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

The development of a human Brucella mucosal vaccine: What should be considered?

Brucellosis is a chronic infectious disease that is zoonotic in nature. Brucella can infect humans through interactions with livestock, primarily via the digestive tract, respiratory tract, and oral cavity. This bacterium has the potential to be utilized as a biological weapon and is classified as a Category B pathogen by the Centers for Disease Control and Prevention. Currently, there is no approved vaccine for humans against Brucella, highlighting an urgent need for the development of a vaccine to mitigate the risks posed by this pathogen. Brucella primarily infects its host by adhering to and penetrating mucosal surfaces. Mucosal immunity plays a vital role in preventing local infections, clearing microorganisms from mucosal surfaces, and inhibiting the spread of pathogens. As mucosal vaccine strategies continue to evolve, the development of a safe and effective mucosal vaccine against Brucella appears promising.This paper reviews the immune mechanism of mucosal vaccines, the infection mechanism of Brucella, successful Brucella mucosal vaccines in animals, and mucosal adjuvants. Additionally, it elucidates targeting and optimization strategies for mucosal vaccines to facilitate the development of human vaccines against Brucella.

CD8+ tissue-resident memory T cells are expanded in primary Sjögren's disease and can be therapeutically targeted by CD103 blockade

OBJECTIVE

Tissue-resident memory cells (Trm) are a subset of T cells residing persistently and long-term within specific tissues that contribute to persistent inflammation and tissue damage. We characterised the phenotype and function of Trm and the role of CD103 in primary Sjogren's syndrome (pSS).

METHODS

In both pSS and non-pSS sicca syndrome patients, we examined Trm frequency, cytokine production in salivary glands (SG) and peripheral blood (PB). We also analysed Trm-related gene expression in SG biopsies through bulk and single-cell RNA sequencing (scRNAseq). Additionally, we investigated Trm properties in an immunisation-induced animal model of pSS (experimental SS, ESS) mouse model and assessed the effects of Trm inhibition via intraglandular anti-CD103 monoclonal antibody administration.

RESULTS

Transcriptomic pSS SG showed an upregulation of genes associated with tissue recruitment and long-term survival of Trm cells, confirmed by a higher frequency of CD8+CD103+CD69+ cells in pSS SG, compared with non-specific sialadenitis (nSS). In SG, CD8+ CD103+ Trm contributed to the secretion of granzyme-B and interferon-γ, CD8+ Trm cells were localised within inflammatory infiltrates, where PD1+CD8+ T cells were also increased compared with nSS and MALT lymphoma. scRNAseq of PB and pSS SG T cells confirmed expression of CD69, ITGAE, GZMB, GZMK and HLA-DRB1 among CD3+CD8+ SG T cells. In the SG of ESS, CD8+CD69+CD103+ Trm producing Granzyme B progressively expanded. However, intraglandular blockade of CD103 in ESS reduced Trm, reduced glandular damage and improved salivary flow.

CONCLUSIONS

CD103+CD8+Trm cells are expanded in the SG of pSS and ESS, participate in tissue inflammation and can be therapeutically targeted.

Preschool-age children maintain a distinct memory CD4+ T cell and memory B cell response after SARS-CoV-2 infection

The development of the human immune system lasts for several years after birth. The impact of this maturation phase on the quality of adaptive immunity and the acquisition of immunological memory after infection at a young age remains incompletely defined. Here, using an antigen-reactive T cell (ARTE) assay and multidimensional flow cytometry, we profiled circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-reactive CD3+CD4+CD154+ T cells in children and adults before infection, during infection, and 11 months after infection, stratifying children into separate age groups and adults according to disease severity. During SARS-CoV-2 infection, children younger than 5 years old displayed a lower antiviral CD4+ T cell response, whereas children older than 5 years and adults with mild disease had, quantitatively and phenotypically, comparable virus-reactive CD4+ T cell responses. Adults with severe disease mounted a response characterized by higher frequencies of virus-reactive proinflammatory and cytotoxic T cells. After SARS-CoV-2 infection, preschool-age children not only maintained neutralizing SARS-CoV-2-reactive antibodies postinfection comparable to adults but also had phenotypically distinct memory T cells displaying high inflammatory features and properties associated with migration toward inflamed sites. Moreover, preschool-age children had markedly fewer circulating virus-reactive memory B cells compared with the other cohorts. Collectively, our results reveal unique facets of antiviral immunity in humans at a young age and indicate that the maturation of adaptive responses against SARS-CoV-2 toward an adult-like profile occurs in a progressive manner.

