Minocycline and neurodegenerative diseases

The possible role of CREB-BDNF signaling pathway in neuroprotective effects of minocycline against alcohol-induced neurodegeneration: molecular and behavioral evidences

Abuse of alcohol triggers neurodegeneration in human brain. Minocycline has characteristics conferring neuroprotection. Current study evaluates the role of the CREB-BDNF signaling pathway in mediating minocycline's neuroprotective effects against alcohol-induced neurodegeneration. Seventy adult male rats were randomly split into groups 1 and 2 that received saline and alcohol (2 g/kg/day by gavage, once daily), respectively, and groups 3, 4, 5, and 6 were treated simultaneously with alcohol and minocycline (10, 20, 30 and 40 mg/kg I.P, respectively) for 21 days. Group 7 received minocycline alone (40 mg/kg, i.p) for 21 days. Morris water maze (MWM) has been used to assess cognitive activity. Hippocampal neurodegenerative and histological parameters as well as cyclic AMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) levels were assessed. Alcohol impaired cognition, and concurrent therapy with various minocycline doses attenuated alcohol-induced cognition disturbances. Additionally, alcohol administration boosted lipid peroxidation and levels of glutathione in oxidized form (GSSG), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and Bax protein, while decreased reducing type of glutathione (GSH), Bcl-2 protein, phosphorylated CREB, and BDNF levels in rat hippocampus. Alcohol also decreased the activity in the hippocampus of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR). In comparison, minocycline attenuated alcohol-induced neurodegeneration; elevating expression levels of P-CREB and BDNF and inhibited alcohol induced histopathological changes in both dentate gyrus (DG) and CA1 of hippocampus. Thus, minocycline is likely to provide neuroprotection against alcohol-induced neurodegeneration through mediation of the P-CREB/BDNF signaling pathway.

Doxycycline reverses cognitive impairment, neuroinflammation and oxidative imbalance induced by D-amphetamine mania model in mice: A promising drug repurposing for bipolar disorder treatment?

Immune-inflammatory mechanisms are involved in the pathophysiology of bipolar disorder. Tetracyclines present neuroprotective actions based on their anti-inflammatory and microglia suppressant effects. Doxycycline (DOXY) is a tetracycline that demonstrates a better usage profile with protective actions against inflammation and CNS injury. Here, we investigated the effects of DOXY against behavioral, neuroinflammatory, and pro-oxidative changes induced by the d-amphetamine mania model. Adult mice were given d-amphetamine 2.0 mg/kg or saline for 14 days. Between days 8 and 14, received lithium, DOXY (25 or 50 mg/kg), or their combination (lithium+DOXY) on both doses. We collected the brain areas prefrontal cortex (PFC), hippocampus, and amygdala to evaluate inflammatory and oxidative alterations. D-amphetamine induced hyperlocomotion and impairment in recognition and working memory. Lithium reversed hyperlocomotion but could not restore cognitive alterations. DOXY alone (at both doses) or combined with lithium reversed d-amphetamine-induced cognitive changes. DOXY, better than lithium, reversed the d-amphetamine-induced rise in TNFα, MPO, and lipid peroxidation. DOXY reduced the hippocampal expression of Iba1 (a marker of microglial activation), inducible nitric oxide synthase (iNOS), and nitrite. Combined with lithium, DOXY increased the phosphorylated (inactivated) form of GSK3β (Ser9). Therefore, DOXY alone or combined with lithium reversed cognitive impairment and neuroinflammation induced by the mice's d-amphetamine model. This study points to DOXY as a promising adjunctive tool for bipolar disorder treatment focused on cognition and neuroimmune changes. Our data provide the first rationale for clinical trials investigating DOXY therapeutic actions in bipolar disorder mania.

Iron Dysregulation and Inflammagens Related to Oral and Gut Health Are Central to the Development of Parkinson's Disease

Neuronal lesions in Parkinson's disease (PD) are commonly associated with α-synuclein (α-Syn)-induced cell damage that are present both in the central and peripheral nervous systems of patients, with the enteric nervous system also being especially vulnerable. Here, we bring together evidence that the development and presence of PD depends on specific sets of interlinking factors that include neuroinflammation, systemic inflammation, α-Syn-induced cell damage, vascular dysfunction, iron dysregulation, and gut and periodontal dysbiosis. We argue that there is significant evidence that bacterial inflammagens fuel this systemic inflammation, and might be central to the development of PD. We also discuss the processes whereby bacterial inflammagens may be involved in causing nucleation of proteins, including of α-Syn. Lastly, we review evidence that iron chelation, pre-and probiotics, as well as antibiotics and faecal transplant treatment might be valuable treatments in PD. A most important consideration, however, is that these therapeutic options need to be validated and tested in randomized controlled clinical trials. However, targeting underlying mechanisms of PD, including gut dysbiosis and iron toxicity, have potentially opened up possibilities of a wide variety of novel treatments, which may relieve the characteristic motor and nonmotor deficits of PD, and may even slow the progression and/or accompanying gut-related conditions of the disease.

