ICOS co-stimulatory receptor is essential for T-cell activation and function

NMR-derived secondary structure of the full-length Ox40 mRNA 3'UTR and its multivalent binding to the immunoregulatory RBP Roquin

Control of posttranscriptional mRNA decay is a crucial determinant of cell homeostasis and differentiation. mRNA lifetime is governed by cis-regulatory elements in their 3′ untranslated regions (UTR). Despite ongoing progress in the identification of cis elements we have little knowledge about the functional and structural integration of multiple elements in 3′UTR regulatory hubs and their recognition by mRNA-binding proteins (RBPs). Structural analyses are complicated by inconsistent mapping and prediction of RNA fold, by dynamics, and size. We here, for the first time, provide the secondary structure of a complete mRNA 3′UTR. We use NMR spectroscopy in a divide-and-conquer strategy complemented with SAXS, In-line probing and SHAPE-seq applied to the 3′UTR of Ox40 mRNA, which encodes a T-cell co-receptor repressed by the protein Roquin. We provide contributions of RNA elements to Roquin-binding. The protein uses its extended bi-modal ROQ domain to sequentially engage in a 2:1 stoichiometry with a 3′UTR core motif. We observe differential binding of Roquin to decay elements depending on their structural embedment. Our data underpins the importance of studying RNA regulation in a full sequence and structural context. This study serves as a paradigm for an approach in analysing structured RNA-regulatory hubs and their binding by RBPs.

Dissecting the cellular landscape and transcriptome network in viral myocarditis by single-cell RNA sequencing

Coxsackievirus B3 (CVB3)-induced myocarditis is commonly employed to study viral pathogenesis in mice. Chronically affected mice may develop dilated cardiomyopathy, which may involve the mediation of immune and nonimmune cells. To dissect this complexity, we performed single-cell RNA sequencing on heart cells from healthy and myocarditic mice, leading us to note significant proportions of myeloid cells, T cells, and fibroblasts. Although the transcriptomes of myeloid cells were mainly of M2 phenotype, the Th17 cells, CTLs, and Treg cells had signatures critical for cytotoxic functions. Fibroblasts were heterogeneous expressing genes important in fibrosis and regulation of inflammation and immune responses. The intercellular communication networks revealed unique interactions and signaling pathways in the cardiac cellulome, whereas myeloid cells and T cells had upregulated unique transcription factors modulating cardiac remodeling functions. Together, our data suggest that M2 cells, T cells, and fibroblasts may cooperatively or independently participate in the pathogenesis of viral myocarditis.

B Cells Are Not Involved in the Regulation of Adenoviral TGF-β1- or Bleomycin-Induced Lung Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is an irreversible, age-related diffuse parenchymal lung disease of poorly defined etiology. Many patients with IPF demonstrate distinctive lymphocytic interstitial infiltrations within remodeled lung tissue with uncertain pathogenetic relevance. Histopathological examination of explant lung tissue of patients with IPF revealed accentuated lymphoplasmacellular accumulations in close vicinity to, or even infiltrating, remodeled lung tissue. Similarly, we found significant accumulations of B cells interfused with T cells within remodeled lung tissue in two murine models of adenoviral TGF-β1 or bleomycin (BLM)-induced lung fibrosis. Such B cell accumulations coincided with significantly increased lung collagen deposition, lung histopathology, and worsened lung function in wild-type (WT) mice. Surprisingly, B cell-deficient µMT knockout mice exhibited similar lung tissue remodeling and worsened lung function upon either AdTGF-β1 or BLM as for WT mice. Comparative transcriptomic profiling of sorted B cells collected from lungs of AdTGF-β1- and BLM-exposed WT mice identified a large set of commonly regulated genes, but with significant enrichment observed for Gene Ontology terms apparently not related to lung fibrogenesis. Collectively, although we observed B cell accumulations in lungs of IPF patients as well as two experimental models of lung fibrosis, comparative profiling of characteristic features of lung fibrosis between WT and B cell-deficient mice did not support a major involvement of B cells in lung fibrogenesis in mice.

Expression of Immune Checkpoint Molecules PD1, PD-L1 and ICOS in Mycosis Fungoides and Sézary Syndrome: Association with Disease Stage and Clinical Outcome

Background

The relationship between immune checkpoint status and disease outcome is a major focus of research in cutaneous T‐cell lymphoma (CTCL), a disfiguring neoplastic dermatological disorder. Mycosis fungoides (MF) and Sézary syndrome (SS) are the two most common types of CTCL.

Objectives

The aim was to evaluate the immune checkpoint markers programmed death protein 1 (PD1), inducible T‐cell co‐stimulator (ICOS) and programmed death‐ligand 1 (PD‐L1) in skin biopsies from patients with CTCL relative to disease stage and overall survival.

Methods

This consecutive case series enrolled 47 patients: 57% had stage IA–IIA disease and 43% had stage IIB–IVA2 disease (including seven with SS).

Results

PD1, PD‐L1 and ICOS expression was seen in all biopsies. Notably, PD‐L1 was predominantly expressed on histiocytes/macrophages, but focal expression on CTCL cells was seen. High expression of either ICOS or PD‐L1 was associated with advanced‐stage disease (P = 0·007 for both) and with the appearance of large‐cell transformation (LCT), a histopathological feature associated with a poor prognosis (ICOS: P = 0·02; PD‐L1: P = 0·002). PD1 expression was not significantly associated with disease stage (P = 0·12) or LCT (P = 0·49), but expression was high in SS biopsies. A high combined checkpoint marker score (PD1, PD‐L1 and ICOS) was associated with advanced‐stage disease (P = 0·001), LCT (P = 0·021) and lower overall survival (P = 0·014).

Conclusions

These findings demonstrate the existence of a complex immunoregulatory microenvironment in CTCL and support the development of immunotherapies targeting ICOS and PD‐L1 in advanced disease.

CD4+ICOS+Foxp3+: a sub-population of regulatory T cells contribute to malaria pathogenesis

BACKGROUND

Regulatory T cells are known to play a key role to counter balance the protective immune response and immune mediated pathology. However, the role of naturally occurring regulatory cells CD4⁺CD25⁺Foxp3⁺ in malaria infection during the disease pathogenesis is controversial. Beside this, ICOS molecule has been shown to be involved in the development and function of regulatory T cell enhance IL-10 production. Therefore, possible involvement of the ICOS dependent regulatory CD4⁺ICOS⁺Foxp3⁺ T cells in resistance/susceptibility during malaria parasite is explored in this study.

METHODS

5 × 10⁵ red blood cells infected with non-lethal and lethal parasites were inoculated in female Balb/c mice by intra-peritoneal injection. Infected or uninfected mice were sacrificed at early (3rd day post infection) and later stage (10th day post infection) of infection. Harvested cells were analysed by using flow cytometer and serum cytokine by Bioplex assay.

RESULTS

Thin blood films show that percentages of parasitaemia increases with disease progression in infections with the lethal malaria parasite and mice eventually die by day 14th post-infection. Whereas in case of non-lethal malaria parasite, parasitaemia goes down by 7th day post infection and gets cleared within 13th day. The number of CD4⁺ ICOS⁺ T cells increases in lethal infection with disease progression. Surprisingly, in non-lethal parasite, ICOS expression decreases after day 7th post infection as parasitaemia goes down. The frequency of CD4⁺ICOS⁺FoxP3⁺ Tregs was significantly higher in lethal parasitic infection as compared to the non-lethal parasite. The level of IL-12 cytokine was remarkably higher in non-lethal infection compared to the lethal infection. In contrast, the level of IL-10 cytokines was higher in lethal parasite infection compared to the non-lethal parasite.

CONCLUSION

Taken together, these data suggest that lethal parasite induce immunosuppressive environment, protecting from host immune responses and help the parasite to survive whereas non-lethal parasite leads to low frequencies of Treg cells seldom impede immune response that allow the parasite to get self-resolved.

Egg-Phosphatidylcholine Attenuates T-Cell Dysfunction in High-Fat Diet Fed Male Wistar Rats

Obesity is associated with immune dysfunction including an impaired T-cell function characterized by a lower IL-2 (proliferation marker) production after stimulation. Phosphatidylcholine (PC), a form of choline mostly found in eggs, has been shown to beneficially modulate T-cell responses during the lactation period by increasing the production of IL-2. To determine the impact of egg-PC as part of a high-fat diet on immune function we randomly fed male Wistar rats one of three diets containing the same amount of total choline but differing in the form of choline: 1-Control low fat [CLF, 10% wt/wt fat, 100% free choline (FC)]; 2- Control high-fat (CHF, 25% wt/wt fat, 100% FC); 3- PC high-fat (PCHF, 25% wt/wt, 100% PC). After 9 weeks of feeding, rats were euthanized. Cell phenotypes and ex vivo cytokine production by splenocytes stimulated with phorbol 12-myristate 13-acetate plus ionomycin (PMA+I), lipopolysaccharide (LPS) and pokeweed (PWM) were measured by flow cytometry and ELISA, respectively. Rats fed the PCHF diet had a lower proportion of CD3+ cells when compared to both the CLF and the CHF. Following PMA+I stimulation, splenocytes from the CHF group produced less IL-2 and TNF-α compared to CLF and PCHF groups. No significant differences in cytokine production were found among groups after LPS and PWM stimulation. Our results show that feeding a high-fat diet impairs T-cell responses, as measured by ex vivo cytokine production, which can be attenuated by providing egg-PC.