MAdCAM-1 co-stimulation combined with retinoic acid and TGF-β induces blood CD8+ T cells to adopt a gut CD101+ TRM phenotype

Resident memory T cells (TRMs) help control local immune homeostasis and contribute to tissue-protective immune responses. The local cues that guide their differentiation and localization are poorly defined. We demonstrate that mucosal vascular addressin cell adhesion molecule 1, a ligand for the gut-homing receptor α4β7 integrin, in the presence of retinoic acid and transforming growth factor-β (TGF-β) provides a co-stimulatory signal that induces blood cluster of differentiation (CD8+ T cells to adopt a TRM-like phenotype. These cells express CD103 (integrin αE) and CD69, the two major TRM cell-surface markers, along with CD101. They also express C-C motif chemokine receptors 5 (CCR5) , C-C motif chemokine receptors 9 (CCR9), and α4β7, three receptors associated with gut homing. A subset also expresses E-cadherin, a ligand for αEβ7. Fluorescent lifetime imaging indicated an αEβ7 and E-cadherin cis interaction on the plasma membrane. This report advances our understanding of the signals that drive the differentiation of CD8+ T cells into resident memory T cells and provides a means to expand these cells in vitro, thereby affording an avenue to generate more effective tissue-specific immunotherapies.

Neoadjuvant durvalumab plus radiation versus durvalumab alone in stages I-III non-small cell lung cancer: survival outcomes and molecular correlates of a randomized phase II trial

We previously reported the results of a randomized phase II trial (NCT02904954) in patients with early-stage non-small cell lung cancer (NSCLC) who were treated with either two preoperative cycles of the anti-PD-L1 antibody durvalumab alone or combined with immunomodulatory doses of stereotactic radiation (DRT). The trial met its primary endpoint of major pathological response, which was significantly higher following DRT with no new safety signals. Here, we report on the prespecified secondary endpoint of disease-free survival (DFS) regardless of treatment assignment and the prespecified exploratory analysis of DFS in each arm of the trial. DFS at 2 and 3 years across patients in both arms of the trial were 73% (95% CI: 62.1-84.5) and 65% (95% CI: 52.5-76.9) respectively. For the exploratory endpoint of DFS in each arm of the trial, three-year DFS was 63% (95% CI: 46.0-80.4) in the durvalumab monotherapy arm compared to 67% (95% CI: 49.6-83.4) in the dual therapy arm. In addition, we report post hoc exploratory analysis of progression-free survival as well as molecular correlates of response and recurrence through high-plex immunophenotyping of sequentially collected peripheral blood and gene expression profiles from resected tumors in both treatment arms. Together, our results contribute to the evolving landscape of neoadjuvant treatment regimens for NSCLC and identify easily measurable potential biomarkers of response and recurrence.

Tissue-resident memory T cells in renal autoimmune diseases

The discovery of tissue-resident memory T cells (T_RM cells) reinterpreted the potential of human tissue-specific immunity. Following T cell receptor (TCR) activation and clonal expansion, effector T cells migrate to peripheral tissues where they remain long-term and differentiate to T_RM cells after antigen clearance. This allows for prompt immunological responses upon antigen re-encounter. In addition to their protective properties in acute infections, recent studies have revealed that T_RM cells might lead to aggravation of autoimmune diseases, such as lupus nephritis (LN) and anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (GN). These diseases present as proliferative and crescentic glomerulonephritis (cGN), which is a life-threatening condition leading to end-stage renal disease (ESRD) if left untreated. A better understanding of renal T_RM cells might lead to identifying new therapeutic targets for relapsing autoimmune diseases of the kidney. In this review, we summarize the current knowledge of renal T_RM cells and discuss their potential pathophysiological roles in renal autoimmune diseases.

When secretion turns into excretion - the different roles of IgA

IgA deficiency is the commonest immunodeficiency affecting up to 1 in 700 individuals. The effects of IgA deficiency are difficult to see in many individuals, are mild in many fewer and severe in fewer still. While monovalent IgA is found in serum, dimeric IgA is secreted through mucosal surfaces where it helps to maintain epithelial homeostasis. Studies with knockout mice have taught us that there are subtle inflammatory consequences of removing secretory IgA (sIgA), and the best explanation for these changes can be related by the loss of the 'excretory' immune system. The excretion of antigens is a logical process in regulating the immune system, given the long half-life of complement fixing antibodies. But the function of IgA as an immune or inflammation regulator may go beyond antigen removal.