Immunotherapy of Autoimmune Diseases with Nonantibiotic Properties of Tetracyclines

Tetracyclines, which have long been used as broad-spectrum antibiotics, also exhibit a variety of nonantibiotic activities including anti-inflammatory and immunomodulatory properties. Tetracyclines bind to the 30S ribosome of the bacteria and inhibit protein synthesis. Unlike antimicrobial activity, the primary molecular target for the nonantibiotic activity of tetracycline remains to be clarified. Nonetheless, the therapeutic efficacies of tetracyclines, particularly minocycline and doxycycline, have been demonstrated in various animal models of autoimmune disorders, such as multiple sclerosis, rheumatoid arthritis, and asthma. In this study, we summarized the anti-inflammatory and immunomodulatory activities of tetracyclines, focusing on the mechanisms underlying these activities. In addition, we highlighted the on-going or completed clinical trials with reported outcomes.

Minocycline for the management of multiple sclerosis: repositioning potential, opportunities, and challenges

INTRODUCTION

Multiple sclerosis (MS) is a chronic demyelinating inflammatory disorder with variable clinical and pathologic characteristics reflecting multiple underlying pathophysiologic mechanisms. Repositioning of existing drugs for the new indications offers several advantages including significant reduction in the cost and time of drug development and exemption from early phase clinical trials. Minocycline has been reported to exhibit immunomodulation in several pre-clinical and clinical studies through suppression of migratory inflammatory cells, modulation of peripheral immune response, and inhibition of microglial activation within the CNS.

AREAS COVERED

Here, the authors review the repositioning potential of minocycline for the treatment of MS along with appraisal of the evidence obtained from preclinical and clinical research. The authors also discuss the advantages and potential safety concerns related to the use of minocycline for the management of MS.

EXPERT OPINION

Minocycline offers several distinct advantages in terms of well-known safety profile, lower cost of therapy, widespread availability, and being available as an oral formulation. The authors call upon the public and private funders to facilitate well designed and adequately powered randomized clinical trials that can provide conclusive evidence regarding the safety and efficacy of minocycline in patients with MS.

Combining hydroxychloroquine and minocycline: potential role in moderate to severe COVID-19 infection

INTRODUCTION

Patients with moderate to severe COVID-19 infection require specific drugs to prevent the morbidity and mortality. Hydroxychloroquine (HCQ) has shown some promise in the management of COVID 19. Minocycline, because of its anticytokine and other useful properties can be an ideal candidate for combining with HCQ.

AREAS COVERED

Here we review the need and mechanisms and reasons for combining HCQ and minocycline moderate to severe COVID-19 infection. We also reviewed the advantages, potential safety concerns and precautions to be taken, while combining HCQ and minocycline.

EXPERT OPINION

Combining HCQ and minocycline offers many advantages in the management of moderate to severe COVID-19 infection. Both drugs are cheaper, widely available and long-term safety data and contraindications are well known. We do not recommend this combination for prophylaxis or use in asymptomatic or mild disease patients as this can lead to unnecessary safety concerns. Additive antimicrobial and anticytokine effects of both drugs may reduce the morbidity and mortality among patients with COVID-19 and may act as a cheaper alternative to the costlier drugs, however, thorough clinical research is warranted. We call upon public and private healthcare bodies to come up with large well-designed clinical studies for generating evidence-based recommendations.

Revisiting Traumatic Brain Injury: From Molecular Mechanisms to Therapeutic Interventions

Studying the complex molecular mechanisms involved in traumatic brain injury (TBI) is crucial for developing new therapies for TBI. Current treatments for TBI are primarily focused on patient stabilization and symptom mitigation. However, the field lacks defined therapies to prevent cell death, oxidative stress, and inflammatory cascades which lead to chronic pathology. Little can be done to treat the mechanical damage that occurs during the primary insult of a TBI; however, secondary injury mechanisms, such as inflammation, blood-brain barrier (BBB) breakdown, edema formation, excitotoxicity, oxidative stress, and cell death, can be targeted by therapeutic interventions. Elucidating the many mechanisms underlying secondary injury and studying targets of neuroprotective therapeutic agents is critical for developing new treatments. Therefore, we present a review on the molecular events following TBI from inflammation to programmed cell death and discuss current research and the latest therapeutic strategies to help understand TBI-mediated secondary injury.

Minocycline for Depressive Symptoms: a Meta-Analysis of Randomized, Double-Blinded, Placebo-Controlled Trials

Neuroinflammation appears to be associated with the neurobiology of depression, and treatments targeting inflammation have shown promising results in depression. This meta-analysis examined the efficacy and safety of minocycline, an anti-inflammatory drug, for the treatment of depressive symptoms. A systematic electronic literature search was independently conducted by two investigators. Standardized mean differences (SMDs) and risk ratio (RR) with their 95% confidence interval (CI) were calculated using a random-effect model. Four RCTs (n = 211) were identified for meta-analysis. Minocycline showed a significant trend of improvement in depressive symptoms compared to placebo [4 RCTs, n = 190, SMD: -0.54 (95%CI:-1.12, 0.04), P = 0.07; I² = 73%]. Subgroup analyses showed that minocycline was superior to placebo in improving depressive symptoms in studies of unipolar depression (3 RCTs, n = 151, SMD: -0.77 (95%CI:-1.32, -0.22), P = 0.006; I² = 60%) and in studies using minocycline monotherapy [SMD: -1.06 (95%CI:-1.68, -0.44), P = 0.0008]. The rates of discontinuation due to any reasons [RR: 1.48 (95%CI: 0.79, 2.77), P = 0.22, I² = 0%] and adverse drug reactions [RR: 0.32 to 1.98 (95%CI: 0.03, 14.74), P = 0.19 to 0.84, I² = 0% to 31%] were similar between minocycline and placebo. Minocycline appears to be effective and well-tolerated in ameliorating depressive symptoms in unipolar depression. Future large RCTs with sufficient duration is needed to confirm the positive effects of minocycline in treating depressive symptoms.