Coccidiosis: Recent Progress in Host Immunity and Alternatives to Antibiotic Strategies

Coccidiosis is an avian intestinal disease caused by several distinct species of Eimeria parasites that damage the host’s intestinal system, resulting in poor nutrition absorption, reduced growth, and often death. Increasing evidence from recent studies indicates that immune-based strategies such as the use of recombinant vaccines and various dietary immunomodulating feed additives can improve host defense against intracellular parasitism and reduce intestinal damage due to inflammatory responses induced by parasites. Therefore, a comprehensive understanding of the complex interactions between the host immune system, gut microbiota, enteroendocrine system, and parasites that contribute to the outcome of coccidiosis is necessary to develop logical strategies to control coccidiosis in the post-antibiotic era. Most important for vaccine development is the need to understand the protective role of the local intestinal immune response and the identification of various effector molecules which mediate anti-coccidial activity against intracellular parasites. This review summarizes the current understanding of the host immune response to coccidiosis in poultry and discusses various non-antibiotic strategies which are being developed for coccidiosis control. A better understanding of the basic immunobiology of pertinent host–parasite interactions in avian coccidiosis will facilitate the development of effective anti-Eimeria strategies to mitigate the negative effects of coccidiosis.

Pathogenic TNF-α drives peripheral nerve inflammation in an Aire-deficient model of autoimmunity

Immune cells infiltrate the peripheral nervous system (PNS) after injury and with autoimmunity, but their net effect is divergent. After injury, immune cells are reparative, while in inflammatory neuropathies (e.g., Guillain Barré Syndrome and chronic inflammatory demyelinating polyneuropathy), immune cells are proinflammatory and promote autoimmune demyelination. An understanding of immune cell phenotypes that distinguish these conditions may, therefore, reveal new therapeutic targets for switching immune cells from an inflammatory role to a reparative state. In an autoimmune regulator (Aire)-deficient mouse model of inflammatory neuropathy, we used single-cell RNA sequencing of sciatic nerves to discover a transcriptionally heterogeneous cellular landscape, including multiple myeloid, innate lymphoid, and lymphoid cell types. Analysis of cell-cell ligand-receptor interactions uncovered a macrophage-mediated tumor necrosis factor-α (TNF-α) signaling axis that is induced by interferon-γ and required for initiation of autoimmune demyelination. Developmental trajectory visualization suggested that TNF-α signaling is associated with metabolic reprogramming of macrophages and polarization of macrophages from a reparative state in injury to a pathogenic, inflammatory state in autoimmunity. Autocrine TNF-α signaling induced macrophage expression of multiple genes (Clec4e, Marcksl1, Cxcl1, and Cxcl10) important in immune cell activation and recruitment. Genetic and antibody-based blockade of TNF-α/TNF-α signaling ameliorated clinical neuropathy, peripheral nerve infiltration, and demyelination, which provides preclinical evidence that the TNF-α axis may be effectively targeted to resolve inflammatory neuropathies.

Expression Profiles and Prognostic Value of Multiple Inhibitory Checkpoints in Head and Neck Lymphoepithelioma-Like Carcinoma

Background

Inhibitory checkpoints are promising antitumor targets and predictive biomarkers in a variety of cancers. We aimed to identify the expression levels and prognostic value of multiple inhibitory checkpoints supported by preclinical and clinical evidence in head and neck lymphoepithelioma-like carcinoma (HNLELC).

Methods

The expression of seven inhibitory checkpoints were evaluated in the tumor nest (TN) and tumor stroma (TS) of 102 HNLELC specimens using immunohistochemistry and digital pathology, and an inhibitory checkpoint-based signature (ICS) was subsequently constructed using the LASSO Cox regression model.

Results

PD-L1, B7H3, and IDO-1 were mostly expressed in the TN, with median H-score of TN vs TS: 63.6 vs 14.6; 8.1 vs 1.0; 61.5 vs 34.7 (all P < 0.001), whereas PD-1, TIM-3, LAG-3, and VISTA were mainly observed in the TS, with median H-score of TN vs TS: 0.2 vs 12.4, 3.4 vs 7.1, 6.2 vs 11.9, 16.4 vs 47.2 (all P < 0.001), respectively. The most common simultaneously expressed combinations consisted of PD-L1 + B7H3 + IDO-1 + TIM-3 + LAG-3 + VISTA and B7H3 + IDO-1 + TIM-3 + LAG-3 in the TN (both occurring in 8.8% of patients) and PD-L1 + B7H3 + IDO-1 in the TS (4.9%). In addition, high-ICS patients had shorter 5-year disease-free (40.6% vs 81.7%; P < 0.001), regional recurrence-free (63.5% vs 88.2%; P = 0.003), and overall survival (73.5% vs 92.9%; P = 0.006) than low-ICS patients. Multivariate analysis revealed that ICS represented an independent predictor, which could significantly complement the predictive performance of TNM stage for 3-year (AUC 0.724 vs 0.619, P = 0.014), 5-year (AUC 0.727 vs 0.640, P = 0.056), and 10-year disease-free survival (AUC 0.815 vs 0.709, P = 0.023).

Conclusions

The expression of inhibitory checkpoints and ICS classifier may increase the prognostic value of the TNM staging system and guide the rational design of personalized inhibitory checkpoint blockade therapy in HNLELC.

Identification of key regulators in Sarcoidosis through multidimensional systems biological approach

Sarcoidosis is a multi-organ disorder where immunology, genetic and environmental factors play a key role in causing Sarcoidosis, but its molecular mechanism remains unclear. Identification of its genetics profiling that regulates the Sarcoidosis network will be one of the main challenges to understand its aetiology. We have identified differentially expressed genes (DEGs) by analyzing the gene expression profiling of Sarcoidosis and compared it with healthy control. Gene set enrichment analysis showed that these DEGs were mainly enriched in the inflammatory response, immune system, and pathways in cancer. Sarcoidosis protein interaction network was constructed by a total of 877 DEGs (up-down) and calculated its network topological properties, which follow hierarchical scale-free fractal nature up to six levels of the organization. We identified a large number of leading hubs that contain six key regulators (KRs) including ICOS, CTLA4, FLT3LG, CD33, GPR29 and ITGA4 are deeply rooted in the network from top to bottom, considering a backbone of the network. We identified the transcriptional factors (TFs) which are closely interacted with KRs. These genes and their TFs regulating the Sarcoidosis network are expected to be the main target for the therapeutic approaches and potential biomarkers. However, experimental validations of KRs needed to confirm their efficacy.

ICOS expression is required for maintenance but not the formation of germinal centers in the spleen in response to P. yoelii infection

Inducible T cell co-stimulator (ICOS) plays a key role in the differentiation and maintenance of follicular helper T (Tfh) cells and thus germinal center (GC) formation. Previously, our lab showed in a Plasmodium chabaudi infection model that Icos^-/- mice were significantly impaired in their ability to form GCs despite a persistent infection and thus a continued antigen (Ag) load. Here, we show that resolution of a primary infection with P. yoelii, was delayed in Icos^-/- mice. This phenotype was associated with a reduction in the accumulation of Tfh-like and GC Tfh cells and an early deficiency in Ag-specific antibody (Ab) production. However, Icos^-/- mice could form GCs, though they were less frequent in number than in wild-type (WT) mice. Nonetheless, the Ag-specific Abs from Icos^-/- mice lacked signs of affinity maturation, suggesting functional defects associated with these GCs. Eventually, these GC structures dissipated more rapidly in Icos^-/- mice than in WT mice. Moreover, the ability of Icos^-/- mice to form these GC structures is not reliant on the high Ag load associated with P. yoelii infections, as GC formation was preserved in Icos^-/- mice treated with atovaquone. Finally, mice were unable to form secondary GCs in the absence of ICOS after re-challenge. Overall, these data demonstrate the necessity of ICOS in the maintenance of Tfh cells, the formation and maintenance of sufficient numbers of functioning GCs, and the ability to generate new GC structures after re-infection with P. yoelii.

