Luxshimi Lal

Antiretroviral use and other risks for HIV-associated neuropathies in an international cohort

Objective: To explore the association between specific nucleoside reverse transcriptase inhibitors and sensory neuropathies (SNs) and define the modifying roles of hepatitis C (HCV), vitamin B12 deficiency, and impaired glucose tolerance. Methods: The authors conducted a prospective cohort study of 147 HIV-infected adults at two sites chosen to emphasize demographic differences. Standardized assessments included detailed antiretroviral histories, neurologic examinations, skin biopsies for epidermal nerve quantitation, and quantitative sensory testing. Results: There were significant differences between subjects at Johns Hopkins University (JHU) and Monash University (MU) in gender, race, HIV transmission route, and HCV seroprevalence. Symptomatic SN was present in 49% at JHU and 55% at MU (χ2 = 4.02, p = 0.134) and was significantly more common in those at least age 40 than younger patients (odds ratio [OR] = 2.87, 95% CI = 1.27, 6.49). After adjusting for site, age, and CD4 cell count, exposure to didanosine (ddI) or stavudine (d4T) was associated with an significantly increased likelihood of symptomatic SN (ddI: OR = 3.21, 95% CI: 1.56, 6.60; d4T: OR = 7.66, 95% CI: 2.89, 20.33). Plasma HIV RNA, lactate, and HCV were not associated with SN. Quantitative vibratory testing identified neuropathy with a positive predictive value of 76% and epidermal nerve fiber densities 59%. Conclusions: Exposure to stavudine and didanosine was significantly associated with a heightened risk for symptomatic sensory neuropathy. Reduced vibration thresholds and epidermal nerve fiber densities had the highest diagnostic efficiency of the laboratory indicators of neuropathy examined, but were relatively insensitive in isolation.

Evaluation of a clinical screening tool for HIV-associated sensory neuropathies

Objective: To evaluate the performance characteristics of a brief clinical neuropathy screening tool for use in sensory neuropathies complicating HIV infection. Methods: The authors assessed 80 patients using the Brief Peripheral Neuropathy Screen (BPNS). Patients were defined as having neuropathy if they had both symptoms and signs consistent with this diagnosis. All subjects underwent sensory threshold testing and lower limb epidermal nerve fiber quantification using punch skin biopsy as objective measures. Results: Individuals defined as having neuropathy using the BPNS (n = 37) performed less well on sensory threshold testing than other HIV-infected individuals (p < 0.0001 for warming, cooling, and vibration) and also had lower distal calf epidermal nerve fiber densities (p < 0.0001). Individuals who had symptoms but no neuropathic signs (n = 13) did not perform differently on any objective testing compared with neuropathy-free individuals, supporting the decision to require signs as well as symptoms as an operational criterion for the diagnosis of neuropathy. Of the symptoms listed in the screening tool, the presence of numbness had the greatest diagnostic efficiency for identifying those with neuropathy. Conclusion: The Brief Neuropathy Screening Tool (and the chosen definition of neuropathy) accurately detects those HIV-infected individuals with the greatest degree of peripheral nerve dysfunction and pathology. This is a valid neuropathy screening tool for use in the context of HIV infection, and is simple enough to be applicable in resource-limited settings.

Use of laser capture microdissection to detect integrated HIV-1 DNA in macrophages and astrocytes from autopsy brain tissues

The importance of astrocytes as a reservoir of human immunodeficiency virus type 1 (HIV-1) in the brain remains elusive. By combining immunohistochemistry, laser capture microdissection, and triple-nested Alu-PCR, we demonstrate integrated HIV-1 in astrocytes and macrophages isolated directly from autopsy brain tissues of HIV-1-infected subjects. The ability of HIV-1 to integrate in terminally differentiated astrocytes suggests a permanent reservoir of provirus in brain that will impact the development and likely success of strategies aimed at eradicating HIV-1.

Neurologic disorders are prevalent in HIV-positive outpatients in the Asia-Pacific region