Molecular, histological and behavioral evidences for neuroprotective effects of minocycline against nicotine-induced neurodegeneration and cognition impairment: Possible role of CREB-BDNF signaling pathway

AIM

Neurodegeneration is one of the serious adverse effects of stimulant agents such as nicotine. Minocycline possess established neuroprotective properties. The role of CREB-BDNF signaling pathway in mediating the neuroprotective effects of minocycline against nicotine-induced neurodegeneration in rats was evaluated in current study.

METHODS

Seventy adult male rats were divided randomly into seven groups. Group 1 and 2, received 0.7 ml/rat of normal saline (i.p) and nicotine (10 mg/kg, s.c) respectively. Groups 3, 4, 5 and 6, treated concurrently with nicotine (10 mg/kg) and minocycline (10, 20, 30 and 40 mg/kg, i.p, respectively) for 21 days. Group 7 received minocycline alone (40 mg/kg, i.p) for 21 days. From 17th to 21 st days of experiment, Morris water maze (MWM) was used to evaluate learning and spatial memory in rats treated in different groups. According to the critical role of hippocampus in cognitive behavior, hippocampal neurodegenerative parameters (oxidative stress and inflammatory biomarkers) and also cyclic AMP response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) levels were evaluated in isolated hippocampus in day 22 of experiment and after drug treatment. Also hippocampal cell density and tissue changes were evaluated by hematoxylin and eosin staining.

RESULT

Nicotine administration impaired the learning and spatial memory in rats and simultaneous treatment with various doses of minocycline attenuated the nicotine-induced cognition disturbances. In addition, nicotine treatment increased lipid peroxidation and the levels of oxidized form of glutathione (GSSG), interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and Bax protein, while decreasing reduced form of glutathione (GSH), Bcl-2 protein, P-CREB and BDNF levels in the hippocampus of experimental animals. Nicotine also reduced the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) in the hippocampus. Minocycline attenuated nicotine-induced neurodegeneration and elevating CREB (both forms) and BDNF levels. Also minocycline treatment alone increases the cognitive activity and increased CREB (both forms) and BDNF levels and decreased oxidative stress, inflammation and apoptotic biomarkers. Minocycline at high doses cause inhibition of nicotine induced cell density and changes in both area of dentate gyrus (DG) and CA1 in hippocampus.

CONCLUSION

It can be concluded that minocycline, probably through activation of P-CREB/BDNF signaling pathway, confers neuroprotection against nicotine-induced neurodegeneration in rat hippocampus.

Potential Enzymatic Targets in Alzheimer's: A Comprehensive Review

Alzheimer's, a degenerative cause of the brain cells, is called as a progressive neurodegenerative disease and appears to have a heterogeneous etiology with main emphasis on amyloid-cascade and hyperphosphorylated tau-cascade hypotheses, that are directly linked with macromolecules called enzymes such as β- & γ-secretases, colinesterases, transglutaminases, and glycogen synthase kinase (GSK-3), cyclin-dependent kinase (cdk-5), microtubule affinity-regulating kinase (MARK). The catalytic activity of the above enzymes is the result of cognitive deficits, memory impairment and synaptic dysfunction and loss, and ultimately neuronal death. However, some other enzymes also lead to these dysfunctional events when reduced to their normal activities and levels in the brain, such as α- secretase, protein kinase C, phosphatases etc; metabolized to neurotransmitters, enzymes like monoamine oxidase (MAO), catechol-O-methyltransferase (COMT) etc. or these abnormalities can occur when enzymes act by other mechanisms such as phosphodiesterase reduces brain nucleotides (cGMP and cAMP) levels, phospholipase A2: PLA2 is associated with reactive oxygen species (ROS) production etc. On therapeutic fronts, several significant clinical trials are underway by targeting different enzymes for development of new therapeutics to treat Alzheimer's, such as inhibitors for β-secretase, GSK-3, MAO, phosphodiesterase, PLA2, cholinesterases etc, modulators of α- & γ-secretase activities and activators for protein kinase C, sirtuins etc. The last decades have perceived an increasing focus on findings and search for new putative and novel enzymatic targets for Alzheimer's. Here, we review the functions, pathological roles, and worth of almost all the Alzheimer's associated enzymes that address to therapeutic strategies and preventive approaches for treatment of Alzheimer's.

