Minocycline Attenuates Microglia/Macrophage Phagocytic Activity and Inhibits SAH-Induced Neuronal Cell Death and Inflammation

The pivotal role of microglia in injury and the prognosis of subarachnoid hemorrhage

Subarachnoid hemorrhage leads to a series of pathological changes, including vascular spasm, cellular apoptosis, blood-brain barrier damage, cerebral edema, and white matter injury. Microglia, which are the key immune cells in the central nervous system, maintain homeostasis in the neural environment, support neurons, mediate apoptosis, participate in immune regulation, and have neuroprotective effects. Increasing evidence has shown that microglia play a pivotal role in the pathogenesis of subarachnoid hemorrhage and affect the process of injury and the prognosis of subarachnoid hemorrhage. Moreover, microglia play certain neuroprotective roles in the recovery phase of subarachnoid hemorrhage. Several approaches aimed at modulating microglia function are believed to attenuate subarachnoid hemorrhage injury. This provides new targets and ideas for the treatment of subarachnoid hemorrhage. However, an in-depth and comprehensive summary of the role of microglia after subarachnoid hemorrhage is still lacking. This review describes the activation of microglia after subarachnoid hemorrhage and their roles in the pathological processes of vasospasm, neuroinflammation, neuronal apoptosis, blood-brain barrier disruption, cerebral edema, and cerebral white matter lesions. It also discusses the neuroprotective roles of microglia during recovery from subarachnoid hemorrhage and therapeutic advances aimed at modulating microglial function after subarachnoid hemorrhage. Currently, microglia in subarachnoid hemorrhage are targeted with TLR inhibitors, nuclear factor-κB and STAT3 pathway inhibitors, glycine/tyrosine kinases, NLRP3 signaling pathway inhibitors, Gasdermin D inhibitors, vincristine receptor α receptor agonists, ferroptosis inhibitors, genetic modification techniques, stem cell therapies, and traditional Chinese medicine. However, most of these are still being evaluated at the laboratory stage. More clinical studies and data on subarachnoid hemorrhage are required to improve the treatment of subarachnoid hemorrhage.

Natural polyphenol mangiferin delays neuronal cell senescence by inhibiting neuroinflammation mediated by microglial activation

Extracellular β-amyloid protein (Aβ) plaques are prominent pathological feature of Alzheimer's disease (AD). Aβ oligomers and plaques induce sustained microglial activation via the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/interferon regulatory factor 5 (IRF5) signaling pathway. This microglial activation-mediated neuroinflammation can accelerate neuronal cell senescence. Consequently, the regulation of the AMPK/mTOR/IRF5 pathway presents a potential therapeutic target for AD, as it may inhibit neuroinflammation and delay neuronal cell senescence. Mangiferin, a bioactive natural polyphenol extracted from the leaves of Mangifera indica Linn., has garnered significant attention for its anti-inflammatory properties. However, it remains unclear whether mangiferin can modulate the AMPK/mTOR/IRF5 pathway to inhibit microglial activation-mediated neuroinflammation and delay neuronal cell senescence. This study employed both cellular and animal models of neuronal cell senescence to explore the effects of mangiferin on the regulation of the AMPK/mTOR/IRF5 pathway, aiming to inhibit neuroinflammation and delay neuronal cell senescence in vitro and in vivo. Specifically, SH-SY5Y neuroblastoma cells were subjected to a neuroinflammatory microenvironment induced by Aβ1-42-mediated HMC3 microglial activation to induce neuronal cell senescence in vitro. Additionally, SAMP8 accelerated aging mice were utilized as an aging animal model. The results indicate that mangiferin significantly enhances AMPK phosphorylation in microglial cells, inhibits mTOR activation, and downregulates IRF5 expression. These effects collectively suppress microglial activation and markedly reduce the production of pro-inflammatory cytokines by activated microglia. Consequently, there is a decrease in the proportion of neurons arrested in the G0/G1 phase and a reduction in the number of senescence-associated β-galactosidase (SA-β-gal) positive neurons. Furthermore, mangiferin significantly decreases the expression of neuronal cell senescence markers P16Ink4a and P21Cip1. Collectively, these findings suggest that mangiferin effectively regulates the AMPK/mTOR/IRF5 pathway, inhibits neuroinflammation mediated by microglial activation, and delays neuronal cell senescence. This study underscores the potential of mangiferin for the treatment of neuroinflammation and neurodegenerative diseases.

