BLK positively regulates TLR/IL-1R signaling by catalyzing TOLLIP phosphorylation.

TLR/IL-1R signaling plays a critical role in sensing various harmful foreign pathogens and mounting efficient innate and adaptive immune responses, and it is tightly controlled by intracellular regulators at multiple levels. In particular, TOLLIP forms a constitutive complex with IRAK1 and sequesters it in the cytosol to maintain the kinase in an inactive conformation under unstimulated conditions. However, the underlying mechanisms by which IRAK1 dissociates from TOLLIP to activate TLR/IL-1R signaling remain obscure. Herein, we show that BLK positively regulates TLR/IL-1R-mediated inflammatory response. BLK-deficient mice produce less inflammatory cytokines and are more resistant to death upon IL-1ß challenge. Mechanistically, BLK is preassociated with IL1R1 and IL1RAcP in resting cells. IL-1ß stimulation induces heterodimerization of IL1R1 and IL1RAcP, which further triggers BLK autophosphorylation at Y309. Activated BLK directly phosphorylates TOLLIP at Y76/86/152 and further promotes TOLLIP dissociation from IRAK1, thereby facilitating TLR/IL-1R-mediated signal transduction. Overall, these findings highlight the importance of BLK as an active regulatory component in TLR/IL-1R signaling.

Tyrosine phosphorylation of IRF3 by BLK facilitates its sufficient activation and innate antiviral response.

Viral infection triggers the activation of transcription factor IRF3, and its activity is precisely regulated for robust antiviral immune response and effective pathogen clearance. However, how full activation of IRF3 is achieved has not been well defined. Herein, we identified BLK as a key kinase that positively modulates IRF3-dependent signaling cascades and executes a pre-eminent antiviral effect. BLK deficiency attenuates RNA or DNA virus-induced ISRE activation, interferon production and the cellular antiviral response in human and murine cells, whereas overexpression of BLK has the opposite effects. BLK-deficient mice exhibit lower serum cytokine levels and higher lethality after VSV infection. Moreover, BLK deficiency impairs the secretion of downstream antiviral cytokines and promotes Senecavirus A (SVA) proliferation, thereby supporting SVA-induced oncolysis in an in vivo xenograft tumor model. Mechanistically, viral infection triggers BLK autophosphorylation at tyrosine 309. Subsequently, activated BLK directly binds and phosphorylates IRF3 at tyrosine 107, which further promotes TBK1-induced IRF3 S386 and S396 phosphorylation, facilitating sufficient IRF3 activation and downstream antiviral response. Collectively, our findings suggest that targeting BLK enhances viral clearance via specifically regulating IRF3 phosphorylation by a previously undefined mechanism.

[Multisystemic inflammatory syndrome in children after severe acute respiratory syndrome coronavirus 2 infection: a clinical analysis of four cases]. / æ–°åž‹å† çŠ¶ç— æ¯’æ„ŸæŸ“åŽå„¿ç«¥å¤šç³»ç»Ÿç‚Žç—‡ç»¼åˆå¾4例.

OBJECTIVES: To investigate the clinical features and treatment strategies of multisystemic inflammatory syndrome in children (MIS-C) after severe acute respiratory syndrome coronavirus 2 infection. METHODS: A retrospective analysis was performed on the medical data of four children with MIS-C who were admitted to the Department of Cardiology, Xuzhou Children's Hospital, Xuzhou Medical Universityfrom January to February 2023. RESULTS: All four children had multiple organ involvements and elevated inflammatory markers, with a poor response to standard therapy for Kawasaki disease after admission. Two children were treated with intravenous immunoglobulin therapy pulse therapy twice, and all four children were treated with glucocorticoids. The children had a good prognosis after the treatment. CONCLUSIONS: MIS-C often appears within 4-6 weeks or a longer time after severe acute respiratory syndrome coronavirus 2 infection, and anti-inflammatory therapy in addition to the standard treatment regimen for Kawasaki disease can help to achieve a favorable treatment outcome.

Study on the levels of 25(OH)D, inflammation markers and glucose and fat metabolism indexes in pregnant women of Han nationality in Jiangsu province with gestational diabetes mellitus.

The aim of this study is to investigate the levels of 25(OH)D, inflammation markers and glucose and fat metabolism indexes in pregnant women with Gestational diabetes mellitus (GDM).One hundred and ten cases GDM and 100 cases healthy pregnant women in the First People's Hospital of Lianyungang City from October 2016 to December 2018 were recruited for this observational cross-sectional study. Each participant's anthropometric and demographic data was recorded. Blood samples were collected and analyzed to determine the levels of 25(OH)D, high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), fasting blood glucose, fasting blood insulin, hemoglobin A1c (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), cholesterol and triglycerides.Inflammatory markers and glucose and fat metabolism indexes were all significantly higher in the GDM group than that in the control group, while Serum 25(OH)D level in the GDM group was significantly lower. Serum 25(OH)D levels were negatively correlated with hs-CRP, while not with TNF-α. Furthermore, Serum 25(OH)D, hs-CRP and TNF-α levels were all associated with increased risk of developing GDM.Nowadays, the reports on the association between 25(OH)D level and GDM were controversial. Our results are consistent with the view that there was association between 25(OH)D level and GDM, and expand the literature by showing the roles of 25(OH)D, inflammation markers as well as glucose and fat metabolism indexes in the risk of developing GDM in the pregnant women with the low overall levels of 25(OH)D before delivery. This broadens our knowledge on the pathophysiology of GDM, which may be helpful in prevention and treatment of GDM.