Minocycline, focus on mechanisms of resistance, antibacterial activity, and clinical effectiveness: Back to the future

OBJECTIVES

The increasing crisis regarding multidrug-resistant (MDR) and extensively drug-resistant microorganisms leads to appealing therapeutic options.

METHODS

During the last 30 years, minocycline, a wide-spectrum antimicrobial agent, has been effective against MDR Gram-positive and Gram-negative bacterial infections. As with other tetracyclines, the mechanism of action of minocycline involves attaching to the bacterial 30S ribosomal subunit and preventing protein synthesis.

RESULTS

This antimicrobial agent has been approved for the treatment of acne vulgaris, some sexually transmitted diseases and rheumatoid arthritis. Although many reports have been published, there remains limited information regarding the prevalence, mechanism of resistance and clinical effectiveness of minocycline.

CONCLUSION

Thus, we summarize here the currently available data concerning pharmacokinetics and pharmacodynamics, mechanism of action and resistance, antibacterial activity and clinical effectiveness of minocycline.

Neuroinflammation

Neuroinflammation is implicated in contributing to a variety of neurologic and somatic illnesses including Alzheimer's disease (AD), Parkinson's disease (PD), and depression. In this chapter, we focus on the role of neuroinflammation in mediating these three illnesses and portray interactions between the immune response and the central nervous system in the context of sex differences in disease progression. The majority of this chapter is supported by clinical findings; however, we occasionally utilize preclinical models where human studies are currently lacking. We begin by detailing the pathology of neuroinflammation, distinguishing between acute and chronic inflammation, and examining contributions from the innate and adaptive immune systems. Next, we summarize potential mechanisms of immune cell mediators including interleukin-1 beta (IL-1β), tumor necrosis factor α, and IL-6 in AD, PD, and depression development. Given the strong sex bias seen in these illnesses, we additionally examine the role of sex hormones, e.g., estrogen and testosterone in mediating neuroinflammation at the cellular level. Systematically, we detail how sex hormones may contribute to distinct behavioral and clinical symptoms and prognosis between males and females with AD, PD, or depression. Finally, we highlight the possible role of exercise in alleviating neuroinflammation, as well as evidence that antiinflammatory drug therapies improve cognitive symptoms observed in brain-related diseases.

Minocycline Attenuates Experimental Subarachnoid Hemorrhage in Rats

Backgroud

The aim of this study was to evaluate the therapeutic effect of minocycline on treating experimental subarachnoid hemorrhage (SAH) in rats and to explore its possible molecular mechanism.

Methods

SAH was induced in male Sprague-Dawley rats by endovascular perforation. The rats were treated with minocycline (25 mg/kg or 50 mg/kg) or saline at 2 hand 12 h post SAH. Neurological function, cerebral hemorrhage, and edema were scored at 48 h post SAH. Cell death and P2X4 receptor (P2X4R) expression were observed in the prefrontal cortex (PFC).

Results

Treatment with a highdose of minocycline significantly improved the neurological function score, and attenuated cerebral hemorrhage and edema. Low-dose minocycline could reduce hemorrhage, but the effect on neurological deficits and brain edema was not obvious. Minocycline treatment could alleviate neuronal apoptosis in the PFC, which was related to reduced expression of inflammatory cytokines. Immunofluorescence showed that P2X4R on microglia was activated after SAH. Minocycline treatment inhibited P2X4R activation and further suppressed the phosphorylation of downstream p38 MAPK.

Conclusions

Minocycline plays a neuroprotective role by attenuating early brain injury after experimental SAH. The therapeutic mechanism of minocycline may be mediated by the inhibition of P2X4R on microglia.

Neuronal Death in the Contralateral Un-Injured Retina after Unilateral Axotomy: Role of Microglial Cells

For years it has been known that unilateral optic nerve lesions induce a bilateral response that causes an inflammatory and microglial response in the contralateral un-injured retinas. Whether this contralateral response involves retinal ganglion cell (RGC) loss is still unknown. We have analyzed the population of RGCs and the expression of several genes in both retinas of pigmented mice after a unilateral axotomy performed close to the optic nerve head (0.5 mm), or the furthest away that the optic nerve can be accessed intraorbitally in mice (2 mm). In both retinas, RGC-specific genes were down-regulated, whereas caspase 3 was up-regulated. In the contralateral retinas, there was a significant loss of 15% of RGCs that did not progress further and that occurred earlier when the axotomy was performed at 2 mm, that is, closer to the contralateral retina. Finally, the systemic treatment with minocycline, a tetracycline antibiotic that selectively inhibits microglial cells, or with meloxicam, a non-steroidal anti-inflammatory drug, rescued RGCs in the contralateral but not in the injured retina. In conclusion, a unilateral optic nerve axotomy triggers a bilateral response that kills RGCs in the un-injured retina, a death that is controlled by anti-inflammatory and anti-microglial treatments. Thus, contralateral retinas should not be used as controls.

