsequent days 35 and 180 serological responses as measured by the microneutralisation, haemagglutination inhibition, and single radial hemolysis assays. Results presented here show that the virosomal H5N1 vaccine induced balanced Th1/Th2 cytokine responses and that Matrix M(TM) is a promising adjuvant for future development of candidate pandemic influenza vaccines.

HIV-1 Tat immunization restores immune homeostasis and attacks the HAART-resistant blood HIV DNA: results of a randomized phase II exploratory clinical trial

BACKGROUND

The phase II multicenter, randomized, open label, therapeutic trial (ISS T-002, Clinicaltrials.gov NCT00751595) was aimed at evaluating the immunogenicity and the safety of the biologically active HIV-1 Tat protein administered at 7.5 or 30 μg, given 3 or 5 times monthly, and at exploring immunological and virological disease biomarkers. The study duration was 48 weeks, however, vaccinees were followed until the last enrolled subject reached the 48 weeks. Reported are final data up to 144 weeks of follow-up. The ISS T-002 trial was conducted in 11 clinical centers in Italy on 168 HIV positive subjects under Highly Active Antiretroviral Therapy (HAART), anti-Tat Antibody (Ab) negative at baseline, with plasma viremia <50 copies/mL in the last 6 months prior to enrollment, and CD4(+) T-cell number ≥200 cells/μL. Subjects from a parallel observational study (ISS OBS T-002, Clinicaltrials.gov NCT0102455) enrolled at the same clinical sites with the same criteria constituted an external reference group to explore biomarkers of disease.

RESULTS

The vaccine was safe and well tolerated and induced anti-Tat Abs in most patients (79%), with the highest frequency and durability in the Tat 30 μg groups (89%) particularly when given 3 times (92%). Vaccination promoted a durable and significant restoration of T, B, natural killer (NK) cells, and CD4(+) and CD8(+) central memory subsets. Moreover, a significant reduction of blood proviral DNA was seen after week 72, particularly under PI-based regimens and with Tat 30 μg given 3 times (30 μg, 3x), reaching a predicted 70% decay after 3 years from vaccination with a half-life of 88 weeks. This decay was significantly associated with anti-Tat IgM and IgG Abs and neutralization of Tat-mediated entry of oligomeric Env in dendritic cells, which predicted HIV-1 DNA decay. Finally, the 30 μg, 3x group was the only one showing significant increases of NK cells and CD38(+)HLA-DR(+)/CD8(+) T cells, a phenotype associated with increased killing activity in elite controllers.

CONCLUSIONS

Anti-Tat immune responses are needed to restore immune homeostasis and effective anti-viral responses capable of attacking the virus reservoir. Thus, Tat immunization represents a promising pathogenesis-driven intervention to intensify HAART efficacy.

CD4 T-cell memory generation and maintenance

Immunologic memory is the adaptive immune system's powerful ability to remember a previous antigen encounter and react with accelerated vigor upon antigen re-exposure. It provides durable protection against reinfection with pathogens and is the foundation for vaccine-induced immunity. Unlike the relatively restricted immunologic purview of memory B cells and CD8 T cells, the field of CD4 T-cell memory must account for multiple distinct lineages with diverse effector functions, the issue of lineage commitment and plasticity, and the variable distribution of memory cells within each lineage. Here, we discuss the evidence for lineage-specific CD4 T-cell memory and summarize the known factors contributing to memory-cell generation, plasticity, and long-term maintenance.

Distinct p21 requirements for regulating normal and self-reactive T cells through IFN-γ production

Self/non-self discrimination characterizes immunity and allows responses against pathogens but not self-antigens. Understanding the principles that govern this process is essential for designing autoimmunity treatments. p21 is thought to attenuate autoreactivity by limiting T cell expansion. Here, we provide direct evidence for a p21 role in controlling autoimmune T cell autoreactivity without affecting normal T cell responses. We studied C57BL/6, C57BL/6/lpr and MRL/lpr mice overexpressing p21 in T cells, and showed reduced autoreactivity and lymphadenopathy in C57BL/6/lpr, and reduced mortality in MRL/lpr mice. p21 inhibited effector/memory CD4(+) CD8(+) and CD4(-)CD8(-) lpr T cell accumulation without altering defective lpr apoptosis. This was mediated by a previously non-described p21 function in limiting T cell overactivation and overproduction of IFN-γ, a key lupus cytokine. p21 did not affect normal T cell responses, revealing differential p21 requirements for autoreactive and normal T cell activity regulation. The underlying concept of these findings suggests potential treatments for lupus and autoimmune lymphoproliferative syndrome, without compromising normal immunity.

Mechanisms of Memory T Cell Activation and Effective Immunity

Effective immunization induces the development of populations of robust effector lymphocytes specific for the immunizing antigens. Amongst them are cytotoxic/CD8(+)T lymphocytes, which few will further differentiate into long-lived memory cells persisting in the host and exhibiting improved functional characteristics. The current model is that such memory cells can confer rapid host protection upon cognate antigen-mediated activation and direct killing of infected cells. In this chapter, we discuss work from our group and others that highlight the contribution of inflammatory cytokines to memory CD8(+) T cell activation and of cytolysis-independent mechanisms of host protection.