Sunlight induced progression of AIDS

Tryptophan Metabolism Activates Aryl Hydrocarbon Receptor-Mediated Pathway To Promote HIV-1 Infection and Reactivation

Multiple cellular metabolic pathways are altered by HIV-1 infection, with an impact on immune activation, inflammation, and acquisition of non-AIDS comorbid diseases. The dysfunction of tryptophan (Trp) metabolism has been observed clinically in association with accelerated HIV-1 pathogenesis, but the underlying mechanism remains unknown. In this study, we demonstrated that the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, is activated by Trp metabolites to promote HIV-1 infection and reactivation. AHR directly binds to the HIV-1 5' long terminal repeat (5'-LTR) at the molecular level to activate viral transcription and infection, and AHR activation by Trp metabolites increases its nuclear translocation and association with the HIV 5'-LTR; moreover, the binding of AHR with HIV-1 Tat facilitates the recruitment of positive transcription factors to viral promoters. These findings not only elucidate a previously unappreciated mechanism through which cellular Trp metabolites affect HIV pathogenesis but also suggest that a downstream target AHR may be a potential target for modulating HIV-1 infection.IMPORTANCE Cellular metabolic pathways that are altered by HIV-1 infection may accelerate disease progression. Dysfunction in tryptophan (Trp) metabolism has been observed clinically in association with accelerated HIV-1 pathogenesis, but the mechanism responsible was not known. This study demonstrates that Trp metabolites augment the activation of aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, to promote HIV-1 infection and transcription. These findings not only elucidate a previously unappreciated mechanism through which cellular Trp metabolites affect HIV pathogenesis but also suggest that a downstream target AHR may be a potential target for modulating HIV-1 infection.

Vitamin-D pathway genes and HIV-1 disease progression in injection drug users

Vitamin-D has pleiotropic effects on calcium and bone metabolism, cellular growth control, cell differentiation and modulation of both innate and acquired immune response. Previous studies revealed the association of vitamin-D receptor gene (VDR) polymorphism with infection diseases including HIV-1 infection. To assess for association between polymorphisms of vitamin-D pathway genes CYP27B1, vitamin-D binding protein (VDBP) and VDR with HIV-1 infection, disease progression to acquired immunodeficiency syndrome (AIDS) was analysed according to CDC93 criteria in a cohort of 185 HIV-1 seroprevalent patients belonging to the injection drug users. Genotype data was obtained from rs10877012, rs3782130 and rs4646536 markers at CYP27B1 locus; rs7041 and rs4588 at VDBP locus; and rs11568820, rs4516035, rs2228570, rs1544410 and rs17878969 at VDR locus. Distribution of genotypes between patients grouped by outcome was compared by contingency table analysis. Marker-marker interaction was assessed by a MDR analysis. Assuming an additive model for VDR markers, a Kaplan-Meier survival analysis was employed to evaluate association with disease progression. Among vitamin-D pathway genes, VDR locus reveals specific 5'UTR and 3'UTR diplotype combinations associated with both, slower and faster progression to AIDS. Marker-marker interaction analysis indicates a strong interaction between VDR markers and a redundant effect for CYP27B1 markers. According to our results, VDR locus association follows an additive model in which increased genetic risk score for the VDR is directly correlated with AIDS progression rates. Our data supports a role of vitamin-D pathway gene variability on HIV-1 disease progression.

Combined imiquimod and acitretin for non-surgical treatment of basal cell carcinoma

We report the successful outcome of treatment of a basal cell carcinoma (BCC) with topical imiquimod and systemic acitretin in a 48-year-old woman. We think that this treatment is a possible option for management of these non-life-threatening tumours. Experimental evidence suggests that combination treatment with retinoids increase the effects of imiquimod and would therefore seem to be possible when treating superficial tumours in areas where the cosmetic outcome is particularly important.

A role for ultraviolet radiation immunosuppression in non-melanoma skin cancer as evidenced by gene-environment interactions

The genotoxic effects of ultraviolet (UV) radiation are well-known causes of skin cancers; however, UV radiation also suppresses the immune system, decreasing the body's surveillance for tumor cells. In experimental systems, UV radiation immunosuppression is at least partially mediated through urocanic acid (UCA), an UV radiation-absorbing molecule in the stratum corneum. We tested the hypothesis that genetic variation in the histidase gene (HAL), which catalyzes the formation of UCA in the skin, modifies risk of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) in a population-based study (914 BCC, 702 SCC and 848 controls). We observed no evidence of a main gene effect for the HAL I439V polymorphism (rs7297245) and BCC or SCC. However, we found a HAL genotype-sunburn interaction in association with BCC (P for interaction = 0.040) and SCC (P for interaction = 0.018). A HAL genotype-SCC association was observed primarily among women (odds ratio = 1.5, 95% confidence interval 1.1-2.2), and among women, we found an interaction between HAL genotype and oral contraceptive use on SCC risk (P = 0.040). The variant HAL allele likewise appeared to modify the SCC risk associated with glucocorticoid steroid usage (P for interaction = 0.0004). In conclusion, our findings are a first step in determining the genetic underpinnings of UV immune suppression and have identified important new genetic interactions contributing to the etiology of skin cancer.

