PLZF Acetylation Levels Regulate NKT Cell Differentiation

Early RSV infection aggravates asthma-related Th2 responses by increasing the number of CD4 + TRM cells through upregulation of PLZF

Respiratory syncytial virus (RSV) infection is correlated with the chronic pathogenesis and exacerbation of asthma. However, the mechanism remains unclear. In this study, acute and memory (Mem) asthma models with early RSV infection are established to explore the persistence of the effects of RSV infection on asthma. Intravascular injection of an anti-CD45 antibody is performed to define CD4 + TRM cells accurately. RSV infection has a sustained impact on asthma exacerbation for at least six weeks, with high Th2 cytokine secretion in lung tissue instead of IgE response-related B cells. CD45 -CD4 + TRM cells are positively correlated with RSV-related asthma exacerbation and severe airway inflammation. Mechanistically, overexpression of the transcription factor PLZF in vitro increases the number of CD4 + TRM cells, and conditional knockout of Zbtb16 (encoding PLZF) can decrease the number of CD4 + TRM cells to aggravate allergic inflammation and reduce Th2 responses. This study provides evidence for potential combined strategies that might benefit asthma patients.

Eed-dependent histone modification orchestrates the iNKT cell developmental program alleviating liver injury

Polycomb repressive complex 2 (PRC2) is an evolutionarily conserved epigenetic modifier responsible for tri-methylation of lysine 27 on histone H3 (H3K27me3). Previous studies have linked PRC2 to invariant natural killer T (iNKT) cell development, but its physiological and precise role remained unclear. To address this, we conditionally deleted Eed, a core subunit of PRC2, in mouse T cells. The results showed that Eed-deficient mice exhibited a severe reduction in iNKT cell numbers, particularly NKT1 and NKT17 cells, while conventional T cells and NKT2 cells remained intact. Deletion of Eed disrupted iNKT cell differentiation, leading to increased cell death, which was accompanied by a severe reduction in H3K27me3 levels and abnormal expression of Zbtb16, Cdkn2a, and Cdkn1a. Interestingly, Eed-deficient mice were highly susceptible to acetaminophen-induced liver injury and inflammation in an iNKT cell-dependent manner, highlighting the critical role of Eed-mediated H3K27me3 marks in liver-resident iNKT cells. These findings provide further insight into the epigenetic orchestration of iNKT cell-specific transcriptional programs.

Promyelocytic leukemia zinc finger controls type 2 immune responses in the lungs by regulating lineage commitment and the function of innate and adaptive immune cells

Type 2 immune responses are critical for host defense, mediate allergy and Th2-high asthma. The transcription factor, promyelocytic leukemia zinc finger (PLZF), has emerged as a significant regulator of type 2 inflammation in the lung; however, its exact mechanism remains unclear. In this review, we summarized recent findings regarding the ability of PLZF to control the development and function of innate lymphoid cells (ILCs), iNKT cells, memory T cells, basophils, and other immune cells that drive type 2 responses. We discussed the important role of PLZF in the pathogenesis of Th2-high asthma. Collectively, prior studies have revealed the critical role of PLZF in the regulation of innate and adaptive immune cells involved in type 2 inflammation in the lung. Therefore, targeting PLZF signaling represents a promising therapeutic approach to suppress Th2-high asthma.

Lung transcriptomics of K18-hACE2 mice highlights mechanisms and genes involved in the MVA-S vaccine-mediated immune response and protection against SARS-CoV-2 infection

Unravelling the molecular mechanism of COVID-19 vaccines through transcriptomic pathways involved in the host response to SARS-CoV-2 infection is key to understand how vaccines work, and for the development of optimized COVID-19 vaccines that can prevent the emergence of SARS-CoV-2 variants of concern (VoCs) and future outbreaks. In this study, we investigated the effects of vaccination with a modified vaccinia virus Ankara (MVA)-based vector expressing the full-length SARS-CoV-2 spike protein (MVA-S) on the lung transcriptome from susceptible K18-hACE2 mice after SARS-CoV-2 infection. One dose of MVA-S regulated genes related to viral infection control, inflammation processes, T-cell response, cytokine production and IFN-γ signalling. Down-regulation of Rhcg and Tnfsf18 genes post-vaccination with one and two doses of MVA-S may represent a mechanism for controlling infection immunity and vaccine-induced protection. One dose of MVA-S provided partial protection with a distinct lung transcriptomic profile to healthy animals, while two doses of MVA-S fully protected against infection with a transcriptomic profile comparable to that of non-vaccinated healthy animals. This suggests that the MVA-S booster generates a robust and rapid antigen-specific immune response preventing virus infection. Notably, down-regulation of Atf3 and Zbtb16 genes in mice vaccinated with two doses of MVA-S may contribute to vaccine control of innate immune system and inflammation processes in the lungs during SARS-CoV-2 infection. This study shows host transcriptomic mechanisms likely involved in the MVA-S vaccine-mediated immune response against SARS-CoV-2 infection, which could help in improving vaccine dose assessment and developing novel, well-optimized SARS-CoV-2 vaccine candidates against prevalent or emerging VoCs.

