Publications

BACKGROUND

Human immunodeficiency virus (HIV) infection-induced indoleamine 2,3-dioxygenase-1 (IDO) expression in activated monocytes and dendritic cells catabolizes tryptophan to kynurenine and other downstream catabolites that inhibit T-cell proliferation and interleukin 17 (IL-17) production. The prognostic significance of this pathway in treated HIV disease is unknown.

METHODS

We measured systemic IDO activity (calculated as the ratio of plasma levels of kynurenine to tryptophan; hereafter, the "KT ratio") in HIV-infected Ugandans before and during antiretroviral therapy (ART)-mediated viral suppression and its association with the rate of subsequent CD4(+) T-cell count recovery and mortality.

RESULTS

Among 435 participants, a higher pre-ART KT ratio was associated with a higher plasma virus load (P < .001) and lipopolysaccharide level (P = .018), a lower CD4(+) T-cell count (P < .001), and female sex (P = .047). Through month 12 of ART-mediated viral suppression, the plasma KT ratio decreased by approximately 50% (P < .001). After adjustment for pre-ART CD4(+) T-cell count, virus load, age, and sex, a higher month 12 KT ratio predicted a slower rate of subsequent CD4(+) T-cell count recovery (P = .001). Thirty-nine participants died. After adjustment for pre-ART CD4(+) T-cell count, virus load, body mass index, sex, and age, a higher pre-ART and month 6 KT ratio predicted increased mortality (P ≤ .016).

CONCLUSIONS

The kynurenine pathway of tryptophan catabolism independently predicts poor CD4(+) T-cell count recovery and increased mortality among HIV-infected Ugandans initiating ART and may be an important target for interventions.

BACKGROUND

Unlike cytomegalovirus (CMV) infection and aging, human immunodeficiency virus (HIV) decreases the proportion of CD28(-)CD8(+) T cells expressing CD57. Whether this abnormality predicts mortality in treated HIV infection and can be reversed by early antiretroviral therapy (ART) remains unknown.

METHODS

We sampled recently HIV-infected individuals (<6 months) and HIV-uninfected controls and compared longitudinal changes in the proportion of CD28(-)CD8(+) T cells expressing CD57 between those who initiated ART early (<6 months) vs later (≥2 years). We also assessed the relationship between this phenotype and mortality in a nested case-control study of ART-suppressed chronically infected individuals.

RESULTS

Compared to HIV-uninfected controls (n = 15), individuals who were recently infected with HIV had lower proportions of CD28(-)CD8(+) T cells expressing CD57 (P < .001), and these proportions increased during ART. The early ART group (n = 33) achieved normal levels, whereas the later ART group (n = 30) continued to have lower levels than HIV-uninfected controls (P = .02). Among 141 ART-suppressed participants in the SOCA study, those in the lowest quartile of CD28(-)CD8(+) T cells expressing CD57 had 5-fold higher odds of mortality than those in the highest quartile (95% CI, 1.6-15.9, P = .007).

CONCLUSIONS

Abnormally low proportions of CD28(-)CD8(+) T cells expressing CD57 predict increased mortality during treated HIV infection and may be reversed with early ART initiation.

BACKGROUND

Chronic antigenic stimulation by cytomegalovirus (CMV) is thought to increase "immunosenesence" of aging, characterized by accumulation of terminally differentiated CD28- CD8+ T cells and increased CD57, a marker of proliferative history. Whether chronic HIV infection causes similar effects is currently unclear.

METHODS

We compared markers of CD8+ T cell differentiation (e.g., CD28, CD27, CCR7, CD45RA) and CD57 expression on CD28- CD8+ T cells in healthy HIV-uninfected adults with and without CMV infection and in both untreated and antiretroviral therapy (ART)-suppressed HIV-infected adults with asymptomatic CMV infection.

