Rise and fall of minocycline in neuroprotection: need to promote publication of negative results

Caspases: structural and molecular mechanisms and functions in cell death, innate immunity, and disease

Caspases are critical regulators of cell death, development, innate immunity, host defense, and disease. Upon detection of pathogens, damage-associated molecular patterns, cytokines, or other homeostatic disruptions, innate immune sensors, such as NLRs, activate caspases to initiate distinct regulated cell death pathways, including non-lytic (apoptosis) and innate immune lytic (pyroptosis and PANoptosis) pathways. These cell death pathways are driven by specific caspases and distinguished by their unique molecular mechanisms, supramolecular complexes, and enzymatic properties. Traditionally, caspases are classified as either apoptotic (caspase-2, -3, -6, -7, -8, -9, and -10) or inflammatory (caspase-1, -4, -5, and -11). However, extensive data from the past decades have shown that apoptotic caspases can also drive lytic inflammatory cell death downstream of innate immune sensing and inflammatory responses, such as in the case of caspase-3, -6, -7, and -8. Therefore, more inclusive classification systems based on function, substrate specificity, or the presence of pro-domains have been proposed to better reflect the multifaceted roles of caspases. In this review, we categorize caspases into CARD-, DED-, and short/no pro-domain-containing groups and examine their critical functions in innate immunity and cell death, along with their structural and molecular mechanisms, including active site/exosite properties and substrates. Additionally, we highlight the emerging roles of caspases in cellular homeostasis and therapeutic targeting. Given the clinical relevance of caspases across multiple diseases, improved understanding of these proteins and their structure-function relationships is critical for developing effective treatment strategies.

A Comprehensive Insight into Apoptosis: Molecular Mechanisms, Signaling Pathways, and Modulating Therapeutics

Apoptosis, or programmed cell death, is a fundamental biological process essential for maintaining tissue homeostasis. Dysregulation of apoptosis is implicated in a variety of diseases, including cancer, neurodegenerative disorders, and autoimmune conditions. This review provides an in-depth insight into the molecular mechanisms and signaling pathways that regulate apoptosis, highlighting both intrinsic and extrinsic pathways. Additionally, the review explains the tumor microenvironment's influence on apoptosis and its implications for cancer therapy resistance. Understanding the complex interplay between apoptotic signaling and cellular responses is crucial for developing targeted therapies that can effectively manage diseases associated with apoptosis dysregulation. The effects of conventional therapeutics and alternative substances with natural sources such as herbal compounds, alongside vitamins, minerals, and trace elements on cellular homeostasis and disease pathogenesis have been thoroughly investigated. Moreover, recent advances in therapeutic strategies aimed at modulating apoptosis are discussed, with a focus on novel interventions such as nutrition bio shield dietary supplement. These emerging approaches offer potential benefits beyond conventional treatments by selectively targeting apoptotic pathways to inhibit cancer progression and metastasis. By integrating insights from recent studies, this review aims to enhance our understanding of apoptosis and guide future research in developing innovative therapeutic approaches.

Discovery of novel protective agents for infection-related delirium through bispectral electroencephalography

Delirium is a multifactorial medical condition of waxing and waning impairment across various domains of mental functioning over time. Importantly, delirium is also one of the greatest risk factors for prolonged hospitalization, morbidity, and mortality. Studying this important condition is challenging due to the difficulty in both objective diagnosis in patients and validation of laboratory models. As a result, there is a lack of protective treatments for delirium. Our recent studies report the efficacy of bispectral electroencephalography (BSEEG) in diagnosing delirium in patients and predicting patient outcomes, advancing the concept that this simple measure could represent an additional vital sign for patients. Here, we applied BSEEG to characterize and validate a novel lipopolysaccharide (LPS) mouse model of infection-related delirium. We then applied this model to evaluate the protective efficacy of three putative therapeutic agents: the conventional antipsychotic medication haloperidol, the neuroprotective compound P7C3-A20, and the antibiotic minocycline. Aged mice were more susceptible than young mice to LPS-induced aberration in BSEEG, reminiscent of the greater vulnerability of older adults to delirium. In both young and old mice, P7C3-A20 and minocycline administration prevented LPS-induced BSEEG abnormality. By contrast, haloperidol did not. P7C3-A20 and minocycline have been shown to limit different aspects of LPS toxicity, and our data offers proof of principle that these agents might help protect patients from developing infection-related delirium. Thus, utilization of BSEEG in a mouse model for infection-related delirium can identify putative therapeutic agents for applications in patient clinical trials.

Phytocompound identification of aqueous Zingiber officinale rhizome (ZOME) extract reveals antiproliferative and reactive oxygen species mediated apoptotic induction within cervical cancer cells: an in vitro and in silico approach

The prevalence of cervical cancer in women is in the fourth position among various other types of cancer globally. Many established therapies, including surgery, chemotherapy, and immunomodulation, are present, but high levels of side effects cause mortality and morbidity among the patients. Zingiber officinale rhizome (ZOME) has been potentially used to cure a variety of ailments and diseases. The aqueous ZOME extract also contains ample phytochemical constituents having anticancer effects on different cancers. The cell viability of HeLa cells was evaluated using MTT assay with IC50 at 97 µg/mL. Furthermore, a significant level of ROS generation causes the apoptosis of the cells. Nuclear staining dye DAPI and Hoechst 33342 showed DNA's fragmented and condensed form. Propidium Iodide staining showed necrotic or late-apoptotic cells. While acidic organelle dye LysoTracker and MitoTracker dye along with dual staining showed significant results. In silico studies were carried out using identified phytochemicals from GC-MS analysis with pharmacokinetics properties (ADMET), and targeted toward receptor proteins for molecular docking. Ligands with high docked scores were subjected to molecular dynamics simulations at 310 K for 100 ns. In vitro and in silico investigations in our studies showed that aqueous ZOME extract can be used as an efficient therapy against cervical cancer treatment as it showed significant cytotoxic and antiproliferative effects toward the HeLa cell line.Communicated by Ramaswamy H. Sarma.

Post-weaning social isolation alters sociability in a sex-specific manner

Adolescence is a critical period for brain development in humans and stress exposure during this time can have lasting effects on behavior and brain development. Social isolation and loneliness are particularly salient stressors that lead to detrimental mental health outcomes particularly in females, although most of the preclinical work on social isolation has been done in male animals. Our lab has developed a model of post-weaning adolescent social isolation that leads to increased drug reward sensitivity and altered neuronal structure in limbic brain regions. The current study utilized this model to determine the impact of adolescent social isolation on a three-chamber social interaction task both during adolescence and adulthood. We found that while post-weaning isolation does not alter social interaction during adolescence (PND45), it has sex-specific effects on social interaction in young adulthood (PND60), potentiating social interaction in male mice and decreasing it in female mice. As early life stress can activate microglia leading to alterations in neuronal pruning, we next examined the impact of inhibiting microglial activation with daily minocycline administration during the first 3 weeks of social isolation on these changes in social interaction. During adolescence, minocycline dampened social interaction in male mice, while having no effect in females. In contrast, during young adulthood, minocycline did not alter the impact of adolescent social isolation in males, with socially isolated males exhibiting higher levels of social interaction compared to their group housed counterparts. In females, adolescent minocycline treatment reversed the effect of social isolation leading to increased social interaction in the social isolation group, mimicking what is seen in naïve males. Taken together, adolescent social isolation leads to sex-specific effects on social interaction in young adulthood and adolescent minocycline treatment alters the effects of social isolation in females, but not males.

