Anti-Inflammatory Effects of RTD-1 in a Murine Model of Chronic Pseudomonas aeruginosa Lung Infection: Inhibition of NF-κB, Inflammasome Gene Expression, and Pro-IL-1β Biosynthesis
Year: 2021
Type: article
Abstract: Vicious cycles of chronic airway obstruction, lung infections with Pseudomonas aeruginosa, and neutrophil-dominated inflammation contribute to morbidity and mortality in cystic fibrosis (CF) patients. Rhesus theta defensin-1 (RTD-1) is an antimicrobial macrocyclic peptide with immunomodulatory properties. Our objective was to investigate the anti-inflammatory effect of RTD-1 in a murine model of chronic P. aeruginosa lung infection. Mice received nebulized RTD-1 daily for 6 days. Bacterial burden, leukocyte counts, and cytokine concentrations were evaluated. Microarray analysis was performed on bronchoalveolar lavage fluid (BALF) cells and lung tissue homogenates. In vitro effects of RTD-1 in THP-1 cells were assessed using quantitative reverse transcription PCR, enzyme-linked immunosorbent assays, immunoblots, confocal microscopy, enzymatic activity assays, and NF-κB-reporter assays. RTD-1 significantly reduced lung white blood cell counts on days 3 (−54.95%; p = 0.0003) and 7 (−31.71%; p = 0.0097). Microarray analysis of lung tissue homogenates and BALF cells revealed that RTD-1 significantly reduced proinflammatory gene expression, particularly inflammasome-related genes (nod-like receptor protein 3, Mediterranean fever gene, interleukin (IL)-1α, and IL-1β) relative to the control. In vitro studies demonstrated NF–κB activation was reduced two-fold (p ≤ 0.0001) by RTD-1 treatment. Immunoblots revealed that RTD-1 treatment inhibited proIL-1β biosynthesis. Additionally, RTD-1 treatment was associated with a reduction in caspase-1 activation (FC = −1.79; p = 0.0052). RTD-1 exhibited potent anti-inflammatory activity in chronically infected mice. Importantly, RTD-1 inhibits inflammasome activity, which is possibly a downstream effect of NF-κB modulation. These findings support that this immunomodulatory peptide may be a promising therapeutic for CF-associated lung disease.
Source: Antibiotics
Language: English
Subfield: Microbiology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $1,944
Funders: American Foundation for Pharmaceutical Education, Southern California Clinical and Translational Science Institute, Crohn's and Colitis Foundation, Cystic Fibrosis Research, National Institutes of Health, National Cancer Institute, National Institute of Allergy and Infectious Diseases, National Institute of Dental and Craniofacial Research
Awards: G1096387360, G1128497147, G2984450067, G342425680, Cyclic Orynotides for Systemic MDR Candidiasis, Host defense-stimulating macrocyclic peptides for treatment of MDR bacterial infections, G5577468519, G5895764547, G6171967099, G6393062315, University of Southern California Norris Comprehensive Cancer Center Support Grant (CCSG), Doctoral and Post-doctoral Training in Craniofacial Biology, G905063056
OpenAlex ID: W3196130514