RESULTS

Compared to HIV-uninfected adults without CMV (n=12), those with asymptomatic CMV infection (n=31) had a higher proportion of CD28-CD8+ T cells expressing CD57 (P=0.005). Older age was also associated with greater proportions of CD28-CD8+ T cells expressing CD57 (rho: 0.47, P=0.007). In contrast, untreated HIV-infected CMV+ participants (n=55) had much lower proportions of CD28- CD8+ cells expressing CD57 than HIV-uninfected CMV+ participants (P<0.0001) and were enriched for less well-differentiated CD28- transitional memory (TTR) CD8+ T cells (P<0.0001). Chronically HIV-infected adults maintaining ART-mediated viral suppression (n=96) had higher proportions of CD28-CD8+ T cells expressing CD57 than untreated patients (P<0.0001), but continued to have significantly lower levels than HIV-uninfected controls (P=0.001). Among 45 HIV-infected individuals initiating their first ART regimen, the proportion of CD28-CD8+ T cells expressing CD57 declined (P<0.0001), which correlated with a decline in percent of transitional memory CD8+ T cells, and appeared to be largely explained by a decline in CD28-CD57- CD8+ T cell counts rather than an expansion of CD28-CD57+ CD8+ T cell counts.

CONCLUSIONS

Unlike CMV and aging, which are associated with terminal differentiation and proliferation of effector memory CD8+ T cells, HIV inhibits this process, expanding less well-differentiated CD28- CD8+ T cells and decreasing the proportion of CD28- CD8+ T cells that express CD57.

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) in human immunodeficiency virus (HIV)-infected patients remains high despite treatment with antiretroviral therapy (ART).

METHODS

We evaluated NHL incidence in HIV-infected patients followed in the Centers for AIDS Research Network of Integrated Clinical Systems who started combination ART and achieved suppression of HIV. We estimated the hazard ratio for NHL by time-varying HIV viremia categories, accounting for time-varying CD4 cell count using marginal structural models.

RESULTS

We observed 37 incident NHL diagnoses during 21 607 person-years of follow-up in 6036 patients (incidence rate, 171 per 100 000 person-years; 95% confidence interval [CI], 124-236). NHL incidence was high even among patients with nadir CD4 cell count >200 cells/µL (140 per 100 000 person-years [95% CI, 80-247]). Compared with ≤50 copies/mL, hazard ratios (HRs) for NHL were higher among those with HIV viremia of 51-500 copies/mL (HR current = 1.66 [95% CI, .70-3.94]; HR 3-month lagged = 2.10 [95% CI, .84-5.22]; and HR 6-month lagged = 1.46 [95% CI, .60-3.60]) and >500 copies/mL (HR current = 2.39 [95% CI, .92-6.21]; HR 3-month lagged = 3.56 [95% CI, 1.21-10.49]; and HR 6-month lagged = 2.50 [95% CI, .91-6.84]). Current HIV RNA as a continuous variable was also associated with NHL (HR = 1.42 per log10 copies/mL [95% CI, 1.05-1.92]).

CONCLUSIONS

Our findings demonstrate a high incidence of NHL among HIV-infected patients on ART and suggest a role of HIV viremia in the pathogenesis of NHL. Earlier initiation of potent ART and maximal continuous suppression of HIV viremia may further reduce NHL risk.

Preterm birth affects 1 out of 9 infants in the United States and is the leading cause of long-term neurologic handicap and infant mortality, accounting for 35% of all infant deaths in 2008. Although cytokines including interferon-γ (IFN-γ), interleukin-10 (IL-10), IL-6, and IL-1 are produced in response to in utero infection and are strongly associated with preterm labor, little is known about how human fetal immune cells respond to these cytokines. We demonstrate that fetal and adult CD14(+)CD16(-) classical monocytes are distinct in terms of basal transcriptional profiles and in phosphorylation of signal transducers and activators of transcription (STATs) in response to cytokines. Fetal monocytes phosphorylate canonical and noncanonical STATs and respond more strongly to IFN-γ, IL-6, and IL-4 than adult monocytes. We demonstrate a higher ratio of SOCS3 to IL-6 receptor in adult monocytes than in fetal monocytes, potentially explaining differences in STAT phosphorylation. Additionally, IFN-γ signaling results in upregulation of antigen presentation and costimulatory machinery in adult, but not fetal, monocytes. These findings represent the first evidence that primary human fetal and adult monocytes are functionally distinct, potentially explaining how these cells respond differentially to cytokines implicated in development, in utero infections, and the pathogenesis of preterm labor.