Peptides for Respiratory & Lung Health

Peptides may influence respiratory health through several mechanisms:

1. Pulmonary Vasodilation and Haemodynamic Effects VIP is a potent vasodilator that has demonstrated specific effects in the pulmonary vasculature. It relaxes pulmonary artery smooth muscle, reduces pulmonary vascular resistance, and improves right ventricular function. Clinical studies — including inhaled VIP administration in pulmonary hypertension — have shown significant improvements in pulmonary haemodynamics and exercise capacity. VIP also has anti-proliferative effects on pulmonary artery smooth muscle cells, potentially addressing the vascular remodelling that characterises pulmonary arterial hypertension. Its bronchodilatory effects are relevant to COPD and asthma.

2. Antimicrobial Defence in the Respiratory Tract LL-37, the only human cathelicidin, is expressed by respiratory epithelial cells, alveolar macrophages, and neutrophils, providing innate immune defence against respiratory pathogens. It has broad-spectrum activity against bacteria (including Pseudomonas aeruginosa, Staphylococcus aureus, and Mycobacterium tuberculosis), viruses, and fungi. Beyond direct antimicrobial activity, LL-37 modulates immune responses at mucosal surfaces — recruiting immune cells, promoting wound healing, and regulating inflammation. Deficiency in LL-37 expression has been associated with susceptibility to respiratory infections.

3. Immune Modulation in Respiratory Infection and Inflammation Thymosin-alpha-1 modulates both innate and adaptive immunity — enhancing T-cell maturation, NK cell activity, and dendritic cell function. It has been evaluated in clinical trials for COVID-19 and other respiratory infections, with some studies suggesting improved immune recovery and reduced mortality in severely immunocompromised patients. Its immunomodulatory rather than immunosuppressive mechanism distinguishes it from corticosteroids, theoretically allowing immune enhancement without the infection risk associated with immunosuppression.

4. Anti-Inflammatory and Anti-Fibrotic Effects Chronic respiratory diseases (COPD, asthma, pulmonary fibrosis) involve sustained inflammation and, in fibrotic conditions, progressive scarring of lung tissue. BPC-157 has demonstrated anti-inflammatory effects including modulation of TNF-alpha, IL-6, and other pro-inflammatory cytokines. PACAP has potent anti-inflammatory properties in pulmonary models, reducing inflammatory cell infiltration and cytokine release. These anti-inflammatory and potentially anti-fibrotic effects are relevant to the chronic inflammatory component of respiratory disease, though lung-specific evidence is limited.

5. Post-COVID Respiratory Recovery The COVID-19 pandemic has generated substantial interest in peptides for post-infectious respiratory recovery. SARS-CoV-2 infection can cause persistent lung inflammation, fibrotic changes, and impaired gas exchange. Thymosin-alpha-1 has been evaluated in COVID-19 clinical trials for immune support. BPC-157's tissue healing properties are theoretically relevant to lung repair. VIP's anti-inflammatory and vasodilatory effects may support pulmonary recovery. Research into peptide-based approaches for long COVID respiratory symptoms is an active and evolving field.