Measuring and monitoring apoptosis and drug toxicity in HIV patients by ligation-mediated polymerase chain reaction

Current trends in luminescence-based assessment of apoptosis

Apoptosis, the most extensively studied type of cell death, is known to play a crucial role in numerous processes such as elimination of unwanted cells or cellular debris, growth, control of the immune system, and prevention of malignancies. Defective regulation of apoptosis can trigger various diseases and disorders including cancer, neurological conditions, autoimmune diseases and developmental disorders. Knowing the nuances of the cell death type induced by a compound can help decipher which therapy is more effective for specific diseases. The detection of apoptotic cells using classic methods has brought significant contribution over the years, but innovative methods are quickly emerging and allow more in-depth understanding of the mechanisms, aside from a simple quantification. Due to increased sensitivity, time efficiency, pathway specificity and negligible cytotoxicity, these innovative approaches have great potential for both in vitro and in vivo studies. This review aims to shed light on the importance of developing and using novel nanoscale methods as an alternative to the classic apoptosis detection techniques.

Nucleoside reverse transcriptase inhibitor-induced rat oocyte dysfunction and low fertility mediated by autophagy

Low fertility is one of the most common side effects caused by nucleoside reverse transcriptase inhibitors (NRTIs), whereas the molecular mechanism underlying this process were largely unclear. This study was conducted to investigate whether autophagy plays a role in NRTIs-induced oocyte dysfunction and low fertility in female rat. Both in vivo and in vitro experiments were conducted. For the in vivo experiment, female adult Sprague-Dawley rats were subjected to zidovudine (AZT) and lamivudine (3TC) intragastric treatment for 3, 6, 9, and 12 weeks; a control was also set. Oocytes were collected for maturation evaluation, in vitro fertilization and mitochondrial function assays, and apoptosis and autophagy analysis. For the in vitro experiment, oocytes were collected and assigned to the control, 3-methyladenine (3-MA, an effective autophagy inhibitor), AZT, AZT+3-MA, 3TC, and 3TC+3-MA groups. The oocytes were cultured with the abovementioned drugs for 24, 48, and 72 h and then, subjected to the same assays as in the in vivo study. The results showed a significant time-dependent decrease in oocyte maturation-related maker levels, oocyte cleavage rate, blastocyst formation rate, mitochondrial DNA copy number and adenosine triphosphate level, and apoptosis, and a significant increase in the reactive oxygen species levels (all P-values < 0.05), in both the in vivo and the in vitro experiments. These changes, except for the changes in the oocyte maturation-related markers, were partially attenuated by 3-MA. In conclusion, we demonstrated that NRTIs can cause rat oocyte dysfunction and low fertility, and this damage was, at least partially, mediated by autophagy.

Age-related hearing loss: prevention of threshold declines, cell loss and apoptosis in spiral ganglion neurons

Age-related hearing loss (ARHL) -presbycusis - is the most prevalent neurodegenerative disease and number one communication disorder of our aged population; and affects hundreds of millions of people worldwide. Its prevalence is close to that of cardiovascular disease and arthritis, and can be a precursor to dementia. The auditory perceptual dysfunction is well understood, but knowledge of the biological bases of ARHL is still somewhat lacking. Surprisingly, there are no FDA-approved drugs for treatment. Based on our previous studies of human subjects, where we discovered relations between serum aldosterone levels and the severity of ARHL, we treated middle age mice with aldosterone, which normally declines with age in all mammals. We found that hearing thresholds and suprathreshold responses significantly improved in the aldosterone-treated mice compared to the non-treatment group. In terms of cellular and molecular mechanisms underlying this therapeutic effect, additional experiments revealed that spiral ganglion cell survival was significantly improved, mineralocorticoid receptors were upregulated via post-translational protein modifications, and age-related intrinsic and extrinsic apoptotic pathways were blocked by the aldosterone therapy. Taken together, these novel findings pave the way for translational drug development towards the first medication to prevent the progression of ARHL.

Upregulation of Apoptosis Pathway Genes in Peripheral Blood Mononuclear Cells of HIV-Infected Individuals with Antiretroviral Therapy-Associated Mitochondrial Toxicity

A case-control study of the effect of antiretroviral therapy (ART) on apoptosis pathway genes comprising 16 cases (HIV infected with mitochondrial toxicity) and 16 controls (HIV uninfected) was conducted. A total of 26 of 84 genes of the apoptosis pathway were differentially expressed. Two of the upregulated genes, DFFA and TNFRSF1A, classified 75% of study participants correctly as either a case or control. Thus, apoptosis may be in the causal pathway of ART-associated mitochondrial toxicity. These two genes could be markers for detecting and monitoring ART-induced mitochondrial toxicity.

