BCAP inhibits proliferation and differentiation of myeloid progenitors in the steady state and during demand situations

Mitochondrial pyruvate metabolism and glutaminolysis toggle steady-state and emergency myelopoiesis

To define the metabolic requirements of hematopoiesis, we examined blood lineages in mice conditionally deficient in genes required for long-chain fatty acid oxidation (Cpt2), glutaminolysis (Gls), or mitochondrial pyruvate import (Mpc2). Genetic ablation of Cpt2 or Gls minimally impacted most blood lineages. In contrast, deletion of Mpc2 led to a sharp decline in mature myeloid cells and a slower reduction in T cells, whereas other hematopoietic lineages were unaffected. Yet MPC2-deficient monocytes and neutrophils rapidly recovered due to a transient and specific increase in myeloid progenitor proliferation. Competitive bone marrow chimera and stable isotope tracing experiments demonstrated that this proliferative burst was progenitor intrinsic and accompanied by a metabolic switch to glutaminolysis. Myeloid recovery after loss of MPC2 or cyclophosphamide treatment was delayed in the absence of GLS. Reciprocally, MPC2 was not required for myeloid recovery after cyclophosphamide treatment. Thus, mitochondrial pyruvate metabolism maintains myelopoiesis under steady-state conditions, while glutaminolysis in progenitors promotes emergency myelopoiesis.

Mechanistic insight into the protective and pathogenic immune-responses against SARS-CoV-2

COVID-19 is a severe respiratory illness that has emerged as a devasting health problem worldwide. The disease outcome is heterogeneous, which is most likely dependent on the immunity of an individual. Asymptomatic and mildly/moderate symptomatic (non-severe) patients likely develop an effective early immune response and clear the virus. However, severe symptoms dominate due to a failure in the generation of an effective and specific early immune response against SARS-CoV-2. Moreover, a late surge in pathogenic inflammation involves dysregulated innate and adaptive immune responses leading to local and systemic tissue damage and the emergence of severe disease symptoms. In this review, we describe the potential mechanisms of protective and pathogenic immune responses in "mild/moderate" and "severe" symptomatic SARS-CoV-2 infected people, respectively, and discuss the immune components that are currently targeted for therapeutic intervention.

Overexpression of long non-coding RNA WT1-AS or silencing of PIK3AP1 are inhibitory to cervical cancer progression

Accumulating evidence demonstrate that long non-coding RNAs (lncRNAs) play an important role in regulating the biological function of cervical cancer cells. However, the regulatory role of lncRNA Wilms tumor 1 homolog antisense RNA (WT1-AS) in cervical cancer cells remains uncertain. In this study, we explored the participation of WT1-AS in cervical cancer by first using the reverse transcription quantitative polymerase-chain reaction (RT-qPCR) was to analyze the expression of WT1-AS and phosphoinositide-3-kinase adaptor protein 1 (PIK3AP1) in cervical cancer tissues and cells. Dual-luciferase reporter gene assay, RNA pull-down/RNA immunoprecipitation (RIP) assays and Chromatin Immunoprecipitation (ChIP) assay were conducted to explore the interactions among WT1-AS, PIK3AP1, and SPI1. Gain- and loss-of-function approaches were carried out to determine the effects of lncRNA WT1-AS, PIK3AP1 on cell biological characteristics, followed by assays of cell proliferation, autophagy, and apoptosis abilities using, respectively, EdU, monodansylcadaverine (MDC) staining, and flow cytometry. Finally, we measured growth of xenograft tumors in nude mice. We found decreased expression of lncRNA WT1-AS and increased expression of PIK3AP1 in cervical cancer samples. Moreover, PIK3AP1 was negatively regulated by WT1-AS, which promoted apoptosis, but inhibited cell proliferation and autophagy of cervical cancer cells. Furthermore, WT1-AS inhibited PIK3AP1 expression by recruiting SPI1, and inhibited the progression of cervical cancer through the SPI1/PIK3AP1 axis in vivo and in vitro. In summary, lncRNA WT1-AS repressed the development of cervical cancer by reducing PIK3AP1 expression through an interaction with SPI1, which may suggest new therapeutic approaches for treating cervical cancer.Abbreviations: HPV, human papillomavirus; lncRNAs, Long non-coding RNAs; WT1-AS, wilms tumor 1 antisense RNA; HCC, hepatocellular carcinoma; SFFV, Spleen focus forming virus; SPI1, Spleen focus forming virus proviral integration oncogene 1; TF, transcription factor; PIK3AP1, Phosphoinositide-3-kinase adaptor protein 1; NCBI, National Center for Biotechnology Information; oe, overexpressed; sh-PIK3AP1, short hairpin RNA against PIK3AP1; RIPA, radioimmunoprecipitation; PMSF, phenylmethylsulfonyl fluoride; HRP, horseradish peroxidase; IgG, immunoglobulin G; GAPDH, Glyceraldehyde-3-phosphate dehydrogenase; PCR, polymerase chain reaction; EP, Eppendorf; RIP, RNA-binding protein immunoprecipitation; CHIP, Chromatin immunoprecipitation; EdU, 5-ethynyl-2'-deoxyuridine; PI, propidium iodide; MDC, Monodansylcadaverine; PFA, paraformaldehyde; SPF, specific pathogen free; TV, tumor volume; DLG1-AS1, discs large MAGUK scaffold protein 1 antisense RNA 1; TOB1-AS1, transducer of epidermal growth factor receptor-2.1 antisense RNA 1; LC3II, light chain 3 type II; LC3I, light chain 3 type I; IRF4, interferon regulatory factor 4.

