Interferon-gamma receptors in HIV-1 infection.

We studied in vitro production of interferon-gamma and expression of interferon-gamma receptors (R1 and R2) by the peripheral blood mononuclear cells of 24 HIV-1-infected patients and 12 healthy volunteers. Interferon-gamma production was lower in HIV-1-infected patients compared with healthy volunteers (p < 0.05), and it further declined in patients with lower CD4+ T-cell counts. In contrast, expression of interferon-gamma R1 by CD4+ T lymphocytes was higher in HIV-infected patients than healthy volunteers (25% versus 10%, p < 0.05). In the HIV-infected group, interferon-gamma R1 expression increased with a decline in CD4+ T-cell count (r = -0.64, p < 0.001). Interferon-gamma R2 expression directly correlated with interferon-gamma R1 expression (p < 0.001). When stimulated with heat-killed Mycobacterium avium complex (MAC) and phorbol myristic acetate (PMA), the mononuclear cells of patients with advanced HIV-1 infection had lowered ability to produce additional interferon-gamma (either MAC or PMA) and interferon-gamma receptors (MAC). In conclusion, with progression of HIV-1 infection, interferon-gamma production declines whereas expression of interferon-gamma receptors (R1 and R2) increases. Persistent upregulation of both interferon-gamma R1 and R2 receptors probably favors development of type 2 T-helper cells environment and promotes viral replication. This dysfunction in the interferon-gamma pathway contributes to a further impairment in cellular immune function in patients with advanced HIV-1 infection, which may further increase susceptibility to opportunistic infections.

Prevention of noise- and drug-induced hearing loss with D-methionine.

A number of otoprotective agents are currently being investigated. Various types of agents have been found in animal studies to protect against hearing loss induced by cisplatin, carboplatin, aminoglycosides, or noise exposure. For over a decade we have been investigating D-methionine (D-met) as an otoprotective agent. Studies in our laboratory and others around the world have documented D-met's otoprotective action, in a variety of species, against a variety of ototoxic insults including cisplatin-, carboplatin-, aminoglycoside- and noise-induced auditory threshold elevations and cochlear hair cell loss. For cisplatin-induced ototoxicity, protection of the stria vascularis has also been documented. Further D-met has an excellent safety profile. D-met may act as both a direct and indirect antioxidant. In this report, we provide the results of three experiments, expanding findings in D-met protection in three of our translational research areas: protection from platinum based chemotherapy-, aminoglycoside- and noise-induced hearing loss. These experiments demonstrate oral D-met protection against cisplatin-induced ototoxicity, D-met protection against amikacin-induced ototoxicity, and D-met rescue from permanent noise-induced hearing loss when D-met is initiated 1h after noise exposure. These studies demonstrate some of the animal experiments needed as steps to translate a protective agent from bench to bedside.