**5. Concluding Remarks**

The landscape of asthma treatment has changed drastically over the last decade with the FDA approval of biologics that target specific molecules that contribute to allergic inflammation. Antibodies against IgE, IL-5, the IL-4 receptor α, and TSLP are all clinically efficacious. However, there remain patients who have uncontrolled asthma despite adequate trials of biological therapies, and this may be where prostacyclin may be useful. Future steps towards potentially utilizing prostacyclin analogs for allergic inflammation, particularly asthma, would require clinical trials. A study that examined the feasibility of administering inhaled iloprost in human patients with mild asthma found that this prostacyclin analog was safe [37]. While there are still aspects to learn about the mechanism for how prostacyclin signaling reduces allergic inflammatory responses, the published data in this review support further research into repurposing prostacyclin as a possible treatment for allergic inflammation and asthma.

**Author Contributions:** K.P. wrote all drafts of the manuscript and R.S.P.J. edited the manuscript drafts. All authors have read and agreed to the published version of the manuscript.

**Funding:** This project was supported by NIH/NIAID 5RO1 AI124456, 5RO1 AI145265, 5R21 AI145397, 2U19 AI095227, and U.S. Department of Veterans Affairs 5I01BX004299.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