Background: A total of 8.3 million HIV-positive people live in the Asia-Pacific region. The burden of HIV-associated neurocognitive impairment and symptomatic sensory neuropathy in this region is unknown. Methods: Between July 2005 and March 2006, we undertook a cross-sectional study at 10 sentinel sites within eight Asia-Pacific countries to determine the prevalence of moderate to severe HIV-related neurocognitive impairment and symptomatic sensory neuropathy. We clinically assessed and administered sensitive neuropsychological and peripheral neuropathy screening tools to 658 patients infected with HIV. Univariate and logistic regression analyses were applied to the data. Results: The results showed that 76 patients (11.7%) (95% CI 9.3–14.2) were significantly neurocognitively impaired, 235 patients (36.4%) (95% CI 32.7–40.2) were depressed, and 126 patients (19.7%) (95% CI 16.6–22.8) had either definite or probable symptomatic sensory neuropathy; 63% of this last group had exposure to stavudine, didanosine, or zalcitabine. Several potential confounders including depression (OR 1.49, 95% CI 0.88–2.51, p = 0.11) and prior CNS AIDS illness (OR 1.28, 95% CI 0.50–2.89, p = 0.54) were not significantly associated with neurocognitive impairment. Conclusions: A total of 12% of patients had moderate to severe HIV-related neurocognitive impairment, 20% of patients had symptomatic sensory neuropathy, and 36% of patients had evidence of depression. This study provides a broad regional estimate of the burden of HIV-related neurologic disease and depression in the Asia-Pacific region.

Tissue-specific associations between mitochondrial DNA levels and current treatment status in HIV-infected individuals.

Background: Tissue mitochondrial DNA (mtDNA) levels have been proposed as a marker of nucleoside analouge reverse transcriptase inhibitor (NRTI) toxicity. However, clinical studies have yielded conflicting data regarding possible associations with mtDNA levels. This study examined mtDNA levels in matched samples of peripheral blood mononuclear cells (PBMCs) and subcutaneous fat from a large Australian cohort to examine treatment, clinical, and demographic associations with mtDNA depletion. Methods: mtDNA was quantified by real-time polymerase chain reaction. Results were compared across patient treatment and demographic details using linear mixed models. Results: One hundred sixty-three PBMCs and 161 fat samples were available from 61 individuals. Current NRTI exposure was the major determinant of mtDNA levels. Both ddI (didanosine) and d4T (stavudine) exposures were associated with mtDNA depletion in fat (P ≤ 0.0001 vs. those not on NRTIs). DdI exposure (P = 0.003), but not d4T exposure (P = 0.5), was associated with mtDNA depletion in PBMCs. No association between patient demographics or time on current therapy and mtDNA was observed. Conclusions: Current NRTI exposure is the major determinant of tissue mtDNA, but the precise determinants are tissue specific. Both ddI and d4T exposure are associated with fat mtDNA depletion, whereas ddI exposure was the only observed association with mtDNA depletion in PBMCs.

Thymic plasmacytoid dendritic cells are susceptible to productive HIV-1 infection and efficiently transfer R5 HIV-1 to thymocytes in vitro

BackgroundHIV-1 infection of the thymus contributes to the defective regeneration and loss of CD4+ T cells in HIV-1-infected individuals. As thymic dendritic cells (DC) are permissive to infection by HIV-1, we examined the ability of thymic DC to enhance infection of thymocytes which may contribute to the overall depletion of CD4+ T cells. We compared productive infection in isolated human thymic and blood CD11c+ myeloid DC (mDC) and CD123+ plasmacytoid DC (pDC) using enhanced green fluorescent protein (EGFP) CCR5 (R5)-tropic NL(AD8) and CXCR4 (X4)-tropic NL4-3 HIV-1 reporter viruses. Transfer of productive HIV-1 infection from thymic mDC and pDC was determined by culturing these DC subsets either alone or with sorted thymocytes.ResultsProductive infection was observed in both thymic pDC and mDC following exposure to R5 HIV-1 and X4 HIV-1. Thymic pDC were more frequently productively infected by both R5 and X4 HIV-1 than thymic mDC (p = 0.03; n = 6). Thymic pDC efficiently transferred productive R5 HIV-1 infection to both CD3hi (p = 0.01; mean fold increase of 6.5; n = 6) and CD3lo thymocytes (mean fold increase of 1.6; n = 2). In comparison, transfer of productive infection by thymic mDC was not observed for either X4 or R5 HIV-1.ConclusionsThe capacity of thymic pDC to efficiently transfer R5 HIV-1 to both mature and immature thymocytes that are otherwise refractory to R5 virus may represent a pathway to early infection and impaired production of thymocytes and CD4+ T cells in HIV-1-infected individuals.