Features that distinguish age-related macular degeneration from aging

Age-related macular degeneration (AMD) is a complex, multifactorial retinal degenerative disease that is influenced by both genetic and environmental factors. However, the strongest risk factor for AMD is advanced age. Several physiological processes are observed in aging tissues including a low level of chronic inflammation (inflammaging), changed lipid and energy metabolism, and senescence. Nevertheless, whereas everyone ages, only a subset of the population develops AMD. The purpose of this review is to delineate the differences on a cellular and molecular level between natural aging changes and those observed in AMD. We provide a unique perspective on how genetic and environmental components modulate aging in the eye, as well as the specific role of the aging RPE and retina in the pathogenesis of AMD. Topics discussed include the mechanism of aging and its relation to the mechanism of AMD, current animal models that can be used to recapitulate some aspects of the pathology, and potential interventions that shift the balance towards healthy aging and therefore attenuate, prevent or delay the initiation of the disease.

Emerging autism and Fragile X syndrome treatments

The limitations of current symptom-focused treatments drive the urgent need for effective therapies for autism and Fragile X syndrome (FXS). Currently, no approved pharmacological interventions target the core symptoms of these disorders. Advances in understanding the underlying biology of autism and FXS make this an important time to explore novel options. Indeed, several treatments have recently been tested in clinical trials, with promising results in treating core symptoms of autism and FXS. We focus on emerging interventions, such as gut microbiome therapies, anti-inflammatory approaches, bumetanide, phosphodiesterase 4D inhibitors, and endocannabinoid modulators. We also discuss factors, such as disorder heterogeneity, which may have contributed to poor efficacy in previously failed late-phase trials and impact recent trials, emphasizing the need for personalized treatment approaches.

Long-Term Minocycline Treatment Exhibits Enhanced Therapeutic Effects on Ischemic Stroke by Suppressing Inflammatory Phenotype of Microglia Through the EMB/MCT4/STING Pathway

BACKGROUND

Neuroinflammation caused by excessive activation of microglia is a significant cause of poor prognosis in ischemic stroke patients. Minocycline, a microglial cell inhibitor, has neuroprotective effects in stroke, but its optimal treatment duration and specific mechanisms of action remain unclear. This study aimed to compare the efficacy of different minocycline treatment durations on stroke and explore their mechanisms of action.

METHODS

We investigated the effects of various durations of minocycline treatment on microglial polarization using cellular and animal models. The mechanisms of long-term minocycline therapy for neuroprotective effects were explored through in vitro and in vivo experiments.

RESULTS

In stroke models, long-term minocycline treatment showed a stronger inhibitory effect on neuroinflammation and improved neuron viability compared with short-term treatment. Further in vitro and in vivo results indicated that long-term minocycline treatment downregulated microglial glycolysis levels through the EMB/MCT4 axis, promoting the transformation of microglia to an anti-inflammatory phenotype by inhibiting the activation of the STING pathway, thereby improving post-stroke neuroinflammation.

CONCLUSION

Long-term minocycline therapy exerts neuroprotective effects in ischemic stroke by regulating the EMB/MCT4/STING axis and inhibiting the inflammatory phenotype of microglia through downregulating cellular glycolysis levels. Extending the treatment duration of minocycline appropriately may further improve ischemic stroke outcomes.

Microglial activation and hypothalamic structural plasticity in HFD obesity: insights from semaglutide and minocycline