Dissociation of innate and adaptive immunity by UVB irradiation

Increasing ultraviolet-B irradiation (UVB) resulting from diminution of stratospheric ozone is becoming a serious international problem. UVB irradiation exerts not only carcinogenic effects on animals but also causes them to become vulnerable to infections by modulating their immune responses. UVB irradiation suppresses innate immune functions of cells such as macrophages, neutrophils, Langerhans cells, dendritic cells, and the serum component, complement. UVB irradiation also causes changes in cytokine profiles, represented by the induction of a paradigm switch involving Th1/Th2 phenotypes. According to earlier studies, Th1 responses are suppressed, whereas Th2 activities are augmented by UVB irradiation. These immune modulations are caused by several pathways via cytokines and neuropeptides, and eventually may lead to increasing incidences of infection, allergy, and cancer. We have reviewed reports concerning UVB-irradiation induced immune modulation from the viewpoint of risks for human diseases and, in addition, for ecosystems and immunity of lower animals.

UVB IRRADIATION SUPPRESSES CYTOKINE PRODUCTION AND INNATE CELLULAR IMMUNE FUNCTIONS IN MICE

We examined whether ultraviolet-B (UVB) irradiation (6 kJ/m2) alters cytokine production and other innate immune reactions by murine peritoneal macrophages and peripheral neutrophils. Along with these experiments, serum IgG levels were also assessed. In addition, using scanning electron microscopy (SEM) we observed macrophages that had been exposed to UVB in vitro. Results showed that UVB irradiation: (1) decreased IL-12 production while increasing IL-1alpha secretion from macrophages, but had no effect on IL-1alpha from neutrophils; (2) suppressed phagocytosis of macrophages but not of neutrophils; (3) diminished active oxygen production of macrophages but not of neutrophils; (4) had no effect on serum IgG levels; and (5) caused significant cell destruction of macrophages in vitro. These results suggested: (1) that UVB irradiation could induce characteristic suppression of innate immunity; (2) that innate cellular immunity was more susceptible to the effects of UVB irradiation than humoral immunity.

Therapeutic response of basal cell carcinoma to the immune response modifier imiquimod 5% cream

BACKGROUND

Basal cell carcinoma (BCC) responds to interferon therapy. Imiquimod is a cytokine and interferon inducer.

OBJECTIVE

This randomized, double-blind pilot trial evaluated the safety and efficacy of imiquimod 5% cream versus vehicle in the treatment of BCC.

METHODS

In this population of 35 patients with BCC, 24 received imiquimod 5% cream and 11 received vehicle cream in 1 of 5 dosing regimens for up to 16 weeks. Six weeks after treatment, an excisional biopsy of the target site was performed.

RESULTS

BCC cleared (on the basis of histologic examination) in all 15 patients (100%) dosed twice daily, once daily, and 3 times weekly; in 3 of 5 (60%) patients dosed twice weekly; 2 of 4 (50%) dosed once weekly; and in 1 of 11 (9%) treated with vehicle. Adverse events were predominantly local reactions at the target tumor site, with the incidence and severity of local skin reactions declining in groups dosed less frequently.

CONCLUSION

Imiquimod 5% cream shows clinical efficacy in the treatment of BCC.

Glutathione deficiency is associated with impaired survival in HIV disease

Glutathione (GSH), a cysteine-containing tripeptide, is essential for the viability and function of virtually all cells. In vitro studies showing that low GSH levels both promote HIV expression and impair T cell function suggested a link between GSH depletion and HIV disease progression. Clinical studies presented here directly demonstrate that low GSH levels predict poor survival in otherwise indistinguishable HIV-infected subjects. Specifically, we show that GSH deficiency in CD4 T cells from such subjects is associated with markedly decreased survival 2-3 years after baseline data collection (Kaplan-Meier and logistic regression analyses, P < 0.0001 for both analyses). This finding, supported by evidence demonstrating that oral administration of the GSH prodrug N-acetylcysteine replenishes GSH in these subjects and suggesting that N-acetylcysteine administration can improve their survival, establishes GSH deficiency as a key determinant of survival in HIV disease. Further, it argues strongly that the unnecessary or excessive use of acetaminophen, alcohol, or other drugs known to deplete GSH should be avoided by HIV-infected individuals.