Post-weaning social isolation alters sociability in a sex-specific manner

Adolescence is a critical period for brain development in humans and stress exposure during this time can have lasting effects on behavior and brain development. Social isolation and loneliness are particularly salient stressors that lead to detrimental mental health outcomes particularly in females, although most of the preclinical work on social isolation has been done in male animals. Our lab has developed a model of post-weaning adolescent social isolation that leads to increased drug reward sensitivity and altered neuronal structure in limbic brain regions. The current study utilized this model to determine the impact of adolescent social isolation on a three-chamber social interaction task both during adolescence and adulthood. We found that while post-weaning isolation does not alter social interaction during adolescence (PND45), it has sex-specific effects on social interaction in adulthood (PND60), potentiating social interaction in male mice and decreasing it in female mice. As early life stress can activate microglia leading to alterations in neuronal pruning, we next examined the impact of inhibiting microglial activation with daily minocycline administration during the first three weeks of social isolation on these changes in social interaction. During adolescence, minocycline dampened social interaction in male mice, while having no effect in females. In contrast, during adulthood, minocycline did not alter the impact of adolescent social isolation in males, with socially isolated males exhibiting higher levels of social interaction compared to their group housed counterparts. In females, adolescent minocycline treatment reversed the effect of social isolation leading to increased social interaction in the social isolation group, mimicking what is seen in naïve males. Taken together, adolescent social isolation leads to sex-specific effects on social interaction in adulthood and adolescent minocycline treatment alters the effects of social isolation in females, but not males.

Direct Interaction of Minocycline to p47phox Contributes to its Attenuation of TNF-α-Mediated Neuronal PC12 Cell Death: Experimental and Simulation Validation

Minocycline, a repurposed approved medication, shows promise in treating neurodegeneration. However, the specific pathways targeted by minocycline remain unclear despite the identification of molecular targets. This study explores minocycline's potential protective effects against TNF-α-mediated neuronal death in PC12 cells, with a focus on unraveling its interactions with key molecular targets. The study begins by exploring minocycline's protective role against TNF-α-mediated neuronal death in PC12 cells, showcasing a substantial reduction in cleaved caspase-3 expression, DNA fragmentation, and intracellular ROS levels following minocycline pretreatment. Subsequently, a comprehensive analysis utilizing pull-down assays, computational docking, mutation analysis, molecular dynamics simulations, and free energy calculations is conducted to elucidate the direct interaction between minocycline and p47phox-the organizer subunit of NADPH oxidase-2 (NOX2) complex. Computational insights, including a literature survey and analysis of key amino acid residues, reveal a potential binding site for minocycline around Trp193 and Cys196. In silico substitutions of Trp193 and Cys196 further confirm their importance in binding with minocycline. These integrated findings underscore minocycline's protective mechanisms, linking its direct interaction with p47phox to the modulation of NOX2 activity and attenuation of NOX-derived ROS generation. Minocycline demonstrates protective effects against TNF-α-induced PC12 cell death, potentially linked to its direct interaction with p47phox. This interaction leads to a reduction in NOX2 complex assembly, ultimately attenuating NOX-derived ROS generation. These findings hold significance for researchers exploring neuroprotection and the development of p47phox inhibitors.

Intrathecal minocycline does not block the adverse effects of repeated, intravenous morphine administration on recovery of function after SCI

Opioids are among the most effective analgesics for the management of pain in the acute phase of a spinal cord injury (SCI), and approximately 80% of patients are treated with morphine in the first 24 h following SCI. We have found that morphine treatment in the first 7 days after SCI increases symptoms of pain at 42 days post-injury and undermines the recovery of locomotor function in a rodent model. Prior research has implicated microglia/macrophages in opioid-induced hyperalgesia and the development of neuropathic pain. We hypothesized that glial activation may also underlie the development of morphine-induced pain and cell death after SCI. Supporting this hypothesis, our previous studies found that intrathecal and intravenous morphine increase the number of activated microglia and macrophages present at the spinal lesion site, and that the adverse effects of intrathecal morphine can be blocked with intrathecal minocycline. Recognizing that the cellular expression of opioid receptors, and the intracellular signaling pathways engaged, can change with repeated administration of opioids, the current study tested whether minocycline was also protective with repeated intravenous morphine administration, more closely simulating clinical treatment. Using a rat model of SCI, we co-administered intravenous morphine and intrathecal minocycline for the first 7 days post injury and monitored sensory and locomotor recovery. Contrary to our hypothesis and previous findings with intrathecal morphine, we found that minocycline did not prevent the negative effects of morphine. Surprisingly, we also found that intrathecal minocycline alone is detrimental for locomotor recovery after SCI. Using ex vivo cell cultures, we investigated how minocycline and morphine altered microglia/macrophage function. Commensurate with published studies, we found that minocycline blocked the effects of morphine on the release of pro-inflammatory cytokines but, like morphine, it increased glial phagocytosis. While phagocytosis is critical for the removal of cellular and extracellular debris at the spinal injury site, increased phagocytosis after injury has been linked to the clearance of stressed but viable neurons and protracted inflammation. In sum, our data suggest that both morphine and minocycline alter the acute immune response, and reduce locomotor recovery after SCI.

A long way to go: caspase inhibitors in clinical use

Caspases are an evolutionary conserved family of cysteine-dependent proteases that are involved in many vital cellular processes including apoptosis, proliferation, differentiation and inflammatory response. Dysregulation of caspase-mediated apoptosis and inflammation has been linked to the pathogenesis of various diseases such as inflammatory diseases, neurological disorders, metabolic diseases, and cancer. Multiple caspase inhibitors have been designed and synthesized as a potential therapeutic tool for the treatment of cell death-related pathologies. However, only a few have progressed to clinical trials because of the consistent challenges faced amongst the different types of caspase inhibitors used for the treatment of the various pathologies, namely an inadequate efficacy, poor target specificity, or adverse side effects. Importantly, a large proportion of this failure lies in the lack of understanding various caspase functions. To overcome the current challenges, further studies on understanding caspase function in a disease model is a fundamental requirement to effectively develop their inhibitors as a treatment for the different pathologies. Therefore, the present review focuses on the descriptive properties and characteristics of caspase inhibitors known to date, and their therapeutic application in animal and clinical studies. In addition, a brief discussion on the achievements, and current challenges faced, are presented in support to providing more perspectives for further development of successful therapeutic caspase inhibitors for various diseases.

