Publications by authors named "Rachel Chun-Yee Tam"

Memory T cells play a key role in immune protection against cancer. Vaccine-induced tissue-resident memory T (TRM) cells in the lung have been shown to protect against lung metastasis. Identifying the source of lung TRM cells can help to improve strategies, preventing tumor metastasis.

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  • COVID-19 can lead to heart issues, and different SARS-CoV-2 variants vary in how they impact heart cells (cardiomyocytes).
  • The study examined the effects of these variants using human heart cells grown in labs and tested them in Golden Syrian hamsters, revealing that the Omicron BA.2 variant had the most significant harmful effects on heart cells.
  • Findings indicate that Omicron BA.2 infects heart cells through a unique process and causes changes that could lead to heart dysfunction, suggesting that even variants seen as mild can pose serious risks for cardiac health and warrant further research.
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An intranasal COVID-19 vaccine, DelNS1-based RBD vaccines composed of H1N1 subtype (DelNS1-nCoV-RBD LAIV) was developed to evaluate the safety and immunogenicity in healthy adults. We conducted a phase 1 randomized, double-blinded, placebo-controlled study on healthy participants, age 18-55 and COVID-19 vaccines naïve, between March and September 2021. Participants were enrolled and randomly assigned (2:2:1) into the low and high dose DelNS1-nCoV-RBD LAIV manufactured in chicken embryonated eggs or placebo groups.

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Current available vaccines for COVID-19 are effective in reducing severe diseases and deaths caused by SARS-CoV-2 infection but less optimal in preventing infection. Next-generation vaccines which are able to induce mucosal immunity in the upper respiratory to prevent or reduce infections caused by highly transmissible variants of SARS-CoV-2 are urgently needed. We have developed an intranasal vaccine candidate based on a live attenuated influenza virus (LAIV) with a deleted NS1 gene that encodes cell surface expression of the receptor-binding-domain (RBD) of the SARS-CoV-2 spike protein, designated DelNS1-RBD4N-DAF.

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Background: Vaccines in emergency use are efficacious against COVID-19, yet vaccine-induced prevention against nasal SARS-CoV-2 infection remains suboptimal.

Methods: Since mucosal immunity is critical for nasal prevention, we investigated the efficacy of an intramuscular PD1-based receptor-binding domain (RBD) DNA vaccine (PD1-RBD-DNA) and intranasal live attenuated influenza-based vaccines (LAIV-CA4-RBD and LAIV-HK68-RBD) against SARS-CoV-2.

Findings: Substantially higher systemic and mucosal immune responses, including bronchoalveolar lavage IgA/IgG and lung polyfunctional memory CD8 T cells, were induced by the heterologous PD1-RBD-DNA/LAIV-HK68-RBD as compared with other regimens.

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  • Emerging variants of SARS-CoV-2, like the Alpha variant (B.1.1.7), quickly outcompete original strains in humans soon after they appear.
  • Research showed that the Alpha variant has higher competitive fitness, meaning it can spread more effectively than earlier strains.
  • In hamster models, the Alpha variant was able to replicate and be shed more efficiently in the nasal cavity, highlighting its potential for causing rapid transmission due to lower infection doses.
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  • - SARS-CoV-2, which originated from animals, has a specific genetic feature (PRRA polybasic cleavage motif) that helps it infect humans effectively.
  • - Researchers have developed a modified variant of the virus called Ca-DelMut, which shows better replication in lab cells but does not cause disease in hamsters despite replication in their respiratory tissues.
  • - Ca-DelMut stimulates a strong immune response in hamsters and mice and provides complete protection against a wild type SARS-CoV-2 challenge, showing it can induce sterilizing immunity.
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The neonatal mouse heart is capable of transiently regenerating after injury from postnatal day (P) 0-7 and macrophages are found important in this process. However, whether macrophages alone are sufficient to orchestrate this regeneration; what regulates cardiomyocyte proliferation; why cardiomyocytes do not proliferate after P7; and whether adaptive immune cells such as regulatory T-cells (Treg) influence neonatal heart regeneration have less studied. : We employed both loss- and gain-of-function transgenic mouse models to study the role of Treg in neonatal heart regeneration.

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  • - CLEC16A is linked to several autoimmune diseases, but its exact role in autoimmunity is not well understood.
  • - Recent research indicates that CLEC16A inhibits starvation-induced autophagy by activating the mTOR pathway, affecting how cells respond to nutrient availability.
  • - The study finds that CLEC16A is located in cytosolic vesicles and the Golgi, where it may regulate mTOR activity and autophagy, suggesting a connection to autoimmune mechanisms.
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Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease characterized by hyperactivated immune responses to self-antigens and persistent systemic inflammation. Previously, we reported abnormalities in circulating and bone marrow (BM)-derived plasmacytoid dendritic cells (pDCs) from SLE patients. Here, we aim to seek for potential regulators that mediate functional aberrations of pDCs in SLE.

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Autoreactive B cells are one of the key immune cells that have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). In addition to the production of harmful auto-antibodies (auto-Abs), B cells prime autoreactive T cells as antigen-presenting cells and secrete a wide range of pro-inflammatory cytokines that have both autocrine and paracrine effects. Agents that modulate B cells may therefore be of potential therapeutic value.

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