Inflammatory and interferon gene expression signatures in patients with mitochondrial disease.

BACKGROUND: People with mitochondrial disease (MtD) are susceptible to metabolic decompensation and neurological symptom progression in response to an infection. Increasing evidence suggests that mitochondrial dysfunction may cause chronic inflammation, which may promote hyper-responsiveness to pathogens and neurodegeneration. We sought to examine transcriptional changes between MtD patients and healthy controls to identify common gene signatures of immune dysregulation in MtD. METHODS: We collected whole blood from a cohort of MtD patients and healthy controls and performed RNAseq to examine transcriptomic differences. We performed GSEA analyses to compare our findings against existing studies to identify commonly dysregulated pathways. RESULTS: Gene sets involved in inflammatory signaling, including type I interferons, interleukin-1ß and antiviral responses, are enriched in MtD patients compared to controls. Monocyte and dendritic cell gene clusters are also enriched in MtD patients, while T cell and B cell gene sets are negatively enriched. The enrichment of antiviral response corresponds with an independent set of MELAS patients, and two mouse models of mtDNA dysfunction. CONCLUSIONS: Through the convergence of our results, we demonstrate translational evidence of systemic peripheral inflammation arising from MtD, predominantly through antiviral response gene sets. This provides key evidence linking mitochondrial dysfunction to inflammation, which may contribute to the pathogenesis of primary MtD and other chronic inflammatory disorders associated with mitochondrial dysfunction.

Wogonin, a flavonoid isolated from Scutellaria baicalensis, has anti-viral activities against influenza infection via modulation of AMPK pathways.

Wogonin, a flavonoid isolated from Scutellaria baicalensis, has attracted increasing scientific attention in recent years because of its potent anti-tumor activity. Its role during viral infection has largely been unexplored. Wogonin treatment effectively suppressed both influenza A and B virus replication in Madin-Darby Canine Kidney (MDCK) cells and human lung epithelial (A549) cells. In contrast, wogonin treatment following influenza A virus infection led to up-regulation of interferon (IFN)-induced antiviral signaling. Additionally, influenza A virus infection in A549 cells induced 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and activation in a time-dependent manner and wogonin treatment led to the suppression of AMPK phosphorylation. Furthermore, the treatment with AMPK-specific inhibitor (compound C; CC) attenuated influenza A virus replication. These data suggest that wogonin possesses a potent anti-influenza activity mediated by regulation of AMPK activation, suggesting that wogonin has the potential to be developed as an anti-influenza drug.

A Src-family-tyrosine kinase, Lyn, is required for efficient IFN-ß expression in pattern recognition receptor, RIG-I, signal pathway by interacting with IPS-1.

Retinoic acid-inducible gene I (RIG-I) plays an important role in antiviral immunity as a cytosolic receptor recognizing invading viruses. The activation of downstream signaling pathways led by IFN-ß promoter stimulator-1 (IPS-1), an adaptor, is known to culminate in the activation of IRFs and the expression of type I interferons. However, the role of Src-family-tyrosine kinases (STKs) in the RIG-I signaling pathway has not been fully evaluated. Through a combined approach of immunoprecipitation and micro reversed phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) analysis, we established that Lyn, one of the STKs, is associated with RIG-I in macrophages. The association of Lyn and RIG-I was confirmed by co-immunoprecipitation study with 293T cells overexpressing Lyn and RIG-I. Suppression of Lyn by siRNA knockdown or a pharmacological inhibitor (PP2) resulted in the attenuation of IRF3 activation and IFN-ß expression induced by short poly I:C, a RIG-I agonist, in macrophages. Lyn activation, as determined by phosphorylation of Tyr396 residue, was observed upon short poly I:C stimulation in the mitochondria of macrophages. Short poly I:C induced the formation of speckle-like aggregates of Lyn, which are prominent in mitochondria. Lyn associated with IPS-1, an adaptor protein of RIG-I, which resides on mitochondria membrane. Helicase domain of RIG-I and CARD of IPS-1 are responsible for the interaction with Lyn while SH3 and SH2 domains in Lyn are required for the association with RIG-I and IPS-1. Collectively, our results indicate that Lyn plays a positive regulatory role in RIG-I-mediated interferon expression as a downstream component of IPS-1. They provide further information as to how tyrosine kinases such as STKs play a role in the regulation of antiviral immunity.

Viral infection of the lung: host response and sequelae.

Because of its essential role in gas exchange and oxygen delivery, the lung has evolved a variety of strategies to control inflammation and maintain homeostasis. Invasion of the lung by pathogens (and in some instances exposure to certain noninfectious particulates) disrupts this equilibrium and triggers a cascade of events aimed at preventing or limiting colonization (and more importantly infection) by pathogenic microorganisms. In this review we focus on viral infection of the lung and summarize recent advances in our understanding of the triggering of innate and adaptive immune responses to viral respiratory tract infection, mechanisms of viral clearance, and the well-recognized consequences of acute viral infection complicating underlying lung diseases, such as asthma.

Targeting whole body metabolism and mitochondrial bioenergetics in the drug development for Alzheimer's disease.

