Publications

Mycobacterium tuberculosis is a highly successful pathogen that can persist and cause disease despite an immune response. One potential mechanism for resisting elimination is by inhibiting the action of IFN-gamma. We have previously shown that live M. tuberculosis inhibits selected macrophage responses to IFN-gamma, and that purified M. tuberculosis 19-kDa lipoprotein inhibits induction of selected IFN-gamma-responsive genes through a TLR2-dependent pathway, whereas peptidoglycan inhibits responses to IFN-gamma by a TLR2-independent pathway. To determine the relative contribution of lipoproteins to the inhibition of responses to IFN-gamma, we deleted the M. tuberculosis gene (lspA) that encodes lipoprotein signal peptidase. This revealed that M. tuberculosis lipoprotein processing is indispensable for stimulation of TLR2 reporter cells, but that the lspA mutant inhibits macrophage responses to IFN-gamma to the same extent as wild-type bacteria. Macrophages lacking TLR2 are more resistant to inhibition by either strain of M. tuberculosis, suggesting that nonlipoprotein TLR2 agonists contribute to inhibition. Indeed, we found that phosphatidylinositol mannan from M. tuberculosis inhibits macrophage responses to IFN-gamma. M. tuberculosis inhibition of responses to IFN-gamma requires new protein synthesis, indicating that a late effect of innate immune stimulation is the inhibition of responses to IFN-gamma. These results establish that M. tuberculosis possesses multiple mechanisms of inhibiting responses to IFN-gamma.

GspB and Hsa are homologous surface glycoproteins of Streptococcus gordonii that bind sialic acid moieties on platelet membrane glycoprotein Ibalpha. Since this species is an important member of the oral flora, we examined the direct binding of these adhesins to human salivary proteins. Both GspB and Hsa bound low-molecular-weight salivary mucin MG2 and salivary agglutinin. Hsa also bound several other salivary proteins, including secretory immunoglobulin A. Screening of six oral streptococcal isolates revealed that at least two of the strains expressed GspB homologues. These results indicate that GspB-like adhesins may be important for oral bacterial colonization.

BACKGROUND

Recent clinical trials from Uganda have shown that the risk of failure following antimalarial therapy varies geographically. We tested the hypothesis that geographic differences in the response to therapy could be explained by differences in the prevalence of known molecular markers of drug resistance.

METHODS

Samples from 2084 patients treated with chloroquine (CQ) plus sulfadoxine-pyrimethamine (SP) and amodiaquine (AQ) plus SP were tested for the presence of known molecular markers of resistance. Differences in the risk of treatment failure across 6 sites were compared, and age and complexity of infection were controlled for.

RESULTS

The prevalence of molecular markers of drug resistance was high at all of the sites: 61%-91% of patients were infected with parasites containing the pfcrt Thr-76 mutation and dhfr/dhps quintuple mutation. The risk of treatment failure decreased with increasing transmission intensity for both CQ plus SP (73% to 19%) and AQ plus SP (38% to 2%). Restricting the analyses to patients infected with parasites containing all 6 mutations of interest did not affect these trends.

CONCLUSIONS

The risk of treatment failure was inversely proportional to transmission intensity and was not explained by differences in molecular markers of antimalarial drug resistance. Our findings strongly suggest that geographic differences in response to antimalarial therapy in Uganda are primarily mediated by acquired immunity associated with malaria transmission intensity, rather than by parasite factors.

OBJECTIVE

To evaluate the efficacy and safety of oxandrolone in promoting body weight and body cell mass (BCM) gain in HIV-associated weight loss.

METHODS

Randomized, double-blind, placebo-controlled trial. Two hundred sixty-two HIV-infected men with documented 10% to 20% weight loss or body mass index < or =20 kg/m were randomized to placebo or to 20, 40, or 80 mg of oxandrolone daily. After 12 weeks, subjects were allowed to receive open-label oxandrolone at a dose of 20 mg for another 12 weeks.

RESULTS

Body weight increased in all groups, including the group receiving placebo, during the double-blind phase (1.1 +/- 2.7, 1.8 +/- 3.9, 2.8 +/- 3.3, and 2.3 +/- 2.9 kg in placebo and 20-, 40-, and 80-mg oxandrolone groups, respectively; all P < 0.014 vs. baseline). BCM increased from baseline in all groups (0.45 +/- 1.7, 0.91 +/- 2.2, 1.5 +/- 2.5, and 1.8 +/- 1.8 kg in placebo and 20-, 40-, and 80-mg oxandrolone groups, respectively). At 12 weeks, only the gain in weight at the 40-mg dose of oxandrolone and the gain in BCM at the 40- and 80-mg doses of oxandrolone were greater than those in the placebo group, however. Oxandrolone treatment was associated with significant suppression of sex hormone-binding globulin, luteinizing hormone, follicle-stimulating hormone, and total and free testosterone levels. Treatment was generally well tolerated but accompanied by significant increases in transaminases and low-density lipoprotein as well as decreases in high-density lipoprotein.