Altered expression of costimulatory molecules in dementias

Although the expression of co-stimulatory molecules plays an important role in the immune system, only little is known about their regulation in dementias. Therefore, we determined the expression of CD28, ICOS (CD278) and CTLA-4 (CD152) by CD4 + and CD8 + T cells in the peripheral blood of patients with mild cognitive impairment (MCI; N = 19), Alzheimer's disease (AD; N = 51), vascular dementia (VD; N = 21) and frontotemporal dementia (FTD; N = 6) at the point in time of diagnosis compared to 19 non-demented elderly persons. The expression of CD28 and ICOS by CD4 + and CD8 + T cells was not changed in AD, FTD or VD patients. The expression of the negative regulator CTLA-4 was increased by CD4 + T cells from AD and FTD patients and by CD8 + T cells from VD patients. The classification of the AD patients according to the severity of the disorder showed stage-dependent alterations of CD28, ICOS and CTLA-4 expression. In AD patients, the correlation analysis showed an association between the decline in CD28 + T cells and the increase in CTLA-4 + T cells with cognitive decline, measured by the mini-mental state examination (MMSE), tau proteins and Amyloid-β, important AD biomarkers in cerebrospinal fluid (CSF). In FTD patients, a positive association between Q Albumin, a marker for blood-CSF-barrier function, and CD28 and a negative correlation between Q Albumin and ICOS expression were determined. Our data suggest a dysregulated balance between the expression of negative and positive co-stimulatory molecules by T cells in AD patients, which might contribute to chronic inflammation observed in dementia.

The ICOS-ICOSL pathway tunes thymic selection

Negative selection of developing T cells plays a significant role in T cell tolerance to self-antigen. This process relies on thymic antigen presenting cells which express both self-antigens as well as co-signaling molecules. Inducible T cell costimulator (ICOS) belongs to the CD28 family of co-signaling molecules and binds to ICOS ligand (ICOSL). The ICOS signaling pathway plays important roles in shaping the immune response to infections, but its role in central tolerance is less well understood. Here we show that ICOSL is expressed by subsets of thymic dendritic cells and medullary thymic epithelial cells as well as thymic B cells. ICOS expression is upregulated as T cells mature in the thymus and correlates with T cell receptor signal strength during thymic selection. We also provide evidence of a role for ICOS signaling in mediating negative selection. Our findings suggest that ICOS may fine-tune T cell receptor signals during thymic selection contributing to the generation of a tolerant T cell population.

The role of ICOS in allergic disease: Positive or Negative?

With the rapid increase in the incidence of allergic diseases, the mechanisms underlying the development of these diseases have received a great deal of attention, and this is particularly true in regard to the role of ICOS in allergic diseases. Current studies have revealed that ICOS affects the functional activity of multiple immune cells that modulate the adaptive immune system. Additionally, ICOS also plays a crucial role in mediating cellular immunity and coordinating the response of the entire immune system, and thus, it plays a role in allergic reactions. However, the ICOS/ICOS-ligand (ICOS-L) axis functions in a dual role during the development of multiple allergic diseases. In this review, we explore the role of ICOS/ICOSL in the context of different immune cells that function in allergic diseases, and we summarize recent advances in their contribution to these diseases.

Immune Checkpoints and Innate Lymphoid Cells-New Avenues for Cancer Immunotherapy

Immune checkpoints (IC) are broadly characterized as inhibitory pathways that tightly regulate the activation of the immune system. These molecular "brakes" are centrally involved in the maintenance of immune self-tolerance and represent a key mechanism in avoiding autoimmunity and tissue destruction. Antibody-based therapies target these inhibitory molecules on T cells to improve their cytotoxic function, with unprecedented clinical efficacies for a number of malignancies. Many of these ICs are also expressed on innate lymphoid cells (ILC), drawing interest from the field to understand their function, impact for anti-tumor immunity and potential for immunotherapy. In this review, we highlight ILC specificities at different tissue sites and their migration potential upon inflammatory challenge. We further summarize the current understanding of IC molecules on ILC and discuss potential strategies for ILC modulation as part of a greater anti-cancer armamentarium.

PD-L1 is expressed on human activated naive effector CD4+ T cells. Regulation by dendritic cells and regulatory CD4+ T cells

The T cell expression of various co-signalling receptors from the CD28 immunoglobulin superfamily (Inducible T cell co-stimulator (ICOS), Programmed cell death 1(PD-1), cytotoxic T lymphocyte associated protein 4 (CTLA-4), B and T lymphocyte attenuator (BTLA) or from the tumour necrosis factor receptor superfamily (glucocorticoid-induced TNFR family related (GITR), 4-1BB, and CD27), is essential for T cell responses regulation. Other receptors (such as T cell immunoglobulin and mucin domain-containing protein 3, T cell immunoglobulin and T cell immunoglobulin and ITIM domain (TIGIT), and lymphocyte activation gene 3) are also involved in this regulation. Disturbance of the balance between activating and inhibitory signals can induce autoimmunity. We have developed an in vitro assay to simultaneously assess the function of naive CD4⁺ effector T cells (TEFFs), dendritic cells (DCs) and regulatory T cells (TREGs) and the expression of co-signalling receptors. By running the assay on cells from healthy adult, we investigated the regulation of activated T cell proliferation and phenotypes. We observed that TEFFs activated by DCs mainly expressed BTLA, ICOS and PD-1, whereas activated TREGs mainly expressed TIGIT, ICOS, and CD27. Strikingly, we observed that programmed death-ligand 1 (PD-L1) was significantly expressed on both activated TEFFs and TREGs. Moreover, high PD-L1 expression on activated TEFFs was correlated with a higher index of proliferation. Lastly, and in parallel to the TREG-mediated suppression of TEFF proliferation, we observed the specific modulation of the surface expression of PD-L1 (but not other markers) on activated TEFFs. Our results suggest that the regulation of T cell proliferation is correlated with the specific expression of PD-L1 on activated TEFFs.

Dietary suppression of MHC class II expression in intestinal epithelial cells enhances intestinal tumorigenesis

Little is known about how interactions of diet, intestinal stem cells (ISCs), and immune cells affect early-stage intestinal tumorigenesis. We show that a high-fat diet (HFD) reduces the expression of the major histocompatibility complex class II (MHC class II) genes in intestinal epithelial cells, including ISCs. This decline in epithelial MHC class II expression in a HFD correlates with reduced intestinal microbiome diversity. Microbial community transfer experiments suggest that epithelial MHC class II expression is regulated by intestinal flora. Mechanistically, pattern recognition receptor (PRR) and interferon-gamma (IFNγ) signaling regulates epithelial MHC class II expression. MHC class II-negative (MHC-II-) ISCs exhibit greater tumor-initiating capacity than their MHC class II-positive (MHC-II+) counterparts upon loss of the tumor suppressor Apc coupled with a HFD, suggesting a role for epithelial MHC class II-mediated immune surveillance in suppressing tumorigenesis. ISC-specific genetic ablation of MHC class II increases tumor burden cell autonomously. Thus, HFD perturbs a microbiome-stem cell-immune cell interaction that contributes to tumor initiation in the intestine.

The Positive and Negative Immunoregulatory Role of B7 Family: Promising Novel Targets in Gastric Cancer Treatment

Gastric cancer (GC), with a heterogeneous nature, is the third leading cause of death worldwide. Over the past few decades, stable reductions in the incidence of GC have been observed. However, due to the poor response to common treatments and late diagnosis, this cancer is still considered one of the lethal cancers. Emerging methods such as immunotherapy with immune checkpoint inhibitors (ICIs) have transformed the landscape of treatment for GC patients. There are presently eleven known members of the B7 family as immune checkpoint molecules: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1, CD274), B7-DC (PDCD1LG2, PD-L2, CD273), B7-H2 (B7RP1, ICOS-L, CD275), B7-H3 (CD276), B7-H4 (B7x, B7S1, Vtcn1), B7-H5 (VISTA, Gi24, DD1α, Dies1 SISP1), B7-H6 (NCR3LG1), B7-H7 (HHLA2), and Ig-like domain-containing receptor 2 (ILDR2). Interaction of the B7 family of immune-regulatory ligands with the corresponding receptors resulted in the induction and inhibition of T cell responses by sending co-stimulatory and co-inhibitory signals, respectively. Manipulation of the signals provided by the B7 family has significant potential in the management of GC.

An integrated scalp and blood biomarker approach suggests the systemic nature of alopecia areata

BACKGROUND

Alopecia areata (AA) is characterized by immune dysregulation in both scalp and blood, but a large-scale approach establishing biomarkers of AA incorporating both scalp tissue and serum compartments is lacking. We aimed to characterize the transcriptomic signature of AA lesional and nonlesional scalp compared to healthy scalp and determine its relationship with the blood proteome in the same individuals, with comparative correlations to clinical AA disease severity.

METHODS

We evaluated lesional and nonlesional scalp tissues and serum from patients with moderate-to-severe AA (n = 18) and healthy individuals (n = 8). We assessed 33,118 genes in AA scalp tissue using RNAseq transcriptomic evaluation and 340 inflammatory proteins in serum using OLINK high-throughput proteomics. Univariate and multivariate approaches were used to correlate disease biomarkers with Severity of Alopecia Tool (SALT).

