Hydra-Elastin-like Polypeptides Increase Rapamycin Potency When Targeting Cell Surface GRP78

Rapalogues are powerful therapeutic modalities for breast cancer; however, they suffer from low solubility and dose-limiting side effects. To overcome these challenges, we developed a long-circulating multiheaded drug carrier called 5FA, which contains rapamycin-binding domains linked with elastin-like polypeptides (ELPs). To target these "Hydra-ELPs" toward breast cancer, we here linked 5FA with four distinct peptides which are reported to engage the cell surface form of the 78 kDa glucose-regulated protein (csGRP78). To determine if these peptides affected the carrier solubility, this library was characterized by light scattering and mass spectrometry. To guide in vitro selection of the most potent functional carrier for rapamycin, its uptake and inhibition of mTORC1 were monitored in a ductal breast cancer model (BT474). Using flow cytometry to track cellular association, it was found that only the targeted carriers enhanced cellular uptake and were susceptible to proteolysis by SubA, which specifically targets csGRP78. The functional inhibition of mTOR was monitored by Western blot for pS6K, whereby the best carrier L-5FA reduced mTOR activity by 3-fold compared to 5FA or free rapamycin. L-5FA was further visualized using super-resolution confocal laser scanning microscopy, which revealed that targeting increased exposure to the carrier by ∼8-fold. This study demonstrates how peptide ligands for GRP78, such as the L peptide (RLLDTNRPLLPY), may be incorporated into protein-based drug carriers to enhance targeting.

High-fat diet-induced immune dysregulation in Th17/regulatory T cells promotes inflammation through protein kinase A (PKA) and PPAR-γ pathways

Obesity is a hallmark around the globe, which is defined as a complex situation associated with various metabolic abnormalities and cardiovascular diseases. The increasing evidence suggests that type 1 inflammation-associated immune cells are dominant in adipose tissue and exert metabolically deleterious impacts. The precise mechanism of alteration of adipose tissue immune system and its effect on metabolic homeostasis is far from clear. We investigated how a high-fat diet (HFD) alters adipose tissue (AT) immune system and influences the inflammation. HFD consumption amends the metabolic parameters including body weight, glucose, and insulin levels. We noticed that there is increased infiltration of Th17 cells, dendritic cells, and macrophages in AT of mice fed HFD as compared to a normal diet (ND). In mice consuming HFD, we also find a reduction in regulatory T cells as compared to ND. We noticed a higher level of proinflammatory cytokines and chemokines in the HFD group as compared to ND. We also noticed an increase in IL-6 and KLF4 expression in the AT of HFD as compared to ND. Further, an increased level of AT protein kinase A in HFD fed and a decrease in PPAR-γ as compared to ND, suggesting acting as a negative regulator of Th17 cell differentiation. Taken together, these results suggest that HFD induces Th17, macrophage, dendritic cells, inflammatory cytokine and reduces Tregs and PPAR-γ to sustain AT inflammation. This study supports a key role of Th17/Tregs dysregulation and macrophages to induce AT inflammation through PKA and PPAR-γ pathways during obesity.

(Supported by NIH grant R01 AI140405).

Supported by NIH grant R01 AI140405.

Inverse-agonist (SMM-189) suppresses colitis by inducing endogenous cannabinoids and attenuating Th17, neutrophils, natural killer cells

The cause of inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are multi-factorial and include activated immune cells, chronic inflammation, genetics, and environmental exposure. It is well known that endocannabinoids mediate protection against intestinal inflammation and other autoimmune diseases. However, the effect of cannabinoid receptors induction by inverse-agonist during experimental colitis has not been investigated. Here, we investigate the activation of the cannabinoid receptor-2 (CB2) by SMM-189, a potent CB2 inverse agonist, on the inhibition of dextran sodium sulfate (DSS) induced colitis. In the present study, we found that SMM-189 effectively attenuated the overall clinical score, reversed colitis-associated pathogenesis, increased body weight and colon length while increasing the expression of CB2 receptors and protein kinase A (PKA) in the colon lamina propria (LPs). We also measured a decrease in the percentage and number of Th17 cells in the spleen, mesenteric lymph nodes (MLNs), and LPs treated with SMM-189 compared to DSS controls. Similarly, the percentage and number of natural killer T (NKT) cells and neutrophils are decreased after SMM-189 treatment. SMM-189 also induces the myeloid-derived suppressor cells (MDSCs) during chronic colitis progression as compared to DSS alone. These findings suggest that SMM-189 ameliorates experimental colitis by inducing CB2 receptors and PKA in the LPs, MDSCs and reduces Th17, NKT cells, and neutrophils from the spleen and LPs. Taken together, these data support the idea that the CB2 inverse agonists, such as SMM-189, may be developed as a novel therapeutic target for IBD.

Supported by NIH grant R01 AI140405