Small heterodimer partner (SHP) aggravates ER stress in Parkinson's disease-linked LRRK2 mutant astrocyte by regulating XBP1 SUMOylation

Background

Endoplasmic reticulum (ER) stress is a common feature of Parkinson’s disease (PD), and several PD-related genes are responsible for ER dysfunction. Recent studies suggested LRRK2-G2019S, a pathogenic mutation in the PD-associated gene LRRK2, cause ER dysfunction, and could thereby contribute to the development of PD. It remains unclear, however, how mutant LRRK2 influence ER stress to control cellular outcome. In this study, we identified the mechanism by which LRRK2-G2019S accelerates ER stress and cell death in astrocytes.

Methods

To investigate changes in ER stress response genes, we treated LRRK2-wild type and LRRK2-G2019S astrocytes with tunicamycin, an ER stress-inducing agent, and performed gene expression profiling with microarrays. The XBP1 SUMOylation and PIAS1 ubiquitination were performed using immunoprecipitation assay. The effect of astrocyte to neuronal survival were assessed by astrocytes-neuron coculture and slice culture systems. To provide in vivo proof-of-concept of our approach, we measured ER stress response in mouse brain.

Results

Microarray gene expression profiling revealed that LRRK2-G2019S decreased signaling through XBP1, a key transcription factor of the ER stress response, while increasing the apoptotic ER stress response typified by PERK signaling. In LRRK2-G2019S astrocytes, the transcriptional activity of XBP1 was decreased by PIAS1-mediated SUMOylation. Intriguingly, LRRK2-GS stabilized PIAS1 by increasing the level of small heterodimer partner (SHP), a negative regulator of PIAS1 degradation, thereby promoting XBP1 SUMOylation. When SHP was depleted, XBP1 SUMOylation and cell death were reduced. In addition, we identified agents that can disrupt SHP-mediated XBP1 SUMOylation and may therefore have therapeutic activity in PD caused by the LRRK2-G2019S mutation.

Conclusion

Our findings reveal a novel regulatory mechanism involving XBP1 in LRRK2-G2019S mutant astrocytes, and highlight the importance of the SHP/PIAS1/XBP1 axis in PD models. These findings provide important insight into the basis of the correlation between mutant LRRK2 and pathophysiological ER stress in PD, and suggest a plausible model that explains this connection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00747-1.

Minocycline differentially modulates human spatial memory systems

Microglia play a critical role in many processes fundamental to learning and memory in health and are implicated in Alzheimer's pathogenesis. Minocycline, a centrally-penetrant tetracycline antibiotic, inhibits microglial activation and enhances long-term potentiation, synaptic plasticity, neurogenesis and hippocampal-dependent spatial memory in rodents, leading to clinical trials in human neurodegenerative diseases. However, the effects of minocycline on human memory have not previously been investigated. Utilising a double-blind, randomised crossover study design, we recruited 20 healthy male participants (mean 24.6 ± 5.0 years) who were each tested in two experimental sessions: once after 3 days of Minocycline 150 mg (twice daily), and once 3 days of placebo (identical administration). During each session, all completed an fMRI task designed to tap boundary- and landmark-based navigation (thought to rely on hippocampal and striatal learning mechanisms respectively). Given the rodent literature, we hypothesised that minocycline would selectively modulate hippocampal learning. In line with this, minocycline biased use of boundary- compared to landmark-based information (t980 = 3.140, p = 0.002). However, though this marginally improved performance for boundary-based objects (t980 = 1.972, p = 0.049), it was outweighed by impaired landmark-based navigation (t980 = 6.374, p < 0.001) resulting in an overall performance decrease (t980 = 3.295, p = 0.001). Furthermore, against expectations, minocycline significantly reduced activity during memory encoding in the right caudate (t977 = 2.992, p = 0.003) and five other cortical regions, with no significant effect in the hippocampus. In summary, minocycline impaired human spatial memory performance, likely through disruption of striatal processing resulting in greater biasing towards reliance on boundary-based navigation.

Current Management and Emerging Therapies in Multiple System Atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disease variably associated with motor, nonmotor, and autonomic symptoms, resulting from putaminal and cerebellar degeneration and associated with glial cytoplasmic inclusions enriched with α-synuclein in oligodendrocytes and neurons. Although symptomatic treatment of MSA can provide significant improvements in quality of life, the benefit is often partial, limited by adverse effects, and fails to treat the underlying cause. Consistent with the multisystem nature of the disease and evidence that motor symptoms, autonomic failure, and depression drive patient assessments of quality of life, treatment is best achieved through a coordinated multidisciplinary approach driven by the patient's priorities and goals of care. Research into disease-modifying therapies is ongoing with a particular focus on synuclein-targeted therapies among others. This review focuses on both current management and emerging therapies for this devastating disease.

Minocycline in Treating Glioblastoma Multiforme: Far beyond a Conventional Antibiotic

One of the most lethal forms of CNS pathologies is glioblastoma multiforme (GBM) that represents high invasiveness, uncontrolled proliferation, and angiogenic features. Its invasiveness is responsible for the high recurrence even after maximal surgical interventions. Minocycline is a semisynthetic analog of tetracyclines with potential anti-inflammatory and anticancer effects, distinct from its antimicrobial activity. In this review, we highlight the importance and the cytotoxic mechanisms of minocycline on GBM pathophysiology. Considering the role of certain enzymes in autophagy, apoptosis, tumor cell invasion, and metastatic ability, the possible use of tetracyclines for cancer therapy should be investigated, especially GBM. The present study is, therefore, going to cover the main topics in minocycline pharmacology to date, encouraging its consideration as a new treatment approach for cancer and GBM.

Identification of distinct pathological signatures induced by patient-derived α-synuclein structures in nonhuman primates

Dopaminergic neuronal cell death, associated with intracellular α-synuclein (α-syn)-rich protein aggregates [termed "Lewy bodies" (LBs)], is a well-established characteristic of Parkinson's disease (PD). Much evidence, accumulated from multiple experimental models, has suggested that α-syn plays a role in PD pathogenesis, not only as a trigger of pathology but also as a mediator of disease progression through pathological spreading. Here, we have used a machine learning-based approach to identify unique signatures of neurodegeneration in monkeys induced by distinct α-syn pathogenic structures derived from patients with PD. Unexpectedly, our results show that, in nonhuman primates, a small amount of singular α-syn aggregates is as toxic as larger amyloid fibrils present in the LBs, thus reinforcing the need for preclinical research in this species. Furthermore, our results provide evidence supporting the true multifactorial nature of PD, as multiple causes can induce a similar outcome regarding dopaminergic neurodegeneration.