High-fat diet (HFD)-induced microglial activation contributes to hypothalamic inflammation and obesity, but the mechanisms linking microglia to structural changes remain unclear. This study explored the role of microglia in impairing hypothalamic synaptic plasticity in diet-induced obesity mice and evaluated the therapeutic potential of semaglutide (Sema) and minocycline (MI). Six-week-old C57BL/6J mice were divided into low-fat diet and HFD groups. At week 30, the HFD-fed mice were treated daily with Sema or MI for six weeks. Confocal microscopy assessed hypothalamic dendritic spines, synaptic organization, and microglia-synapse interactions. We also analyzed microglial morphology, CD68/CD11b colocalization with Iba-1, synaptic marker expression, and phagocytosis-related pathways (C1q, C3, CD11b). BV2 microglia were used to examine the direct effects of Sema or MI on microglia and validate the in vivo findings. HFD feeding induced microglial activation, as indicated by increased colocalization of CD68 or synaptophysin and CD11b with Iba-1, along with elevated C1q, C3, and CD11b expression, signaling enhanced synaptic phagocytosis. This was accompanied by reduced hypothalamic dendritic spines, decreased synaptic marker expression, and disrupted excitatory/inhibitory synaptic organization in the melanocortin system, as well as impaired glucose metabolism, disrupted leptin-ghrelin balance, and increased food intake and body weight. Sema and MI treatments reversed the pathological changes of microglial activation and restored hypothalamic synaptic structure, although their effects on synaptic organization and metabolic outcomes differed. Our findings highlight the key role of microglial activation in hypothalamic synaptic impairment in diet-induced obesity models, with Sema and MI possibly offering distinct therapeutic pathways to mitigate these impairments.

Targeting Oligodendrocyte Dynamics and Remyelination: Emerging Therapies and Personalized Approaches in Multiple Sclerosis Management

Multiple sclerosis (MS) is a progressive autoimmune condition that primarily affects young people and is characterized by demyelination and neurodegeneration of the central nervous system (CNS). This in-depth review explores the complex involvement of oligodendrocytes, the primary myelin- producing cells in the CNS, in the pathophysiology of MS. It discusses the biochemical processes and signalling pathways required for oligodendrocytes to function and remain alive, as well as how they might fail and cause demyelination to occur. We investigate developing therapeutic options that target remyelination, a fundamental component of MS treatment. Remyelination approaches promote the survival and differentiation of oligodendrocyte precursor cells (OPCs), restoring myelin sheaths. This improves nerve fibre function and may prevent MS from worsening. We examine crucial parameters influencing remyelination success, such as OPC density, ageing, and signalling pathway regulation (e.g., Retinoid X receptor, LINGO-1, Notch). The review also examines existing neuroprotective and antiinflammatory medications being studied to see if they can assist oligodendrocytes in surviving and reducing the severity of MS symptoms. The review focuses on medicines that target the myelin metabolism in oligodendrocytes. Altering oligodendrocyte metabolism has been linked to reversing demyelination and improving MS patient outcomes through various mechanisms. We also explore potential breakthroughs, including innovative antisense technologies, deep brain stimulation, and the impact of gut health and exercise on MS development. The article discusses the possibility of personalized medicine in MS therapy, emphasizing the importance of specific medicines based on individual molecular profiles. The study emphasizes the need for reliable biomarkers and improved imaging tools for monitoring disease progression and therapy response. Finally, this review focuses on the importance of oligodendrocytes in MS and the potential for remyelination therapy. It also underlines the importance of continued research to develop more effective treatment regimens, taking into account the complexities of MS pathology and the different factors that influence disease progression and treatment.

Minocycline inhibits microglial activation in the CA1 hippocampal region and prevents long-term cognitive sequel after experimental cerebral malaria

Cerebral malaria is the worst complication of malaria infection, has a high mortality rate, and may cause different neurodysfunctions, including cognitive decline. Neuroinflammation is an important cause of cognitive damage in neurodegenerative diseases, and microglial cells can be activated in a disease-associated profile leading to tissue damage and neuronal death. Here, we demonstrated that treatment with minocycline reduced blood-brain barrier breakdown and modulated ICAM1 mRNA expression; reduced proinflammatory cytokines, such as TNF-α, IL-1β, IFN-γ, and IL-6; and prevented long-term cognitive decline in contextual and aversive memory tasks. Taken together, our data suggest that microglial cells are activated during experimental cerebral malaria, leading to neuroinflammatory events that end up in cognitive damage. In addition, pharmacological modulation of microglial activation, by drugs such as minocycline may be an important therapeutic strategy in the prevention of long-term memory impairment.

