Publications

The proliferation and migration of arterial smooth muscle cells (SMCs) are key events in the vascular restenosis that frequently follows angioplasty. Furthermore, SMC migration and neointimal hyperplasia are promoted by degradation of the extracellular matrix by matrix metalloproteinases (MMPs). Because we demonstrated previously that the proinflammatory and proatherogenic cytokine interleukin-18 (IL-18) stimulates SMC proliferation (Chandrasekar, B., Mummidi, S., Valente, A. J., Patel, D. N., Bailey, S. R., Freeman, G. L., Hatano, M., Tokuhisa, T., and Jensen, L. E. (2005) J. Biol. Chem. 280, 26263-26277), we investigated whether IL-18 induces SMC migration in an MMP-dependent manner and whether the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor atorvastatin can inhibit this response. IL-18 treatment increased both mRNA and protein expression of MMP9 in human coronary artery SMCs. Gel shift, enzyme-linked immunosorbent, and chromatin immunoprecipitation assays revealed a strong induction of IL-18-mediated AP-1 (c-Fos, c-Jun, and Fra-1) and NF-kappaB (p50 and p65) activation and stimulation of MMP9 promoter-dependent reporter gene activity in an AP-1- and NF-kappaB-dependent manner. Ectopic expression of p65, c-Fos, c-Jun, and Fra-1 induced MMP9 promoter activity. Specific antisense or small interfering RNA reagents for these transcription factors reduced IL-18-mediated MMP9 transcription. Furthermore, IL-18 stimulated SMC migration in an MMP9-dependent manner. Atorvastatin effectively suppressed IL-18-mediated AP-1 and NF-kappaB activation, MMP9 expression, and SMC migration. Together, our results indicate for the first time that the proatherogenic cytokine IL-18 induces human coronary artery SMC migration in an MMP9-dependent manner. Atorvastatin inhibits IL-18-mediated aortic SMC migration and has therapeutic potential for attenuating the progression of atherosclerosis and restenosis.

BACKGROUND

Studies of malaria in well-defined cohorts offer important data about the epidemiology of this complex disease, but few have been done in urban African populations. To generate a sampling frame for a longitudinal study of malaria incidence and treatment in Kampala, Uganda, a census, mapping and survey project was conducted.

METHODS

All households in a geographically defined area were enumerated and mapped. Probability sampling was used to recruit a representative sample of children and collect baseline descriptive data for future longitudinal studies.

RESULTS

16,172 residents living in 4931 households in a densely-populated community (18,824 persons/km2) were enumerated. A total of 582 households were approached with at least one child less than 10 years of age in order to recruit 601 children living in 322 households. At enrollment, 19% were parasitaemic, 24% were anaemic, 43% used bednets, and 6% used insecticide-treated nets. Low G6PD activity (OR = 0.33, P = 0.009) and bednet use (OR = 0.64, P = 0.045) were associated with a decreased risk of parasitaemia. Increasing age (OR = 0.62 for each year, P < 0.001) and bednet use (OR = 0.58, P = 0.02) were associated with a decreased risk of anaemia

CONCLUSION

Detailed surveys of target populations in urban Africa can provide valuable descriptive data and provide a sampling frame for recruitment of representative cohorts for longitudinal studies. Plans to use a multi-disciplinary approach to improve the understanding of the distribution and determinants of malaria incidence and response to therapy in this population are discussed.

OBJECTIVE

Antiretroviral-treated individuals with drug-resistant HIV experience slower CD4 cell count declines than untreated individuals, independent of degree of viremia. As immune activation independently predicts disease progression, we hypothesized that patients with drug-resistant viremia would have less immune activation than patients with wild-type viremia, independent of plasma HIV RNA levels and that these differences would not be explained by a direct drug effect of protease inhibitors.

METHODS

Percentages of activated (CD38/HLA-DR) T cells were compared between untreated participants with wild-type viremia and antiretroviral-treated participants with drug-resistant viremia, after adjusting for plasma HIV RNA levels among other factors associated with T cell activation. Changes in T cell activation were also assessed in subjects discontinuing protease inhibitors while continuing other antiretroviral medications.

RESULTS

Twenty-one untreated participants with wild-type viremia and 70 antiretroviral-treated participants with drug-resistant viremia were evaluated. Relative to untreated participants, those with drug-resistant viremia had 29% fewer activated CD4 (P = 0.051) and CD8 (P = 0.012) T cells after adjustment for plasma HIV RNA levels among other factors. There was no evidence for an early change in T cell activation among 13 subjects with drug-resistant viremia interrupting protease inhibitors while continuing other antiretroviral medications, but a significant increase in T cell activation with complete or partial emergence of wild-type sequences in protease.

CONCLUSIONS

Antiretroviral-treated patients with drug-resistant viremia have less T cell activation than untreated patients, independent of plasma HIV RNA level. Decreased ability of drug-resistant variants to cause T cell activation likely contributes to slower CD4 cell count declines among patients with drug-resistant viremia.

The native retinal pigment epithelium (RPE) exists as a monolayer structure and is critically involved in the maintenance of photoreceptors. Damage or destruction of the RPE due to a variety of diseases therefore often results in loss of vision. With regenerative purposes in mind, we have examined various culture conditions such as the initial cell density and the addition of various supplements in an effort to produce transplantable RPE cell sheets that can be harvested without defects. We demonstrate that the cell density in cultured RPE sheets increased linearly with the number of seeded cells and that RPE sheets were harvested without defects and limited contraction due to cytoskeletal reorganization, when TGF-beta2 was added to the growth medium. Results from histological analysis and the measurement of trans-epithelial resistance also demonstrates that these RPE cell sheets exist as monolayer structure, similar to the native RPE, with intact cell-to-cell junctions. Therefore, these methods provide significant insight into the fabrication of transplantable RPE cell sheets that can be applied to RPE regenerative therapies to restore lost vision.

Efficient gas exchange in the lungs depends on regulation of the amount of fluid in the thin (average 0.2 mum) liquid layer lining the alveolar epithelium. Fluid fluxes are regulated by ion transport across the alveolar epithelium, which is composed of alveolar type I (TI) and type II (TII) cells. The accepted paradigm has been that TII cells, which cover <5% of the internal surface area of the lung, transport Na(+) and Cl(-) and that TI cells, which cover >95% of the surface area, provide a route for water absorption. Here we present data that TI cells contain functional epithelial Na(+) channels (ENaC), pimozide-sensitive cation channels, K(+) channels, and the cystic fibrosis transmembrane regulator. TII cells contain ENaC and cystic fibrosis transmembrane regulator, but few pimozide-sensitive cation channels. These findings lead to a revised paradigm of ion and water transport in the lung in which (i) Na(+) and Cl(-) transport occurs across the entire alveolar epithelium (TI and TII cells) rather than only across TII cells; and (ii) by virtue of their very large surface area, TI cells are responsible for the bulk of transepithelial Na(+) transport in the lung.