Local SARS-CoV-2 peptide-specific Immune Responses in Convalescent and Uninfected Human Lung Tissue Models

Heavy Metal Exposure-Mediated Dysregulation of Sphingolipid Metabolism

Exposure to heavy metals (HMs) is often associated with inflammation and cell death, exacerbating respiratory diseases including asthma. Most inhaled particulate HM exposures result in the deposition of HM-bound fine particulate matter, PM2.5, in pulmonary cell populations. While localized high concentrations of HMs may be a causative factor, existing studies have mostly evaluated the effects of systemic or low-dose chronic HM exposures. This report investigates the impact of local high concentrations of specific HMs (NaAsO2, MnCl2, and CdCl2) on sphingolipid homeostasis and oxidative stress, as both play a role in mediating responses to HM exposure and have been implicated in asthma. Utilizing an in vitro model system and three-dimensional ex vivo human tissue models, we evaluated the expression of enzymatic regulators of the salvage, recycling, and de novo synthesis pathways of sphingolipid metabolism, and observed differential modulation in these enzymes between HM exposures. Sphingolipidomic analyses of specific HM-exposed cells showed increased levels of anti-apoptotic sphingolipids and reduced pro-apoptotic sphingolipids, suggesting activation of the salvage and de novo synthesis pathways. Differential sphingolipid regulation was observed within HM-exposed lung tissues, with CdCl2 exposure and NaAsO2 exposure activating the salvage and de novo synthesis pathway, respectively. Additionally, using spatial transcriptomics and quantitative real-time PCR, we identified HM exposure-induced transcriptomic signatures of oxidative stress in epithelial cells and human lung tissues.

Pulmonary resident memory T cells in respiratory virus infection and their inspiration on therapeutic strategies

The immune system generates memory cells on infection with a virus for the first time. These memory cells play an essential role in protection against reinfection. Tissue-resident memory T (TRM) cells can be generated in situ once attacked by pathogens. TRM cells dominate the defense mechanism during early stages of reinfection and have gradually become one of the most popular focuses in recent years. Here, we mainly reviewed the development and regulation of various TRM cell signaling pathways in the respiratory tract. Moreover, we explored the protective roles of TRM cells in immune response against various respiratory viruses, such as Respiratory Syncytial Virus (RSV) and influenza. The complex roles of TRM cells against SARS-CoV-2 infection are also discussed. Current evidence supports the therapeutic strategies targeting TRM cells, providing more possibilities for treatment. Rational utilization of TRM cells for therapeutics is vital for defense against respiratory viruses.

Expansion of cytotoxic tissue-resident CD8+ T cells and CCR6+CD161+ CD4+ T cells in the nasal mucosa following mRNA COVID-19 vaccination

Vaccines against SARS-CoV-2 have shown high efficacy in clinical trials, yet a full immunologic characterization of these vaccines, particularly within the human upper respiratory tract, is less well known. Here, we enumerate and phenotype T cells in nasal mucosa and blood using flow cytometry before and after vaccination with the Pfizer-BioNTech COVID-19 vaccine (n = 21). Tissue-resident memory (Trm) CD8+ T cells expressing CD69+CD103+ increase in number ~12 days following the first and second doses, by 0.31 and 0.43 log10 cells per swab respectively (p = 0.058 and p = 0.009 in adjusted linear mixed models). CD69+CD103+CD8+ T cells in the blood decrease post-vaccination. Similar increases in nasal CD8+CD69+CD103- T cells are observed, particularly following the second dose. CD4+ cells co-expressing CCR6 and CD161 are also increased in abundance following both doses. Stimulation of nasal CD8+ T cells with SARS-CoV-2 spike peptides elevates expression of CD107a at 2- and 6-months (p = 0.0096) post second vaccine dose, with a subset of donors also expressing increased cytokines. These data suggest that nasal T cells may be induced and contribute to the protective immunity afforded by this vaccine.

Ex Vivo Culture Models of Hidradenitis Suppurativa for Defining Molecular Pathogenesis and Treatment Efficacy of Novel Drugs

Hidradenitis suppurativa (HS) is a complex and debilitating inflammatory skin disease for which no effective treatment is available currently. This is partly because of the lack of adequate human or animal models for defining the pathobiology of the disease. Here, we describe the development of air-liquid (A-L) interface, liquid-submersion (L-S), and bioreactor (Bio) ex vivo skin culture models. All three ex vivo platforms were effective for culturing skin samples for up to 14 days. Tissue architecture and integrity remained intact for at least 3 days for healthy skin and 14 days for HS skin. Up to day 3, no significant differences were observed in % early apoptotic cells among all three platforms. However, late apoptotic/necrotic cell death was increased in HS skin at day 3 in A-L and Bio culture. These cultures efficiently support the growth of various cells populations, including keratinocytes and immune cells. Profiling inflammatory gene signatures in HS skin from these ex vivo cultures showed dynamic changes in expression at day 3 and day 14. All three culture platforms were necessary to represent the inflammatory gene status of HS skin at day 0, suggesting that not all gene clusters were identically altered in each culture method. Similarly, cytokine/chemokine profiling of the supernatants from vehicle- and drug-treated ex vivo HS cultures again showed a better prediction of drug efficacy against HS. Overall, development of these three culture systems collectively provides a powerful tool to uncover the pathobiology of HS progression and screen various drugs against HS.