TLR2/NF-κB signaling in macrophage/microglia mediated COVID-pain induced by SARS-CoV-2 envelope protein

Pain has become a major symptom of long COVID-19 without effective therapy. Apart from viral infection pathological process, SARS-CoV-2 membranal proteins (envelope [S2E], spike [S2S] and membrane [S2M]) also present pro-inflammatory feature independently. Here, we aim to uncover the neuroinflammatory mechanism of COVID-pain induced by SARS-CoV-2 membranal proteins. We detected the three proteins in both peripheral sensory ganglions and spinal dorsal horn of COVID-19 donors. After intradermal and intrathecal injection, only S2E triggered pain behaviors, accompanied with upregulated-phosphorylation nuclear factor kappa B (NF-κB), which was significantly attenuated by minocycline in mice. We further identified Toll-like receptor 2 (TLR2) among TLRs as the target of S2E to evoke inflammatory responses leading to COVID-pain. This study identified the nociceptive effect of S2E through directly interacting with macrophage/microglia TLR2 and inducing the following NF-κB inflammatory storm. Clearing away S2E and inhibiting macrophage/microglia TLR2 served as perspective therapeutic strategies for COVID-19 pain.

Looking Back to Move Forward: Research in Stress, Behavior, and Immune Function

BACKGROUND

From the original studies investigating the effects of adrenal gland secretion to modern high-throughput multidimensional analyses, stress research has been a topic of scientific interest spanning just over a century.

SUMMARY

The objective of this review was to provide historical context for influential discoveries, surprising findings, and preclinical models in stress-related neuroimmune research. Furthermore, we summarize this work and present a current understanding of the stress pathways and their effects on the immune system and behavior. We focus on recent work demonstrating stress-induced immune changes within the brain and highlight studies investigating stress effects on microglia. Lastly, we conclude with potential areas for future investigation concerning microglia heterogeneity, bone marrow niches, and sex differences.

KEY MESSAGES

Stress is a phenomenon that ties together not only the central and peripheral nervous system, but the immune system as well. The cumulative effects of stress can enhance or suppress immune function, based on the intensity and duration of the stressor. These stress-induced immune alterations are associated with neurobiological changes, including structural remodeling of neurons and decreased neurogenesis, and these contribute to the development of behavioral and cognitive deficits. As such, research in this field has revealed important insights into neuroimmune communication as well as molecular and cellular mediators of complex behaviors relevant to psychiatric disorders.

Beyond nimodipine: advanced neuroprotection strategies for aneurysmal subarachnoid hemorrhage vasospasm and delayed cerebral ischemia

The clinical management of aneurysmal subarachnoid hemorrhage (SAH)-associated vasospasm remains a challenge in neurosurgical practice, with its prevention and treatment having a major impact on neurological outcome. While considered a mainstay, nimodipine is burdened by some non-negligible limitations that make it still a suboptimal candidate of pharmacotherapy for SAH. This narrative review aims to provide an update on the pharmacodynamics, pharmacokinetics, overall evidence, and strength of recommendation of nimodipine alternative drugs for aneurysmal SAH-associated vasospasm and delayed cerebral ischemia. A PRISMA literature search was performed in the PubMed/Medline, Web of Science, ClinicalTrials.gov, and PubChem databases using a combination of the MeSH terms "medical therapy," "management," "cerebral vasospasm," "subarachnoid hemorrhage," and "delayed cerebral ischemia." Collected articles were reviewed for typology and relevance prior to final inclusion. A total of 346 articles were initially collected. The identification, screening, eligibility, and inclusion process resulted in the selection of 59 studies. Nicardipine and cilostazol, which have longer half-lives than nimodipine, had robust evidence of efficacy and safety. Eicosapentaenoic acid, dapsone and clazosentan showed a good balance between effectiveness and favorable pharmacokinetics. Combinations between different drug classes have been studied to a very limited extent. Nicardipine, cilostazol, Rho-kinase inhibitors, and clazosentan proved their better pharmacokinetic profiles compared with nimodipine without prejudice with effective and safe neuroprotective role. However, the number of trials conducted is significantly lower than for nimodipine. Aneurysmal SAH-associated vasospasm remains an area of ongoing preclinical and clinical research where the search for new drugs or associations is critical.

Incidence and Factors in Delayed Neurological Deficits after Subarachnoid Hemorrhage in Mice

Background

Delayed cerebral ischemia (DCI) is one of the most feared complications in aneurysmal subarachnoid hemorrhage (SAH). Animal models are crucial to studying the disease mechanisms and potential treatments. DCI in rodents was thought to not exist; herein we examine literature and our experience with DCI in rodents.