Aging is by far the most prominent risk factor for Alzheimer's disease (AD), and both aging and AD are associated with apparent metabolic alterations. As developing effective therapeutic interventions to treat AD is clearly in urgent need, the impact of modulating whole-body and intracellular metabolism in preclinical models and in human patients, on disease pathogenesis, have been explored. There is also an increasing awareness of differential risk and potential targeting strategies related to biological sex, microbiome, and circadian regulation. As a major part of intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been considered for AD therapeutic interventions. This review summarizes and highlights these efforts.

Flavivirus Nonstructural Protein NS5 Dysregulates HSP90 to Broadly Inhibit JAK/STAT Signaling.

Pathogenic flaviviruses antagonize host cell Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling downstream of interferons α/ß. Here, we show that flaviviruses inhibit JAK/STAT signaling induced by a wide range of cytokines beyond interferon, including interleukins. This broad inhibition was mapped to viral nonstructural protein 5 (NS5) binding to cellular heat shock protein 90 (HSP90), resulting in reduced Janus kinase-HSP90 interaction and thus destabilization of unchaperoned JAKs (and other kinase clients) of HSP90 during infection by Zika virus, West Nile virus, and Japanese encephalitis virus. Our studies implicate viral dysregulation of HSP90 and the JAK/STAT pathway as a critical determinant of cytokine signaling control during flavivirus infection.

A Type III CRISPR Ancillary Ribonuclease Degrades Its Cyclic Oligoadenylate Activator.

Cyclic oligoadenylate (cOA) secondary messengers are generated by type III CRISPR systems in response to viral infection. cOA allosterically activates the CRISPR ancillary ribonucleases Csx1/Csm6, which degrade RNA non-specifically using a HEPN (Higher Eukaryotes and Prokaryotes, Nucleotide binding) active site. This provides effective immunity but can also lead to growth arrest in infected cells, necessitating a means to deactivate the ribonuclease once viral infection has been cleared. In the crenarchaea, dedicated ring nucleases degrade cA4 (cOA consisting of 4 AMP units), but the equivalent enzyme has not been identified in bacteria. We demonstrate that, in Thermus thermophilus HB8, the uncharacterized protein TTHB144 is a cA4-activated HEPN ribonuclease that also degrades its activator. TTHB144 binds and degrades cA4 at an N-terminal CARF (CRISPR-associated Rossman fold) domain. The two activities can be separated by site-directed mutagenesis. TTHB144 is thus the first example of a self-limiting CRISPR ribonuclease.

Combinatorial cytokine code generates anti-viral state in dendritic cells.

The physiological function of the immune system and the response to therapeutic immunomodulators may be sensitive to combinatorial cytokine micro-environments that shape the responses of specific immune cells. Previous work shows that paracrine cytokines released by virus-infected human dendritic cells (DC) can dictate the maturation state of naïve DCs. To understand the effects of paracrine signaling, we systematically studied the effects of combinations cytokines in this complex mixture in generating an anti-viral state. After naïve DCs were exposed to either IFNß or to paracrine signaling released by DCs infected by Newcastle disease virus (NDV), microarray analysis revealed a large number of genes that were differently regulated by the DC-secreted paracrine signaling. In order to identify the cytokine mechanisms involved, we identified 20 cytokines secreted by NDV infected DCs for which the corresponding receptor gene is expressed in naïve DCs. By exposing cells to all combinations of 19 cytokines (leave-one-out studies), we identified five cytokines (IFNß, TNFα, IL-1ß, TNFSF15, and IL28) as candidates for regulating DC maturation markers. Subsequent experiments identified IFNß, TNFα, and IL1ß as the major contributors to this anti-viral state. This finding was supported by infection studies in vitro, by T-cell activation studies and by in vivo infection studies in mouse. Combination of cytokines can cause response states in DCs that differ from those achieved by the individual cytokines alone. These results suggest that the cytokine microenvironment may act via a combinatorial code to direct the response state of specific immune cells. Further elucidation of this code may provide insight into responses to infection and neoplasia as well as guide the development of combinatorial cytokine immunomodulation for infectious, autoimmune, and immunosurveillance-related diseases.

UXT plays dual opposing roles on SARM-induced apoptosis.

Apoptosis is a vital defense mechanism for the clearance of infected cells. Ubiquitously expressed transcript (UXT), which exists in two isoforms (V1 and V2), interact with both apoptotic and cellular proteins. By yeast two-hybrid analysis, we found that UXT interacts with SARM (sterile α and HEAT armadillo motif-containing protein). Since SARM is a TLR adaptor which induces intrinsic apoptosis following immune activation, we were prompted to query whether UXT and SARM might co-regulate apoptosis. We found that the UXT isoforms elicit dual opposing regulatory effects on SARM-induced apoptosis; while UXT V1, co-expressed with SARM, caused a reduction in caspase 8 activity, UXT V2 strongly increased caspase 8 activity and enhanced SARM-induced apoptosis by activating the extrinsic pathway and depolarizing the mitochondria.