Post-Ischaemic Immunological Response in the Brain: Targeting Microglia in Ischaemic Stroke Therapy

Microglia, the major endogenous immune cells of the central nervous system, mediate critical degenerative and regenerative responses in ischaemic stroke. Microglia become "activated", proliferating, and undergoing changes in morphology, gene and protein expression over days and weeks post-ischaemia, with deleterious and beneficial effects. Pro-inflammatory microglia (commonly referred to as M1) exacerbate secondary neuronal injury through the release of reactive oxygen species, cytokines and proteases. In contrast, microglia may facilitate neuronal recovery via tissue and vascular remodelling, through the secretion of anti-inflammatory cytokines and growth factors (a profile often termed M2). This M1/M2 nomenclature does not fully account for the microglial heterogeneity in the ischaemic brain, with some simultaneous expression of both M1 and M2 markers at the single-cell level. Understanding and regulating microglial activation status, reducing detrimental and promoting repair behaviours, present the potential for therapeutic intervention, and open a longer window of opportunity than offered by acute neuroprotective strategies. Pharmacological modulation of microglial activation status to promote anti-inflammatory gene expression can increase neurogenesis and improve functional recovery post-stroke, based on promising preclinical data. Cell-based therapies, using preconditioned microglia, are of interest as a method of therapeutic modulation of the post-ischaemic inflammatory response. Currently, there are no clinically-approved pharmacological options targeting post-ischaemic inflammation. A major developmental challenge for clinical translation will be the selective suppression of the deleterious effects of microglial activity after stroke whilst retaining (or enhancing) the neurovascular repair and remodelling responses of microglia.

Its complicated: The relationship between alcohol and microglia in the search for novel pharmacotherapeutic targets for alcohol use disorders

Alcohol use disorder (AUD) is a chronic relapsing disorder with wide-ranging health consequences. Alcohol targets the central nervous system producing neurodegeneration and subsequent cognitive and behavioral deficits, but the mechanisms behind these effects remain unclear. Recently, evidence has been mounting for the role of neuroimmune activation in the pathogenesis of AUDs, but our nascent state of knowledge about the interaction of alcohol with the neuroimmune system supports that the relationship is complicated. As the resident macrophage of the central nervous system, microglia are a central focus. Human and animal research on the interplay between microglia and alcohol in AUDs has proven to be complex, and though early research focused on a pro-inflammatory phenotype of microglia, the anti-inflammatory and homeostatic roles of microglia must be considered. How these new roles for microglia should be incorporated into our thinking about the neuroimmune system in AUDs is discussed in the context of developing novel pharmacotherapies for AUDs.

Glatiramer Acetate Reverses Motor Dysfunction and the Decrease in Tyrosine Hydroxylase Levels in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease and there are no effective treatments that either slow or reverse the degeneration of the dopamine (DA) pathway. Using a 4-week progressive MPTP (1-methyl-1,2,3,6-tetrahydropyridine) neurotoxin model of PD, which is characterized by neuroinflammation, loss of nigrostriatal DA, and motor dysfunction, as seen in patients with PD, we tested whether post-MPTP treatment with glatiramer acetate (GA), an immunomodulatory drug, could reverse these changes. GA restored the grip dysfunction and gait abnormalities that were evident in the MPTP treated group. The reversal of the motor dysfunction was attributable to the substantial recovery in tyrosine hydroxylase (TH) protein expression in the striatum. Within the substantia nigra pars compacta, surface cell count analysis showed a slight increase in TH+ cells following GA treatment in the MPTP group, which was not statistically different from the vehicle (VEH) group. This was associated with the recovery of BDNF (brain derived neurotrophic factor) protein levels and a reduction in the microglial marker, IBA1, protein expression within the midbrain. Alpha synuclein (syn-1) levels within the midbrain and striatum were decreased following MPTP, while GA facilitated recovery to VEH levels in the striatum in the MPTP group. Although DA tissue analysis revealed no significant increase in striatal DA or 3,4-Dihydroxyphenylacetic acid levels (DOPAC) in the MPTP group treated with GA, DA turnover (DOPAC/DA) recovered back to VEH levels following GA treatment. GA treatment effectively reversed clinical (motor dysfunction) and pathology (TH, IBA1, BDNF expression) of PD in a murine model.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

An Evaluation of Publication Bias in High-Impact Orthopaedic Literature

Background:

Statistical analysis of systematic reviews allows the results of previous studies to be combined and synthesized to assess the overall health effect of the intervention in question. Systematic reviews can also be used to guide the creation of clinical practice guidelines and are considered to have a high level of evidence. Thus, it is important that their methodological quality is of the highest standard. Publication bias presents 2 problems: (1) studies with significant results may be overrepresented in systematic reviews and meta-analyses (“false positives”) and (2) studies without significant results may not be included in systematic reviews and meta-analyses (“false negatives”) because each study, on its own, was underpowered, meaning that some treatment options that may have clinical benefit will not be adopted.

Methods:

We performed a study to evaluate the techniques used by authors to report and evaluate publication bias in the top 10 orthopaedic journals as well as 3 orthopaedic-related Cochrane groups. Two authors independently screened the titles and abstracts to identify systematic reviews and meta-analyses. We assessed publication bias in the systematic reviews that did not assess publication bias themselves.

Results:

Our final sample included 694 systematic reviews or meta-analyses that met our inclusion criteria. Our review included 502 studies (72%) that focused on clinical outcomes, with the majority of the remaining studies focused on predictive and prognostic accuracy (20%) or diagnostic accuracy (5%). Publication bias was discussed in 295 (42.5%) of the included studies and was assessed in 135 (19.5%). Of the studies that assessed publication bias, 31.9% demonstrated evidence of publication bias. Only 43% and 22% of studies that involved use of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines discussed and assessed publication bias, respectively.

Conclusions:

Publication bias is infrequently discussed and assessed in the high-impact orthopaedic literature. Furthermore, nearly one-third of the studies that assessed for publication bias demonstrated evidence of publication bias. In addition to these shortcomings, fewer than half of these studies involved use of the PRISMA guidelines and yet only one-fourth of the studies assessed for publication bias.

Clinical Relevance:

By understanding the degree to which publication bias is discussed and presented in high-impact orthopaedic literature, changes can be made by journals and researchers alike to improve the overall quality of research produced and reported.

Cell-based high-throughput screen for small molecule inhibitors of Bax translocation

Aberrant regulation of programmed cell death (PCD) has been tied to an array of human pathologies ranging from cancers to autoimmune disorders to diverse forms of neurodegeneration. Pharmacologic modulation of PCD signalling is therefore of central interest to a number of clinical and biomedical applications. A key component of PCD signalling involves the modulation of pro‐ and anti‐apoptotic Bcl‐2 family members. Among these, Bax translocation represents a critical regulatory phase in PCD. In the present study, we have employed a high‐content high‐throughput screen to identify small molecules which inhibit the cellular process of Bax re‐distribution to the mitochondria following commitment of the cell to die. Screening of 6246 Generally Recognized As Safe compounds from four chemical libraries post‐induction of cisplatin‐mediated PCD resulted in the identification of 18 compounds which significantly reduced levels of Bax translocation. Further examination revealed protective effects via reduction of executioner caspase activity and enhanced mitochondrial function. Consistent with their effects on Bax translocation, these compounds exhibited significant rescue against in vitro and in vivo cisplatin‐induced apoptosis. Altogether, our findings identify a new set of clinically useful small molecules PCD inhibitors and highlight the role which cAMP plays in regulating Bax‐mediated PCD.