Methods

Daily behavioral performance was assessed every day from day 1 to up to 7 days post-SAH on mice from 5 different studies that used the endovascular perforation model. Performance was graded using an 8-test sensorimotor neuroscore previously described. The daily neuroscore was then used to identify the incidence and timing of delayed neurological deficits, a clinical surrogate for DCI. A total number of 298 mice (134 males, 164 females) were subjected to SAH. Fifty-one mice had histological staining done to identify infarct volume.

Results

The overall incidence of DND was 33.9%; 27.6% in males and 39.0% in females, but this difference was not statistically significant. The overall incidence of delayed death was 21.1%, and there was no significant difference for delayed mortality in females versus male mice. There is a non-statistically significant trend towards increased infarct volume in mice suffering DND.

Conclusions

Mice with endovascular puncture induced SAH develop DND at rates comparable to human patients. Future work needs to correlate the DND seen with decreased regional cerebral blood flow, another hallmark of DCI, but in spite of this need, researchers may use the murine models to test therapies for DCI after SAH.

Inflammation and Huntington's disease - a neglected therapeutic target?

INTRODUCTION

Huntington's Disease (HD) is a genetic neurodegenerative disease for which there is currently no disease-modifying treatment. One of several underlying mechanisms proposed to be involved in HD pathogenesis is inflammation; there is now accumulating evidence that the immune system may play an integral role in disease pathology and progression. As such, modulation of the immune system could be a potential therapeutic target for HD.

AREAS COVERED

To date, the number of trials targeting immune aspects of HD has been limited. However, targeting it, may have great advantages over other therapeutic areas, given that many drugs already exist that have actions in this system coupled to the fact that inflammation can be measured both peripherally and, to some extent, centrally using CSF and PET imaging. In this review, we look at evidence that the immune system and the newly emerging area of the microbiome are altered in HD patients, and then present and discuss clinical trials that have targeted different parts of the immune system.

EXPERT OPINION

We then conclude by discussing how this field might develop going forward, focusing on the role of imaging and other biomarkers to monitor central immune activation and response to novel treatments in HD.

Established and emerging techniques for the study of microglia: visualization, depletion, and fate mapping

The central nervous system (CNS) is an essential hub for neuronal communication. As a major component of the CNS, glial cells are vital in the maintenance and regulation of neuronal network dynamics. Research on microglia, the resident innate immune cells of the CNS, has advanced considerably in recent years, and our understanding of their diverse functions continues to grow. Microglia play critical roles in the formation and regulation of neuronal synapses, myelination, responses to injury, neurogenesis, inflammation, and many other physiological processes. In parallel with advances in microglial biology, cutting-edge techniques for the characterization of microglial properties have emerged with increasing depth and precision. Labeling tools and reporter models are important for the study of microglial morphology, ultrastructure, and dynamics, but also for microglial isolation, which is required to glean key phenotypic information through single-cell transcriptomics and other emerging approaches. Strategies for selective microglial depletion and modulation can provide novel insights into microglia-targeted treatment strategies in models of neuropsychiatric and neurodegenerative conditions, cancer, and autoimmunity. Finally, fate mapping has emerged as an important tool to answer fundamental questions about microglial biology, including their origin, migration, and proliferation throughout the lifetime of an organism. This review aims to provide a comprehensive discussion of these established and emerging techniques, with applications to the study of microglia in development, homeostasis, and CNS pathologies.

