Largemouth bass Rel exerts antiviral role against fish virus and regulates the expression of interleukin-10

Nuclear factor-κB (NF-κB)/Rel is a group of transcription factors that can be activated and regulates various aspects of innate and adaptive immune functions, which play a crucial role in mediating inflammatory responses. Interleukin-10 (IL-10) is a highly pleiotropic cytokine that has a central role in limiting the immune response to pathogens during infection and thereby alleviating damage to the host. This study aims to investigate the function of the Rel gene in virus infection and its regulatory effect on IL-10 in the largemouth bass (Micropterus salmoides). The ORF sequence of MsRel was 1941 bp, containing 646 amino acids with two conserved functional domains, including RHD and IPT domain. In healthy largemouth bass, the mRNA of MsRel was detected in all the tested tissues, including gill, liver, kidney, heart, spleen, intestine, stomach, skin, brain, fin and muscle. The expression of MsRel was induced by challenge with largemouth bass virus (LMBV) or red grouper nervous necrosis virus (RGNNV), as well as treatment with lipopolysaccharide (LPS) or poly (I:C) in vivo. As evidenced by the detection of viral gene mRNA levels, the infectivity of LMBV and morphological cytopathic effect (CPE), we found that overexpression of MsRel inhibited the infection and replication of LMBV, suggesting its antiviral roles in fish. Besides, the promoter analysis was carried out to determine whether MsRel was a regulator of MsIL-10. The results of the luciferase reporter assay indicated that MsRel has a positive regulatory role in MsIL-10 expression. Further analysis revealed that the potential binding sites of MsIL-10 may be located in the MsIL10-5-M (-42 to +8 bp) region of the MsIL-10 promoter. Furthermore, we observed that MsRel enhanced IFN-I and IFN-III promoter activities. Taken together, our findings demonstrated that MsRel affect LMBV infection by regulating the immune responses, and providing a new idea of the mechanisms how Rel regulate the expression of IL-10 in bony fish.

Analysis of Metagenomic Next-Generation Sequencing (mNGS) in the Diagnosis of Herpes Simplex Virus (HSV) Encephalitis with Normal Cerebrospinal Fluid (CSF)

Background

Metagenomic next-generation sequencing (mNGS) is becoming increasingly extensive in diagnosing herpes simplex encephalitis (HSE). However, many HSE patients with normal cerebrospinal fluid (CSF) diagnosed by mNGS have been found during the clinical application. This study aimed to summarize and analyze the clinical characteristics, supplementary examinations, and prognosis of patients with HSE whose cerebrospinal fluid was confirmed to be normal by mNGS.

Methods

This retrospective study evaluated the clinical characteristics, auxiliary examinations, and patient prognosis of patients with HSE that were diagnosed by mNGS but had normal CSF. Clinical data collected included baseline information, signs and symptoms upon admission, and risk factors for infection. Auxiliary examinations included indirect immunofluorescence assay (IIF), cell-based assay (CBA), and CSF testing. Prognosis was evaluated based on hospital stay and patient survival.

Results

Seven of the nine patients (77.8%) experienced headaches, and four (44.4%) had a fever of 38°C or higher. The average leukocyte count in the CSF was 2.6 ± 2.3/L. According to the mNGS, the median sequence count of HSV was 2 (1, 16). Magnetic resonance imaging (MRI) revealed one bilateral temporal lobe lesion (11.1%), two isolated bilateral frontal lobe lesions (22.2%), and one bilateral cingulate gyrus lesion (11.1%). One patient (11.1%) was admitted to the intensive care unit and passed away in the hospital. The remaining patients (88.9%) had a positive prognosis upon discharge.

Conclusion

Patients with HSE who had normal CSF were typically middle-aged women with normal immune function. They showed typical HSE clinical features, such as fever, headache and epilepsy, that did not differ from those of other HSE patients. A normal CSF result is generally associated with a low viral load and the body's ability to mount an effective immune response. Most of these patients have a favorable prognosis.