The Opening of Connexin 43 Hemichannels Alters Hippocampal Astrocyte Function and Neuronal Survival in Prenatally LPS-Exposed Adult Offspring

Clinical evidence has revealed that children born from mothers exposed to viral and bacterial pathogens during pregnancy are more likely to suffer various neurological disorders including schizophrenia, autism bipolar disorder, major depression, epilepsy, and cerebral palsy. Despite that most research has centered on the impact of prenatal inflammation in neurons and microglia, the potential modifications of astrocytes and neuron-astrocyte communication have received less scrutiny. Here, we evaluated whether prenatally LPS-exposed offspring display alterations in the opening of astrocyte hemichannels and pannexons in the hippocampus, together with changes in neuroinflammation, intracellular Ca²⁺ and nitric oxide (NO) signaling, gliotransmitter release, cell arborization, and neuronal survival. Ethidium uptake recordings revealed that prenatal LPS exposure enhances the opening of astrocyte Cx43 hemichannels and Panx1 channels in the hippocampus of adult offspring mice. This enhanced channel activity occurred by a mechanism involving a microglia-dependent production of IL-1β/TNF-α and the stimulation of p38 MAP kinase/iNOS/[Ca²⁺]_i-mediated signaling and purinergic/glutamatergic pathways. Noteworthy, the activity of Cx43 hemichannels affected the release of glutamate, [Ca²⁺]_i handling, and morphology of astrocytes, whereas also disturbed neuronal function, including the dendritic arbor and spine density, as well as survival. We speculate that excitotoxic levels of glutamate triggered by the activation of Cx43 hemichannels may contribute to hippocampal neurotoxicity and damage in prenatally LPS-exposed offspring. Therefore, the understanding of how astrocyte-neuron crosstalk is an auspicious avenue toward the development of broad treatments for several neurological disorders observed in children born to women who had a severe infection during gestation.

Immune Mediated Degeneration and Possible Protection in Glaucoma

The underlying pathomechanisms for glaucoma, one of the most common causes of blindness worldwide, are still not identified. In addition to increased intraocular pressure (IOP), oxidative stress, excitotoxicity, and immunological processes seem to play a role. Several pharmacological or molecular/genetic methods are currently investigated as treatment options for this disease. Altered autoantibody levels were detected in serum, aqueous humor, and tissue sections of glaucoma patients. To further analyze the role of the immune system, an IOP-independent, experimental autoimmune glaucoma (EAG) animal model was developed. In this model, immunization with ocular antigens leads to antibody depositions, misdirected T-cells, retinal ganglion cell death and degeneration of the optic nerve, similar to glaucomatous degeneration in patients. Moreover, an activation of the complement system and microglia alterations were identified in the EAG as well as in ocular hypertension models. The inhibition of these factors can alleviate degeneration in glaucoma models with and without high IOP. Currently, several neuroprotective approaches are tested in distinct models. It is necessary to have systems that cover underlying pathomechanisms, but also allow for the screening of new drugs. In vitro models are commonly used, including single cell lines, mixed-cultures, and even organoids. In ex vivo organ cultures, pathomechanisms as well as therapeutics can be investigated in the whole retina. Furthermore, animal models reveal insights in the in vivo situation. With all these models, several possible new drugs and therapy strategies were tested in the last years. For example, hypothermia treatment, neurotrophic factors or the blockage of excitotoxity. However, further studies are required to reveal the pressure independent pathomechanisms behind glaucoma. There is still an open issue whether immune mechanisms directly or indirectly trigger cell death pathways. Hence, it might be an imbalance between protective and destructive immune mechanisms. Moreover, identified therapy options have to be evaluated in more detail, since deeper insights could lead to better treatment options for glaucoma patients.

Self-Assembly of DNA-Minocycline Complexes by Metal Ions with Controlled Drug Release

Here we reported a study of metal ions-assisted assembly of DNA-minocycline (MC) complexes and their potential application for controlling MC release. In the presence of divalent cations of magnesium or calcium ions (M²⁺), MC, a zwitterionic tetracycline analogue, was found to bind to phosphate groups of nucleic acids via an electrostatic bridge of phosphate (DNA)-M²⁺-MC. We investigated multiple parameters for affecting the formation of DNA-Mg²⁺-MC complex, including metal ion concentrations, base composition, DNA length, and single- versus double-stranded DNA. For different nitrogen bases, single-stranded poly(A)₂₀ and poly(T)₂₀ showed a higher MC entrapment efficiency of DNA-Mg²⁺-MC complex than poly(C)₂₀ and poly(G)₂₀. Single-stranded DNA was also found to form a more stable DNA-Mg²⁺-MC complex than double-stranded DNA. Between different divalent metal ions, we observed that the formation of DNA-Ca²⁺-MC complex was more stable and efficient than the formation of DNA-Mg²⁺-MC complex. Toward drug release, we used agarose gel to encapsulate DNA-Mg²⁺-MC complexes and monitored MC release. Some DNA-Mg²⁺-MC complexes could prolong MC release from agarose gel to more than 10 days as compared with the quick release of free MC from agarose gel in less than 1 day. The released MC from DNA-Mg²⁺-MC complexes retained the anti-inflammatory bioactivity to inhibit nitric oxide production from pro-inflammatory macrophages. The reported study of metal ion-assisted DNA-MC assembly not only increased our understanding of biochemical interactions between tetracycline molecules and nucleic acids but also contributed to the development of a highly tunable drug delivery system to mediate MC release for clinical applications.