RESULTS

A total of 608 inflammatory genes were differentially expressed in lesional AA scalp (fold change/FCH>1.5, false discovery rate/FDR<0.05) including Th1 (IFNG/IL12B/CXCL11), Th2 (IL13/CCL18), and T-cell activation-related (ICOS) products. Th1/Th2-related markers were significantly correlated with AA clinical severity in lesional/nonlesional tissue, while keratins (KRT35/KRT83/KRT81) were significantly downregulated in lesional compared to healthy scalp (p < .05). Expression of cardiovascular/atherosclerosis-related markers (MMP9/CCL2/IL1RL1/IL33R/ST2/AGER) in lesional scalp correlated with their corresponding serum expression (p < .05). AA scalp demonstrated significantly greater biomarker dysregulation compared to blood. An integrated multivariate approach combining scalp and serum biomarkers improved correlations with disease severity/SALT.

CONCLUSION

This study contributes a unique understanding of the phenotype of moderate-to-severe AA with an integrated scalp and serum biomarker model suggesting the systemic nature of the disease, advocating for the need for immune-based systemic treatment.

Scalable, multimodal profiling of chromatin accessibility, gene expression and protein levels in single cells

Recent technological advances have enabled massively parallel chromatin profiling with scATAC-seq (single-cell assay for transposase accessible chromatin by sequencing). Here we present ATAC with select antigen profiling by sequencing (ASAP-seq), a tool to simultaneously profile accessible chromatin and protein levels. Our approach pairs sparse scATAC-seq data with robust detection of hundreds of cell surface and intracellular protein markers and optional capture of mitochondrial DNA for clonal tracking, capturing three distinct modalities in single cells. ASAP-seq uses a bridging approach that repurposes antibody:oligonucleotide conjugates designed for existing technologies that pair protein measurements with single-cell RNA sequencing. Together with DOGMA-seq, an adaptation of CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing) for measuring gene activity across the central dogma of gene regulation, we demonstrate the utility of systematic multi-omic profiling by revealing coordinated and distinct changes in chromatin, RNA and surface proteins during native hematopoietic differentiation and peripheral blood mononuclear cell stimulation and as a combinatorial decoder and reporter of multiplexed perturbations in primary T cells.

PD-1/PD-L1 blockade: Prospectives for immunotherapy in cancer and autoimmunity

Immune checkpoint blockade therapy (ICBT) has become a successful cancer treatment approach in the field of cancer immunotherapy. Blockade of programmed death 1 (PD-1) and programmed death-ligand 1 (PD-L1) with monoclonal antibodies have been known as successful examples of cancer immunotherapy in recent years. Although ICBT has been shown to be beneficial in cancers, such benefits have only been seen in a portion of cancer patients. In this regard, enhancing the therapeutic effects of inhibiting PD-1 and PD-L1 and reducing the side effects of this approach can be considered as a potential approach in a successful ICBT. In this review, we have highlighted new viewpoints regarding improving the therapeutic effect of PD-1 and PD-L1 blockades in cancer therapy. Besides, their expression levels as a biomarker with prognostic value, their role in intestinal microbiota modulation, combination therapy, and immune-related side effects (irAEs) have been discussed.

Effect of Cellular-Based Artificial Antigen Presenting Cells Expressing ICOSL, in T-cell Subtypes Differentiation and Activation

Purposes: Effective and selective T-cell activation and proliferation during the T-cell expansion phase of a cellular adoptive immunotherapy method, challenging because recent studies revealed the importance of each subtype of T-cells in different immunologic strategies against tumors, like CAR-T cell therapies. Artificial antigen presenting cells (aAPCs) regarded as a natural way to manipulate T-cell subtypes activation and specific proliferation. In the current study, we utilized K562 cells based aAPC method expressing the ICOSL molecule, to evaluate T-cell subtypes differentiation rate and functional status. Methods: CD3+T-cells isolated and, co-cultured with ICOSL expressing K562 cells. After 4, 6, and 10 days selective CD markers of T-cell subtypes and each subtype's activity-related genes levels evaluated by qPCR methods. Results: During the culture period, CD4+ Th related phenotype reduced continuously, and in day 10^th of culture CD4+ T-cell's population significantly reduced (P =0.029). In contrast, the CD8+ population ratio was ascending during the study period but was not statistically significant. FoxP3+CD25-, Treg population ratio was significantly increased during the time in comparison with the control group, as well as memory T-cell phenotypic marker, CD127+, expressing cells ratio. T-cell subpopulations activity-related genes expression levels evaluated too, and the Th1 related IL-2 and INF-γ reductions observed alongside regulatory T-cells gene (IL-10) and Cytotoxic T-cell's related gene (Geranzym-A) elevations. Conclusion: We concluded that the K562-ICOSL based aAPC system is working and effective in T-cell short to medium culture periods, and this approach preparing relatively selective milieu for CD8+ T-Cell differentiation and much less Treg differentiation.

Azoximer Bromide: Mystery, Serendipity, and Promise

Azoximer bromide (AZB) was identified as an immunomodulator, and was initially developed and currently successfully indicated as one of several natural polyelectrolytes, a vaccine adjuvant, and an effective agent for the treatment of infectious and inflammatory diseases of viral, bacterial, and fungal origin. AZB has the potential to increase an individual's resistance to local and general infection and is indicated for the treatment of viral infections, and has also demonstrated clinical efficacy in the treatment of a variety of secondary immunodeficiencies. However, AZB may offer long-term promise beyond use against infection. Multiple clinical trials and research studies in cancer patients have reported favourable outcomes with AZB as well as an optimal safety and tolerability profile. The findings raise the possibility of direct antitumor properties. This literature review analyses the novel mechanisms that mediate the AZB direct anticancer effects. Overall, the evidence suggests that AZB has the hallmark of an agent that could be used to support existing cancer treatments at different stages of disease.

Defining the RBPome of primary T helper cells to elucidate higher-order Roquin-mediated mRNA regulation

Post-transcriptional gene regulation in T cells is dynamic and complex as targeted transcripts respond to various factors. This is evident for the Icos mRNA encoding an essential costimulatory receptor that is regulated by several RNA-binding proteins (RBP), including Roquin-1 and Roquin-2. Here, we identify a core RBPome of 798 mouse and 801 human T cell proteins by utilizing global RNA interactome capture (RNA-IC) and orthogonal organic phase separation (OOPS). The RBPome includes Stat1, Stat4 and Vav1 proteins suggesting unexpected functions for these transcription factors and signal transducers. Based on proximity to Roquin-1, we select ~50 RBPs for testing coregulation of Roquin-1/2 targets by induced expression in wild-type or Roquin-1/2-deficient T cells. Besides Roquin-independent contributions from Rbms1 and Cpeb4 we also show Roquin-1/2-dependent and target-specific coregulation of Icos by Celf1 and Igf2bp3. Connecting the cellular RBPome in a post-transcriptional context, we find contributions from multiple RBPs to the prototypic regulation of mRNA targets by individual trans-acting factors.

An extensive RNA binding protein atlas (RBPome) for primary T cells would be a useful resource. Here the authors use two different methods to characterise the mouse and human T cell RBPome and show regulation of Roquin-1/2 dependent and independent pathways.

Innate immune activation by checkpoint inhibition in human patient-derived lung cancer tissues

Although Pembrolizumab-based immunotherapy has significantly improved lung cancer patient survival, many patients show variable efficacy and resistance development. A better understanding of the drug’s action is needed to improve patient outcomes. Functional heterogeneity of the tumor microenvironment (TME) is crucial to modulating drug resistance; understanding of individual patients’ TME that impacts drug response is hampered by lack of appropriate models. Lung organotypic tissue slice cultures (OTC) with patients’ native TME procured from primary and brain-metastasized (BM) non-small cell lung cancer (NSCLC) patients were treated with Pembrolizumab and/or beta-glucan (WGP, an innate immune activator). Metabolic tracing with ¹³C₆-Glc/¹³C₅,¹⁵N₂-Gln, multiplex immunofluorescence, and digital spatial profiling (DSP) were employed to interrogate metabolic and functional responses to Pembrolizumab and/or WGP. Primary and BM PD-1⁺ lung cancer OTC responded to Pembrolizumab and Pembrolizumab + WGP treatments, respectively. Pembrolizumab activated innate immune metabolism and functions in primary OTC, which were accompanied by tissue damage. DSP analysis indicated an overall decrease in immunosuppressive macrophages and T cells but revealed microheterogeneity in immune responses and tissue damage. Two TMEs with altered cancer cell properties showed resistance. Pembrolizumab or WGP alone had negligible effects on BM-lung cancer OTC but Pembrolizumab + WGP blocked central metabolism with increased pro-inflammatory effector release and tissue damage. In-depth metabolic analysis and multiplex TME imaging of lung cancer OTC demonstrated overall innate immune activation by Pembrolizumab but heterogeneous responses in the native TME of a patient with primary NSCLC. Metabolic and functional analysis also revealed synergistic action of Pembrolizumab and WGP in OTC of metastatic NSCLC.