Reconciling Mouse and Human Immunology at the Altar of Genetics

Immunity to infection has been extensively studied in humans and mice bearing naturally occurring or experimentally introduced germline mutations. Mouse studies are sometimes neglected by human immunologists, on the basis that mice are not humans and the infections studied are experimental and not natural. Conversely, human studies are sometimes neglected by mouse immunologists, on the basis of the uncontrolled conditions of study and small numbers of patients. However, both sides would agree that the infectious phenotypes of patients with inborn errors of immunity often differ from those of the corresponding mutant mice. Why is that? We argue that this important question is best addressed by revisiting and reinterpreting the findings of both mouse and human studies from a genetic perspective. Greater caution is required for reverse-genetics studies than for forward-genetics studies, but genetic analysis is sufficiently strong to define the studies likely to stand the test of time. Genetically robust mouse and human studies can provide invaluable complementary insights into the mechanisms of immunity to infection common and specific to these two species.

The c-Rel transcription factor limits early interferon and neuroinflammatory responses to prevent herpes simplex encephalitis onset in mice

Herpes simplex virus type 1 (HSV-1) is the predominant cause of herpes simplex encephalitis (HSE), a condition characterized by acute inflammation and viral replication in the brain. Host genetics contribute to HSE onset, including monogenic defects in type I interferon signaling in cases of childhood HSE. Mouse models suggest a further contribution of immune cell-mediated inflammation to HSE pathogenesis. We have previously described a truncating mutation in the c-Rel transcription factor (Rel^C307X) that drives lethal HSE in 60% of HSV-1-infected Rel^C307X mice. In this study, we combined dual host-virus RNA sequencing with flow cytometry to explore cell populations and mechanisms involved in Rel^C307X-driven HSE. At day 5 postinfection, prior to HSE clinical symptom onset, elevated HSV-1 transcription was detected together with augmented host interferon-stimulated and inflammatory gene expression in the brainstems of high-responding Rel^C307X mice, predictive of HSE development. This early induction of host gene expression preceded pathological infiltration of myeloid and T cells in Rel^C307X mice at HSE onset by day 7. Thus, we establish c-Rel as an early regulator of viral and host responses during mouse HSE. These data further highlight the importance of achieving a balanced immune response and avoiding excess interferon-driven inflammation to promote HSE resistance.

E3 ligase Nedd4l promotes antiviral innate immunity by catalyzing K29-linked cysteine ubiquitination of TRAF3

Ubiquitination is one of the most prevalent protein posttranslational modifications. Here, we show that E3 ligase Nedd4l positively regulates antiviral immunity by catalyzing K29-linked cysteine ubiquitination of TRAF3. Deficiency of Nedd4l significantly impairs type I interferon and proinflammatory cytokine production induced by virus infection both in vitro and in vivo. Nedd4l deficiency inhibits virus-induced ubiquitination of TRAF3, the binding between TRAF3 and TBK1, and subsequent phosphorylation of TBK1 and IRF3. Nedd4l directly interacts with TRAF3 and catalyzes K29-linked ubiquitination of Cys56 and Cys124, two cysteines that constitute zinc fingers, resulting in enhanced association between TRAF3 and E3 ligases, cIAP1/2 and HECTD3, and also increased K48/K63-linked ubiquitination of TRAF3. Mutation of Cys56 and Cys124 diminishes Nedd4l-catalyzed K29-linked ubiquitination, but enhances association between TRAF3 and the E3 ligases, supporting Nedd4l promotes type I interferon production in response to virus by catalyzing ubiquitination of the cysteines in TRAF3.

Novel transcription regulatory sequences and factors of the immune evasion protein ICP47 (US12) of herpes simplex viruses

BACKGROUND

Herpes simplex virus (HSV) can cause encephalitis. Its infected cell polypeptide 47 (ICP47), encoded by immediate-early gene US12, promotes immune escape. ICP47 was modified in the clinically approved oncolytic HSV (oHSV) T-Vec. However, transcription regulatory sequence (TRS) and transcription regulatory factor (TRF) of HSV US12 are seldom reported.

