Mucosal Immunity

Five Bacteria You Should Know About Their Role In Human Cancer


1- Helicobacter pylori binds to gastric epithelial cells and injects a virulence factor, which… | 42 comments on LinkedIn

Targeted public health interventions for an emerging epidemic are essential for preventing pandemics. During 2020-2022, China invested significant efforts in strict zero-COVID measures to contain outbreaks of varying scales caused by different SARS-CoV-2 variants. Based on a multi-year empirical dataset containing 131 outbreaks observed in China from April 2020 to May 2022 and simulated scenarios, we ranked the relative intervention effectiveness by their reduction in instantaneous reproduction number. We found that, overall, social distancing measures (38% reduction, 95% prediction interval 31-45%), face masks (30%, 17-42%) and close contact tracing (28%, 24-31%) were most effective. Contact tracing was crucial in containing outbreaks during the initial phases, while social distancing measures became increasingly prominent as the spread persisted. In addition, infections with higher transmissibility and a shorter latent period posed more challenges for these measures. Our findings provide quantitative evidence on the effects of public-health measures for zeroing out emerging contagions in different contexts. China maintained a ‘zero-COVID’ policy from early in the pandemic until late 2022 that employed various public health interventions with the aim of COVID-19 containment. Here, the authors use data from 131 outbreaks in China to estimate the effects of a range of interventions against different SARS-CoV-2 variants in diverse settings.

One of the most preferable characteristics for a COVID-19 vaccine candidate is the ability to reduce transmission and infection of SARS-CoV-2, in addition to disease prevention. Unlike intramuscular vaccines, intranasal COVID-19 vaccines may offer this by generating mucosal immunity. In this open-label, randomised, multicentre, phase 3 clinical trial (CTRI/2022/02/40065; ClinicalTrials.gov: NCT05522335), healthy adults were randomised to receive two doses, 28 days apart, of either intranasal adenoviral vectored SARS-CoV-2 vaccine (BBV154) or licensed intramuscular vaccine, Covaxin®. Between April 16 and June 4, 2022, we enrolled 3160 subjects of whom, 2971 received 2 doses of BBV154 and 161 received Covaxin. On Day 42, 14 days after the second dose, BBV154 induced significant serum neutralization antibody titers against the ancestral (Wuhan) virus, which met the pre-defined superiority criterion for BBV154 over Covaxin®. Further, both vaccines showed cross protection against Omicron BA.5 variant. Salivary IgA titers were found to be higher in BBV154. In addition, extensive evaluation of T cell immunity revealed comparable responses in both cohorts due to prior infection. However, BBV154 showed significantly more ancestral specific IgA-secreting plasmablasts, post vaccination, whereas Covaxin recipients showed significant Omicron specific IgA-secreting plasmablasts only at day 42. Both vaccines were well tolerated. Overall reported solicited reactions were 6.9% and 25.5% and unsolicited reactions were 1.2% and 3.1% in BBV154 and Covaxin® participants respectively.

New mapping effort, using spatial technology, reveals the organization of the human intestine at single-cell resolution for the first time.

HIV-1 infection causes severe alterations of gut mucosa, microbiota and immune system, which can be curbed by early antiretroviral therapy. Here, we investigate how treatment timing affects intestinal memory B-cell and plasmablast repertoires of HIV-1-infected humans. We show that only class-switched memory B cells markedly differ between subjects treated during the acute and chronic phases of infection. Intestinal memory B-cell monoclonal antibodies show more prevalent polyreactive and commensal bacteria-reactive clones in late- compared to early-treated individuals. Mirroring this, serum IgA polyreactivity and commensal-reactivity are strongly increased in late-treated individuals and correlate with intestinal permeability and systemic inflammatory markers. Polyreactive blood IgA memory B cells, many of which egressed from the gut, are also substantially enriched in late-treated individuals. Our data establish gut and systemic B-cell polyreactivity to commensal bacteria as hallmarks of chronic HIV-1 infection and suggest that initiating treatment early may limit intestinal B-cell abnormalities compromising HIV-1 humoral response. HIV-1 infection is known to impact the gut mucosa, effecting the microbiota and immune system, but early antiretroviral therapy is linked to partial reversal of this phenomena. Here the authors explore the impact of early commencement of antiretroviral therapy and show this can limit the abnormal responses of intestinal B cells associated with HIV-1 infection.

The human oral microbiota is highly diverse and has a complex ecology, comprising bacteria, microeukaryotes, archaea and viruses. These communities have elaborate and highly structured biogeography that shapes metabolic exchange on a local scale and results from the diverse microenvironments present in the oral cavity. The oral microbiota also interfaces with the immune system of the human host and has an important role in not only the health of the oral cavity but also systemic health. In this Review, we highlight recent advances including novel insights into the biogeography of several oral niches at the species level, as well as the ecological role of candidate phyla radiation bacteria and non-bacterial members of the oral microbiome. In addition, we summarize the relationship between the oral microbiota and the pathology of oral diseases and systemic diseases. Together, these advances move the field towards a more holistic understanding of the oral microbiota and its role in health, which in turn opens the door to the study of novel preventive and therapeutic strategies. In this Review, He and co-workers explore the structure and diversity of the oral microbiota, and they discuss the role of the oral microbiota in the pathology of both oral and systemic diseases.

Tissue-resident memory lymphocytes at mucosal surfaces have been shown to be critical in long-term protection following mucosal infection. Tissue-resident memory T cells (Trm) have been well characterized in animal models and in humans, while knowledge about tissue-resident memory B cells (Brm) is currently more limited. Due to specific features of tissue-resident memory lymphocytes such as cross-reactivity and polyfunctionality, Trm and Brm have been demonstrated to be an ideal target for vaccine strategies aiming to induce protection at mucosal surfaces. The route of vaccine administration, the choice of antigenic epitopes and the impact of microenvironment appeared to be crucial parameters in the development of vaccine-induced mucosal tissue-resident memory responses in animal models. However, it remains significant gaps in understanding systemic and local signals needed to establish and maintain protective mucosal Trm subsets without inducing pathogenic populations. In addition, the development of Brm is currently not well understood. Discovery of innovative recombinant antigens and identification of safe mucosal adjuvants will be crucial in the development of vaccine formulations efficient to induce Trm and Brm at mucosal surfaces. This Opinion article will describe current knowledge about mucosal Trm and Brm and vaccine approaches already tested to induce tissue-resident memory lymphocytes at mucosal surfaces. It will pinpoint gaps in knowledge. It will sugges

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This report identifies a central role for type I interferons in governing the activation and effector functions of murine and human MAIT cells during pulmonary