Re-Programming Autoreactive T Cells Into T-Regulatory Type 1 Cells for the Treatment of Autoimmunity

Systemic delivery of peptide-major histocompatibility complex (pMHC) class II-based nanomedicines can re-program cognate autoantigen-experienced CD4+ T cells into disease-suppressing T-regulatory type 1 (TR1)-like cells. In turn, these TR1-like cells trigger the formation of complex regulatory cell networks that can effectively suppress organ-specific autoimmunity without impairing normal immunity. In this review, we summarize our current understanding of the transcriptional, phenotypic and functional make up of TR1-like cells as described in the literature. The true identity and direct precursors of these cells remain unclear, in particular whether TR1-like cells comprise a single terminally-differentiated lymphocyte population with distinct transcriptional and epigenetic features, or a collection of phenotypically different subsets sharing key regulatory properties. We propose that detailed transcriptional and epigenetic characterization of homogeneous pools of TR1-like cells will unravel this conundrum.

Approaches for Controlling Antibody-Mediated Allograft Rejection Through Targeting B Cells

Both acute and chronic antibody-mediated allograft rejection (AMR), which are directly mediated by B cells, remain difficult to treat. Long-lived plasma cells (LLPCs) in bone marrow (BM) play a crucial role in the production of the antibodies that induce AMR. However, LLPCs survive through a T cell-independent mechanism and resist conventional immunosuppressive therapy. Desensitization therapy is therefore performed, although it is accompanied by severe side effects and the pathological condition may be at an irreversible stage when these antibodies, which induce AMR development, are detected in the serum. In other words, AMR control requires the development of a diagnostic method that predicts its onset before LLPC differentiation and enables therapeutic intervention and the establishment of humoral immune monitoring methods providing more detailed information, including individual differences in the susceptibility to immunosuppressive agents and the pathological conditions. In this study, we reviewed recent studies related to the direct or indirect involvement of immunocompetent cells in the differentiation of naïve-B cells into LLPCs, the limitations of conventional methods, and the possible development of novel control methods in the context of AMR. This information will significantly contribute to the development of clinical applications for AMR and improve the prognosis of patients who undergo organ transplantation.

Memory Generation and Re-Activation in Food Allergy

Recent evidence has highlighted the critical role of memory cells in maintaining lifelong food allergies, thereby identifying these cells as therapeutic targets. IgG⁺ memory B cells replenish pools of IgE-secreting cells upon allergen exposure, which contract thereafter due to the short lifespan of tightly regulated IgE-expressing cells. Advances in the detection and highly dimensional analysis of allergen-specific B and T cells from allergic patients have provided insight on their phenotype and function. The newly identified Th2A and Tfh13 populations represent a leap in our understanding of allergen-specific T cell phenotypes, although how these populations contribute to IgE memory responses remains poorly understood. Within, we discuss the mechanisms by which memory B and T cells are activated, integrating knowledge from human systems and fundamental research. We then focus on memory reactivation, specifically, on the pathways of secondary IgE responses. Throughout, we identify areas of future research which will help identify immunotargets for a transformative therapy for food allergy.

Orthogonal quantification of soluble inducible T-cell costimulator (ICOS) in healthy and diseased human serum

Inducible T-cell costimulator (ICOS), a homodimeric protein expressed on the surface of activated T-cells, is being investigated as a potential therapeutic target to treat various cancers. Recent studies have reported aberrant increases in the soluble form of ICOS (sICOS) in human serum in disease-state patients, primarily using commercial ELISA kits. However, results from our in-house immunoassay did not show these aberrant increases, leading us to speculate that commercial sICOS ELISAs may be prone to interference. We directly tested that hypothesis and found that one widely used commercial kit yields false-positives and is prone to human anti-mouse antibody interference. We then analyzed a panel of healthy, cancer, chronic hepatitis C virus, systemic lupus erythematosus, and diffuse cutaneous systemic sclerosis human serum using our in-house immunoassay and reported the measured sICOS concentrations in these populations. Since even well characterized immunoassay methods are prone to non-specific interference, we also developed a novel sICOS LC-MS/MS method to confirm the results. Using these orthogonal approaches, we show that sICOS is a low abundance soluble protein that cannot be measured above approximately 20 pg/mL in human serum.

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Soluble ICOS is a low-abundance protein that is not detectable above approximately 20 pg/mL in human serum.

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Commercial soluble ICOS kits may be prone to HAMA interference and thus false-positives.

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Off-the-shelf assay kits should be well characterized in order to minimize non-specific interferences.

Single-nucleotide polymorphisms in 3'-untranslated region inducible costimulator gene and the important roles of miRNA in alopecia areata

Background

Alopecia areata (AA) spares the stem cell compartment and attacks only the base of the hair follicle, which is surrounded by infiltrating lymphocytes. AA is associated with polymorphisms in immune-related genes and with decreased function of CD4+CD25+ T regulatory (Treg) cells. Treg function is modulated by the costimulatory molecules, like inducible costimulator (ICOS) that are crucial in orienting T cell differentiation and function so that they strongly impact on the immunologic decision between tolerance or autoimmunity development.

Objective

The aim of our study was to investigate the possible association of AA with single-nucleotide polymorphisms (SNP) present in the ICOS 3'-untranslated region (3'UTR) region and to elucidate how SNPs modulate ICOS gene expression by affecting miRNA binding sites.

Methods

This is a case-control study performed in 184 patients with AA and 200 controls. ICOS gene and miRNA expression were analyzed by real-time polymerase chain reaction.

Results

The genotype carrying the rs4404254(C) [p = 0.012, OR (95% CI): 0.5 (0.3-0.8)] and rs4675379(C) [p = 0.015, OR (95% CI): 0.3 (0.1-0.8)] 3' UTR alleles was more frequently observed in AA patients than in controls and correlated with a reduced ICOS expression. miR-1276 significantly suppressed ICOS expression by binding to the 3'UTR of ICOS mRNA. Also, we observed that, miR-101 and miR-27b are upregulated, while miR-103 and miR-2355-3p are downregulated in peripheral blood mononuclear cells of AA patients compared to controls.

Conclusion

Our data show that rs4404254 and rs4675379 SNPs of ICOS gene are associated with AA and also reveal that the presence of rs4404254 polymorphism correlates with ICOS post-transcriptional repression by microRNA binding.

Differential gene expression analysis of ankylosing spondylitis shows deregulation of the HLA-DRB, HLA-DQB, ITM2A, and CTLA4 genes

Background

Ankylosing spondylitis (AS) is a rare inflammatory disorder affecting the spinal joints. Although we know some of the genetic factors that are associated with the disease, the molecular basis of this illness has not yet been fully elucidated, and the genes involved in AS pathogenesis have not been entirely identified. The current study aimed at constructing a gene network that may serve as an AS gene signature and biomarker, both of which will help in disease diagnosis and the identification of therapeutic targets. Previously published gene expression profiles of 16 AS patients and 16 gender- and age-matched controls that were profiled on the Illumina HumanHT-12 V3.0 Expression BeadChip platform were mined. Patients were Portuguese, 21 to 64 years old, were diagnosed based on the modified New York criteria, and had Bath Ankylosing Spondylitis Disease Activity Index scores > 4 and Bath Ankylosing Spondylitis Functional Index scores > 4. All patients were receiving only NSAIDs and/or sulphasalazine. Functional enrichment and pathway analysis were performed to create an interaction network of differentially expressed genes.

Results

ITM2A, ICOS, VSIG10L, CD59, TRAC, and CTLA-4 were among the significantly differentially expressed genes in AS, but the most significantly downregulated genes were the HLA-DRB6, HLA-DRB5, HLA-DRB4, HLA-DRB3, HLA-DRB1, HLA-DQB1, ITM2A, and CTLA-4 genes. The genes in this study were mostly associated with the regulation of the immune system processes, parts of cell membrane, and signaling related to T cell receptor and antigen receptor, in addition to some overlaps related to the IL2 STAT signaling, as well as the androgen response. The most significantly over-represented pathways in the data set were associated with the “RUNX1 and FOXP3 which control the development of regulatory T lymphocytes (Tregs)” and the “GABA receptor activation” pathways.

Conclusions

Comprehensive gene analysis of differentially expressed genes in AS reveals a significant gene network that is involved in a multitude of important immune and inflammatory pathways. These pathways and networks might serve as biomarkers for AS and can potentially help in diagnosing the disease and identifying future targets for treatment.

