Explore the vast range of titles available.

Immunotherapy is a curable treatment for certain cancers, but it is still only effective in a small subset of patients. We have recently reported that programmed cell death protein-1 (PD-1) ligand (PD-L1) expression is regulated by lactate present at high levels in the tumor microenvironment (TME). We hypothesized that the efficacy of anti-PD-1 treatment can be improved by blocking the lactate-generating enzyme, lactate dehydrogenase-A (LDH-A). Anti-PD-1 treatment of mice harboring LDH-A deficient B16-F10 melanoma tumors led to an increase in anti-tumor immune responses compared to mice implanted with tumors expressing LDH-A. Specifically, we observed heightened infiltration of natural killer (NK) cells and CD8+ cytotoxic T cells in the LDH-A deficient tumors. These infiltrated cytotoxic cells had an elevated production of interferon-γ (IFN-γ) and granzyme B. Mechanistically, CD8+ T cells isolated from the TME of LDH-A deficient B16-F10 melanoma tumors and treated with anti-PD-1 showed enhanced mitochondrial activity and increased reactive oxygen species (ROS) levels. Moreover, infiltration of T regulatory (Treg) cells was diminished in LDH-A deficient tumors treated with anti-PD-1. These altered immune cell profiles were clinically relevant as they were accompanied by significantly reduced tumor growth. Our study suggests that blocking LDH-A in the tumor might improve the efficacy of anti-PD-1 therapy.

Mortalin is a chaperone protein that regulates physiological functions of cells. Its multifactorial role allows cells to survive pathological conditions. Pharmacological, chemical, and siRNA-mediated downregulation of mortalin increases oxidative stress, mitochondrial dysfunction leading to unregulated inflammation. In addition to its well-characterized function in controlling oxidative stress, mitochondrial health, and maintaining physiological balance, recent evidence from human brain autopsies and cell culture–based studies suggests a critical role of mortalin in attenuating the damage seen in several neurodegenerative diseases. Overexpression of mortalin provides an important line of defense against accumulated proteins, inflammation, and neuronal loss, a key characteristic feature observed in neurodegeneration. Neurodegenerative diseases are a group of progressive disorders, sharing pathological features in Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and HIV-associated neurocognitive disorder. Aggregation of insoluble amyloid beta-proteins and neurofibrillary tangles in Alzheimer’s disease are among the leading cause of neuropathology in the brain. Parkinson’s disease is characterized by the degeneration of dopamine neurons in substantia nigra pars compacta. A substantial synaptic loss leading to cognitive decline is the hallmark of HIV-associated neurocognitive disorder (HAND). Brain autopsies and cell culture studies showed reduced expression of mortalin in Alzheimer’s, Parkinson’s, and HAND cases and deciphered the important role of mortalin in brain cells. Here, we discuss mortalin and its regulation and describe how neurotoxic conditions alter the expression of mortalin and modulate its functions. In addition, we also review the neuroprotective role of mortalin under neuropathological conditions. This knowledge showcases the importance of mortalin in diverse brain functions and offers new opportunities for the development of therapeutic targets that can modulate the expression of mortalin using chemical compounds.

Neurotropic viruses can cross the otherwise dynamically regulated blood-brain barrier (BBB) and affect the brain cells. Zika virus (ZIKV) is an enveloped neurotropic Flavivirus known to cause severe neurological complications, such as encephalitis and fetal microcephaly. In the present study, we employed human brain microvascular endothelial cells (hBMECs) and astrocytes derived from human progenitors to establish a physiologically relevant BBB model. We used this model to investigate the effects of ZIKV envelope (E) protein on properties of cells comprising the BBB. E protein is the principal viral protein involved in interaction with host cell surface receptors, facilitating the viral entry. Our findings show that the presence of ZIKV E protein leads to activation of both hBMECs and astrocytes. In hBMECs, we observed a decrease in the expression of crucial endothelial junction proteins such as ZO-1, Occludin and VE-Cadherin, which are vital in establishment and maintenance of the BBB. Consequently, the ZIKV E protein induced changes in BBB integrity and permeability. We also found upregulation of genes involved in leukocyte recruitment along with increased proinflammatory chemokines and cytokines upon exposure to E protein. Additionally, the E protein also led to astrogliosis, evident from the elevated expression of GFAP and Vimentin. Both cell types comprising the BBB exhibited inflammatory response upon exposure to E protein which may influence viral access into the central nervous system (CNS) and subsequent infection of other CNS cells. Overall, our study provides valuable insights into the transient changes that occur at the site of BBB upon ZIKV infection.

