Triggering microglia through toll-like receptor 2 pathway induced interferon β expression in cell and animal model of Alzheimer’s disease

Unravelling the role of protein kinase R (PKR) in neurodegenerative disease: a review

Protein Kinase R is an essential regulator of many cell activities and belongs to one of the largest and most functionally complex gene families. These are found all over the body, and by adding phosphate groups to the substrate proteins, they regulate their activity and coordinate the action of almost all cellular processes. Recent research has illuminated the involvement of PKR in the pathogenesis of neurodegenerative disorders (NDs), thereby expanding our understanding of intricate molecular mechanisms underlying disease progression. Through their inhibition or activation, they hold potential therapeutic targets for the pathogenesis or protection of NDs. In the case of AD (AD), PKR contributes to the protection or elevation of Aβ accumulation, neuroinflammation, synaptic plasticity alterations, and neuronal excitability. Similarly, in Parkinson's disease (PD), PKR again has a dual role in dopaminergic neuronal loss, gene mutations, and mitochondrial dysfunction via various pathways. Notably, neuronal excitotoxicity, as well as genetic mutations, have been linked to ALS. In Huntington's disease (HD), PKR is associated with decreased or increased mutated genes, striatal neuron degeneration, neuroinflammation, and excitotoxicity. This review emphasizes strategies that target PKR for the treatment of neurodegenerative disorders. Doing so offers valuable insights that can guide future research endeavors and the development of innovative therapeutic approaches.

Microglial modulation as a therapeutic strategy in Alzheimer's disease: Focus on microglial preconditioning approaches

Alzheimer's disease (AD) is a progressive disease that causes an impairment of learning and memory. Despite the highly complex pathogenesis of AD, amyloid beta (Aβ) deposition and neurofibrillary tangles (NFTs) formation are the main hallmarks of AD. Neuroinflammation also has a crucial role in the development of AD. As the central nervous system's innate immune cells, microglial cells are activated in AD and induce inflammation by producing pro-inflammatory mediators. However, microglial activation is not always deleterious. M2-activated microglial cells are considered anti-inflammatory cells, which develop neuroprotection. Various approaches are proposed for managing AD, yet no effective therapy is available for this disorder. Considering the potential protective role of M2 microglia in neurodegenerative disorders and the improvement of these disorders by preconditioning approaches, it can be suggested that preconditioning of microglial cells may be beneficial for managing AD progression. Therefore, this study review microglial preconditioning approaches for preventing and improving AD.

Natural products - Dawn of keloid treatment

Keloids are prevalent pathological scars, often leading to cosmetic deformities and hindering joint mobility.They cause discomfort, including burning and itching, while gradually expanding and potentially posing a risk of cancer.Developing effective drugs and treatments for keloids has been a persistent challenge in the medical field. Natural products are an important source of innovative drugs and a breakthrough for many knotty disease.Herein, keywords of "natural, plant, compound, extract" were combined with "keloid" and searched in PubMed and Google Scholar, respectively. A total of 32 natural products as well as 9 extracts possessing the potential for treating keloids were ultimately identified.Current research in this field faces a significant challenge due to the lack of suitable animal models, resulting in a predominant reliance on in vitro studies.In vivo and clinical studies are notably scarce as a result.Moreover, there is a notable deficiency in research focusing on the role of nutrients in keloid formation and treatment.The appropriate dosage form (oral, topical, injectable) is crucial for the development of natural product drugs. Finally, the conclusion was hereby made that natural products, when used as adjuncts to other treatments, hold significant potential in the management of keloids.By summarizing the natural products and elucidating their mechanisms in keloid treatment, the present study aims to stimulate further discoveries and research in drug development for effectively addressing this challenging condition.

Interferon beta attenuates recognition memory impairment and improves brain glucose uptake in a rat model of Alzheimer's disease: Involvement of mitochondrial biogenesis and PI3K pathway

Interferon beta (IFNβ) is a cytokine with anti-apoptotic and anti-inflammatory properties, and its beneficial effects on Alzheimer's disease (AD) have been recently shown. The alterations in cerebral glucose uptake are closely linked to memory deficit and AD progression. The current study was designed to determine if IFNβ can improve recognition memory and brain glucose uptake in a rat model of AD. The lentiviruses expressing mutant human amyloid precursor protein were injected bilaterally to the rat hippocampus. From day 23 after virus injection, rats were intranasally treated with recombinant IFNβ protein (68,000 IU/rat) every other day until day 50. Recognition memory performance was evaluated by novel object recognition test on days 46-49. The 18F-2- fluoro-deoxy-d-glucose positron emission tomography (18F-FDG-PET) was used to determine changes in brain glucose metabolism on day 50. The expression of the PI3K/Akt pathway components, neurotrophins and mitochondrial biogenesis factors were also measured by qPCR in the hippocampus. Our results showed that IFNβ treatment improves recognition memory performance in parallel with increased glucose uptake and neuronal survival in the hippocampus of the AD rats. The neuroprotective effect of IFNβ could be attributed, at least partly, to activation of PI3K-Akt-mTOR signaling pathway, increased expression of NGF, and mitochondrial biogenesis. Taken together, our findings suggest the therapeutic potential of IFNβ for AD.

