HIV Promotes Neurocognitive Impairment by Damaging the Hippocampal Microvessels

HIF-1α promotes virus replication and cytokine storm in H1N1 virus-induced severe pneumonia through cellular metabolic reprogramming

The mortality of patients with severe pneumonia caused by H1N1 infection is closely related to viral replication and cytokine storm. However, the specific mechanisms triggering virus replication and cytokine storm are still not fully elucidated. Here, we identified hypoxia inducible factor-1α (HIF-1α) as one of the major host molecules that facilitates H1N1 virus replication followed by cytokine storm in alveolar epithelial cells. Specifically, HIF-1α protein expression is upregulated after H1N1 infection. Deficiency of HIF-1α attenuates pulmonary injury, viral replication and cytokine storm in vivo. In addition, viral replication and cytokine storm were inhibited after HIF-1α knockdown in vitro. Mechanistically, the invasion of H1N1 virus into alveolar epithelial cells leads to a shift in glucose metabolism to glycolysis, with rapid production of ATP and lactate. Inhibition of glycolysis significantly suppresses viral replication and inflammatory responses. Further analysis revealed that H1N1-induced HIF-1α can promote the expression of hexokinase 2 (HK2), the key enzyme of glycolysis, and then not only provide energy for the rapid replication of H1N1 virus but also produce lactate, which reduces the accumulation of the MAVS/RIG-I complex and inhibits IFN-α/β production. In conclusion, this study demonstrated that the upregulation of HIF-1α by H1N1 infection augments viral replication and cytokine storm by cellular metabolic reprogramming toward glycolysis mainly through upregulation of HK2, providing a theoretical basis for finding potential targets for the treatment of severe pneumonia caused by H1N1 infection.

PKCε activator protects hippocampal microvascular disruption and memory defect in 3×Tg-Alzheimer's disease mice with cerebral microinfarcts

Background

Current evidence suggests that microvessel disease is involved in Alzheimer's disease (AD). Cerebrovascular disease correlates with cardiovascular disease and is complicated in ≈40% of AD patients. The protein kinase C (PKC) ε activator DCPLA can stimulate human antigen (Hu) R that prevents degradation and promotes the translation of mitochondrial Mn-superoxide dismutase (MnSOD) and vascular endothelial growth factor-A (VEGF) mRNAs.

Methods

To induce brain microinfarcts, we injected triple transgenic (3×Tg) and wild-type (WT) control mice with microbeads (20 μm caliber) into common carotid arteries, with or without the DCPLA-ME (methyl-ester) for 2 weeks. After water maze training, mice at 16 months old were examined for confocal immunohistochemistry at a single cell or microvessel level in the hippocampal CA1 area, important for spatial memory storage, and in the dorsal hippocampus by western blots.

Results

In 3×Tg mice without cerebral microinfarcts, an accelerating age-related increase in (mild) oxidative stress and hypoxia inducible factor (HIF)-1α, but a reduction in VEGF, mitochondrial transcription factor A (TFAM), and MnSOD were associated with capillary loss. The change was less pronounced in arterioles. However, in 3×Tg mice with cerebral microinfarcts, increasing arteriolar diameter and their wall cells were related with the strong oxidative DNA damage 8-hydroxy-2'-deoxyguanosine (8-OHdG), apoptosis (cleaved caspase 3), and sustained hypoxia (increased HIF-1α and VEGF/PKCε/extracellular signal regulated kinase or ERK pathway). Microocclusion enhanced the loss of the synaptic marker spinophilin, astrocytic number, and astrocyte-vascular coupling areas and demyelination of axons. DCPLA-ME prevented spatial memory defect; strong oxidative stress-related apoptosis; sustained hypoxia (by reducing HIF-1α and VEGF); and exaggerated cell repair in arteriolar walls, pericapillary space dilation, neuro-glial-vascular disruption, and demyelination.

Conclusion

In conclusion, in 3×Tg mice with cerebral microinfarcts, sustained hypoxia (increased HIF-1α and VEGF signals) is dominant with arteriolar wall thickening, and DCPLA has a protective effect on sustained hypoxia.

Disruption of blood-brain barrier: effects of HIV Tat on brain microvascular endothelial cells and tight junction proteins

Although the widespread use of antiretroviral therapy (ART) has prolonged the life span of people living with HIV (PLWH), the incidence of HIV-associated neurocognitive disorders (HAND) in PLWH is also gradually increasing, seriously affecting the quality of life for PLWH. However, the pathogenesis of HAND has not been elucidated, which leaves HAND without effective treatment. HIV protein transactivator of transcription (Tat), as an important regulatory protein, is crucial in the pathogenesis of HAND, and its mechanism of HAND has received widespread attention. The blood-brain barrier (BBB) and its cellular component brain microvascular endothelial cells (BMVECs) play a necessary role in protecting the central nervous system (CNS), and their damage associated with Tat is a potential therapeutic target of HAND. In this review, we will study the Tat-mediated damage mechanism of the BBB and present multiple lines of evidence related to BMVEC damage caused by Tat.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

Cocaine sensitizes the CD4+ T cells for HIV infection by co-stimulating NFAT and AP-1

The productive infection of HIV, which generates new viral progeny, depends on the activation status of the cell. In this study, we found cocaine exposure sensitizes partially active CD4+ T cells and makes them poised for productive HIV infection. We discovered that cocaine treatment enhances the metabolic state of the cells by co-stimulating several transcription factors, mainly NFAT and AP-1, the two transcription factors, which specifically play a crucial role in enhancing both HIV and the overall cellular gene expression in T cells. We found that cocaine-induced AP-1 works in tandem with NFAT to boost HIV transcription. The enhanced HIV transcription upon cocaine exposure was further confirmed through higher phosphorylation of the crucial serine residues at the carboxyl-terminal domain (CTD) of RNA polymerase II. The insights gained from this study could aid in developing highly specialized therapeutics combating the deleterious effects of cocaine on the cocaine-using HIV population.