Although normally dormant, hair follicle stem cells (HFSCs) quickly become activated to divide during a new hair cycle. The quiescence of HFSCs is known to be regulated by a number of intrinsic and extrinsic mechanisms. Here we provide several lines of evidence to demonstrate that HFSCs utilize glycolytic metabolism and produce significantly more lactate than other cells in the epidermis. Furthermore, lactate generation appears to be critical for the activation of HFSCs as deletion of lactate dehydrogenase (Ldha) prevented their activation. Conversely, genetically promoting lactate production in HFSCs through mitochondrial pyruvate carrier 1 (Mpc1) deletion accelerated their activation and the hair cycle. Finally, we identify small molecules that increase lactate production by stimulating Myc levels or inhibiting Mpc1 carrier activity and can topically induce the hair cycle. These data suggest that HFSCs maintain a metabolic state that allows them to remain dormant and yet quickly respond to appropriate proliferative stimuli. Flores et al. show that hair follicle stem cells rely on the production of lactate via the LDHA enzyme to become activated. Inducing Ldha through Mpc1 inhibition or Myc activation successfully reactivates the hair cycle in quiescent follicles.

In this study we have tested the efficacy of citrate therapy in various cancer models. We found that citrate administration inhibited A549 lung cancer growth and additional benefit accrued in combination with cisplatin. Interestingly, citrate regressed Ras-driven lung tumors. Further studies indicated that citrate induced tumor cell differentiation. Additionally, citrate treated tumor samples showed significantly higher infiltrating T-cells and increased blood levels of numerous cytokines. Moreover, we found that citrate inhibited IGF-1R phosphorylation. In vitro studies suggested that citrate treatment inhibited AKT phosphorylation, activated PTEN and increased expression of p-eIF2a. We also found that p-eIF2a was decreased when PTEN was depleted. These data suggest that citrate acts on the IGF-1R-AKT-PTEN-eIF2a pathway. Additionally, metabolic profiling suggested that both glycolysis and the tricarboxylic acid cycle were suppressed in a similar manner in vitro in tumor cells and in vivo but only in tumor tissue. We reproduced many of these observations in an inducible Her2/Neu-driven breast cancer model and in syngeneic pancreatic tumor (Pan02) xenografts. Our data suggests that citrate can inhibit tumor growth in diverse tumor types and via multiple mechanisms. Dietary supplementation with citrate may be beneficial as a cancer therapy.

Cellular metabolism has key roles in T cells differentiation and function. CD4 + T helper-1 (Th1), Th2, and Th17 subsets are highly glycolytic while regulatory T cells (Tregs) use glucose during expansion but rely on fatty acid oxidation for function. Upon uptake, glucose can enter pentose phosphate pathway (PPP) or be used in glycolysis. Here, we showed that blocking 6-phosphogluconate dehydrogenase (6PGD) in the oxidative PPP resulted in substantial reduction of Tregs suppressive function and shifts toward Th1, Th2, and Th17 phenotypes which led to the development of fetal inflammatory disorder in mice model. These in turn improved anti-tumor responses and worsened the outcomes of colitis model. Metabolically, 6PGD blocked Tregs showed improved glycolysis and enhanced non-oxidative PPP to support nucleotide biosynthesis. These results uncover critical role of 6PGD in modulating Tregs plasticity and function, which qualifies it as a novel metabolic checkpoint for immunotherapy applications.

Background In human immunodeficiency virus-1 (HIV-1) infection, activation of astrocytes induces imbalance in physiological functions due to perturbed astrocytic functions that unleashes toxicity on neurons. This leads to inflammatory response finally culminating into neurocognitive dysfunction. In neuroAIDS, HIV-1 protein, transactivator of transcription (Tat) is detected in the cerebrospinal fluid of infected patients. Mortalin, a multifunctional protein, has anti-inflammatory role following its activation in various stress conditions. Recent studies demonstrate downregulation of mortalin in neurodegenerative diseases. Here, we explored the mechanisms of mortalin in modulating HIV-1 Tat-mediated neuroinflammation. Methods Expression of mortalin in autopsy section in normal and diseased individuals were examined using immunohistochemistry. To decipher the role of mortalin in HIV-1 Tat-induced activation, human fetal brain-derived astrocytes were transiently transfected with Tat and mortalin using expression vectors. HIV-1 Tat-mediated damage was analyzed using RT-PCR and western blotting. Modulatory role of mortalin was examined by coexpressing it with Tat, followed by examination of mitochondrial morphodynamics using biochemical assay and confocal and electron microscopy. Extracellular ATP release was monitored using luciferase assay. Neuroinflammation in astrocytes was examined using flow cytometry, dye based study, immunocytochemistry, immunoprecipitation, and western blotting. Indirect neuronal damage was also analyzed. Results HIV-1 Tat downregulates the expression of mortalin in astrocytes, and this is corroborated with autopsy sections of HIV-1 patients. We found that overexpression of mortalin with Tat reduced inflammation and also rescued astrocytic-mediated neuronal death. Using bioinformatics, we discovered that binding of mortalin with Tat leads to Tat degradation and rescues the cell from neuroinflammation. Blocking of proteosomal pathway rescued the Tat degradation and revealed the ubiquitination of Tat. Conclusion Overall, our data demonstrated the protective role of mortalin in combating HIV-1 Tat-mediated damage. We also showed that mortalin could degrade Tat through direct binding with HIV-1 Tat. Overexpression of mortalin in the presence of Tat could significantly reduce cytotoxic effects of Tat in astrocytes. Indirect neuronal death was also found to be rescued. Our in vitro findings were validated as we found attenuated expression of mortalin in the autopsy sections of HIV-1 patients.

