Preclinical Mechanisms of Topical PRN473, a Bruton Tyrosine Kinase Inhibitor, in Immune-Mediated Skin Disease Models.

The expression of Bruton tyrosine kinase (BTK) in B cells and innate immune cells provides essential downstream signaling for BCR, Fc receptors, and other innate immune cell pathways. The topical covalent BTK inhibitor PRN473 has shown durable, reversible BTK occupancy with rapid on-rate and slow off-rate binding kinetics and long residence time, resulting in prolonged, localized efficacy with low systemic exposure in vivo. Mechanisms of PRN473 include inhibition of IgE (FcεR)-mediated activation of mast cells and basophils, IgG (FcγR)-mediated activation of monocytes, and neutrophil migration. In vivo, oral PRN473 was efficacious and well tolerated in the treatment of canine pemphigus foliaceus. In this study, we evaluated in vitro selectivity and functionality, in vivo skin Ab inflammatory responses, and systemic pharmacology with topically administered PRN473. Significant dose-dependent inhibition of IgG-mediated passive Arthus reaction in rats was observed with topical PRN473 and was maintained when given 16 h prior to challenge, reinforcing extended activity with once-daily administration. Similarly, topical PRN473 resulted in significant dose-dependent inhibition of the mouse passive cutaneous anaphylaxis IgE-mediated reaction. Multiday treatment with topical PRN473 in rodents resulted in low-to-no systemic accumulation, suggesting that efficacy was mainly due to localized exposure. Reduced skin Ab inflammatory activity was also confirmed with oral PRN473. These preclinical studies provide a strong biologic basis for targeting innate immune cell responses locally in the skin, with rapid onset of action following once-daily topical PRN473 administration and minimal systemic exposure. Dose-dependent inhibition in these preclinical models of immune-mediated skin diseases support future clinical studies.

Improved uptake and therapeutic intervention of curcumin via designing binary lipid nanoparticulate formulation for oral delivery in inflammatory bowel disorder.

This study was focussed on development of curcumin loaded solid binary lipid nanoparticles (C-SBLNs) to ameliorate stability, uptake and therapeutic potential of curcumin during inflammatory bowel disease (IBD). C-SBLNs with nano-size range (210.56 ± 41.22 nm) and high entrapment efficiency (83.12 ± 6.57%) were prepared by solvent emulsification evaporation method using binary lipids i.e. stearic acid and tristearin after optimizing various formulation and process variables. Physicochemical characterization of C-SBLNs by ATR-FTIR confirmed drug entrapment whereas thermal and pXRD study corroborated loss of crystallinity of drug into C-SBLNs. Lyophilized C-SBLNs were found to be spherical shaped with good gastrointestinal stability and prolonged drug release up to 24 h. Optimized C-SBLNs formulation displayed significantly enhanced cellular uptake and localization in inflamed tissues during IBD. Oral administration of C-SBLNs in DSS induced colitis model revealed significant reduction in leucocyte infiltration, oxidative stress, pro-inflammatory cytokine (TNF-α) secretion and maintenance of colonic structure similar to healthy animal group compared to curcumin. Thus, in vitro and preclinical findings of study clearly confirmed that C-SBLNs could be a stable and efficacious alternative platform for curcumin delivery with strong competence in IBD chemotherapy.