Topical Ocular Drug Delivery to the Back of the Eye by Mucus-Penetrating Particles.

PURPOSE: Enhanced drug exposure to the ocular surface typically relies on inclusion of viscosity-enabling agents, whereas delivery to the back of the eye generally focuses on invasive means, such as intraocular injections. Using our novel mucus-penetrating particle (MPP) technology, which rapidly and uniformly coats and penetrates mucosal barriers, we evaluated if such drug formulations could increase ocular drug exposure and improve topical drug delivery. METHODS: Pharmacokinetic (PK) profiling of topically administered loterprednol etabonate formulated as MPP (LE-MPP) was performed in rabbits and a larger species, the mini-pig. Pharmacodynamic evaluation was done in a rabbit model of VEGF-induced retinal vascular leakage. Cellular potency and PK profile were determined for a second compound, KAL821, a novel receptor tyrosine kinase inhibitor (RTKi). RESULTS: We demonstrated in animals that administration of LE-MPP increased exposure at the ocular surface and posterior compartments. Furthermore using a rabbit vascular leakage model, we demonstrated that biologically effective drug concentrations of LE were delivered to the back of the eye using the MPP technology. We also demonstrated that a novel RTKi formulated as MPPs provided drug levels to the back of the eye above its cellular inhibitory concentration. CONCLUSIONS: Topical dosing of MPPs of LE or KAL821 enhanced drug exposure at the front of the eye, and delivered therapeutically relevant drug concentrations to the back of the eye, in animals. TRANSLATIONAL RELEVANCE: These preclinical data support using MPP technology to engineer topical formulations to deliver therapeutic drug levels to the back of the eye and could provide major advancements in managing sight-threatening diseases.

T helper differentiation in resistant and susceptible B7-deficient mice infected with Leishmania major.

The contribution of the costimulatory molecules B7-1 and B7-2 to the in vivo differentiation of Th cells remains controversial. The infection of resistant and susceptible strains of mice with the parasite Leishmania major provides a well-established model for studying in vivo differentiation of CD4+ T cells. We have infected B7-1/B7-2-deficient mice on the BALB/c and 129 background with L. major and subsequently examined different parameters of infection and cytokine responses upon restimulation of lymph node cells in vitro. BALB/c B7-2-deficient and B7-1/B7-2-double deficient mice are resistant to L. major, whereas BALB/c B7-1-deficient mice remain as susceptible as wild-type BALB/c mice. Differential expression of B7-1 and B7-2 can explain the distinct roles observed for these B7 costimulators in L. major infection.

IL-10 is critical for host resistance and survival during gastrointestinal helminth infection.

Resistance to many intestinal nematodes is dependent on the induction of polarized type 2 cytokine responses, whereas type 1 responses can exacerbate these infections. The contributions of IL-4 and IL-13 to the development of resistance have been well described for a variety of intestinal parasites; however, the role of IL-10 has not been previously investigated. In this study we infected IL-10-, IL-10/IL-4-, IL-10/IL-12-, IL-4-, and IL-12-deficient mice with Trichuris muris to determine whether IL-10 contributes to the development of immunity. Interestingly, T. muris-infected IL-10-, IL-4-, and IL-10/IL-4-deficient mice failed to expel the parasite, and animals deficient in IL-10 displayed marked morbidity and mortality. In contrast, double IL-10/IL-12-deficient mice were completely resistant and mounted a highly polarized type 2 cytokine response, demonstrating that the increased susceptibility of IL-10-deficient mice was dependent on IL-12. Further study suggested that the susceptibility of IL-10- and IL-10/IL-4-deficient mice was probably attributable to a marked increase in type 1 cytokine production in those animals. The mortality observed in T. muris-infected IL-10- and IL-10/IL-4-deficient mice correlated with increased inflammation, loss of Paneth cells, and absence of mucus in the cecum. Interestingly, survival was enhanced in T. muris-infected IL-10/IL-4-deficient mice if a broad spectrum antibiotic was administered, suggesting that an outgrowth of opportunistic bacteria was contributing to the high degree of morbidity and mortality. Overall, these studies reveal a critical role for IL-10 in the polarization of Th2 responses, development of resistance during T. muris infection, and maintenance of barrier function in the colon.