The NLRP3 inflammasome inhibitor, OLT1177®, ameliorates experimental allergic asthma in mice (2021)

Despite differences, all types of asthma share a complex symptomatology that derives from chronic inflammation of the airways. Since a curative therapy is not yet available, standard of care treatment regimens aim to control symptoms by reducing this inflammation through inhaled corticosteroids. Though this approach has proved to be a reliable and effective treatment option in the majority of patients with mild-to-moderate asthma, patients with severe, neutrophilic, difficult-to-treat, or uncontrolled asthma frequently experience acute exacerbations and loss of symptom control despite permanent corticosteroid treatment. A safe and more tolerable treatment option for these patients remains an unmet medical need.1 Consequently, evaluating selective NLRP3 inhibitor, OLT1177® (dapansutrile) on the pathologic features of experimental allergic asthma (EAA) in different mouse models, became the focus of our studies. Upon activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3), the formation of the NLRP3 inflammasome occurs, leading to the release of caspase-1-dependent proinflammatory cytokines interleukin (IL) 1β and IL-18 as well as pyroptosis, which actually facilitates clearance of inhaled pathogens. However, overactivation of this axis has been implicated in the development and exacerbation of asthma.2 In our first model, intra-peritoneal treatment with 60 mg/kg body weight (bw) OLT1177® of mice with ovalbumin- (OVA-) induced asthma showed reduced NLRP3 expression and caspase-1 activation in lung tissue, and levels of activated IL-1β in broncho-alveolar lavage fluid (BAL) fluid (Figure 1A, B, G). All pathophysiologic hallmarks of this Th2-high, eosinophilic asthma endotype were also diminished, such as inflammatory cell counts in BALF and airway tissue, goblet cell hyperplasia, airway hyper-responsiveness (AHR), and BAL levels of T helper 2 (Th2) type (IL-4, IL-5, IL-13) and proinflammatory (IL-6, tumor necrosis factor [TNF]) cytokines (Figure 1C–G). Next, we evaluated two models that mimic other asthma endotypes or diseases stages, namely HDM-induced EAA and poly(I:C)-triggered exacerbation of EAA. In mice with HDM-induced EAA i.p., OLT1177® diminished airway inflammation as evidenced by reduced eosinophil and neutrophil numbers in BAL and inflammatory cell infiltrate in lung tissue and significantly reduced AHR (Figure 2A–C). Comparable effects of OLT1177® were also observed in mice undergoing the induction of an acute exacerbation of OVA-induced EAA.3 Consistent with the previous findings, OLT1177® treatment markedly reduced eosinophil and neutrophil numbers in BAL, inflammatory cell infiltrate in lung tissue, and lowered AHR (Figure 2D–F). Since drug administration requiring repeated injection is known to have low compliance in patients, we tested the effectiveness of OLT1177® in the oral route of administration in mice with OVA-induced EAA. OLT1177® delivered via enriched mouse feed reaching therapeutic exposure confirmed by pharmacokinetic evaluation (Figure S1A), demonstrated therapeutic benefit on the pathophysiologic hallmarks of EAA comparable to the findings using i.p. treatment (Figure 2G–I). During the study, no signs of negative effects of OLT1177® were seen in any study animal. This is consistent with our previous findings from administration of OLT1177® in animals,4 as well as the safety outcomes in all its six human trials to date, including in patients with acute gout flares5 or with heart failure.6 Taken together, we have shown that systemic treatment, both i.p. and orally, with OLT1177® is consistently bioactive and well-tolerated, inhibited NLRP3 and caspase-1 activity in vivo, reduced the release of proinflammatory IL-1β, and diminished the pathophysiological hallmarks of three different mouse models of EAA. These findings not only suggest that NLRP3 is a therapeutic target in asthma, but also highlight the translational potential of OLT1177® to be tested in patients with asthma. L.P.L., C.V., and M.W. declare to have no conflict of interest. D.B.S. serves as Chairman and Chief Executive Officer of Olatec; C.A.D. serves as Chairman of Olatec's Scientific Advisory Board, is co-Chief Scientific Officer, and has equity in Olatec. This study was supported by the German Center for Lung Research (DZL). We thank Franziska Beyersdorf and Linda Lang for their excellent technical support and appreciate the contributions of Karina Stein and Holger Heine. The study was also supported by Olatec Therapeutics LLC and the Interleukin Foundation. We appreciate the contributions of Carlo Marchetti, PhD, Amy Poshusta PhD and Bob Fielding MS. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.