Longitudinal assessment of fractional anisotropy alterations caused by simian immunodeficiency virus infection: a
Zhenchao Tang1, Enqing Dong2, Jiaojiao Liu3
1School of Mechanical, Electrical & Information Engineering, Shandong University, Weihai, Shandong Province, 264209, China.
Abstract:
Previous diffusion tensor imaging (DTI) studies found that human immunodeficiency virus (HIV) infection led to white matter (WM) microstructure degeneration. Most of the DTI studies were cross-sectional and thus merely investigated only one specific point in the disease. In order to systematically study the WM impairments caused by HIV infection, more longitudinal studies are needed. However, longitudinal studies on HIV patients are very difficult to conduct. To address this question, we employed the simian immunodeficiency virus (SIV)-infected rhesus monkeys model to carry out a longitudinal DTI study. We aimed to longitudinally access the WM abnormalities of SIV-infected rhesus monkeys by studying the fractional anisotropy (FA) alterations with Tract Based Spatial Statistic (TBSS) analysis. Four rhesus monkeys inoculated intravenously with SIVmac239 were utilized in the study. DTI scans and peripheral blood CD4(+) and CD8(+) T cell counts were acquired prior to virus inoculation (as the baseline) and in the 12th and 24th week postvirus inoculation. Significant FA alterations were found in the two areas of the inferotemporal regions (iTE), respectively located in the ventral subregion of posterior iTE (iTEpv) and the dorsal subregion of iTE (iTEpd). The decreased FA values in iTEpd were found significantly negatively correlated with the elevated peripheral blood CD4(+)/CD8(+) ratios. It might suggest that WM in iTEpd was still impaired even though the immune dysfunction alleviated temporally.
Insights
This study used a simian immunodeficiency virus (SIV) rhesus monkey model to longitudinally track white matter (WM) changes. Findings reveal persistent WM impairments in specific brain regions, even with temporary immune recovery.
Area of Science:
- Neuroimaging
- Primate Models
- Immunodeficiency Virus Research
Background:
- Human immunodeficiency virus (HIV) infection is known to cause white matter (WM) degeneration.
- Previous diffusion tensor imaging (DTI) studies were mostly cross-sectional, limiting understanding of disease progression.
- Longitudinal studies are crucial for understanding HIV-associated WM impairments but are challenging in human patients.
Purpose of the Study:
- To longitudinally assess white matter (WM) abnormalities in simian immunodeficiency virus (SIV)-infected rhesus monkeys.
- To investigate fractional anisotropy (FA) alterations using Tract-Based Spatial Statistics (TBSS) analysis.
- To correlate WM changes with peripheral blood CD4(+) and CD8(+) T cell counts over time.
Main Methods:
- A longitudinal DTI study was conducted on four rhesus monkeys inoculated with SIVmac239.
- DTI scans and CD4(+)/CD8(+) T cell counts were acquired at baseline, 12 weeks, and 24 weeks post-inoculation.
- Tract-Based Spatial Statistics (TBSS) was used to analyze fractional anisotropy (FA) alterations in white matter.
Main Results:
- Significant fractional anisotropy (FA) alterations were observed in the inferotemporal regions (iTE), specifically in the iTEpv and iTEpd subregions.
- Decreased FA values in the iTEpd region showed a significant negative correlation with elevated peripheral blood CD4(+)/CD8(+) ratios.
- These findings suggest that white matter in the iTEpd region may remain impaired despite temporary improvements in immune dysfunction.
Conclusions:
- The SIV-infected rhesus monkey model provides a valuable platform for longitudinal studies of HIV-associated neurological damage.
- Longitudinal DTI reveals persistent white matter abnormalities in specific brain regions, such as the inferotemporal cortex.
- The correlation between decreased FA in iTEpd and CD4(+)/CD8(+) ratios highlights a potential link between immune status and white matter integrity.
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