We previously reported that combining a phosphoinositide 3-kinase (PI3K) inhibitor with a poly-ADP Rib polymerase (PARP)-inhibitor enhanced DNA damage and cell death in breast cancers that have genetic aberrations in BRCA1 and TP53. Here, we show that enhanced DNA damage induced by PI3K inhibitors in this mutational background is a consequence of impaired production of nucleotides needed for DNA synthesis and DNA repair. Inhibition of PI3K causes a reduction in all four nucleotide triphosphates, whereas inhibition of the protein kinase AKT is less effective than inhibition of PI3K in suppressing nucleotide synthesis and inducing DNA damage. Carbon flux studies reveal that PI3K inhibition disproportionately affects the nonoxidative pentose phosphate pathway that delivers Rib-5-phosphate required for base ribosylation. In vivo in a mouse model of BRCA1-linked triple-negative breast cancer (K14-Cre BRCA1 f/fp53f/f), the PI3K inhibitor BKM120 led to a precipitous drop in DNA synthesis within 8 h of drug treatment, whereas DNA synthesis in normal tissues was less affected. In this mouse model, combined PI3K and PARP inhibition was superior to either agent alone to induce durable remissions of established tumors.

Japanese encephalitis virus (JEV), which is a causative agent of sporadic encephalitis, harbours itself inside the neural stem/progenitor cells. It is a well-known fact that JEV infects neural stem/progenitor cells and decreases their proliferation capacity. With mass spectrometry-based quantitative proteomic study, it is possible to reveal the impact of virus on the stem cells at protein level. Our aim was to perceive the stem cell proteomic response upon viral challenge. We performed a two-dimensional gel electrophoresis-based proteomic study of the human neural stem cells (hNS1 cell line) post JEV infection and found that 13 proteins were differentially expressed. The altered proteome profile of hNS1 cell line revealed sustained endoplasmic reticulum stress, which deteriorated normal cellular activities leading to cell apoptosis. The proteomic changes found in hNS1 cell line were validated in vivo in the subventricular zone of JE infected BALB/c mice. Congruent alterations were also witnessed in multipotent neural precursor cells isolated from human foetus and in autopsy samples of human brain clinically diagnosed as cases of JE patients. Endoplasmic reticulum resident chaperone GRP78, mitochondrial protein Prohibitin and heterogeneous nuclear ribonucleoprotein hnRNPC (C1/C2) have been shown to interact with viral RNA. Hence it is proposed that these are the principle candidates governing endoplasmic reticulum stress-induced apoptosis in JEV infection.

Amyloid beta is a major constituent of the plaques found in the brains of patients suffering from Alzheimer’s disease (AD). A growing body of research work suggests that neuroinflammation plays important roles in the development of AD. Thus, considerable efforts are directed towards identification of compounds that can reduce or inhibit neuroinflammation. Here, we show that sinomenine, a compound present in a Chinese medicinal plant, Sinomenium acutum, inhibits oligomeric amyloid beta-induced production of reactive oxygen species (ROS), nitric oxide (NO) and inflammation-related molecules from astrocytic cells. The conditioned medium from oligomeric amyloid beta-treated astrocytic cells induces cell death in the hippocampal neuronal cells. Importantly, sinomenine inhibits this cell death. In addition, this compound has inhibitory effects on the production of ROS, NO and inflammation-related factors from oligomeric amyloid-beta treated human astrocytes. Finally, the conditioned medium from oligomeric amyloid beta-treated human astrocytes induces cell death in the primary culture of human neurons, which is inhibited by sinomenine. Thus, sinomenine inhibits amyloid beta-induced production of toxic factors from astrocytes, and confers protection to hippocampal neuronal cells as well as human neurons against indirect toxicity. The results suggest that this compound could provide beneficial effects in AD and other neurodegenerative conditions by reducing inflammation and neuronal cell death.