Leukemia vaccine overcomes limitations of checkpoint blockade by evoking clonal T cell responses in a murine acute myeloid leukemia model

We have developed a personalized vaccine whereby patient derived leukemia cells are fused to autologous dendritic cells, evoking a polyclonal T cell response against shared and neo-antigens. We postulated that the dendritic cell (DC)/AML fusion vaccine would demonstrate synergy with checkpoint blockade by expanding tumor antigen specific lymphocytes that would provide a critical substrate for checkpoint blockade mediated activation. Using an immunocompetent murine leukemia model, we examined the immunologic response and therapeutic efficacy of vaccination in conjunction with checkpoint blockade with respect to leukemia engraftment, disease burden, survival and the induction of tumor specific immunity. Mice treated with checkpoint blockade alone had rapid leukemia progression and demonstrated only a modest extension of survival. Vaccination with DC/AML fusions resulted in the expansion of tumor specific lymphocytes and disease eradication in a subset of animals, while the combination of vaccination and checkpoint blockade induced a fully protective tumor specific immune response in all treated animals. Vaccination followed by checkpoint blockade resulted in upregulation of genes regulating activation and proliferation in memory and effector T cells. Long term survivors exhibited increased T cell clonal diversity and were resistant to subsequent tumor challenge. The combined DC/AML fusion vaccine and checkpoint blockade treatment offers unique synergy inducing the durable activation of leukemia specific immunity, protection from lethal tumor challenge and the selective expansion of tumor reactive clones.

ICOS signaling limits regulatory T cell accumulation and function in visceral adipose tissue

A unique population of Foxp3+ regulatory T cells (TRs) resides in visceral adipose tissue (VAT) that regulates adipose inflammation and helps preserve insulin sensitivity. Inducible T cell co-stimulator (ICOS) is highly expressed on effector (e)TRs that migrate to nonlymphoid tissues, and contributes to their maintenance and function in models of autoimmunity. In this study, we report an unexpected cell-intrinsic role for ICOS expression and downstream phosphoinositide 3-kinase (PI3K) signaling in limiting the abundance, VAT-associated phenotype, and function of TRs specifically in VAT. Icos-/- mice and mice expressing a knock-in form of ICOS that cannot activate PI3K had increased VAT-TR abundance and elevated expression of canonical VAT-TR markers. Loss of ICOS signaling facilitated enhanced accumulation of TRs to VAT associated with elevated CCR3 expression, and resulted in reduced adipose inflammation and heightened insulin sensitivity in the context of a high-fat diet. Thus, we have uncovered a new and surprising molecular pathway that regulates VAT-TR accumulation and function.

Bacterial-fungal interactions in the neonatal gut influence asthma outcomes later in life

Bacterial members of the infant gut microbiota and bacterial-derived short-chain fatty acids (SCFAs) have been shown to be protective against childhood asthma, but a role for the fungal microbiota in asthma etiology remains poorly defined. We recently reported an association between overgrowth of the yeast Pichia kudriavzevii in the gut microbiota of Ecuadorian infants and increased asthma risk. In the present study, we replicated these findings in Canadian infants and investigated a causal association between early life gut fungal dysbiosis and later allergic airway disease (AAD). In a mouse model, we demonstrate that overgrowth of P. kudriavzevii within the neonatal gut exacerbates features of type-2 and -17 inflammation during AAD later in life. We further show that P. kudriavzevii growth and adherence to gut epithelial cells are altered by SCFAs. Collectively, our results underscore the potential for leveraging inter-kingdom interactions when designing putative microbiota-based asthma therapeutics.

Recruitment and Expansion of Tregs Cells in the Tumor Environment-How to Target Them?

Simple Summary

The immune response against cancer is generated by effector T cells, among them cytotoxic CD8⁺ T cells that destroy cancer cells and helper CD4⁺ T cells that mediate and support the immune response. This antitumor function of T cells is tightly regulated by a particular subset of CD4⁺ T cells, named regulatory T cells (Tregs), through different mechanisms. Even if the complete inhibition of Tregs would be extremely harmful due to their tolerogenic role in impeding autoimmune diseases in the periphery, the targeted blockade of their accumulation at tumor sites or their targeted depletion represent a major therapeutic challenge. This review focuses on the mechanisms favoring Treg recruitment, expansion and stabilization in the tumor microenvironment and the therapeutic strategies developed to block these mechanisms.

Abstract

Regulatory T cells (Tregs) are present in a large majority of solid tumors and are mainly associated with a poor prognosis, as their major function is to inhibit the antitumor immune response contributing to immunosuppression. In this review, we will investigate the mechanisms involved in the recruitment, amplification and stability of Tregs in the tumor microenvironment (TME). We will also review the strategies currently developed to inhibit Tregs’ deleterious impact in the TME by either inhibiting their recruitment, blocking their expansion, favoring their plastic transformation into other CD4⁺ T-cell subsets, blocking their suppressive function or depleting them specifically in the TME to avoid severe deleterious effects associated with Treg neutralization/depletion in the periphery and normal tissues.

SRSF1 serves as a critical posttranscriptional regulator at the late stage of thymocyte development

The underlying mechanisms of thymocyte maturation remain largely unknown. Here, we report that serine/arginine-rich splicing factor 1 (SRSF1) intrinsically regulates the late stage of thymocyte development. Conditional deletion of SRSF1 resulted in severe defects in maintenance of late thymocyte survival and a blockade of the transition of TCRβ^hiCD24⁺CD69⁺ immature to TCRβ^hiCD24^-CD69^- mature thymocytes, corresponding to a notable reduction of recent thymic emigrants and diminished periphery T cell pool. Mechanistically, SRSF1 regulates the gene networks involved in thymocyte differentiation, proliferation, apoptosis, and type I interferon signaling pathway to safeguard T cell intrathymic maturation. In particular, SRSF1 directly binds and regulates Irf7 and Il27ra expression via alternative splicing in response to type I interferon signaling. Moreover, forced expression of interferon regulatory factor 7 rectifies the defects in SRSF1-deficient thymocyte maturation via restoring expression of type I interferon-related genes. Thus, our work provides new insight on SRSF1-mediated posttranscriptional regulatory mechanism of thymocyte development.

ICOS ligand and IL-10 synergize to promote host-microbiota mutualism

Genome-wide association studies have identified ICOSLG, which encodes the inducible costimulator ligand (ICOSLG or ICOSL) as a susceptibility locus for inflammatory bowel disease. ICOSL has been implicated in the enhancement of pattern recognition receptor signaling in dendritic cells, induction of IL-10 production by CD4 T cells, and the generation of high-affinity antibodies to specific antigens-all of which can potentially explain its involvement in gastrointestinal inflammation. Here, we show that murine ICOSL deficiency results in significant enrichment of IL-10-producing CD4 T cells particularly in the proximal large intestine. Transient depletion of IL-10-producing cells from adult ICOSL-deficient mice induced severe colonic inflammation that was prevented when mice were first treated with metronidazole. ICOSL-deficient mice displayed reduced IgA and IgG antibodies in the colon mucus and impaired serum antibody recognition of microbial antigens, including flagellins derived from mucus-associated bacteria of the Lachnospiraceae family. Confirming the synergy between ICOSL and IL-10, ICOSL deficiency coupled with CD4-specific deletion of the Il10 gene resulted in juvenile onset colitis that was impeded when pups were fostered by ICOSL-sufficient dams. In this setting, we found that both maternally acquired and host-derived antibodies contribute to the life anti-commensal antibody repertoire that mediates this protection in early life. Collectively, our findings reveal a partnership between ICOSL-dependent anti-commensal antibodies and IL-10 in adaptive immune regulation of the microbiota in the large intestine. Furthermore, we identify ICOSL deficiency as an effective platform for exploring the functions of anti-commensal antibodies in host-microbiota mutualism.

ICOSL in host defense at epithelial barriers: lessons from ICOSLG deficiency

Autosomal recessive mutations in Inducible T Cell Costimulator Ligand (ICOSLG) result in a combined immunodeficiency syndrome of humans, saliently marked by recurrent respiratory tract infections and significant disease with DNA-based viruses at epithelial barriers, including human papillomavirus (HPV). These features are also seen in persons with loss of function of the complementary gene, ICOS. The infection phenotypes associated with these natural experiments disclose a critical role of the corresponding proteins, ICOSL and ICOS, in human immunity at mucocutaneous barriers. Here, we review the syndromes of ICOSL and ICOS deficiency and explore the mechanisms by which the ICOSL:ICOS axis mediates epithelial host defenses.

IgG Epitopes Processed and Presented by IgG+ B Cells Induce Suppression by Human Thymic-Derived Regulatory T Cells

We described a human regulatory T cell (Treg) population activated by IgG⁺ B cells presenting peptides of the heavy C region (Fc) via processing of the surface IgG underlying a model for B cell-Treg cooperation in the human immune regulation. Functionally, Treg inhibited the polarization of naive T cells toward a proinflammatory phenotype in both a cognate and a noncognate fashion. Their fine specificities were similar in healthy donors and patients with rheumatoid arthritis, a systemic autoimmune disease. Four immunodominant Fc peptides bound multiple HLA class II alleles and were recognized by most subjects in the two cohorts. The presentation of Fc peptides that stimulate Treg through the processing of IgG by dendritic cells (DC) occurred in myeloid DC classical DC 1 and classical DC 2. Different routes of Ag processing of the IgG impacted Treg expansion in rheumatoid arthritis patients.

