APOE ε4 moderates abnormal CSF-abeta-42 levels, while neurocognitive impairment is associated with abnormal CSF tau levels in HIV+ individuals - a cross-sectional observational study.

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers Aß1-42, t-tau and p-tau have a characteristic pattern in Alzheimer's Disease (AD). Their roles in HIV-associated neurocognitive disorder (HAND) remains unclear. METHODS: Adults with chronic treated HIV disease were recruited (n = 43, aged 56.7 ± 7.9; 32% aged 60+; median HIV duration 20 years, >95% plasma and CSF HIV RNA <50 cp/mL, on cART for a median 24 months). All underwent standard neuropsychological testing (61% had HAND), APOE genotyping (30.9% carried APOE ε4 and 7.1% were ε4 homozygotes) and a lumbar puncture. Concentrations of Aß1-42, t-tau and p-tau were assessed in the CSF using commercial ELISAs. Current neurocognitive status was defined using the continuous Global Deficit Score, which grades impairment in clinically relevant categories. History of HAND was recorded. Univariate correlations informed multivariate models, which were corrected for nadir CD4-T cell counts and HIV duration. RESULTS: Carriage of APOE ε4 predicted markedly lower levels of CSF Aß1-42 in univariate (r = -.50; p = .001) and multivariate analyses (R(2) = .25; p < .0003). Greater levels of neurocognitive impairment were associated with higher CSF levels of p-tau in univariate analyses (r = .32; p = .03) and multivariate analyses (R(2) = .10; p = .03). AD risk prediction cut-offs incorporating all three CSF biomarkers suggested that 12.5% of participants had a high risk for AD. Having a CSF-AD like profile was more frequent in those with current (p = .05) and past HIV-associated dementia (p = .03). CONCLUSIONS: Similarly to larger studies, APOE ε4 genotype was not directly associated with HAND, but moderated CSF levels of Aß1-42 in a minority of participants. In the majority of participants, increased CSF p-tau levels were associated with current neurocognitive impairment. Combined CSF biomarker risk for AD in the current HIV+ sample is more than 10 times greater than in the Australian population of the same age. Larger prospective studies are warranted.

Role of TNF block genetic variants in HIV-associated sensory neuropathy in black Southern Africans.

HIV-associated sensory neuropathy (HIV-SN) is a common neurological complication of HIV infection. The TNF block is a region within the central MHC that contains many immunoregulatory genes. Polymorphisms and haplotypes of the TNF block have been associated with increased risk of HIV-SN in Asians and whites. Here we investigated genetic associations with HIV-SN in 342 black Southern Africans (190 cases and 152 neuropathy-free controls) using single nucleotide polymorphisms (SNPs) spanning the TNF block and a set of haplotypes defined by 31 SNPs in Asian and white populations (denoted FVa). We included population-appropriate tagSNPs derived from an African population (Yoruban, YRI, HapMap) and derived extended haplotypes comprising 61 SNPs (denoted FVa_ext b). We found no association between HIV-SN and carriage of two SNPs (TNF-1031/rs1799964*C and BAT1 (intron10)/rs9281523*C) associated with HIV-SN in whites and Asians. Additionally, a haplotype containing TNF-1031/rs1799964*C associated with increased risk of HIV-SN in Asians, but was not present in this African population. However, alleles of seven SNPs associated with reduced risk of HIV-SN (corrected for age, height and multiple comparisons). These were rs11796*A, rs3130059*G, rs2071594*C, NFKBIL1-62/rs2071592*A, rs2071591*A, LTA+252/rs909253*G, rs1041981*C. One haplotype (FV18_ext1), not containing these alleles, was associated with increased risk of HIV-SN after correction for age, height and multiple comparisons. Our results confirm the involvement of genes in the TNF block in altering risk for HIV-SN, but genotypes critical in this African population differed from those affecting HIV-SN in whites and Asians. These differences support the need for genetic association studies in diverse populations.

A longitudinal study of the effects of ART on plasma chemokine levels in Malaysian HIV patients.

OBJECTIVES: Chemokines influence the migration of leukocytes to secondary lymphoid tissue and sites of inflammation. In HIV patients, they are implicated in inflammatory complications of antiretroviral therapy (ART), notably Immune Reconstitution Disease (IRD) and Sensory Neuropathy (SN). However most chemokines have not been monitored as patients begin ART or correlated with IRD and SN. METHODS: Plasma chemokine levels were assessed longitudinally using commercial ELISAs in 69 patients treated in Kuala Lumpur, Malaysia. Plasma was available at baseline and after 6, 12, 24 and 48 weeks on ART. Chemokine genotypes were assessed using allele-specific fluorescent probes. IRD were diagnosed in 15 patients. 30 patients were screened for SN using the ACTG BPNS tool after six months on ART. SN was detected in 8 patients. RESULTS: Plasma CXCL10 levels decreased on ART compared to baseline (p=0.002-0.0001), but remain higher than healthy controls (p≤ 0.0001). The decline was clearer in patients without IRD. CCL5 levels rose on ART but remained similar to controls. CCL2 levels were higher in patients than controls after week 12. Plasma chemokine levels were not affected by CD4+ T-cell counts or any genotypes tested. Several patients with SN displayed higher CCL5 levels throughout therapy compared to patients without neuropathy. Levels of other chemokines and chemokine genotypes were not associated with SN. CONCLUSIONS: Chemokines are differentially affected by ART. CXCL10 and CCL5 may influence IRD and CCL5 warrants further investigation for an effect in SN. These trends are not influenced by chemokine genotypes investigated here.