Neuroinflammation in Synucleinopathies

The causes of most neurodegenerative diseases are attributed to multiple genetic and environmental factors interacting with one another. Above all, inflammation in the nervous system has been implicated in many neurodegenerative diseases. Still, the roles of neuroinflammation in disease mechanisms and the triggers of inflammatory responses in disease-inflicted brain tissues seem to remain unclear. This review will examine previous studies that had been done from genetic, pathological and epidemiological perspectives. These studies assess the involvement of neuroinflammation in synucleinopathies, a group of neurodegenerative diseases that are characterized by deposition of α-synuclein aggregates such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. The review will also discuss the role of α-synuclein aggregates in triggering inflammatory responses from glial cells. It is expected that a precise assessment of the roles and mechanisms of neuroinflammation in neurodegenerative diseases will pave the way for the development of disease-modifying drugs.

Neuroprotective and Neuro-restorative Effects of Minocycline and Rasagiline in a Zebrafish 6-Hydroxydopamine Model of Parkinson's Disease

Parkinson's disease is a common, debilitating, neurodegenerative disorder for which the current gold standard treatment, levodopa (L-DOPA) is symptomatic. There is an urgent, unmet need for neuroprotective or, ideally, neuro-restorative drugs. We describe a 6-hydroxydopamine (6-OHDA) zebrafish model to screen drugs for neuroprotective and neuro-restorative capacity. Zebrafish larvae at two days post fertilization were exposed to 6-OHDA for three days, with co-administration of test drugs for neuroprotection experiments, or for 32 h, with subsequent treatment with test drugs for neuro-restoration experiments. Locomotor activity was assessed by automated tracking and dopaminergic neurons were visualized by tyrosine hydroxylase immuno-histochemistry. Exposure to 6-OHDA for either 32 h or 3 days induced similar, significant locomotor deficits and neuronal loss in 5-day-old larvae. L-DOPA (1 mM) partially restored locomotor activity, but was neither neuroprotective nor neuro-restorative, mirroring the clinical situation. The calcium channel blocker, isradipine (1 µM) did not prevent or reverse 6-OHDA-induced locomotor deficit or neuronal loss. However, both the tetracycline analog, minocycline (10 µM), and the monoamine oxidase B inhibitor, rasagiline (1 µM), prevented the locomotor deficits and neuronal loss due to three-day 6-OHDA exposure. Importantly, they also reversed the locomotor deficit caused by prior exposure to 6-OHDA; rasagiline also reversed neuronal loss and minocycline partially restored neuronal loss due to prior 6-OHDA, making them candidates for investigation as neuro-restorative treatments for Parkinson's disease. Our findings in zebrafish reflect preliminary clinical findings for rasagiline and minocycline. Thus, we have developed a zebrafish model suitable for high-throughput screening of putative neuroprotective and neuro-restorative therapies for the treatment of Parkinson's disease.

Minocycline prevents cerebral malaria, confers neuroprotection and increases survivability of mice during Plasmodium berghei ANKA infection

Cerebral malaria (CM) is a neurological complication arising due to Plasmodium falciparum or Plasmodium vivax infection. Minocycline, a semi-synthetic tetracycline, has been earlier reported to have a neuroprotective role in several neurodegenerative diseases. In this study, we investigated the effect of minocycline treatment on the survivability of mice during experimental cerebral malaria (ECM). The currently accepted mouse model, C57BL/6 mice infected with Plasmodium berghei ANKA, was used for the study. Infected mice were treated with an intra-peritoneal dose of minocycline hydrochloride, 45mg/kg daily for ten days that led to parasite clearance in blood, brain, liver and spleen on 7th day post-infection; and the mice survived until experiment ended (90days) without parasite recrudescence. Evans blue extravasation assay showed that blood-brain barrier integrity was maintained by minocycline. The tumor necrosis factor-alpha protein level and caspase activity, which is related to CM pathogenesis, was significantly reduced in the minocycline-treated group. Fluoro-Jade® C and hematoxylin-eosin staining of the brains of minocycline group revealed a decrease in degenerating neurons and absence of hemorrhages respectively. Minocycline treatment led to decrease in gene expressions of inflammatory mediators like interferon-gamma, CXCL10, CCL5, CCL2; receptors CXCR3 and CCR2; and hence decrease in T-cell-mediated cerebral inflammation. We also proved that this reduction in gene expressions is irrespective of the anti-parasitic property of minocycline. The distinct ability of minocycline to modulate gene expressions of CXCL10 and CXCR3 makes it effective than doxycycline, a tetracycline used as chemoprophylaxis. Our study shows that minocycline is highly effective in conferring neuroprotection during ECM.

Minocycline as a Neuroprotective Agent

Several studies have shown that minocycline, a semisynthetic, second-generation tetracycline derivative, is neuroprotective in animal models of central nervous system trauma and several neurodegenerative diseases. Common to all these reports are the beneficial effects of minocycline in reducing neural inflammation and preventing cell death. Here, the authors review the proposed mechanisms of action of minocycline and suggest that minocycline may inhibit several aspects of the inflammatory response and prevent cell death through the inhibition of the p38 mitogen-activated protein kinase pathway, an important regulator of immune cell function and cell death.

Loss of collapsin response mediator protein 4 suppresses dopaminergic neuron death in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that is characterized by the selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNc). Several lines of evidence suggest that neurodegeneration in PD is accelerated by a vicious cycle in which apoptosis in dopaminergic neurons triggers the activation of microglia and harmful inflammatory processes that further amplify neuronal death. Recently, we demonstrated that the deletion of collapsin response mediator protein 4 (CRMP4) suppresses inflammatory responses and cell death in a mouse model of spinal cord injury, leading to improved functional recovery. We thus hypothesized that Crmp4-/- mice may have limited inflammatory responses and a decrease in the loss of SNc dopaminergic neurons in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. We observed CRMP4 expression in neurons, astrocytes, and microglia/macrophages following the injection of 25 mg/kg MPTP. We compared the number of dopaminergic neurons and the inflammatory response in SNc between Crmp4+/+ and Crmp4-/- mice after MPTP injection. Limited loss of SNc dopaminergic neurons and decreased activations of microglia and astrocytes were observed in Crmp4-/- mice. These results suggest that CRMP4 is a novel therapeutic target in the treatment of PD patients. We demonstrated that genetic CRMP4 deletion delays a vicious cycle of inflammation and neurodegeneration in a Parkinson's disease mouse model. MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) injection to wild-type mice induces collapsin response mediator protein 4 (CRMP4) up-regulation in neurons, astrocytes, and microglia. CRMP4-deficient mice show reduced inflammation and suppressed dopaminergic neuronal death after MPTP injection. These findings suggest that CRMP4 deletion may be a new therapeutic strategy against Parkinson's diseases.