CONCLUSION

Oxandrolone administration is effective in promoting dose-dependent gains in body weight and BCM in HIV-infected men with weight loss.

In a murine model of epidermal hyperplasia reproducing some of the abnormalities of several common skin disorders, we previously demonstrated the antiproliferative and pro-differentiating effects of peroxisome proliferator-activated receptor (PPAR)alpha, PPARbeta/delta, and liver X receptor activators. Unlike other subgroups of PPAR activators, thiazolidinediones (TZDs), a family of PPARgamma ligands, did not inhibit keratinocyte proliferation in normal murine skin. Here, we studied the effects of two TZDs, namely ciglitazone (10 mM) and troglitazone (1 mM), in the same murine model where epidermal hyperproliferation was reproduced by repeated barrier abrogation with tape stripping. Topical treatment with ciglitazone and troglitazone resulted in a marked and significant decrease in epidermal thickness. Furthermore, in all TZD-treated groups, we observed a significant decrease in keratinocyte proliferation using proliferating cell nuclear antigen, 5-bromo-2'-deoxyuridine, and tritiated thymidine incorporation. However, using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, we found no difference in apoptosis between different treatments, emphasizing that it is the antiproliferative role of these activators that accounts for the decrease of epidermal thickness. Finally, using immunohistochemical methods, we determined the effects of ciglitazone on keratinocyte differentiation in this hyperproliferative model. We observed an increased expression of involucrin and filaggrin following ciglitazone treatment, suggesting a pro-differentiating action of TZDs in this model. In summary, topical TZDs significantly reduce epidermal keratinocyte proliferation while promoting differentiation in a murine model of hyperproliferative epidermis. Together, these results suggest that in addition to their metabolic effects currently in use in the treatment of type 2 diabetes, topical TZDs could be considered as potential alternative therapeutic agents in hyperproliferative skin diseases such as psoriasis.

Epithelial-mesenchymal interactions and extracellular matrix remodeling are key processes of embryonic lung development. Lung smooth muscle cells, which are derived from the mesenchyme, form a sheath around bronchi and blood vessels. During lung organogenesis, smooth muscle differentiation coincides with epithelial branching morphogenesis and closely follows developing airways spatially and temporally. The precise function of parabronchial smooth muscle (PBSM) cells in healthy adult lung remains unclear. However, PBSM may regulate epithelial branching morphogenesis during lung development by the induction of mechanical stress or through regulation of paracrine signaling pathways. Alveolar myofibroblasts are interstitial contractile cells that share features and may share an origin with smooth muscle cells. Alveolar myofibroblasts are essential for secondary septation, a process critical for the development of the gas-exchange region of the lung. Dysregulation of PBSM or alveolar myofibroblast development is thought to underlie the pathogenesis of many lung diseases, including bronchopulmonary dysplasia, asthma, and interstitial fibrosis. We review the current understanding of the regulation of PBSM and alveolar myofibroblast development, and discuss the role of PBSM in lung development. We specifically focus on the role of these cells in the context of fibroblast growth factor-10, sonic hedgehog, bone morphogenetic protein-4, retinoic acid, and Wnt signaling pathways in the regulation of lung branching morphogenesis.

UNLABELLED

To evaluate the role of sigma receptors in the sexually dimorphic antianalgesic effect of agonist-antagonist kappa opioids, 2 neuroleptics, haloperidol, a sigma receptor antagonist, and chlorpromazine, which has minimal effect at sigma receptors, were administered with the agonist-antagonist kappa opioid nalbuphine in patients with postoperative pain. Before surgical extraction of bony impacted mandibular third molar teeth, patients received haloperidol (1 mg), chlorpromazine (10 mg), or placebo by oral administration. After surgery, the pain intensity did not differ significantly between the 3 treatment groups, suggesting lack of analgesic effect produced by either haloperidol or chlorpromazine. All patients were then administered nalbuphine (5 mg, intravenous). As previously reported, the group that did not receive a preoperative neuroleptic exhibited sexually dimorphic analgesia, with women experiencing greater analgesia than men. Antianalgesia was also observed, with men experiencing late onset increased pain compared with baseline, starting approximately 1 hour after nalbuphine administration. Both neuroleptics blocked nalbuphine antianalgesia, resulting in enhanced analgesia and elimination of the sex differences. Because chlorpromazine and haloperidol enhanced nalbuphine analgesia and eliminated sexual dimorphism, the receptor at which neuroleptics act to antagonize the "antianalgesia" might be a common site of action to both drugs.

PERSPECTIVE

This study demonstrates that neuroleptics can block the antianalgesic effect of agonist-antagonist kappa opioids. These findings could help inform the development of novel analgesics.