Repurposing of pexidartinib for microglia depletion and renewal

Pexidartinib (PLX3397) is a small molecule receptor tyrosine kinase inhibitor of colony stimulating factor 1 receptor (CSF1R) with moderate selectivity over other members of the platelet derived growth factor receptor family. It is approved for treatment of tenosynovial giant cell tumors (TGCT). CSF1R is highly expressed by microglia, which are macrophages of the central nervous system (CNS) that defend the CNS against injury and pathogens and contribute to synapse development and plasticity. Challenged by pathogens, apoptotic cells, debris, or inflammatory molecules they adopt a responsive state to propagate the inflammation and eventually return to a homeostatic state. The phenotypic switch may fail, and disease-associated microglia contribute to the pathophysiology in neurodegenerative or neuropsychiatric diseases or long-lasting detrimental brain inflammation after brain, spinal cord or nerve injury or ischemia/hemorrhage. Microglia also contribute to the growth permissive tumor microenvironment of glioblastoma (GBM). In rodents, continuous treatment for 1-2 weeks via pexidartinib food pellets leads to a depletion of microglia and subsequent repopulation from the remaining fraction, which is aided by peripheral monocytes that search empty niches for engraftment. The putative therapeutic benefit of such microglia depletion or forced renewal has been assessed in almost any rodent model of CNS disease or injury or GBM with heterogeneous outcomes, but a tendency of partial beneficial effects. So far, microglia monitoring e.g. via positron emission imaging is not standard of care for patients receiving Pexidartinib (e.g. for TGCT), so that the depletion and repopulation efficiency in humans is still largely unknown. Considering the virtuous functions of microglia, continuous depletion is likely no therapeutic option but short-lasting transient partial depletion to stimulate microglia renewal or replace microglia in genetic disease in combination with e.g. stem cell transplantation or as part of a multimodal concept in treatment of glioblastoma appears feasible. The present review provides an overview of the preclinical evidence pro and contra microglia depletion as a therapeutic approach.

Acacetin inhibits activation of microglia to improve neuroinflammation after subarachnoid hemorrhage through the PERK signaling pathway mediated autophagy

PURPOSE

To explore the effect of acacetin on subarachnoid hemorrhage (SAH) and its possible mechanism.

METHODS

SAH model of rat was established, and intraperitoneally injected with three doses of acacetin. To verify the role of PERK pathway, we used the CCT020312 (PERK inhibitor) and Tunicamycin (activators of endoplasmic reticulum stress). The SAH score, neurological function score, brain edema content, and Evans blue (EB) exudate were evaluated. Western blot was used to determine the expression of inflammation-associated proteins and PERK pathway. The activation of microglia was also determined through Iba-1 detection. TEM and immunofluorescence staining of LC3B were performed to observe the autophagy degree of SAH rats after acacetin. Tunel/NeuN staining, HE and Nissl' staining were performed for neuronal damage.

RESULTS

Acacetin increased the neurological function score, reduce brain water content, Evans blue exudation and SAH scores. The microglia in cerebral cortex were activated after SAH, while acacetin could inhibit its activation, and decreased the expression of TNF-α and IL-6 proteins. The pathological staining showed the severe neuronal damage and increased neuronal apoptosis after SAH, while acacetin could improve these pathological changes. We also visualized the alleviated autophagy after acacetin. The expression of Beclin1 and ATF4 proteins were increased, but acacetin could inhibit them. Acacetin also inactivated PERK pathway, which could improve the neuronal injury and neuroinflammation after SAH, inhibit the microglia activation and the overactivated autophagy through PERK pathway.

CONCLUSION

Acacetin may alleviate neuroinflammation and neuronal damage through PERK pathway, thus having the protective effect on EBI after SAH.

Clinical Potential of Immunotherapies in Subarachnoid Hemorrhage Treatment: Mechanistic Dissection of Innate and Adaptive Immune Responses

Subarachnoid hemorrhage (SAH), classified as a medical emergency, is a devastating and severe subtype of stroke. SAH induces an immune response, which further triggers brain injury; however, the underlying mechanisms need to be further elucidated. The current research is predominantly focused on the production of specific subtypes of immune cells, especially innate immune cells, post-SAH onset. Increasing evidence suggests the critical role of immune responses in SAH pathophysiology; however, studies on the role and clinical significance of adaptive immunity post-SAH are limited. In this present study, we briefly review the mechanistic dissection of innate and adaptive immune responses post-SAH. Additionally, we summarized the experimental studies and clinical trials of immunotherapies for SAH treatment, which may form the basis for the development of improved therapeutic approaches for the clinical management of SAH in the future.

Resolution of Cerebral Inflammation Following Subarachnoid Hemorrhage

BACKGROUND

Aneurismal subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke that, despite improvement through therapeutic interventions, remains a devastating cerebrovascular disorder that has a high mortality rate and causes long-term disability. Cerebral inflammation after SAH is promoted through microglial accumulation and phagocytosis. Furthermore, proinflammatory cytokine release and neuronal cell death play key roles in the development of brain injury. The termination of these inflammation processes and restoration of tissue homeostasis are of utmost importance regarding the possible chronicity of cerebral inflammation and the improvement of the clinical outcome for affected patients post SAH. Thus, we evaluated the inflammatory resolution phase post SAH and considered indications for potential tertiary brain damage in cases of incomplete resolution.

