Phosphodiesterase-4 Inhibition Reduces Cutaneous Inflammation and IL-1β Expression in a Psoriasiform Mouse Model but Does Not Inhibit Inflammasome Activation

Apremilast (Otezla®) is an oral small molecule phosphodiesterase 4 (PDE4) inhibitor approved for the treatment of psoriasis, psoriatic arthritis, and oral ulcers associated with Behçet’s disease. While PDE4 inhibition overall is mechanistically understood, the effect of apremilast on the innate immune response, particularly inflammasome activation, remains unknown. Here, we assessed the effect of apremilast in a psoriasis mouse model and primary human cells. Psoriatic lesion development in vivo was studied in K5.Stat3C transgenic mice treated with apremilast for 2 weeks, resulting in a moderate (2 mg/kg/day) to significant (6 mg/kg/day) resolution of inflamed plaques after 2-week treatment. Concomitantly, epidermal thickness dramatically decreased, the cutaneous immune cell infiltrate was reduced, and proinflammatory cytokines were significantly downregulated. Additionally, apremilast significantly inhibited lipopolysaccharide- or anti-CD3-induced expression of proinflammatory cytokines in peripheral mononuclear cells (PBMCs). Notably, inflammasome activation and secretion of IL-1β were not inhibited by apremilast in PBMCs and in human primary keratinocytes. Collectively, apremilast effectively alleviated the psoriatic phenotype of K5.Stat3 transgenic mice, further substantiating PDE4 inhibitor-efficiency in targeting key clinical, histopathological and inflammatory features of psoriasis. Despite lacking direct effect on inflammasome activation, reduced priming of inflammasome components upon apremilast treatment reflected the indirect benefit of PDE4 inhibition in reducing inflammation.

A European pharmacotherapeutic agent Roflumilast exploring integrated preclinical and clinical evidences for SARS CoV-2 mediated inflammation to organ damage

COVID-19 has spread globally, affecting almost 160 million individuals. Elderly and pre-existing patients (such as diabetes, heart disease and asthma), seems more susceptible to serious illness with COVID-19. Roflumilast was licensed for usage in the European Union in July 2010 as a phosphodiesterase-4 (PDE4) inhibitor. Roflumilast has been shown to decrease bleomycin-induced lung fibrosis, lung hydroxyproline, right heart thickning in animal prophylactic. The current study reviewed existing data that the PDE-4 inhibitor protects not just renal tissues but also other major organ systems after COVID-19 infection by decreasing immune cell infiltration. These immune-balancing effects of roflumilast were related with a decrease in oxidative and inflammatory burden, caspase-3 suppression, and increased PKA/cAMP levels in renal and other organ tissue.

Once-Daily Roflumilast Cream 0.3%, a Potent Phosphodiesterase-4 Inhibitor, Provided Safe and Effective Treatment of Psoriasis in the DERMIS-1 and DERMIS-2 Phase 3 Trials

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