HIV treatment and associated mitochondrial pathology: review of 25 years of in vitro, animal, and human studies

Antiretroviral therapy has dramatically reduced mortality in human immunodeficiency virus (HIV) infection. In 1988, the suggestion that the first antiretroviral drug, zidovudine, was the potential cause of muscle pathology in HIV-infected persons resulted in structural and biochemical patient studies demonstrating acquired mitochondrial dysfunction. Assessment of subsequent nucleoside analog reverse transcriptase inhibitor (NRTI) antiretroviral drugs has indicated that mitochondria are a common target of NRTI toxicity in multiple tissues, leading to a wide variety of pathology ranging from lipodystrophy to neuropathy. Overwhelmingly, these complications have emerged during post-licensing human studies. Subsequent animal and in vitro studies have then elucidated the potential pathological mechanisms, suggesting that NRTI-associated mitochondrial toxicity arises principally from inhibition of the sole mitochondrial DNA (mtDNA) polymerase gamma, leading to a reduction in mtDNA content (depletion). Millions of patients have been treated with mitochondrially toxic NRTIs and these drugs remain the backbone of antiretroviral rollout in much of sub-Saharan Africa. Here we describe the 25-year history of antiretroviral associated mitochondrial pathology and critically review the strength of evidence linking clinical, histopathological, and molecular data. We discuss recently described novel mechanisms of NRTI-associated mitochondrial damage and whether or not recently licensed NRTIs may be considered free from mitochondrial toxicity.

Perinatal outcomes, mitochondrial toxicity and apoptosis in HIV-treated pregnant women and in-utero-exposed newborn

OBJECTIVE

Highly active antiretroviral therapy (HAART) has decreased the risk of HIV mother-to-child transmission. However, HIV and HAART have been associated with adverse perinatal outcome. HAART has been associated with mitochondrial dysfunction in nonpregnant adults, and HIV, additionally, to apoptosis. We determined whether mitochondrial toxicity and apoptosis are present in HIV-pregnant women and their newborns and could be the basis of adverse pregnancy outcome.

DESIGN

Single-site, cross-sectional, controlled observational study without intervention.

METHODS

We studied mitochondrial and apoptotic parameters in mononuclear cells from maternal peripheral blood and infant cord blood at delivery in 27 HIV-infected and treated pregnant women, and 35 uninfected controls and their infants, to correlate clinical outcome with experimental findings: mitochondrial number (CS), mtDNA content (ND2/18SrRNA), mitochondrial protein synthesis (COX-II/V-DAC), mitochondrial function (enzymatic activities) and apoptotic rate (caspase-3/β-actin).

RESULTS

Global adverse perinatal outcome, preterm births and small newborn for gestational age were significantly increased in HIV pregnancies [odds ratio (OR) 7.33, 5.77 and 9.71]. Mitochondrial number was unaltered. The remaining mitochondrial parameters were reduced in HIV mothers and their newborn; especially newborn mtDNA levels, maternal and fetal mitochondrial protein synthesis and maternal glycerol-3-phosphate + complex III function (38.6, 25.8, 13.6 and 31.2% reduced, respectively, P < 0.05). All materno-fetal mitochondrial parameters significantly correlated, except mtDNA content. Apoptosis was exclusively increased in infected pregnant women, but not in their newborn. However, adverse perinatal outcome did not correlate mitochondrial or apoptotic findings.

CONCLUSIONS

Transplacental HAART toxicity may cause subclinical mitochondrial damage in HIV-pregnant women and their newborn. Trends to increased maternal apoptosis may be due to maternal-restricted HIV infection. However, we could not demonstrate mitochondrial or apoptotic implication in adverse perinatal outcome.

Apoptosis: a clinically useful measure of antiretroviral drug toxicity?

Antiretroviral therapy (ART) has improved life expectancy with HIV infection, but long-term toxicities associated with these medications are now a major global disease burden. There is a clear need to develop useful methods for monitoring patients on antiretroviral drugs for early signs of toxicity. Assays with predictive utility -- allowing therapy to be changed before serious end organ damage occurs -- would be ideal. Attempts to develop biochemical methods of monitoring ART toxicity have concentrated on the mitochondrial toxicity of nucleoside analogue reverse transcriptase inhibitors and have not generally lead to assays with widespread clinical applications. For example, plasma lactate and peripheral blood measurements of mitochondrial DNA associate with exposure to potentially toxic nucleoside analogue reverse transcriptase inhibitors but have not reliably predicted clinical toxicity. Better assays are needed, including markers of toxicity from additional drug classes. Apoptosis may be a potential marker of ART toxicity. Increased apoptosis has been demonstrated both in vitro and in vivo in association with various antiretroviral drug classes and a range of clinical toxicities. However, quantifying apoptosis on biopsy specimens of tissue (such as adipose tissue) is impractical for patient monitoring. Novel assays have been described that can quantify apoptosis using minute tissue samples and initial results from clinical samples suggest peripheral blood may have utility in predicting ART toxicities. The limitations and potential of such techniques for monitoring patients for drug side effects will be discussed.