(586g) Invited Talk: Yeast Beta-Glucan Microparticles Prepared By Pressurized Gas Expanded Liquid (PGX) Technology As an Inhalable Therapeutic to Treat Pulmonary Fibrosis

Introduction: Pulmonary fibrosis (PF) is a debilitating condition characterized by excessive extracellular matrix (ECM) deposition in the alveolar and interstitial regions of the lung. While many forms of PF exist, idiopathic pulmonary fibrosis (IPF) is one of the most common and deadly forms of PF due to its progressive nature. In IPF, progressive scarring of the lungs leads to impeded gas exchange between the alveoli and surrounding capillaries, resulting in a severe decline in lung function that manifests as increasingly worse coughing and dyspnea for the patient (1). IPF prognosis is extremely poor when left untreated, with a median survival rate of just 2-3 years (2). Fortunately, IPF treatment has significantly improved in recent years due to the FDA approval of two anti-fibrotic drugs, nintedanib and pirfenidone, both of which have been shown to slow the rate of fibrotic progression in IPF patients. However, these drugs are unable to fully halt or reverse fibrosis, and current oral formulations require high doses that cause significant side-effects like nausea, diarrhea, and elevated liver enzymes (3, 4).

While the pathogenesis of IPF is not fully understood, pro-fibrotic “M2-like” macrophages have been identified as key drivers of fibrosis, thus offering the potential to develop targeted IPF therapies. M2-like macrophages support fibrotic progression through the secretion of pro-fibrotic cytokines that can recruit fibroblasts, induce their differentiation into myofibroblasts, and promote the production of ECM components (5). However, macrophages are highly plastic, and their phenotypes can be altered in the presence of both natural and synthetic immunomodulatory materials. One such material is yeast beta-glucan (YBG), a polysaccharide derived from S. cerevisiae. YBG microparticles can bind and activate the glucan-specific Dectin-1 receptor expressed on macrophages; this induces phagocytosis, reactive oxygen species production, and has been shown to convert M2-like macrophages to an anti-fibrotic M1-like phenotype (6). However, current conventional extraction and drying methods can lead to variable/inconsistent physical and biological properties of YBG, thereby limiting the potential for YBG as an immunomodulatory therapeutic.

Methods: We prepared YBG microparticles via Pressurized Gas eXpanded liquid (PGX) technology, a patented biopolymer processing method developed by Ceapro, Inc. The resulting PGX-YBG was compared to commercially available YBGs in terms of size, morphology, density, porosity, and Dectin-1 activation. PGX-YBG was then tested both in vitro and in ex vivo murine lung slices for modulation of various M1/M2 macrophage markers. PGX-YBG was then blended with inhalation-grade lactose and loaded into a capsule-based dry powder inhaler. Finally, PGX-YBG/lactose blends were aerosolized and characterized for respirability using the Next Generation Impactor.

Results: PGX-YBG microparticles exhibited an oval shape, highly wrinkled surface morphology, and monodisperse size between 2-10 µm. Conversely, commercial YBGs were irregularly shaped with smooth surfaces, with only 7% of particles under 10 µm. PGX-YBG had a significantly higher specific surface area (132 ± 5 m²/g) and lower bulk density (0.073 ± 0.01 g/mL) compared to commercial YBGs, properties that are desirable for highly respirable particles. PGX-YBG also demonstrated potent and specific Dectin-1 activation activity without activating TLR2 or TLR4. Immunomodulation assays confirmed PGX-YBG’s ability to prevent M2 polarization and promote an M1-like phenotype both in vitro and ex vivo. Finally, aerosolization tests of PGX-YBG highlighted its respirable nature, suggesting approximately 50% of the emitted dose could reach the lower regions of the lung.

Conclusion: Processing YBG via PGX confers unique particle properties that are beneficial for both immunomodulation and respirability. PGX-YBG has potential as a standalone anti-fibrotic agent that can be delivered directly to the lungs, with the high porosity offering future potential for drug loading to further promote desirable biological responses.

References:

(1) Maher, T. M., Bendstrup, E., Dron, L., Langley, J., Smith, G., Khalid, J. M., Patel, H., Kreuter, M. Respiratory Research 2021, 22(197)

(2) Pergolizzi, J. V., LeQuang, J. A., Varrassi, M., Breve, F., Magnusson, P., Varrassi, G. Advances in Therapy 2023, 40, 1334-1346

(3) Barczi, E., Starobinski, L., Kolonics-Farkas, A., Eszes, N., Bohacs, A., Vasakova, M., Hejduk, K., Müller, V. Advances in Therapy 2019, 36, 1221-1232

(4) Cottin, V., Maher, T. European Respiratory Review 2015, 24, 58-64

(5) Hou, J., Shi, J., Chen, L., Lv, Z., Chen, X., Cao, H., Xiang, Z., Han, X. Cell Communication and Signaling 2018, 16(89)

(6) Su, L. Chen, F. Yang, P. Cheung. Carbohydrate Polymers 2021, 253(117258)