Pulmonary fibrosis (PF) is a chronic, progressive, fatal interstitial lung disease with limited available therapeutic strategies. We recently reported that the protein kinase glycogen synthase kinase-3 β (GSK-3 β ) interacts with and inactivates the ubiquitin-editing enzyme A20 to suppress the degradation of the transcription factor CCAAT/enhancer-binding protein beta (C/EBP β ) in alveolar macrophages (AMs), resulting in a profibrotic phenotype of AMs and promoting the development of PF. Here, we showed that chronic lung injury upregulated the stress response protein tribbles homolog 3 (TRIB3), which interacted with GSK-3 β and stabilized GSK-3 β from ubiquitination and degradation. Elevated GSK-3 β expression phosphorylated A20 to inhibit its ubiquitin-editing activity, causing the accumulation of C/EBP β and the production of several profibrotic factors in AMs and promoting PF development. Activated C/EBP β , in turn, increased the transcription of TRIB3 and GSK-3 β , thereby establishing a positive feedback loop in AMs. The knockdown of TRIB3 expression or the pharmacologic disruption of the TRIB3‒GSK-3 β interaction was an effective PF treatment. Our study reveals an intact profibrotic axis of TRIB3‒GSK-3 β ‒A20‒C/EBP β in AMs, which represents a target that may provide a promising treatment strategy for PF.

In this study, the aim was to investigate the discriminatory power of molecular diagnostics based on mNGS and traditional 16S ribosomal RNA PCR among Nocardia species. A total of fourteen clinical isolates from patients with positive Nocardia cultures and clinical evidence were included between January 2017 and June 2020 in HeNan Provincial People’s Hospital. DNA extraction and 16S rRNA PCR were performed on positive cultures, and pathogens were detected by mNGS in these same samples directly. Among the 14 Nocardia isolates, four species were identified, and N. cyriacigeorgica (8 cases) is the most common species. Twelve of the 14 Nocardia spp. isolates were identified by the two methods, while two strains of N. cyriacigeorgica were not identified by mNGS. All tested isolates showed susceptibility to trimethoprim-sulfamethoxazole (SXT), amikacin and linezolid. Apart from Nocardia species, other pathogens such as Acinetobacter baumannii, Klebsiella pneumonia, Aspergillus, Enterococcus faecalis, Human herpesvirus, etc., were detected from the same clinical samples by mNGS. However, these different pathogens were considered as colonization or contamination. We found that it is essential to accurately identify species for determining antibiotic sensitivity and, consequently, choosing antibiotic treatment. 16S rRNA PCR was useful for identification of nocardial infection among species, while this technique needs the clinicians to make the pre-considerations of nocardiosis. However, mNGS may be a putative tool for rapid and accurate detection and identification of Nocardia, beneficial for applications of antimicrobial drugs and timely adjustments of medication.