The DNA repair enzyme 8-oxoguanine DNA glycosylase 1 (OGG1), which excises 8-oxo-7,8-dihydroguanine lesions induced in DNA by reactive oxygen species, has been linked to the pathogenesis of lung diseases associated with bacterial infections. A recently developed small molecule, SU0268, has demonstrated selective inhibition of OGG1 activity; however, its role in attenuating inflammatory responses has not been tested. In this study, we report that SU0268 has a favorable effect on bacterial infection both in mouse alveolar macrophages (MH-S cells) and in C57BL/6 wild-type mice by suppressing inflammatory responses, particularly promoting type I IFN responses. SU0268 inhibited proinflammatory responses during Pseudomonas aeruginosa (PA14) infection, which is mediated by the KRAS-ERK1-NF-kB signaling pathway. Furthermore, SU0268 induces the release of type I IFN by the mitochondrial DNA-cGAS-STING-IRF3-IFN-b axis, which decreases bacterial loads and halts disease progression. Collectively, our results demonstrate that the small-molecule inhibitor of OGG1 (SU0268) can attenuate excessive inflammation and improve mouse survival rates during PA14 infection. This strong anti-inflammatory feature may render the inhibitor as an alternative treatment for controlling severe inflammatory responses to bacterial infection.
Aldehyde dehydrogenases (ALDH) catalyze the conversion of various aliphatic and aromatic aldehydes to corresponding carboxylic acids. Traditionally considered as housekeeping enzymes, new biochemical roles are being identified for members of ALDH family. Recent work showed that AldA from the plant pathogen Pseudomonas syringae strain PtoDC3000 functions as an indole-3-acetaldehyde dehydrogenase for the synthesis of indole-3-acetic acid (IAA). IAA produced by AldA allows the pathogen to suppress salicylic acid-mediated defenses in the model plant Arabidopsis thaliana. Here we present a biochemical and structural analysis of the AldA indole-3-acetaldehyde dehydrogenase from PtoDC3000. Site-directed mutants targeting the catalytic residues Cys302 and Glu267 resulted in a loss of enzymatic activity. The x-ray crystal structure of the catalytically inactive AldA C302A mutant in complex with IAA and NAD+ showed the cofactor adopting a conformation that differs from the previously reported structure of AldA. These structures suggest that NAD+ undergoes a conformational change during the AldA reaction mechanism similar to that reported for human ALDH. Site-directed mutagenesis of the IAA binding site indicates that changes in the active site surface reduces AldA activity; however, substitution of Phe169 with a tryptophan altered the substrate selectivity of the mutant to prefer octanal. This study highlights the inherent biochemical versatility of members of the ALDH enzyme superfamily in P. syringae.
A 50-year-old female presented with acute epigastric abdominal pain, diarrhea, nausea, and vomiting for two days. Laboratory data showed hyperbilirubinemia and leukocytosis. Abdominal imagining was concerning for a pancreatic head/uncinate process lesion concerning a pancreatic neoplasm. Subsequent esophagogastroduodenoscopy with endoscopic ultrasound and endoscopic retrograde cholangiopancreatography found the major papilla adjacent to an inflamed and infected duodenal diverticulum, which was extrinsically compressing the distal common bile duct, causing biliary obstruction and common bile duct dilation. These findings are consistent with a diagnosis of Lemmel’s syndrome. A biliary sphincterotomy was performed to relieve the obstruction and one temporary plastic biliary stent was placed into the common bile duct. The duodenal diverticulitis was treated with antibiotics for 10 days and the patient made a good recovery.
A 68-year-old man presented in late summer 2021 with fever, myalgias, generalized weakness, dizziness, and headache. Past medical history included rheumatoid arthritis treated with infliximab, congestive heart failure with preserved ejection fraction, and recent travel to Alaska. He was febrile, tachycardic, and tachypneic on admission. Physical exam and admission labs were overall unremarkable. On day 4, he complained of shortness of breath and central chest discomfort. Troponin was mildly elevated, electrocardiogram was unremarkable, and echocardiogram showed new global wall motion abnormalities and ejection fraction of 40%, which was 55% months prior. Serum West Nile IgM antibodies resulted positive near the end of hospitalization. Testing for SARS-CoV-2, influenza as well as multiple other viral, bacterial, and fungal organisms was negative. Overall, the patient recovered clinically including improvement in ejection fraction on echocardiogram with conservative management. West Nile virus (WNV) is associated with a myriad of symptoms and complications, most notably, neuroinvasive disease. However, cardiomyopathy secondary to WNV as illustrated in this case has been infrequently described. Clinicians should be aware of this potential rare complication in patients with WNV to improve rapid detection and treatment of myositis, associated cardiomyopathy, and related complications.
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