The ubiquitin ligase Peli1 inhibits ICOS and thereby Tfh-mediated immunity

T follicular helper (Tfh) cells are crucial for regulating autoimmune inflammation and protective immunity against viral infection. However, the molecular mechanism controlling Tfh cell differentiation is poorly understood. Here, through two mixed bone marrow chimeric experiments, we identified Peli1, a T cell-enriched E3 ubiquitin ligase, as an intrinsic regulator that inhibits Tfh cell differentiation. Peli1 deficiency significantly promoted c-Rel-mediated inducible T-cell costimulator (ICOS) expression, and PELI1 mRNA expression was negatively associated with ICOS expression on human CD4⁺ T cells. Mechanistically, increased ICOS expression on Peli1-KO CD4⁺ T cells enhanced the activation of PI3K-AKT signaling and thus suppressed the expression of Klf2, a transcription factor that inhibits Tfh differentiation. Therefore, reconstitution of Klf2 abolished the differences in Tfh differentiation and germinal center reaction between WT and Peli1-KO cells. As a consequence, Peli1-deficient CD4⁺ T cells promoted lupus-like autoimmunity but protected against H1N1 influenza virus infection in mouse models. Collectively, our findings established Peli1 as a critical negative regulator of Tfh differentiation and indicated that targeting Peli1 may have beneficial therapeutic effects in Tfh-related autoimmunity or infectious diseases.

Targeting transcriptional coregulator OCA-B/Pou2af1 blocks activated autoreactive T cells in the pancreas and type 1 diabetes

The transcriptional coregulator OCA-B promotes expression of T cell target genes in cases of repeated antigen exposure, a necessary feature of autoimmunity. We hypothesized that T cell-specific OCA-B deletion and pharmacologic OCA-B inhibition would protect mice from autoimmune diabetes. We developed an Ocab conditional allele and backcrossed it onto a diabetes-prone NOD/ShiLtJ strain background. T cell-specific OCA-B loss protected mice from spontaneous disease. Protection was associated with large reductions in islet CD8+ T cell receptor specificities associated with diabetes pathogenesis. CD4+ clones associated with diabetes were present but associated with anergic phenotypes. The protective effect of OCA-B loss was recapitulated using autoantigen-specific NY8.3 mice but diminished in monoclonal models specific to artificial or neoantigens. Rationally designed membrane-penetrating OCA-B peptide inhibitors normalized glucose levels and reduced T cell infiltration and proinflammatory cytokine expression in newly diabetic NOD mice. Together, the results indicate that OCA-B is a potent autoimmune regulator and a promising target for pharmacologic inhibition.

Reduced Expression of Autophagy Markers and Expansion of Myeloid-Derived Suppressor Cells Correlate With Poor T Cell Response in Severe COVID-19 Patients

Widespread coronavirus disease (COVID)-19 is causing pneumonia, respiratory and multiorgan failure in susceptible individuals. Dysregulated immune response marks severe COVID-19, but the immunological mechanisms driving COVID-19 pathogenesis are still largely unknown, which is hampering the development of efficient treatments. Here we analyzed ~140 parameters of cellular and humoral immune response in peripheral blood of 41 COVID-19 patients and 16 age/gender-matched healthy donors by flow-cytometry, quantitative PCR, western blot and ELISA, followed by integrated correlation analyses with ~30 common clinical and laboratory parameters. We found that lymphocytopenia in severe COVID-19 patients (n=20) strongly affects T, NK and NKT cells, but not B cells and antibody production. Unlike increased activation of ICOS-1+ CD4+ T cells in mild COVID-19 patients (n=21), T cells in severe patients showed impaired activation, low IFN-γ production and high functional exhaustion, which correlated with significantly down-regulated HLA-DR expression in monocytes, dendritic cells and B cells. The latter phenomenon was followed by lower interferon responsive factor (IRF)-8 and autophagy-related genes expressions, and the expansion of myeloid derived suppressor cells (MDSC). Intriguingly, PD-L1-, ILT-3-, and IDO-1-expressing monocytic MDSC were the dominant producers of IL-6 and IL-10, which correlated with the increased inflammation and accumulation of regulatory B and T cell subsets in severe COVID-19 patients. Overall, down-regulated IRF-8 and autophagy-related genes expression, and the expansion of MDSC subsets could play critical roles in dysregulating T cell response in COVID-19, which could have large implications in diagnostics and design of novel therapeutics for this disease.

Human fetal liver MSCs are more effective than adult bone marrow MSCs for their immunosuppressive, immunomodulatory, and Foxp3+ T reg induction capacity

BACKGROUND

Mesenchymal stem cells (MSCs) exhibit active abilities to suppress or modulate deleterious immune responses by various molecular mechanisms. These cells are the subject of major translational efforts as cellular therapies for immune-related diseases and transplantations. Plenty of preclinical studies and clinical trials employing MSCs have shown promising safety and efficacy outcomes and also shed light on the modifications in the frequency and function of regulatory T cells (T regs). Nevertheless, the mechanisms underlying these observations are not well known. Direct cell contact, soluble factor production, and turning antigen-presenting cells into tolerogenic phenotypes, have been proposed to be among possible mechanisms by which MSCs produce an immunomodulatory environment for T reg expansion and activity. We and others demonstrated that adult bone marrow (BM)-MSCs suppress adaptive immune responses directly by inhibiting the proliferation of CD4+ helper and CD8+ cytotoxic T cells but also indirectly through the induction of T regs. In parallel, we demonstrated that fetal liver (FL)-MSCs demonstrates much longer-lasting immunomodulatory properties compared to BM-MSCs, by inhibiting directly the proliferation and activation of CD4+ and CD8+ T cells. Therefore, we investigated if FL-MSCs exert their strong immunosuppressive effect also indirectly through induction of T regs.

METHODS

MSCs were obtained from FL and adult BM and characterized according to their surface antigen expression, their multilineage differentiation, and their proliferation potential. Using different in vitro combinations, we performed co-cultures of FL- or BM-MSCs and murine CD3+CD25-T cells to investigate immunosuppressive effects of MSCs on T cells and to quantify their capacity to induce functional T regs.

RESULTS

We demonstrated that although both types of MSC display similar cell surface phenotypic profile and differentiation capacity, FL-MSCs have significantly higher proliferative capacity and ability to suppress both CD4+ and CD8+ murine T cell proliferation and to modulate them towards less active phenotypes than adult BM-MSCs. Moreover, their substantial suppressive effect was associated with an outstanding increase of functional CD4+CD25+Foxp3+ T regs compared to BM-MSCs.

CONCLUSIONS

These results highlight the immunosuppressive activity of FL-MSCs on T cells and show for the first time that one of the main immunoregulatory mechanisms of FL-MSCs passes through active and functional T reg induction.

Genetic risk factors for autoimmune hepatitis: implications for phenotypic heterogeneity and biomarkers for drug response

Autoimmune hepatitis (AIH) is a rare chronic progressive liver disease with autoimmune features. It mainly affects middle-aged women. AIH is occasionally complicated with liver cirrhosis that worsens the prognosis. Genetic and environmental factors are involved in the pathogenesis of AIH. Genetic studies of other diseases have been revealing of pathogenesis and drug efficacy. In this review, we summarize the genetic risk factors for AIH, including human leukocyte antigen (HLA) and non-HLA genes. A genome-wide association study (GWAS) on European AIH revealed the strongest associations to be with single nucleotide variants (SNVs) in HLA. Predisposing alleles for AIH were DRB1*03:01 and DRB1*04:01 in Europeans; DRB1*04:04, DRB1*04:05, and DRB1*13:01 in Latin Americans; and DRB1*04:01 and DRB1*04:05 in Japanese. Other risk SNVs in non-HLA genes for AIH were found by a candidate gene approach, but several SNVs were confirmed in replication studies. Some genetic factors of AIH overlapped with those of other autoimmune diseases. Larger-scale GWASs of other ethnic groups are required. The results of genetic studies might provide an explanation for the phenotypic heterogeneity of AIH and biomarkers for drug responses.