METHODS

Subarachnoid hemorrhage was induced through endovascular filament perforation in mice. Animals were killed 1, 7 and 14 days and 1, 2 and 3 months after SAH. Brain cryosections were immunolabeled for ionized calcium-binding adaptor molecule-1 to detect microglia/macrophages. Neuronal nuclei and terminal deoxyuridine triphosphate-nick end labeling staining was used to visualize secondary cell death of neurons. The gene expression of various proinflammatory mediators in brain samples was analyzed by quantitative polymerase chain reaction.

RESULTS

We observed restored tissue homeostasis due to decreased microglial/macrophage accumulation and neuronal cell death 1 month after insult. However, the messenger RNA expression levels of  interleukin 6  and  tumor necrosis factor α were still elevated at 1 and 2 months post SAH, respectively. The gene expression of interleukin 1β reached its maximum on day 1, whereas at later time points, no significant differences between the groups were detected.

CONCLUSIONS

By the herein presented molecular and histological data we provide an important indication for an incomplete resolution of inflammation within the brain parenchyma after SAH. Inflammatory resolution and the return to tissue homeostasis represent an important contribution to the disease's pathology influencing the impact on brain damage and outcome after SAH. Therefore, we consider a novel complementary or even superior therapeutic approach that should be carefully rethought in the management of cerebral inflammation after SAH. An acceleration of the resolution phase at the cellular and molecular levels could be a potential aim in this context.

Is It Time for a Paradigm Shift in the Treatment of Schizophrenia? The Use of Inflammation-Reducing and Neuroprotective Drugs-A Review

Comprehending the pathogenesis of schizophrenia represents a challenge for global mental health. To date, although it is evident that alterations in dopaminergic, serotonergic, and glutamatergic neurotransmission underlie the clinical expressiveness of the disease, neuronal disconnections represent only an epiphenomenon. In recent years, several clinical studies have converged on the hypothesis of microglia hyperactivation and a consequent neuroinflammatory state as a pathogenic substrate of schizophrenia. Prenatal, perinatal, and postnatal factors can cause microglia to switch from M2 anti-inflammatory to M1 pro-inflammatory states. A continuous mild neuroinflammatory state progressively leads to neuronal loss, a reduction in dendritic spines, and myelin degeneration. The augmentation of drugs that reduce neuroinflammation to antipsychotics could be an effective therapeutic modality in managing schizophrenia. This review will consider studies in which drugs with anti-inflammatory and neuroprotective properties have been used in addition to antipsychotic treatment in patients with schizophrenia.

The protective effect of low-dose minocycline on brain microvascular ultrastructure in a rodent model of subarachnoid hemorrhage

The multifaceted nature of subarachnoid hemorrhage (SAH) pathogenesis is poorly understood. To date, no pharmacological agent has been found to be efficacious for the prevention of brain injury when used for acute SAH intervention. This study was undertaken to evaluate the beneficial effects of low-dose neuroprotective agent minocycline on brain microvascular ultrastructures that have not been studied in detail. We studied SAH brain injury using an in vivo prechiasmatic subarachnoid hemorrhage rodent model. We analyzed the qualitative and quantitative ultrastructural morphology of capillaries and surrounding neuropil in the rodent brains with SAH and/or minocycline administration. Here, we report that low-dose minocycline (1 mg/kg) displayed protective effects on capillaries and surrounding cells from significant SAH-induced changes. Ultrastructural morphology analysis revealed also that minocycline stopped endothelial cells from abnormal production of vacuoles and vesicles that compromise blood-brain barrier (BBB) transcellular transport. The reported ultrastructural abnormalities as well as neuroprotective effects of minocycline during SAH were not directly mediated by inhibition of MMP-2, MMP-9, or EMMPRIN. However, SAH brain tissue treated with minocycline was protected from development of other morphological features associated with oxidative stress and the presence of immune cells in the perivascular space. These data advance the knowledge on the effect of SAH on brain tissue ultrastructure in an SAH rodent model and the neuroprotective effect of minocycline when administered in low doses.