Rhesus θ-Defensin-1 Attenuates Endotoxin-induced Acute Lung Injury by Inhibiting Proinflammatory Cytokines and Neutrophil Recruitment

Abstract

Acute lung injury (ALI) is a clinical syndrome characterized by acute respiratory failure and is associated with substantial morbidity and mortality. Rhesus θ-defensin (RTD)-1 is an antimicrobial peptide with immunomodulatory activity. As airway inflammation and neutrophil recruitment and activation are hallmarks of ALI, we evaluated the therapeutic efficacy of RTD-1 in preclinical models of the disease. We investigated the effect of RTD-1 on neutrophil chemotaxis and macrophage-driven pulmonary inflammation with human peripheral neutrophils and LPS-stimulated murine alveolar macrophage (denoted MH-S) cells. Treatment and prophylactic single escalating doses were administered subcutaneously in a well-established murine model of direct endotoxin-induced ALI. We assessed lung injury by histopathology, pulmonary edema, inflammatory cell recruitment, and inflammatory cytokines/chemokines in the BAL fluid. In vitro studies demonstrated that RTD-1 suppressed CXCL8-induced neutrophil chemotaxis, TNF-mediated neutrophil-endothelial cell adhesion, and proinflammatory cytokine release in activated murine alveolar immortalized macrophages (MH-S) cells. Treatment with RTD-1 significantly inhibited in vivo LPS-induced ALI by reducing pulmonary edema and histopathological changes. Treatment was associated with dose- and time-dependent inhibition of proinflammatory cytokines (TNF, IL-1β, and IL-6), peroxidase activity, and neutrophil recruitment into the airways. Antiinflammatory effects were demonstrated in animals receiving RTD-1 up to 12 hours after LPS challenge. Notably, subcutaneously administered RTD-1 demonstrates good peptide stability as demonstrated by the long in vivo half-life. Taken together, these studies demonstrate that RTD-1 is efficacious in an experimental model of ALI through inhibition of neutrophil chemotaxis and adhesion, and the attenuation of proinflammatory cytokines and gene expression from alveolar macrophages.

Daily Intake of Fermented Milk Containing Lactobacillus casei Shirota (Lcs) Modulates Systemic and Upper Airways Immune/Inflammatory Responses in Marathon Runners

“…As previously highlighted by our group, not only alterations in the systemic, but also in the upper airways immune/inflammatory responses are found after a strenuous and prolonged exercise session, as a marathon race [4]. Elevations of TNF-α and IL-1β—two well-known proinflammatory cytokines—can be verified both in acute and chronic airway inflammation [24,25]. Among some properties, both cytokines are responsible for the neutrophil recruitment in the nasal mucosa, since the combined treatment with anti-IL-1β and TNF-α was able to reduce or even abolish neutrophil infiltration in the nasal mucosa and lung tissue in a model of pathological allergic inflammatory reaction [25].…”

Rhesus Theta Defensin 1 Promotes Long Term Survival in Systemic Candidiasis by Host Directed Mechanisms

“…coli sepsis 35 , SARS-coronavirus infection 36 , a mouse model of P . aeruginosa induced cystic fibrosis 37 , and endotoxin-induced lung injury 38 . In a recent study we reported that θ-defensins are potently fungicidal in vitro against MDR C .…”

Macrocyclic θ-defensins suppress tumor necrosis factor-α (TNF-α) shedding by inhibition of TNF-α–converting enzyme

“…Studies in the mouse severe acute respiratory syndrome coronavirus model strongly implicated host-directed anti-inflammatory effects of rhesus macaque -defensin (RTD-1) because the pep-tide had no direct antiviral activity (15). RTD-1 was also effective in reducing pulmonary pathology in murine models of endotoxic lung injury (16) and cystic fibrosis (17) by moderating inflammatory responses. Also, RTD-1 arrested joint inflammation in a rat model of rheumatoid arthritis (RA), pristaneinduced arthritis, an autoimmune disease characterized by dysregulated proinflammatory cytokines and erosive joint changes similar to those associated with RA (18).…”