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.

Reversal of ultrasonic vocalization deficits in a mouse model of Fragile X Syndrome with minocycline treatment or genetic reduction of MMP-9

Fragile X Syndrome (FXS) is a leading genetic cause of autism and intellectual disabilities. The Fmr1 knockout (KO) mouse is a commonly studied pre-clinical model of FXS. Adult male Fmr1 KO mice produce fewer ultrasonic vocalizations (USVs) during mating, suggestive of abnormal social communication. Minocycline treatment for 2 months from birth alleviates a number of FXS phenotypes in mice, including USV call rate deficits. In the current study, we investigated if treatment initiated past the early developmental period would be effective, given that in many cases, individuals with FXS are treated during later developmental periods. Wildtype (WT) and Fmr1 KO mice were treated with minocycline between postnatal day (P) 30 and P58. Mating-related USVs were then recorded from these mice between P75 and P90 and analyzed for call rate, duration, bandwidth, and peak frequency. Untreated Fmr1 KO mice call at a significantly reduced rate compared to untreated WT mice. After minocycline treatment from 1 to 2 months of age, WT and Fmr1 KO mice exhibited similar call rates, due to an increase in calling in the latter group. Minocycline is thought to be effective in reducing FXS symptoms by lowering matrix-metalloproteinase-9 (MMP-9) levels. To determine whether abnormal MMP-9 levels underlie USV deficits, we characterized USVs in Fmr1 KO mice which were heterozygous for MMP-9 (MMP-9^+/-/Fmr1 KO). The MMP-9^+/-/Fmr1 KO mice were between P75 and P90 at the time of recording. MMP-9^+/-/Fmr1 KO mice exhibited significantly increased USV call rates, at times even exceeding WT rates. Taken together, these results suggest that minocycline may reverse USV call rate deficits in Fmr1 KO mice through attenuation of MMP-9 levels. These data suggest targeting MMP-9, even in late development, may reduce FXS symptoms.

Morphine increases macrophages at the lesion site following spinal cord injury: Protective effects of minocycline

Opioids are among the most effective and widely prescribed medications for the treatment of pain following spinal cord injury (SCI). Spinally-injured patients receive opioids within hours of arrival at the emergency room, and prolonged opioid regimens are often employed for the management of post-SCI chronic pain. However, previous studies in our laboratory suggest that the effects of opioids such as morphine may be altered in the pathophysiological context of neurotrauma. Specifically, we have shown that morphine administration in a rodent model of SCI increases mortality and tissue loss at the injury site, and decreases recovery of motor and sensory function, and overall health, even weeks after treatment. The literature suggests that opioids may produce these adverse effects by acting as endotoxins and increasing glial activation and inflammation. To better understand the effects of morphine following SCI, in this study we used flow cytometry to assess immune-competent cells at the lesion site. We observed a morphine-induced increase in the overall number of CD11b+ cells, with marked effects on microglia, in SCI subjects. Next, to investigate whether this increase in the inflammatory profile is necessary to produce morphine's effects, we challenged morphine treatment with minocycline. We found that pre-treatment with minocycline reduced the morphine-induced increase in microglia at the lesion site. More importantly, minocycline also blocked the adverse effects of morphine on recovery of function without disrupting the analgesic efficacy of this opioid. Together, our findings suggest that following SCI, morphine may exacerbate the inflammatory response, increasing cell death at the lesion site and negatively affecting functional recovery.

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.

A hydrogel engineered to deliver minocycline locally to the injured cervical spinal cord protects respiratory neural circuitry and preserves diaphragm function

We tested a biomaterial-based approach to preserve the critical phrenic motor circuitry that controls diaphragm function by locally delivering minocycline hydrochloride (MH) following cervical spinal cord injury (SCI). MH is a clinically-available antibiotic and anti-inflammatory drug that targets a broad range of secondary injury mechanisms via its anti-inflammatory, anti-oxidant and anti-apoptotic properties. However, MH is only neuroprotective at high concentrations that cannot be achieved by systemic administration, which limits its clinical efficacy. We have developed a hydrogel-based MH delivery system that can be injected into the intrathecal space for local delivery of high concentrations of MH, without damaging spinal cord tissue. Implantation of MH hydrogel after unilateral level-C4/5 contusion SCI robustly preserved diaphragm function, as assessed by in vivo recordings of compound muscle action potential (CMAP) and electromyography (EMG) amplitudes. MH hydrogel also decreased lesion size and degeneration of cervical motor neuron somata, demonstrating its central neuroprotective effects within the injured cervical spinal cord. Furthermore, MH hydrogel significantly preserved diaphragm innervation by the axons of phrenic motor neurons (PhMNs), as assessed by both detailed neuromuscular junction (NMJ) morphological analysis and retrograde PhMN labeling from the diaphragm using cholera toxin B (CTB). In conclusion, our findings demonstrate that local MH hydrogel delivery to the injured cervical spinal cord is effective in preserving respiratory function after SCI by protecting the important neural circuitry that controls diaphragm activation.