Critical data-based re-evaluation of minocycline as a putative specific microglia inhibitor

Minocycline, a second generation broad-spectrum antibiotic, has been frequently postulated to be a "microglia inhibitor." A considerable number of publications have used minocycline as a tool and concluded, after achieving a pharmacological effect, that the effect must be due to "inhibition" of microglia. It is, however, unclear how this "inhibition" is achieved at the molecular and cellular levels. Here, we weigh the evidence whether minocycline is indeed a bona fide microglia inhibitor and discuss how data generated with minocycline should be interpreted. GLIA 2016;64:1788-1794.

Selected gene profiles of stressed NSC-34 cells and rat spinal cord following peripheral nerve reconstruction and minocycline treatment

The present study was conducted to investigate the effects of minocycline on the expression of selected transcriptional and translational profiles in the rat spinal cord following sciatic nerve (SNR) transection and microsurgical coaptation. The mRNA and protein expression levels of B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, major histocompatibility complex I (MHC I), tumor necrosis factor-α (TNF-α), activating transcription factor 3 (ATF3), vascular endothelial growth factor (VEGF), matrix metalloproteinase 9 (MMP9), and growth associated protein-43 (GAP-43) were monitored in the rat lumbar spinal cord following microsurgical reconstruction of the sciatic nerves and minocycline treatment. The present study used semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. As a PCR analysis of spinal cord tissue enabled the examination of the expression patterns of all cell types including glia, the motorneuron-like NSC-34 cell line was used to investigate expression level changes in motorneurons. As stressors, oxygen glucose deprivation (OGD) and lipopolysaccharide (LPS) treatment were performed. SNR did not induce significant degeneration of ventral horn motorneurons, whereas microglia activation and synaptic terminal retraction were detectable. All genes were constitutively expressed at the mRNA and protein levels in untreated spinal cord and control cells. SNR significantly increased the mRNA expression levels of all genes, albeit only temporarily. In all genes except MMP9 and GAP-43, the induction was seen ipsilaterally and contralaterally. The effects of minocycline were moderate. The expression levels of MMP9, TNF-α, MHC I, VEGF, and GAP-43 were reduced, whereas those of Bax and Bcl-2 were unaffected. OGD, but not LPS, was toxic for NSC-34 cells. No changes in the expression levels of Bax, caspase-3, MHC I or ATF3 were observed. These results indicated that motorneurons were not preferentially or solely responsible for SNR-mediated upregulation of these genes. MMP9, TNF-α, VEGF and Bcl-2 were stress-activated. These results suggest that a substantial participation of motorneurons in gene expression levels in vivo. Minocycline was also shown to have inhibitory effects. The nuclear factor-κB signalling pathway may be a possible target of minocycline.

Animal models of Huntington's disease for translation to the clinic: best practices

Mouse models of Huntington's disease (HD) recapitulate many aspects of the human disease. These genetically modified mice are powerful tools that are used not only to examine the pathogenesis of the disease, but also to assess the efficacy of potential new treatments. Disappointingly, in the past few years we have seen the success of potential therapies in animal studies, subsequently followed by failure in clinical trials. We discuss here a number of factors that influence the translatability of findings from the preclinical to the clinical realm. In particular, we discuss issues related to sample size, reporting of information regarding experimental protocols and mouse models, assignment to experimental groups, incorporation of cognitive measures for early phases of the disease, environmental enrichment, surrogate measures for survival, and the use of more than one HD mouse model. Although it is reasonable to question the appropriateness of the animal models used, we argue that it is more parsimonious to assume that improvements in experimental design and publication of negative results will lead to improved translatability to the clinic and insights about HD pathophysiology.

Minocycline protection of neomycin induced hearing loss in gerbils

This animal study was designed to determine if minocycline ameliorates cochlear damage is caused by intratympanic injection of the ototoxic aminoglycoside antibiotic neomycin. Baseline auditory-evoked brainstem responses were measured in gerbils that received 40 mM intratympanic neomycin either with 0, 1.2, or 1.5 mg/kg intraperitoneal minocycline. Four weeks later auditory-evoked brainstem responses were measured and compared to the baseline measurements. Minocycline treatments of 1.2 mg/kg and 1.5 mg/kg resulted in significantly lower threshold increases compared to 0 mg/kg, indicating protection of hearing loss between 6 kHz and 19 kHz. Cochleae were processed for histology and sectioned to allow quantification of the spiral ganglion neurons and histological evaluation of organ of Corti. Significant reduction of spiral ganglion neuron density was demonstrated in animals that did not receive minocycline, indicating that those receiving minocycline demonstrated enhanced survival of spiral ganglion neurons, enhanced survival of sensory hairs cells and spiral ganglion neurons, and reduced hearing threshold elevation correlates with minocycline treatment demonstrating that neomycin induced hearing loss can be reduced by the simultaneous application of minocycline.

Minocycline: far beyond an antibiotic

Minocycline is a second-generation, semi-synthetic tetracycline that has been in therapeutic use for over 30 years because of its antibiotic properties against both gram-positive and gram-negative bacteria. It is mainly used in the treatment of acne vulgaris and some sexually transmitted diseases. Recently, it has been reported that tetracyclines can exert a variety of biological actions that are independent of their anti-microbial activity, including anti-inflammatory and anti-apoptotic activities, and inhibition of proteolysis, angiogenesis and tumour metastasis. These findings specifically concern to minocycline as it has recently been found to have multiple non-antibiotic biological effects that are beneficial in experimental models of various diseases with an inflammatory basis, including dermatitis, periodontitis, atherosclerosis and autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease. Of note, minocycline has also emerged as the most effective tetracycline derivative at providing neuroprotection. This effect has been confirmed in experimental models of ischaemia, traumatic brain injury and neuropathic pain, and of several neurodegenerative conditions including Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, Alzheimer's disease, multiple sclerosis and spinal cord injury. Moreover, other pre-clinical studies have shown its ability to inhibit malignant cell growth and activation and replication of human immunodeficiency virus, and to prevent bone resorption. Considering the above-mentioned findings, this review will cover the most important topics in the pharmacology of minocycline to date, supporting its evaluation as a new therapeutic approach for many of the diseases described herein.

Neuroinflammation and neuroimmune dysregulation after acute hypoxic-ischemic injury of developing brain

Hypoxic-ischemic (HI) injury to developing brain results from birth asphyxia in neonates and from cardiac arrest in infants and children. It is associated with varying degrees of neurologic sequelae, depending upon the severity and length of HI. Global HI triggers a series of cellular and biochemical pathways that lead to neuronal injury. One of the key cellular pathways of neuronal injury is inflammation. The inflammatory cascade comprises activation and migration of microglia - the so-called "brain macrophages," infiltration of peripheral macrophages into the brain, and release of cytotoxic and proinflammatory cytokines. In this article, we review the inflammatory and immune mechanisms of secondary neuronal injury after global HI injury to developing brain. Specifically, we highlight the current literature on microglial activation in relation to neuronal injury, proinflammatory and anti-inflammatory/restorative pathways, the role of peripheral immune cells, and the potential use of immunomodulators as neuroprotective compounds.