METHODS

Previously, our laboratory isolated a new HSV strain named HSV-1-LXMW from a male patient with oral herpes in Beijing, China. Firstly, the genetic tree was used to analyze its genetic relationship. The US12 TRS and TRF in HSV-1-LXMW were found by using predictive software. Secondly, the further verification by the multi-sequence comparative analysis shown that the upstream DNA sequence of HSV US12 gene contained the conserved region. Finally, the results of literature search shown that the expression of transcription factors was related to the tissue affinity of HSV-1 and HSV-2, so as to increase the new understanding of the transcriptional regulation of HSV biology and oncolytic virus (OVs) therapy.

RESULTS

Here we reported the transcriptional regulation region sequence of our new HSV-1-LXMW, and its close relationship with HSV-1-CR38 and HSV-1-17. Importantly we identified eight different kinds of novel TRSs and TRFs of HSV US12 for the first time, and found they are conserved among HSV-1 (c-Rel, Elk-1, Pax-4), HSV-2 (Oct-1, CF2-II, E74A, StuAp) or both HSVs (HNF-4). The TRFs c-Rel and Oct-1 are biologically functional respectively in immune escape and viral replication during HSV infection.

CONCLUSIONS

Our findings have important implication to HSV biology, infection, immunity and oHSVs.

A point mutation in the linker domain of mouse STAT5A is associated with impaired NK-cell regulation

The transcription factor STAT5 is critical for peripheral NK-cell survival, proliferation, and cytotoxic function. STAT5 refers to two highly related proteins, STAT5A and STAT5B. In this study, we verified the importance of STAT5A isoform for NK cells. We characterized an incidental chemically induced W484G mutation in the Stat5a gene and found that this mutation was associated with a reduction of STAT5A protein expression. Closer examination of NK-cell subsets from Stat5a mutant mice showed marked reductions in NK-cell number and maturation. IL-15 treatment of Stat5a mutant NK cells exhibited defective induction of both STAT5 and mTOR signaling pathways and reduced expression of granzyme B and IFN-γ. Finally, we observed that Stat5a mutant mice revealed more tumor growth upon injection of RMA-S tumor cell line. Overall, our results demonstrate that the W484G mutation in the linker domain of STAT5A is sufficient to compromise STAT5A function in NK-cell homeostasis, responsiveness, and tumoricidal function.

MiR-146b protects against the inflammation injury in pediatric pneumonia through MyD88/NF-κB signaling pathway

Background: Pneumonia is a common respiratory disease worldwide that can be prevented and treated. However, it is considered to be the leading cause of children death. The present study was aimed to explore the functional role and molecular mechanism of miR-146b in the inflammation injury in pediatric pneumonia.Materials and methods: The lipopolysaccharide (LPS)-induced pulmonary injury cell model was established in WI-38 human lung fibroblasts cells. QRT-PCR and Western blot was applied to detect miR-146b and MyD88 expression. ELISA assay was used to analyze the production of pro-inflammatory factors. Cell viability was evaluated by CCK-8 assay. The apoptosis proteins and the downstream genes of NF-κB pathway were detected by Western blot.Results: we displayed that miR-146b was down-regulated, whereas MyD88 was up-regulated in the serum of children patients with pneumonia and in WI-38 cells treated with LPS. Moreover, re-expression of miR-146b suppressed the production of inflammatory factors in the serum of pneumonia patients and WI-38 cells treated with LPS. In addition, elevating miR-146b expression increased WI-38 cell viability and reduced cell apoptosis. More importantly, bioinformatics analysis revealed that MyD88 was a target of miR-146b and could overturn the protective effect of miR-146b on the inflammation injury in LPS-injured WI-38 cells. Furthermore, miR-146b over-expression inhibited the activation of NF-κB signaling pathway by suppressing MyD88.Conclusion: miR-146b attenuated the inflammation injury in pediatric pneumonia through inhibiting MyD88/NF-κB signaling pathway. These preliminarily findings further deepened our understanding of this mechanism and identified new potential therapeutic targets for pediatric pneumonia.