Tyrosine kinase 2 (Tyk2) is a nonreceptor tyrosine kinase that belongs to the Janus kinase (Jak) family. Here we identified a homozygous Tyk2 mutation in a patient who had been clinically diagnosed with hyper-IgE syndrome. This patient showed unusual susceptibility to various microorganisms including virus, fungi, and mycobacteria and suffered from atopic dermatitis with elevated serum IgE. The patient's cells displayed defects in multiple cytokine signaling pathways including those for type I interferon (IFN), interleukin (IL)-6, IL-10, IL-12, and IL-23. The cytokine signals were successfully restored by transducing the intact Tyk2 gene. Thus, the Tyk2 deficiency is likely to account for the patient's complex clinical manifestations, including the phenotype of impaired T helper 1 (Th1) differentiation and accelerated Th2 differentiation. This study identifies human Tyk2 deficiency and demonstrates that Tyk2 plays obligatory roles in multiple cytokine signals involved in innate and acquired immunity of humans, which differs substantially from Tyk2 function in mice.

Epstein-Barr virus–encoded small RNA (EBER) is nonpolyadenylated, noncoding RNA that forms stem-loop structure by intermolecular base-pairing, giving rise to double-stranded RNA (dsRNA)–like molecules, and exists abundantly in EBV-infected cells. Here, we report that EBER induces signaling from the Toll-like receptor 3 (TLR3), which is a sensor of viral double-stranded RNA (dsRNA) and induces type I IFN and proinflammatory cytokines. A substantial amount of EBER, which was sufficient to induce signaling from TLR3, was released from EBV-infected cells, and the majority of the released EBER existed as a complex with a cellular EBER-binding protein La, suggesting that EBER was released from the cells by active secretion of La. Sera from patients with infectious mononucleosis (IM), chronic active EBV infection (CAEBV), and EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH), whose general symptoms are caused by proinflammatory cytokines contained EBER, and addition of RNA purified from the sera into culture medium induced signaling from TLR3 in EBV-transformed lymphocytes and peripheral mononuclear cells. Furthermore, DCs treated with EBER showed mature phenotype and antigen presentation capacity. These findings suggest that EBER, which is released from EBV-infected cells, is responsible for immune activation by EBV, inducing type I IFN and proinflammatory cytokines. EBER-induced activation of innate immunity would account for immunopathologic diseases caused by active EBV infection.

No abstract

Autophagy is a cellular recycling process induced in response to many types of stress. However, little is known of the signaling pathways that regulate autophagy during acute kidney injury (AKI). Bcl-2/adenovirus E1B 19 kDa-interacting protein (BNIP)3 and sestrin-2 are the target proteins of hypoxia-inducible factor (HIF)-1␣ and p53, respectively. The aim of this study was to investigate the roles of BNIP3 and sestrin-2 in oxidative stressinduced autophagy during AKI. We used rat ischemia-reperfusion injury and cultured renal tubular (NRK-52E) cells as in vivo and in vitro models of AKI, respectively. Renal ischemia-reperfusion injury upregulated the expression of BNIP3 and sestrin-2 in the proximal tubules, as measured by immunohistochemical staining and Western blot analysis. In vitro, NRK-52E cells exposed to hypoxia showed increased expression of BNIP3 mRNA and protein in a HIF-1␣-dependent manner. In contrast, sestrin-2 mRNA and protein expression were upregulated in a p53-dependent manner after exposure to oxidative stress (exogenous H2O2). NRK-52E cells stably transfected with a fusion protein between green fluorescent protein and light chain 3 were used to investigate autophagy. Overexpression of BNIP3 or sestrin-2 in these cells induced light chain 3 expression and formation of autophagosomes. Interestingly, BNIP3-induced autophagosomes were mainly localized to the mitochondria, suggesting that this protein selectively induces mitophagy. These observations demonstrate that autophagy is induced in renal tubules by at least two independent pathways involving p53-sestrin-2 and HIF-1␣-BNIP3, which may be activated by different types of stress to protect the renal tubules during AKI.Bcl-2/adenovirus E1B 19 kDa-interacting protein-3; acute kidney injury; autophagy; mitophagy; sestrin-2 ISCHEMIA is the leading cause of acute kidney injury (AKI) in the adult population. Prominent morphological features of ischemic AKI include effacement and loss of the proximal tubule brush border, patchy loss of tubular cells, focal areas of proximal tubular dilation, and increased apoptosis (9). The mechanisms that dictate the survival or death of renal cells under oxidative stress must be more completely understood before novel therapeutic strategies for the treatment of ischemic AKI can be explored. Proximal renal tubular cells have high rates of ATP consumption and are very sensitive to hypoxia; thus, mitochondrial damage is one of the most important factors in determining the survival of these cells (1,43).Autophagy is one of the cellular processes that protect cells from genotoxic stress, oxidative stress, accumulation of misfolded proteins, and nutrient deprivation. We (20) have previously reported results from a study of autophagy in a mouse model of AKI. Autophagy plays roles in the pathogenesis of many diseases, and, in kidney disease, both beneficial and detrimental effects of autophagy have been reported (19 -22). Our understanding of autophagy has expanded greatly in recent years, largely due to the identification...

Caesarean section (CS) is increasing globally, and women with prior CS are at higher risk of uterine rupture in subsequent pregnancies. However, little is known about the incidence, risk factors, and outcomes of uterine rupture in women with prior CS, especially in developing countries. To investigate this, we conducted a secondary analysis of the World Health Organization Multicountry Survey on Maternal and Newborn Health, which included data on delivery from 359 facilities in 29 countries. The incidence of uterine rupture among women with at least one prior CS was 0.5% (170/37,366), ranging from 0.2% in high-Human Development Index (HDI) countries to 1.0% in low-HDI countries. Factors significantly associated with uterine rupture included giving birth in medium- or low-HDI countries (adjusted odds ratio [AOR] 2.0 and 3.88, respectively), lower maternal educational level (≤6 years) (AOR 1.71), spontaneous onset of labour (AOR 1.62), and gestational age at birth <37 weeks (AOR 3.52). Women with uterine rupture had significantly higher risk of maternal death (AOR 4.45) and perinatal death (AOR 33.34). Women with prior CS, especially in resource-limited settings, are facing higher risk of uterine rupture and subsequent adverse outcomes. Further studies are needed for prevention/management strategies in these settings.