Publications

The murine Leishmania major model has proven fertile ground for the elucidation of CD4+ T cell effector subset differentiation in vivo. The availability of a highly susceptible inbred strain, BALB/c, that develops progressive disease due to the aberrant differentiation of Th2, as opposed to protective Th1, responses, has allowed the identification of both T cell intrinsic as well as T cell extrinsic properties that combine to mediate disease outcome. The intrinsic T cell phenotype relates to the capacity of BALB/c-derived CD4+ T cells to acquire the potential to secrete IL-4 more readily than cells from other strains of mice. The extrinsic T cell phenotype relates to the creation of a T cell repertoire capable of recognizing the immunodominant parasite antigen. Together, the two traits confer the aberrant response seen in susceptible mice challenged with L. major.

The roles of the matrix metalloproteinases (MMPs) and their specific inhibitors, the tissue inhibitors of metalloproteinases (TIMP), in embryologic development in general, and in nephrogenesis in particular, have not been fully elucidated. The activities of these enzymes and their inhibitors may be critical in the extensive extracellular matrix remodeling that accompanies the formation of the full complement of mature nephrons in the developing kidney. The temporal and spatial expression of two critical basal lamina modifying enzymes, the 72 kDa gelatinase A (MMP-2) and the 92 kDa gelatinase B (MMP-9), as well as TIMP-1, -2, and -3 molecules were evaluated in the developing rat kidney. Additionally, transcripts for the recently described membrane-associated matrix metalloproteinase, MT1-MMP (MMP-14), which can act as an activating receptor for MMP-2/TIMP-2 complexes (Strongin et al.[1995] J. Biol. Chem. 270:5331-5338) were localized by in situ hybridization. Our immunohistochemical data demonstrate distinct localization of MMP-2 within immature nephron structures undergoing epithelial differentiation, while MMP-9 localizes only to the invading vascular structures within immature glomeruli. In contrast, by in situ hybridization, MMP-2 transcripts localize to the background undifferentiated mesenchyme and not to those structures undergoing epithelial differentiation. In a pattern similar to the MMP-2 protein, MT1-MMP transcripts were found within developing epithelial structures. Neither MMP-2, MMP-9 nor MT1-MMP were detected in mature nephrons. TIMP-2 and -3 follow a pattern of expression similar to the MMP-2 protein. We conclude that MMP-2 and TIMP play important roles in the remodeling of basal laminae associated with the epithelial structures of the developing kidney, that these enzymes are temporally and spatially regulated, and that the co-localization of MT1-MMP to sites of basement membrane remodeling suggests a potential role for this molecule as a receptor for and/or modulator of MMP-2/TIMP complexes.

How an individual effector T cell acquires a particular cytokine expression pattern from many possible patterns remains unclear. CD4+ T cells from F1 mice, which allowed assignment of the parental origin of interleukin-4 (IL-4) transcripts, were divided into clones that expressed IL-4 biallelically or monoallelically from either allele. The allelic pattern was transmitted as a stable epigenetic trait. Regulation of cytokine expression by a mechanism that treats each allele independently suggests a probabilistic process by which a diverse repertoire of combinatorially assorted cytokine gene expression patterns could be generated among the clonally related daughters of a single precursor cell.

CONTEXT

Observational studies have found lower rates of coronary heart disease (CHD) in postmenopausal women who take estrogen than in women who do not, but this potential benefit has not been confirmed in clinical trials.

OBJECTIVE

To determine if estrogen plus progestin therapy alters the risk for CHD events in postmenopausal women with established coronary disease.

DESIGN

Randomized, blinded, placebo-controlled secondary prevention trial.

SETTING

Outpatient and community settings at 20 US clinical centers.

PARTICIPANTS

A total of 2763 women with coronary disease, younger than 80 years, and postmenopausal with an intact uterus. Mean age was 66.7 years.

INTERVENTION

Either 0.625 mg of conjugated equine estrogens plus 2.5 mg of medroxyprogesterone acetate in 1 tablet daily (n = 1380) or a placebo of identical appearance (n = 1383). Follow-up averaged 4.1 years; 82% of those assigned to hormone treatment were taking it at the end of 1 year, and 75% at the end of 3 years.

MAIN OUTCOME MEASURES

The primary outcome was the occurrence of nonfatal myocardial infarction (MI) or CHD death. Secondary cardiovascular outcomes included coronary revascularization, unstable angina, congestive heart failure, resuscitated cardiac arrest, stroke or transient ischemic attack, and peripheral arterial disease. All-cause mortality was also considered.

RESULTS

Overall, there were no significant differences between groups in the primary outcome or in any of the secondary cardiovascular outcomes: 172 women in the hormone group and 176 women in the placebo group had MI or CHD death (relative hazard [RH], 0.99; 95% confidence interval [CI], 0.80-1.22). The lack of an overall effect occurred despite a net 11% lower low-density lipoprotein cholesterol level and 10% higher high-density lipoprotein cholesterol level in the hormone group compared with the placebo group (each P<.001). Within the overall null effect, there was a statistically significant time trend, with more CHD events in the hormone group than in the placebo group in year 1 and fewer in years 4 and 5. More women in the hormone group than in the placebo group experienced venous thromboembolic events (34 vs 12; RH, 2.89; 95% CI, 1.50-5.58) and gallbladder disease (84 vs 62; RH, 1.38; 95% CI, 1.00-1.92). There were no significant differences in several other end points for which power was limited, including fracture, cancer, and total mortality (131 vs 123 deaths; RH, 1.08; 95% CI, 0.84-1.38).

CONCLUSIONS

During an average follow-up of 4.1 years, treatment with oral conjugated equine estrogen plus medroxyprogesterone acetate did not reduce the overall rate of CHD events in postmenopausal women with established coronary disease. The treatment did increase the rate of thromboembolic events and gallbladder disease. Based on the finding of no overall cardiovascular benefit and a pattern of early increase in risk of CHD events, we do not recommend starting this treatment for the purpose of secondary prevention of CHD. However, given the favorable pattern of CHD events after several years of therapy, it could be appropriate for women already receiving this treatment to continue.