Minocycline attenuates cognitive impairment induced by isoflurane anesthesia in aged rats

Postoperative cognitive dysfunction (POCD) is a clinical phenomenon characterized by cognitive deficits in patients after anesthesia and surgery, especially in geriatric surgical patients. Although it has been documented that isoflurane exposure impaired cognitive function in several aged animal models, there are few clinical interventions and treatments available to prevent this disorder. Minocycline has been well established to exert neuroprotective effects in various experimental animal models and neurodegenerative diseases. Therefore, we hypothesized that pretreatment with minocycline attenuates isoflurane-induced cognitive decline in aged rats. In the present study, twenty-month-old rats were administered minocycline or an equal volume of saline by intraperitoneal injection 12 h before exposure to isoflurane. Then the rats were exposed to 1.3% isoflurane for 4 h. Two weeks later, spatial learning and memory of the rats were examined using the Morris Water Maze. We found that pretreatment with minocycline mitigated isoflurane-induced cognitive deficits and suppressed the isoflurane-induced excessive release of IL-1β and caspase-3 in the hippocampal CA1 region at 4 h after isoflurane exposure, as well as the number of TUNEL-positive nuclei. In addition, minocycline treatment also prevented the changes of synaptic ultrastructure in the hippocampal CA1 region induced by isoflurane. In conclusion, pretreatment with minocycline attenuated isoflurane-induced cognitive impairment in aged rats.

Minocycline prevents paraquat-induced cell death through attenuating endoplasmic reticulum stress and mitochondrial dysfunction

Paraquat (PQ) was demonstrated to induce dopaminergic neuron death and is used as a Parkinson's disease (PD) mimetic; however, its mechanism remains contradictory. Alternatively, minocycline is a second-generation tetracycline and is undergoing clinical trials for treating PD with an unresolved mechanism. We thus investigated the molecular mechanism of minocycline in preventing PQ-induced cytotoxicity. In this study, minocycline was effective in preventing PQ-induced apoptotic cell death, which involves the cleavages of poly (ADP-ribose) polymerase (PARP) and caspase 3 and increased fluorescence intensity of annexin V-FITC. In addition, PQ also quickly induced alterations of unfolded protein responses (UPRs) and subsequently dysfunction of the mitochondria (such as the decrease in membrane potential and increase in membrane permeability and superoxide formation). Finally, the mechanism of minocycline in preventing PQ-induced apoptosis might be mediated by attenuating endoplasmic reticulum (ER) stress and mitochondrial dysfunction, which respectively results in caspase-12 activation and the release of H2O2, HtrA2/Omi, and Smac/Diablo. Thus, minocycline could possibly be used to treat other neurodegenerative disorders with similar pathologic mechanisms.

Minocycline exerts uncoupling and inhibiting effects on mitochondrial respiration through adenine nucleotide translocase inhibition

The present study was aimed to provide a better understanding of the mitochondria-targeted actions of minocycline (MC), a second-generation tetracycline which has cytoprotective effects. Although the specific mechanisms underlying its activity remained elusive, considerable amounts of data indicated mitochondria as the primary pharmacological target of MC. Previous reports have shown that MC affects the oxygen-uptake rate by isolated mitochondria in different respiratory states. Here, we report on the effect of MC, in the range 50-200μM, on mitochondrial respiration. State 3 respiration titration with carboxyatractyloside revealed that MC inhibits the adenine nucleotide translocase. Furthermore, we analyze MC channel-forming capacity in the lipid membrane bilayer. Our results confirmed the crucial role of Δψ and showed a dependence on Ca(2+) for MC to have an effect on mitochondria. Our data also indicated that outer and inner mitochondrial membranes contribute differently to this effect, involving the presence of Δψ (the inner membrane) and VDAC (the outer membrane). Data from three isosmotic media indicate that MC does not increase the permeability of the inner membrane to protons or potassium. In addition, by using mitoplasts and ruthenium red, we showed that Ca(2+) uptake is not involved in the MC effect, suggesting involvement of VDAC in the MC interaction with the outer membrane. Our data contribute to unravel the mechanisms behind the mitochondria-targeted activity of the cytoprotective drug MC.

Attenuation of microglial and IL-1 signaling protects mice from acute alcohol-induced sedation and/or motor impairment

Alcohol-induced proinflammatory central immune signaling has been implicated in the chronic neurotoxic actions of alcohol, although little work has examined if these non-neuronal actions contribute to the acute behavioral responses elicited by alcohol administration. The present study examined if acute alcohol-induced sedation (loss of righting reflex, sleep time test) and motor impairment (rotarod test) were influenced by acute alcohol-induced microglial-dependent central immune signaling. Inhibition of acute alcohol-induced central immune signaling, through the reduction of proinflammatory microglial activation with minocycline, or by blocking interleukin-1 (IL-1) receptor signaling using IL-1 receptor antagonist (IL-1ra), reduced acute alcohol-induced sedation in mice. Mice treated with IL-1ra recovered faster from acute alcohol-induced motor impairment than control animals. However, minocycline led to greater motor impairment induced by alcohol, implicating different mechanisms in alcohol-induced sedation and motor impairment. At a cellular level, IκBα protein levels in mixed hippocampal cells responded rapidly to alcohol in a time-dependent manner, and both minocycline and IL-1ra attenuated the elevated levels of IκBα protein by alcohol. Collectively these data suggest that alcohol is capable of rapid modification of proinflammatory immune signaling in the brain and this contributes significantly to the pharmacology of alcohol.

Melatonin and minocycline for combinatorial therapy to improve functional and histopathological deficits following traumatic brain injury

The biochemical sequelae that follow traumatic brain injury (TBI) are numerous and affect many different brain functions at different points of time as the secondary cascades progress. The complexity of the resulting pathophysiology is such that a singular therapeutic intervention may not provide adequate benefit and a combination of drugs targeting different pathways may be needed. Two of the most widely studied injury mechanisms are oxidative stress and inflammation. Numerous studies have suggested that pharmacological agents targeting either of these pathways may produce an improvement in histological and functional outcome measures. We hypothesized that combining melatonin, a potent antioxidant, with minocycline, a bacteriostatic agent that also inhibit microglia, would provide better neuroprotection than either agent used alone. To test this hypothesis, we subjected anesthetized adult male rats to a 1.5mm controlled cortical impact and administered melatonin or vehicle in the acute post-injury period followed by daily minocycline or vehicle injections beginning the following day in a 2×2 study design. The animals were allowed to recover for 5 days before undergoing Morris water maze (MWM) testing to assess cognitive functioning following injury. There was no significant difference in MWM performance between the vehicle, melatonin, minocycline, or combination treatments. Following sacrifice and histological examination for neuroprotection, we did not observe a significant difference between the groups in the amount of cortical tissue that was spared nor was there a significant difference in [(3)H]-PK11195 binding, a marker for activated microglia. These results suggest that neither drug has therapeutic efficacy, however dosing and/or administration issues may have played a role.

