Funding: National Institutes of Health (NIH) grants D43 CA153717, R01 CA119903, R01 MH054097, U01 CA066529, U01 AI069911 and P30 AI027763.
Journal of Acquired Immune Deficiency Syndromes
Kaposi's sarcoma, Amino acids -- Metabolism, Kynurenine -- Metabolism, AIDS (Disease) -- Treatment -- Uganda
Background—Other than Kaposi's sarcoma (KS)-associated herpesvirus and CD4+ T cell lymphopenia, the mechanisms responsible for KS in the context of HIV are poorly understood. One recently explored pathway of HIV pathogenesis involves induction of the enzyme indoleamine 2,3 dioxygenase-1 (IDO), which catabolizes tryptophan into kynurenine and several other immunologically active metabolites that suppress T cell proliferation. We investigated the role of IDO in the development of KS in HIV disease.
Methods—In a case-control study among untreated HIV-infected Ugandans, cases were adults with KS and controls were without KS. IDO activity was assessed by the ratio of plasma kynurenine to tryptophan levels (KT ratio), measured by liquid chromatography tandem mass spectrometry.
Results—We studied 631 HIV-infected subjects: 222 KS cases and 409 controls. Non-KS controls had a higher median plasma KT ratio (130, IQR: 90 to190 nM/μM) than cases (110, IQR: 90 to 150 nM/μM) (p = 0.004). After adjustment for age, sex, CD4 count and plasma HIV RNA level, subjects with the highest (fourth quartile) plasma KT ratios had a 59% reduction (95% CI: 27% to 77%) in the odds of KS compared to those with the lowest (first quartile) levels. KS was also independently associated with lower CD4+ count, higher plasma HIV RNA, and men.
Conclusions—Among HIV-infected individuals, greater activity of the kynurenine pathway of tryptophan catabolism, as evidenced by higher levels of plasma KT ratio, was associated with lower occurrence of KS. Some consequences of immune activation in HIV infection might actually suppress certain cancers.
Wolters Kluwer Health, Inc.
95. Byakwaga H, Hunt PW, Laker-Oketta M, Glidden DV, Huang Y, Bwana BM, Mocello AR, Bennett J, Walusansa V, Dollard SC, Bangsberg DR, Mbidde EK, Martin JN; The Kynurenine Pathway of Tryptophan Catabolism and AIDS-associated Kaposi's Sarcoma in Africa. J Acquir Immune Defic Syndr.; 2015 Jul 7