A hypothetic role of minocycline as a neuroprotective agent against methylphenidate-induced neuronal mitochondrial dysfunction and tau protein hyper-phosphorylation: Possible role of PI3/Akt/GSK3β signaling pathway

The underlining mechanism in neural mitochondrial dysfunction and consequences neurotoxicity, and cognitive behavior after methylphenidate (MPH) prolonged uses is unclear and proposing of therapeutic approaches for treatment of these types of neurotoxicity is one of the main goals of scientist in this manner. MPH-induced mitochondrial dysfunction in neural cells caused induction of oxidative stress, apoptosis, inflammation and cognition impairment, which leads to neurotoxicity, was reported previously but role of key neural cells proteins and involved signaling pathway in this manner remained indeterminate. Tau protein aggregation is a biomarker for mitochondrial dysfunction, neurodegenerative event and cognition impairment. Tau aggregation occur by stimulation effects of Glycogen synthase kinase-3(GSK3β) and phosphatidylinositol 3-kinase (PI3K) which activates protein kinase B(Akt) and causes inhibition of phosphorylation(activation) of GSK3β, thus Akt activation can cause inhibition of tau aggregation (hyper-phosphorylation). Management of mentioned MPH-induced mitochondrial dysfunction and consequences of neurotoxicity, and cognitive behavior through a new generation neuroprotective combination, based on modulation of disturbed in Akt function and inhibition of GSK3β and tau hyper-phosphorylation can be a prefect therapeutic interventions. Therefore, finding, introduction and development of new neuroprotective properties and explanation of their effects with potential capacity for modulation of tau hyper-phosphorylation via PI3/Akt/GSK signaling pathway is necessitated. During recent years, using new neuroprotective compounds with therapeutic probability for treatment of psychostimulant-induced mitochondrial dysfunction, neurotoxicity and cognitive malicious effects have been amazingly increased. Many previous studies have reported the neuroprotective roles of minocycline (a broad-spectrum and long-acting antibiotic) in multiple neurodegenerative events and diseases in animal model. But the role of neuroprotective effects of this agent against MPH induced mitochondrial dysfunction, neurotoxicity and cognitive malicious and also role of tau hyper-phosphorylation by modulation of PI3/Akt/GSK signaling pathway in this manner remain unknown. Thus we suggested and theorized that by using minocycline in MPH addicted subject, it would provide neuroprotection against MPH-induced mitochondrial dysfunction, neurotoxicity and cognitive malicious. Also we hypothesized that minocycline, via modulation of PI3/Akt/GSK and inhibition of tau hyper-phosphorylation, can inhibit MPH-induced mitochondrial dysfunction, neurotoxicity and cognitive malicious. In this article, we tried to discuss our hypothesis regarding the possible role of minocycline, as a powerful neuroprotective agent, and also role of tau hyper-phosphorylation related to PI3/Akt/GSK signaling pathway in treatment of MPH-induced mitochondrial dysfunction, neurotoxicity and cognitive disturbance.

The effect of minocycline on symptoms in schizophrenia: Results from a randomized controlled trial

BACKGROUND

Studies have hypothesized that immunological abnormalities might contribute to schizophrenia, and basic science studies, as well as several clinical trials suggest that minocycline could be efficacious in ameliorating both positive and negative symptoms of schizophrenia. In this study we examined the effect of minocycline on schizophrenia in a large randomized controlled trial.

METHODS

We performed a 16-week, multi-center, double-blind, randomized, placebo-controlled study on 200 subjects with schizophrenia or schizoaffective disorder randomized to receive either minocycline (200 mg/day, n = 100), or placebo (n = 100) as an add-on to anti-psychotic treatment. The primary outcome measure was the PANSS total score.

RESULTS

Mixed models for repeated measures showed no significant difference between minocycline and placebo for total PANSS (p = 0.862), PANSS subscales, CGI or BACS.

CONCLUSIONS

Minocycline did not improve symptoms or cognition in schizophrenia.

Minocycline reverses diabetes-associated cognitive impairment in rats

BACKGROUND

Minocycline a tetracycline antibiotic is known for anti-inflammatory and neuroprotective actions. Here we determine the therapeutic potential of minocycline against type 2 diabetes associated cognitive decline in rats.

METHODS

High fat diet (HFD) and low dose streptozotocin (STZ; 25 mg/kg) were used to induce diabetes in Sprague-Dawley rats. Fasting blood glucose and haemoglobin (Hb) A1c were measured in these animals. Cognitive parameters were measured using passive avoidance and elevated plus maze test. Hippocampal Acetylcholine esterase (AchE), reduced glutathione (GSH), cytokines, chemokine levels were measured and histopathological evaluations were conducted. The diabetic animals were then given minocycline (50 mg/kg; 15 days) and the above parameters were reassessed. MTT and Lactate dehydrogenase (LDH) assays were conducted on neuronal cells in the presence of glucose with or without minocycline treatment.