Spontaneously Resolved Atopic Dermatitis Shows Melanocyte and Immune Cell Activation Distinct From Healthy Control Skin

Atopic dermatitis (AD) typically starts in infancy or early childhood, showing spontaneous remission in a subset of patients, while others develop lifelong disease. Despite an increased understanding of AD, factors guiding its natural course are only insufficiently elucidated. We thus performed suction blistering in skin of adult patients with stable, spontaneous remission from previous moderate-to-severe AD during childhood. Samples were compared to healthy controls without personal or familial history of atopy, and to chronic, active AD lesions. Skin cells and tissue fluid obtained were used for single-cell RNA sequencing and proteomic multiplex assays, respectively. We found overall cell composition and proteomic profiles of spontaneously healed AD to be comparable to healthy control skin, without upregulation of typical AD activity markers (e.g., IL13, S100As, and KRT16). Among all cell types in spontaneously healed AD, melanocytes harbored the largest numbers of differentially expressed genes in comparison to healthy controls, with upregulation of potentially anti-inflammatory markers such as PLA2G7. Conventional T-cells also showed increases in regulatory markers, and a general skewing toward a more Th1-like phenotype. By contrast, gene expression of regulatory T-cells and keratinocytes was essentially indistinguishable from healthy skin. Melanocytes and conventional T-cells might thus contribute a specific regulatory milieu in spontaneously healed AD skin.

PIK3AP1 and SPON2 Genes Are Differentially Methylated in Patients With Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Adenitis (PFAPA) Syndrome

Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome is the most common autoinflammatory disease in children and is often grouped together with hereditary periodic fever syndromes, although its cause and hereditary nature remain unexplained. We investigated whether differential DNA methylation was present in DNA from peripheral blood mononuclear cells (PBMC) in patients with PFAPA vs. healthy controls. A whole-epigenome analysis (MeDIP and MBD) was performed using pooled DNA libraries enriched for methylated genomic regions and identified candidate genes, two of which were further evaluated with methylation-specific restriction enzymes coupled with qPCR (MSRE-qPCR). The analysis showed that the PIK3AP1 and SPON2 gene regions are differentially methylated in patients with PFAPA. MSRE-qPCR proved to be a quick, reliable, and cost-effective method of confirming results from MeDIP and MBD. Our findings indicate that a B-cell adapter protein (PIK3AP1), as the PI3K binding inhibitor of inflammation, and spondin-2 (SPON2), as a pattern recognition molecule and integrin ligand, could play a role in the etiology of PFAPA. Their role and the impact of changed DNA methylation in PFAPA etiology and autoinflammation need further investigation.

Cutting Edge: BCAP Promotes Lupus-like Disease and TLR-Mediated Type I IFN Induction in Plasmacytoid Dendritic Cells

Systemic lupus erythematosus severity correlates with elevated serum levels of type I IFNs, cytokines produced in large quantities by plasmacytoid dendritic cells (pDC) in response to engagement of TLR7 and TLR9 with endocytosed nucleic acids. B cell adaptor for PI3K (BCAP) promoted many aspects of TLR7-driven lupus-like disease, including Isg15 and Ifit1 expression in blood and an immature pDC phenotype associated with higher IFN production. BCAP^-/- mice produced significantly less serum IFN-α than wild-type mice after injection of TLR9 agonist, and BCAP promoted TLR7 and TLR9-induced IFN-α production specifically in pDC. TLR-induced IFN-α production in pDC requires DOCK2-mediated activation of Rac1 leading to activation of IKKα, a mechanism we show was dependent on BCAP. BCAP^-/- pDC had decreased actin polymerization and Rac1 activation and reduced IKKα phosphorylation upon TLR9 stimulation. We show a novel role for BCAP in promoting TLR-induced IFN-α production in pDC and in systemic lupus erythematosus pathogenesis.