Proton magnetic resonance spectroscopy reveals neuroprotection by oral minocycline in a nonhuman primate model of accelerated NeuroAIDS

BACKGROUND

Despite the advent of highly active anti-retroviral therapy (HAART), HIV-associated neurocognitive disorders continue to be a significant problem. In efforts to understand and alleviate neurocognitive deficits associated with HIV, we used an accelerated simian immunodeficiency virus (SIV) macaque model of NeuroAIDS to test whether minocycline is neuroprotective against lentiviral-induced neuronal injury.

METHODOLOGY/PRINCIPAL FINDINGS

Eleven rhesus macaques were infected with SIV, depleted of CD8+ lymphocytes, and studied until eight weeks post inoculation (wpi). Seven animals received daily minocycline orally beginning at 4 wpi. Neuronal integrity was monitored in vivo by proton magnetic resonance spectroscopy and post-mortem by immunohistochemistry for synaptophysin (SYN), microtubule-associated protein 2 (MAP2), and neuronal counts. Astrogliosis and microglial activation were quantified by measuring glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (IBA-1), respectively. SIV infection followed by CD8+ cell depletion induced a progressive decline in neuronal integrity evidenced by declining N-acetylaspartate/creatine (NAA/Cr), which was arrested with minocycline treatment. The recovery of this ratio was due to increases in NAA, indicating neuronal recovery, and decreases in Cr, likely reflecting downregulation of glial cell activation. SYN, MAP2, and neuronal counts were found to be higher in minocycline-treated animals compared to untreated animals while GFAP and IBA-1 expression were decreased compared to controls. CSF and plasma viral loads were lower in MN-treated animals.

CONCLUSIONS/SIGNIFICANCE

In conclusion, oral minocycline alleviates neuronal damage induced by the AIDS virus.

Minocycline 1-year therapy in multiple-system-atrophy: effect on clinical symptoms and [(11)C] (R)-PK11195 PET (MEMSA-trial)

The aim of the study was to investigate the efficacy of the antibiotic minocycline as a drug treatment in patients with Multiple-System-Atrophy Parkinson-type (MSA-P). Sixty-three patients were randomized to minocycline 200 mg/d (n = 32) or a matching placebo (n = 31). The primary outcome variable was the change in the value of the motor score of the Unified Multiple-System-Atrophy Rating-Scale (UMSARSII) from baseline to 48 weeks. Secondary outcome variables included subscores and individual Parkinsonian symptoms as determined by the UMSARS and the Unified-Parkinson's-Disease Rating-Scale (UPDRS). Health-related quality of life (HrQoL) was assessed using the EQ-5D and SF-12. "Progression rate" was assumed to be reflected in the change in motor function over 48 weeks. At 24 weeks and 48 weeks of follow-up, there was a significant deterioration in motor scores in both groups, but neither the change in UMSARSII nor in UPDRSIII differed significantly between treatment groups, i.e. "progression rate" was considered to be similar in both treatment arms. HrQoL did not differ among the two treatment arms. In a small subgroup of patients (n = 8; minocycline = 3, placebo = 5)[(11)C](R)-PK11195-PET was performed. The three patients in the minocycline group had an attenuated mean increase in microglial activation as compared to the placebo group (P = 0.07) and in two of them individually showed decreased [11C](R)-PK11195 binding actually decreased. These preliminary PET-data suggest that minocycline may interfere with microglial activation. The relevance of this observation requires further investigation. This prospective, 48 week, randomized, double-blind, multinational study failed to show a clinical effect of minocycline on symptom severity as assessed by clinical motor function.

Comprehensive behavioral testing in the R6/2 mouse model of Huntington's disease shows no benefit from CoQ10 or minocycline

Previous studies of the effects of coenzyme Q10 and minocycline on mouse models of Huntington's disease have produced conflicting results regarding their efficacy in behavioral tests. Using our recently published best practices for husbandry and testing for mouse models of Huntington's disease, we report that neither coenzyme Q10 nor minocycline had significant beneficial effects on measures of motor function, general health (open field, rotarod, grip strength, rearing-climbing, body weight and survival) in the R6/2 mouse model. The higher doses of minocycline, on the contrary, reduced survival. We were thus unable to confirm the previously reported benefits for these two drugs, and we discuss potential reasons for these discrepancies, such as the effects of husbandry and nutrition.

Failure of deferoxamine, an iron chelator, to improve outcome after collagenase-induced intracerebral hemorrhage in rats

Intracerebral hemorrhage (ICH) is a devastating stroke with no clinically proven treatment. Deferoxamine (DFX), an iron chelator, is a promising therapy that lessens edema, mitigates peri-hematoma cell death, and improves behavioral recovery after whole-blood-induced ICH in rodents. In this model, blood is directly injected into the brain, usually into the striatum. This mimics many but not all clinical features of ICH (e.g., there is no spontaneous bleed). Thus, we tested whether DFX improves outcome after collagenase-induced striatal ICH in rats. In the first experiment, 3- and 7-day DFX regimens (100 mg/kg twice per day starting 6 h after ICH), similar to those shown effective in the whole-blood model, were compared to saline treatment. Functional recovery was evaluated from 3 to 28 days with several behavioral tests. Except for one instance, DFX failed to lessen ICH-induced behavioral impairments and it did not lessen brain injury, which averaged 43.5 mm(3) at a 28-day survival. In the second experiment, 3 days of DFX treatment were given starting 0 or 6 h after collagenase infusion. Striatal edema occurred, but it was not affected by either DFX treatment (vs. saline treatment). Therefore, in contrast to studies using the whole-blood model, DFX treatment did not improve outcome in the collagenase model. Our findings, when compared to others, suggest that there are critical differences between these ICH models. Perhaps, the current clinical work with DFX will help identify the more clinically predictive model for future neuroprotection studies.

Therapeutic targets and limits of minocycline neuroprotection in experimental ischemic stroke

BACKGROUND

Minocycline, a second-generation tetracycline with anti-inflammatory and anti-apoptotic properties, has been shown to promote therapeutic benefits in experimental stroke. However, equally compelling evidence demonstrates that the drug exerts variable and even detrimental effects in many neurological disease models. Assessment of the mechanism underlying minocycline neuroprotection should clarify the drug's clinical value in acute stroke setting.

RESULTS

Here, we demonstrate that minocycline attenuates both in vitro (oxygen glucose deprivation) and in vivo (middle cerebral artery occlusion) experimentally induced ischemic deficits by direct inhibition of apoptotic-like neuronal cell death involving the anti-apoptotic Bcl-2/cytochrome c pathway. Such anti-apoptotic effect of minocycline is seen in neurons, but not apparent in astrocytes. Our data further indicate that the neuroprotection is dose-dependent, in that only low dose minocycline inhibits neuronal cell death cascades at the acute stroke phase, whereas the high dose exacerbates the ischemic injury.

CONCLUSION

The present study advises our community to proceed with caution to use the minimally invasive intravenous delivery of low dose minocycline in order to afford neuroprotection that is safe for stroke.