Mitochondrial toxicity of nucleoside analogues: mechanism, monitoring and management

Nucleoside analogues (NRTIs) are potent antiretroviral medications and are central to effective highly active antiretroviral therapy (HAART). Their intended action is to inhibit HIV reverse transcriptase. Nucleoside analogues also inhibit replication of mitochondrial DNA, and the pathogenesis of many of the toxicities associated with HAART is thought to be NRTI-induced mitochondrial dysfunction. Individuals with HIV infection may be particularly susceptible to clinically significant mitochondrial toxicity due to possible effects of HIV itself on mitochondria. At present there is no reliable method of detecting subclinical mitochondrial toxicity in patients exposed to NRTIs. Clinical awareness of this problem is therefore important to ensure the early detection of significant side effects and to allow timely consideration of changing therapy in those affected. There is no proven, effective therapy for NRTI-associated mitochondrial toxicity other than ceasing the implicated agent, and even with this strategy, resolution of symptoms may be incomplete. Similarly, there are no established methods for preventing mitochondrial toxicity in those on therapy including NRTIs. Micronutrients may have a role, but further study is needed to clarify optimal prevention as well as monitoring strategies.

NeuroAIDS in the Asia Pacific Region

Over 8.3 million people living in the Asia Pacific region are human immunodeficiency virus (HIV) positive and up to 40% of these individuals have had prior acquired immunodeficiency syndrome (AIDS) illnesses. Recently endeavors have been made to better characterize the burden of HIV-related neurological disease within the Asia Pacific region and, with this in mind, the NeuroAIDS in Asia and the Pacific Rim workshop was held in Sydney, Australia, as an affiliated event of the 4th IAS Conference on HIV Pathogenesis, Treatment and Prevention. The workshop was supported by the National Institute of Neurological Disorders and Stroke (NINDS) and the National Institute of Mental Health (NIMH) of the United States National Institutes of Health and the Australian Government overseas AID program, AusAID. HIV neurologists, infectious disease physicians, pediatricians, psychiatrists, immunologists, virologists, and researchers from 12 countries of the Asia Pacific region (including Australia), the United States, and the United Kingdom attended the meeting. A broad range of topics were addressed, including common HIV neurological disorders, the lack of diagnostic, management, and research infrastructure, central nervous system (CNS) immune restoration disease, pediatric neuroAIDS, and current clinical and laboratory research projects being undertaken within the Asia Pacific region.

Symptoms of depression and rates of neurocognitive impairment in HIV positive patients in Beijing China.

BACKGROUND In China an estimated 780,000 people are living with HIV (PLWH). In high-income countries PLWH are at increased risk of depression, with subsequent adverse consequences for quality of life, and HIV-related morbidity and mortality. There are few data from low-and middle-income countries. The aims of this country-specific investigation of the Asia Pacific NeuroAIDS Consortium (APNAC) study were to establish the point prevalence, severity and HIV-related and non-HIV related correlates of depressive symptoms in PLWH, in Beijing, China. METHOD PLWH attending an outpatient clinic at Ditan Hospital, Beijing were recruited consecutively. Data sources were: study-specific questions about demographic characteristics, and health behaviours, the Centre for Epidemiological Studies Depression Scale (CES-D), the World Health Organisation Self-Reporting Questionnaire (SRQ-20) translated into Mandarin and administered as structured individual interviews, and a screen battery of four standard neuropsychological tests. RESULTS In total 50/51 (98%) eligible patients agreed to participate. Overall 28% scored CES-D≥16 or SRQ20≥10 and 18% in these clinical ranges on both measures; 69% were classified as being neuropsychologically impaired (scoring below 1 SD of the control value on at least two tests). Higher depressive symptom scores were associated with lower education, alcohol overuse and diminished motor ability (all p<0.05), but not neuropsychological impairment CONCLUSION Clinically significant depressive symptoms among this cohort of PLWH in Beijing occurred at 5 times the rate reported among a general Chinese urban population. No participants had been assessed for depression prior to the study and none were treated, indicating that consideration of psychological morbidity and its consequences for health behaviours should be incorporated into routine HIV care in China.

Monitoring HIV-Associated Neurocognitive Disorder Using Screenings: a Critical Review Including Guidelines for Clinical and Research Use

Screening tools to identify HIV-associated neurocognitive disorder (HAND) are primarily devised to detect cognitive impairment on a single occasion. With the chronicity of HIV infection and the risk of HAND developing or progressing despite viral control, it may be pertinent to repeat HAND screening at more than one time point. Despite this, there are limited data on longitudinal use of such screening tools, particularly with regard to the role of practice effects. Additionally, no guidelines currently exist on the timeframe between testing intervals, or recommendation of the magnitude of baseline impairment that warrants follow-up testing. The aim of the current paper was to review existing evidence for longitudinal validity of HAND screening tools. Only those HAND screening tools previously found to have high cross-sectional criterion validity were included. Preliminary recommendations for clinical use and future research are proposed including in international settings.