Genomic and Transcriptional Mechanisms Governing Innate-like T Lymphocyte Development

Innate-like lymphocytes are a subset of lymphoid cells that function as a first line of defense against microbial infection. These cells are activated by proinflammatory cytokines or broadly expressed receptors and are able to rapidly perform their effector functions owing to a uniquely primed chromatin state that is acquired as a part of their developmental program. These cells function in many organs to protect against disease, but they release cytokines and cytotoxic mediators that can also lead to severe tissue pathologies. Therefore, harnessing the capabilities of these cells for therapeutic interventions will require a deep understanding of how these cells develop and regulate their effector functions. In this review we discuss recent advances in the identification of the transcription factors and the genomic regions that guide the development and function of invariant NKT cells and we highlight related mechanisms in other innate-like lymphocytes.

Identification and Isolation of Type II NKT Cell Subsets in Human Blood and Liver

Background

Steatotic livers are more prone to rejection, but are often transplanted owing to the shortage of available organs. Type II NKT (T2NKT) cells are liver-resident lymphocytes that react to lipids presented by CD1d. The role of T2NKT cells in rejection of fatty liver transplants is unclear, partly because of a lack of T2NKT cell markers and their very low frequency in blood. Here, we quantify human T2NKT cells in blood and liver tissue by flow cytometry and provide a strategy for their enrichment and expansion.

Methods

Human T2NKT cells were identified as CD3⁺ CD56⁺ CD161⁺ TCR-γᵹ^- TCRVα7.2^- and TCRVα24^- cells. T2NKT cells were enriched from blood by sequential positive selection using CD56 and CD3 microbeads. These were subsequently FACS-sorted to purity then expanded in vitro for 3 weeks using anti-CD3/CD28 beads and TGF-β1.

Results

The frequency of human T2NKT cells in blood was very low (0.8 ± 0.4% of CD3⁺ T cells) but they were a more abundant population in liver (6.3 ± 0.9%). Enriched T2NKT cells expressed the transcription factor PLZF. A novel subset of FoxP3⁺ T2NKT cells was discovered in blood and liver tissue. T2NKT cells were expanded in culture by 15- to 28-fold over 3 weeks, during which time they maintained expression of all identifying markers, including PLZF and FoxP3.

Conclusions

Our work defines new strategies for identifying and isolating T2NKT cells from human blood and liver tissue. We showed that this rare population can be expanded in vitro in order to obtain experimentally amenable cell numbers. Further, we identified a novel T2NKT cell subset that stably expresses FoxP3, which might play a role in regulating innate-like lymphocyte responses in steatotic liver transplants.

Biallelic DNAH9 mutations are identified in Chinese patients with defective left-right patterning and cilia-related complex congenital heart disease

Defective left-right (LR) pattering results in a spectrum of laterality disorders including situs inversus totalis (SIT) and heterotaxy syndrome (Htx). Approximately, 50% of patients with primary ciliary dyskinesia (PCD) displayed SIT. Recessive variants in DNAH9 have recently been implicated in patients with situs inversus. Here, we describe six unrelated family trios and 2 sporadic patients with laterality defects and complex congenital heart disease (CHD). Through whole exome sequencing (WES), we identified compound heterozygous mutations in DNAH9 in the affected individuals of these family trios. Ex vivo cDNA amplification revealed that DNAH9 mRNA expression was significantly downregulated in these patients carrying biallelic DNAH9 mutations, which cause a premature stop codon or exon skipping. Transmission electron microscopy (TEM) analysis identified ultrastructural defects of the outer dynein arms in these affected individuals. dnah9 knockdown in zebrafish lead to the disturbance of cardiac left-right patterning without affecting ciliogenesis in Kupffer's vesicle (KV). By generating a Dnah9 knockout (KO) C57BL/6n mouse model, we found that Dnah9 loss leads to compromised cardiac function. In this study, we identified recessive DNAH9 mutations in Chinese patients with cardiac abnormalities and defective LR pattering.