Immunological status of peripheral blood is associated with prognosis in patients with bone and soft-tissue sarcoma

Immune-checkpoint inhibitors have shown promising antitumor effects against certain types of cancer. However, specific immune-checkpoint inhibitors for patients with sarcoma have yet to be identified, whereas the immunological status of peripheral blood in patients with bone sarcoma and soft-tissue sarcoma (STS) remains unknown. In addition, it is unclear whether the immunological status from the peripheral blood could be used as a prognostic indicator. Therefore, the present study aimed to clarify the immunological status of peripheral blood samples derived from patients with bone sarcoma and STS. Immune monitoring was performed using the peripheral blood samples of 61 patients with no metastasis of high-grade sarcoma. A total of 25 patients with metastatic sarcoma were used for comparison. A total of 41 immune cell subsets were analyzed using multicolor-flow cytometry. The patients that did not have metastasis demonstrated higher quantities of monocytic myeloid-derived suppressor cells (M-MDSCs) and T cell immunoglobulin and mucin domain-3 (Tim-3)⁺ CD8⁺ T cells, which were significantly associated with poor disease-free survival (DFS) time, while higher quantities of NKG2D⁺ CD8⁺ T cells were significantly associated with improved DFS time. Multivariate Cox regression analysis demonstrated that the number of Tim-3⁺ CD8⁺ T cells was associated with lower DFS time. A significant association was also found between the number of M-MDSCs and progression-free survival (PFS) time in patients with metastasis. The results suggested the occurrence of immune surveillance, which indicated that the host immune reaction against cancer existed in patients with bone sarcoma and STS. Notably, a high number of M-MDSCs was associated with both DFS and PFS time, suggesting a strong prognostic value. The data suggested that the immune status of peripheral blood was associated with the prognosis in patients with sarcoma, as previously reported in patients with other cancer types. In summary, the results may assist with the development of novel strategies for sarcoma treatment, based on the use of biomarkers or immunotherapy.

A High-Dimensional Window into the Micro-Environment of Triple Negative Breast Cancer

Providing effective personalized immunotherapy for triple negative breast cancer (TNBC) patients requires a detailed understanding of the composition of the tumor microenvironment. Both the tumor cell and non-tumor components of TNBC can exhibit tremendous heterogeneity in individual patients and change over time. Delineating cellular phenotypes and spatial topographies associated with distinct immunological states and the impact of chemotherapy will be necessary to optimally time immunotherapy. The clinical successes in immunotherapy have intensified research on the tumor microenvironment, aided by a plethora of high-dimensional technologies to define cellular phenotypes. These high-dimensional technologies include, but are not limited to, single cell RNA sequencing, spatial transcriptomics, T cell repertoire analyses, advanced flow cytometry, imaging mass cytometry, and their integration. In this review, we discuss the cellular phenotypes and spatial patterns of the lymphoid-, myeloid-, and stromal cells in the TNBC microenvironment and the potential value of mapping these features onto tumor cell genotypes.

TNFα priming through its interaction with TNFR2 enhances endothelial progenitor cell immunosuppressive effect: new hope for their widespread clinical application

Background

Bone marrow derived endothelial progenitor cells (EPCs) are immature endothelial cells (ECs) involved in neo-angiogenesis and endothelial homeostasis and are considered as a circulating reservoir for endothelial repair. Many studies showed that EPCs from patients with cardiovascular pathologies are impaired and insufficient; hence, allogenic sources of EPCs from adult or cord blood are considered as good choices for cell therapy applications. However, allogenic condition increases the chance of immune rejection, especially by T cells, before exerting the desired regenerative functions. TNFα is one of the main mediators of EPC activation that recognizes two distinct receptors, TNFR1 and TNFR2. We have recently reported that human EPCs are immunosuppressive and this effect was TNFα-TNFR2 dependent. Here, we aimed to investigate if an adequate TNFα pre-conditioning could increase TNFR2 expression and prime EPCs towards more immunoregulatory functions.

Methods

EPCs were pre-treated with several doses of TNFα to find the proper dose to up-regulate TNFR2 while keeping the TNFR1 expression stable. Then, co-cultures of human EPCs and human T cells were performed to assess whether TNFα priming would increase EPC immunosuppressive and immunomodulatory effect.

Results

Treating EPCs with 1 ng/ml TNFα significantly up-regulated TNFR2 expression without unrestrained increase of TNFR1 and other endothelial injury markers. Moreover, TNFα priming through its interaction with TNFR2 remarkably enhanced EPC immunosuppressive and anti-inflammatory effects. Conversely, blocking TNFR2 using anti-TNFR2 mAb followed by 1 ng/ml of TNFα treatment led to the TNFα-TNFR1 interaction and polarized EPCs towards pro-inflammatory and immunogenic functions.

Conclusions

We report for the first time the crucial impact of inflammation notably the TNFα-TNFR signaling pathway on EPC immunological function. Our work unveils the pro-inflammatory role of the TNFα-TNFR1 axis and, inversely the anti-inflammatory implication of the TNFα-TNFR2 axis in EPC immunoregulatory functions. Priming EPCs with 1 ng/ml of TNFα prior to their administration could boost them toward a more immunosuppressive phenotype. This could potentially lead to EPCs’ longer presence in vivo after their allogenic administration resulting in their better contribution to angiogenesis and vascular regeneration.

Regulations of T Cell Activation by Membrane and Cytoskeleton

Among various types of membrane proteins that are regulated by cytoskeleton, the T cell receptor (TCR) greatly benefits from these cellular machineries for its function. The T cell is activated by the ligation of TCR to its target agonist peptide. However, the binding affinity of the two is not very strong, while the T cell needs to discriminate agonist from many nonagonist peptides. Moreover, the strength and duration of the activation signaling need to be tuned for immunological functions. Many years of investigations revealed that dynamic acto-myosin cytoskeletons and plasma membranes in T cells facilitate such regulations by modulating the spatiotemporal distributions of proteins in plasma membranes and by applying mechanical loads on proteins. In these processes, protein dynamics in multiple scales are involved, ranging from collective molecular motions and macroscopic molecular organizations at the cell–cell interface to microscopic changes in distances between receptor and ligand molecules. In this review, details of how cytoskeletons and membranes regulate these processes are discussed, with the emphasis on how all these processes are coordinated to occur within a single cell system.

Transcriptome Sequencing Reveals Potential Roles of ICOS in Primary Sjögren's Syndrome

Primary Sjögren’s syndrome (pSS) is a chronic systemic autoimmune disease characterized by exocrine gland damage and extraglandular involvements. To identify potential biomarkers for the early detection of pSS and to further investigate the potential roles of the biomarkers in the progression of pSS, our previous RNA sequencing data and four microarray data of salivary glands (SGs) were combined for integrative transcriptome analysis between pSS and non-pSS. Differential gene expression analysis, gene co-expression network analysis, and pathway analysis were conducted to detect hub genes, which were subsequently investigated in peripheral blood mononuclear cell (PBMC) and plasma. Correlation analysis, single-gene Gene Set Enrichment Analysis, and receiver operating characteristic (ROC) curve were applied to investigate the potential function of the hub genes and their classification capacity for pSS. A total of 51 common up-regulated genes were identified among different pSS cohorts. A key module was found to be the most closely linked to pSS, which was significantly associated with inflammation-related pathways. Seven overlapped hub genes (ICOS, SELL, CR2, BANK1, MS4A1, ZC3H12D, and CCR7) were identified, among which ICOS was demonstrated to be involved in most crucial immune pathways. ICOS was up-regulated not only in SGs but also in PBMC and plasma in pSS, and the expression of ICOS was closely associated with lymphocytic infiltration in SGs and disease activity of pSS patients. It showed a strong classification capacity with classic clinical index in SGs (ROC curve 0.9821) and significant distinct discrimination in PBMC (ROC curve 0.9107). These findings are expected to gain a further insight into the pathogenesis of pSS and provide a promising candidate for the early detection of pSS.

Biotherapeutic Antibodies for the Treatment of Head and Neck Cancer: Current Approaches and Future Considerations of Photothermal Therapies

Head and neck cancer (HNC) is a heterogeneous disease that includes a variety of tumors originating in the hypopharynx, oropharynx, lip, oral cavity, nasopharynx, or larynx. HNC is the sixth most common malignancy worldwide and affects thousands of people in terms of incidence and mortality. Various factors can trigger the development of the disease such as smoking, alcohol consumption, and repetitive viral infections. HNC is currently treated by single or multimodality approaches, which are based on surgery, radiotherapy, chemotherapy, and biotherapeutic antibodies. The latter approach will be the focus of this article. There are currently three approved antibodies against HNCs (cetuximab, nivolumab, and pembrolizumab), and 48 antibodies under development. The majority of these antibodies are of humanized (23 antibodies) or human (19 antibodies) origins, and subclass IgG1 represents a total of 32 antibodies. In addition, three antibody drug conjugates (ADCs: telisotuzumab-vedotin, indatuximab-ravtansine, and W0101) and two bispecific antibodies (GBR 1372 and ABL001) have been under development. Despite the remarkable success of antibodies in treating different tumors, success was limited in HNCs. This limitation is attributed to efficacy, resistance, and the appearance of various side effects. However, the efficacy of these antibodies could be enhanced through conjugation to gold nanoparticles (GNPs). These conjugates combine the high specificity of antibodies with unique spectral properties of GNPs to generate a treatment approach known as photothermal therapy. This approach can provide promising outcomes due to the ability of GNPs to convert light into heat, which can specifically destroy cancer cells and treat HNC in an effective manner.