Overexpression of protein kinase Mζ in the hippocampus mitigates Alzheimer's disease-related cognitive deficit in rats

Accumulation of amyloid beta (Aβ) soluble forms in the cerebral parenchyma is the mainstream concept underlying memory deficit in the early phase of Alzheimer's disease (AD). PKMζ plays a critical role in the maintenance of long-term memory. Yet, the role of this brain-specific enzyme has not been addressed in AD. We examined the impact of hippocampal PKMζ overexpression on AD-related memory impairment in rats. Oligomeric form of Aβ (oAβ) or vehicle was bilaterally microinjected into the dorsal hippocampus of male Wistar rats under stereotaxic surgery. One week later, 2 μl of lentiviral vector (10⁸ T.U. / ml.) encoding PKMζ genome was microinjected into the dorsal hippocampus. Seven days later, behavioral performance was assessed using shuttle box and Morris water maze. The expression levels of GluA1, GluA2 and KCC2 were determined in the hippocampus using western blot technique. Our data showed that oAβ impairs both passive avoidance and spatial learning and memory. However, overexpression of PKMζ in the dorsal hippocampus restored the behavioral performance. This improving effect was blocked by microinjection of ZIP, a PKMζ inhibitor, into the hippocampus. oAβ or PKMζ did not significantly change GluA1 level in the hippocampus. Furthermore, PKMζ failed to restore elevated KCC2 level induced by oAβ. However, oAβ decreased GluA2 level, and overexpression of PKMζ restored its expression toward the control level. In conclusion, hippocampal overexpression of PKMζ restored memory dysfunction induced by amyloidopathy in part, through preserving hippocampal GluA2 containing AMPA receptors. PKMζ's signaling pathway could be considered as a therapeutic target to battle memory deficits in the early phase of AD.

Alzheimer's Disease: Protective Effects of Mycobacterium vaccae, a Soil-Derived Mycobacterium with Anti-Inflammatory and Anti-Tubercular Properties, on the Proteomic Profiles of Plasma and Cerebrospinal Fluid in Rats

BACKGROUND

Alzheimer's disease (AD) is an inflammatory neurodegenerative disease that may be associated with prior bacterial infections. Microbial "old friends" can suppress exaggerated inflammation in response to disease-causing infections or increase clearance of pathogens such as Mycobacterium tuberculosis, which causes tuberculosis (TB). One such "old friend" is Mycobacterium vaccae NCTC 11659, a soil-derived bacterium that has been proposed either as a vaccine for prevention of TB, or as immunotherapy for the treatment of TB when used alongside first line anti-TB drug treatment.

OBJECTIVE

The goal of this study was to use a hypothesis generating approach to explore the effects of M. vaccae on physiological changes in the plasma and cerebrospinal fluid (CSF).

METHODS

Liquid chromatography-tandem mass spectrometry-based proteomics were performed in plasma and CSF of adult male rats after immunization with a heat-killed preparation of M. vaccae NCTC 11659 or borate-buffered saline vehicle. Gene enrichment analysis and analysis of protein-protein interactions were performed to integrate physiological network changes in plasma and CSF. We used RT-qPCR to assess immune and metabolic gene expression changes in the hippocampus.

RESULTS

In both plasma and CSF, immunization with M. vaccae increased proteins associated with immune activation and downregulated proteins corresponding to lipid (including phospholipid and cholesterol) metabolism. Immunization with M. vaccae also increased hippocampal expression of interleukin-4 (IL-4) mRNA, implicating anti-inflammatory effects in the central nervous system.

CONCLUSION

M. vaccae alters host immune activity and lipid metabolism. These data are consistent with the hypothesis that microbe-host interactions may protect against possible infection-induced, inflammation-related cognitive impairments.

M2b macrophage subset decrement as an indicator of cognitive function in Alzheimer's disease

AIM

Alzheimer's disease (AD) is a chronic neurodegenerative disease. Various inflammatory processes account for the pathology of AD, and macrophages in particular have a distinct polarization phenotype related to M1/M2 classification. We aimed to investigate macrophage polarization patterns as an indicator of cognitive function in AD.

METHODS

We recruited 54 non-demented individuals as control and 105 AD patients as experimental groups respectively. Percentages of macrophage (PM2K⁺ CD14⁺ and PM2K⁺ CD14^- ) and macrophage polarization subsets (M1, M2a, M2b, and M2c) were assessed using flow cytometry. All AD patients were classified by dementia severity using clinical Dementia Rating scale (CDR) as CDR 0.5, 1 and ≧2. AD patients had cognitive function evaluation using Mini-Mental State Examination (MMSE) and Cognitive Assessment Screening Instrument (CASI). We compared the macrophage polarization patterns between control and patient groups. Cognitive function was evaluated in association with macrophage polarization patterns in AD patients.

RESULTS

The percentages of PM2K⁺ CD14⁺ and PM2K⁺ CD14^- macrophages were higher in AD patients than in controls. M2b macrophage subset decrement and M1 macrophage subset increment of PM2K⁺ CD14⁺ and PM2K⁺ CD14^- macrophages were observed in AD patients compared with controls. Although percentages of macrophage subsets were not consistent with CDR staging, PM2K⁺ CD14⁺ M2b macrophage subset decrement was correlated with worse cognitive functioning by MMSE and CASI in AD patients.

CONCLUSION

M2b macrophage subset decrement and M1 macrophage subset increment were noted in AD patients, while PM2K⁺ CD14⁺ M2b macrophage subset decrement indicated worse cognitive function in such patients.