Interferon-gamma depresses human intestinal smooth muscle cell contractility: Relevance to inflammatory gut motility disturbances.

AIM/BACKGROUND: In addition to absorptive disturbances, inflammatory bowel diseases (IBD) perturb normal contractility of intestinal smooth muscle. Such motility disturbances may reflect both nervous alterations and increased abundance of cytokines (e.g. IL-1ß, TNF-α, and IFN-γ), which impair normal intestinal smooth muscle structure and function. In a previous study, we reported that IL-1ß decreased mesenteric muscular contractility, consistent with cytokine-mediated changes in contraction present in IBD. Here, we considered the impact of pro-inflammatory cytokines on human intestinal smooth muscle cell (HISMC) contractility in vitro, which might provide a method for evaluating treatments for IBD. MATERIALS AND METHODS: We used an in vitro tonic contraction assay to study how HISMC contractility was affected by cell density, serum, and cytokines (IL-1ß, TNF-α, and IFN-γ). MTT (3-(4, 5-dimethyl thiazolyl-2)-2, 5-diphenyltetrazolium bromide) and wound healing analyses were also used to measure cell proliferation and migration in HISMC in response to IFN-γ. KEY FINDINGS: We found that IFN-γ (but not IL-1ß or TNF-α) significantly depressed HISMC tonic contractility over six days. IFN-γ also decreased HISMC proliferation, migration, and smooth muscle F-actin expression in a dose-dependent manner (studied at 4 days). SIGNIFICANCE: Our studies indicate that IFN-γ dose and time-dependently reduces normal HISMC contractility, motility and proliferation which may contribute to dysmotility observed in GI inflammatory disorders and that IFN-γ therapeutics might restore normal HISMC contractility impaired in IBD.

Bryostatin-1 synergizes with histone deacetylase inhibitors to reactivate HIV-1 from latency.

The persistence of latent HIV-infected cellular reservoirs represents the major hurdle to virus eradication on patients treated with HAART. It has been suggested that successful depletion of such latent reservoirs will require a combination of therapeutic agents that can specifically and efficiently act on cells harboring latent HIV-1 provirus. Using Jurkat-LAT-GFP cells, a tractable model of HIV-1 latency, we have found that bryostatin -1 reactivates HIV-1 through a classical PKC-dependent pathway. Bryostatin-1 also activates MAPKs and NF-κB pathways and synergizes with HDAC inhibitors to reactivate HIV-1 from latency. Bryostatin-1 downregulates the expression of the HIV-1 co-receptors CD4 and CXCR4 and prevented de novo HIV-1 infection in susceptible cells. We applied proteomic methods to investigate major changes in protein expression in Jurkat-LAT-GFP under latency and reactivation conditions. We identified up-regulation of proteins that may be involved in the innate anti-HIV-1 response (NKEF-A and MHD2) and in different cell functions (i.e. cofilin-1 and transgelin-2) of the host cells. PKC agonists may represent a valuable pharmacological approach to purge latent HIV from cellular reservoirs and at the moment, the only clinically available PKC agonist is bryostatin-1. This drug has been tested in numerous clinical trials and its pharmacokinetics and toxicity in humans is well known. Moreover, bryostatin-1 potently synergizes with other HDAC inhibitors commonly used in the medical practice such as valproic acid. Therefore, bryostatin-1, alone or in combination with HDAC inhibitors, could be used in HAART treated patients to validate the hypothesis that reactivating HIV-1 from latency could purge HIV-1 reservoirs.

Phospholipid nanosomes.

Phospholipid nanosomes are small, uniform liposomes manufactured utilizing supercritical fluid technologies. Supercritical fluids are first used to solvate phospholipid raw materials, and then decompressed to form phospholipid nanosomes that can encapsulate hydrophilic molecules such as proteins and nucleic acids. Hydrophobic therapeutics are co-solvated with phospholipid raw materials in supercritical fluids that, when decompressed, form phospholipid nanosomes encapsulating these drugs in their lipid bilayers. Mathematical modeling and semi-empirical experiments indicate that the size and character of phospholipid nanosomes depend on the several process parameters and material properties including the size and design of decompression nozzle, bubble size, pressure and the rate of decompression, interfacial forces, charge distribution and the nature of compound being encapsulated. Examples are presented for the encapsulation of a protein and hydrophobic drugs. In vitro and in vivo data on breast cancer cells and xenografts in nude mice indicate that paclitaxel nanosomes are less toxic and much more effective than paclitaxel in Cremophor EL (Taxol). Camptothecin nanosomes demonstrate that the normally very water-insoluble camptothecin can be formulated in a biocompatible aqueous medium while retaining in vivo efficacy against lymphoma xenografts in nude mice. In vitro data for betulinic acid nanosomes demonstrate enhanced efficacy against HIV-1 (EC50 of 1.01 microg/ml versus 6.72 microg/ml for neat betulinic acid). Phospholipid nanosomes may find utility in the enhanced delivery of hydrophilic drugs such as recombinant proteins and nucleic acid as well as hydrophobic anticancer and anti-HIV drugs.