RESULTS

We induced diabetes using HFD and STZ in these animals. Animals showed high fasting blood glucose levels (>245 mg/dl) and HbA1c compared to control animals. Diabetes significantly lowered step down latency and increased transfer latency. Diabetic animals showed significantly higher AchE, Tumor necrosis factor (TNF)-α, Interleukin (IL)-1β and Monocyte chemoattractant protein (MCP)-1 and lower GSH levels and reduced both CA1 and CA3 neuronal density compared to controls. Minocycline treatment partially reversed the above neurobehavioral and biochemical changes and improved hippocampal neuronal density in diabetic animals. Cell line studies showed glucosemediated neuronal death, which was considerably reversed upon minocycline treatment.

CONCLUSIONS

Minocycline, primarily by its anti-inflammatory and antioxidant actions prevented hippocampal neuronal loss thus partially reversing the diabetes-associated cognitive decline in rats.

Neuroimmune nexus of depression and dementia: Shared mechanisms and therapeutic targets

Dysfunctional immune activity is a physiological component of both Alzheimer's disease (AD) and major depressive disorder (MDD). The extent to which altered immune activity influences the development of their respective cognitive symptoms and neuropathologies remains under investigation. It is evident, however, that immune activity affects neuronal function and circuit integrity. In both disorders, alterations are present in similar immune networks and neuroendocrine signalling pathways, immune responses persist in overlapping neuroanatomical locations, and morphological and structural irregularities are noted in similar domains. Epidemiological studies have also linked the two disorders, and their genetic and environmental risk factors intersect along immune-activating pathways and can be synonymous with one another. While each of these disorders individually contains a large degree of heterogeneity, their shared immunological components may link distinct phenotypes within each disorder. This review will therefore highlight the shared immune pathways of AD and MDD, their overlapping neuroanatomical features, and previously applied, as well as novel, approaches to pharmacologically manipulate immune pathways, in each neurological condition. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.

The therapeutic role of minocycline in Parkinson's disease

Minocycline, a semisynthetic tetracycline-derived antibiotic, has been shown to exert anti-apoptotic, anti-inflammatory, and antioxidant effects. Furthermore, there is rapidly growing evidence suggesting that minocycline may have some neuroprotective activity in various experimental models such as cerebral ischemia, traumatic brain injury, amyotrophic lateral sclerosis, Parkinson's disease (PD), Huntington's disease, and multiple sclerosis. In this perspective review, we summarize the preclinical and clinical findings suggesting the neuroprotective role of minocycline in PD.

Minocycline impedes mitochondrial-dependent cell death and stabilizes expression of hypoxia inducible factor-1α in spinal cord injury

INTRODUCTION

One of the crucial mechanisms following spinal cord injury is mitochondria-associated cell death. Minocycline, an anti-inflammatory drug, is well known to impede mitochondrial cell death. However, there has been no study on the effect of minocycline linking Fas cell surface death receptor (FAS)-mediated cell death and hypoxia inducible factor (HIF-1α), the targets involved in mitochondrial cell death.

MATERIAL AND METHODS

Male Sprague Dawley rats (N = 15, divided into three groups) were subjected to traumatic spinal cord injury and were injected with minocycline (n = 5) (90 mg/kg and later a 45 mg/kg dose twice a day (every 12 h)). Injection with sterile PBS in injured animals served as the vehicle (n = 5) and another group comprised healthy animals (n = 5). TUNEL assay was used to quantify cell death. The release of Smac/Diablo, cytochrome-c (cyt-c), HIF-1α, FAS ligand (FASL) and tumour necrosis factor-α (TNF-α) was measured using ELISA. Expression of HIF-1α, FASL and other cell death associated factors was quantified at the mRNA and protein level and confirmed with immunohistochemistry.

RESULTS

There was a marked reduction in the HIF-1α and FASL expression levels in the minocycline-treated group compared to the vehicle. The reduction of HIF-1α and FASL was associated with other factors linked to cell death (Smac/Diablo, cyt-c, TNF-α, p53, caspase-8 and BH3 interacting domain death agonist (BID)) (p < 0.5; *p < 0.05 vs. vehicle group, **p < 0.01 vs. vehicle group).

CONCLUSIONS

The present study focuses on the investigation of minocycline in inhibiting mitochondria-associated cell death by modulating FASL and HIF-1α expression, which are seemingly interlinked mechanisms contributing to cell death.

Plasticity of microglia in remote regions after focal brain injury

The CNS is endowed with an intrinsic ability to recover from and adapt secondary compensatory mechanisms to injury. The basis of recovery stems from brain plasticity, defined as the brain's ability to make adaptive changes on structural and functional levels, ranging from molecular, synaptic, and cellular changes in response to alterations in their environment. In this multitude of responses, microglia have an active role and contribute to brain plasticity through their dynamic responses. This review will provide an overview of microglial responses in the context of acute CNS injury and their function in post-traumatic repair and assess the changes that are induced by damage in remote areas from, but functionally connected to, the primary site of injury. In the second section, we highlight the effects of several therapeutic approaches, with particular interest paid to specialized pro-resolving lipid mediators, in modulating microglial responses in remote regions and enhancing long-term functional recovery via suppression of neurodegenerative cascades that are induced by damage, which may contribute to a translational bridge from bench to bedside.

Activation of microglia synergistically enhances neurodegeneration caused by MPP+ in human SH-SY5Y cells

While MPP⁺ may not directly activate microglia, the initial neuronal damage inflicted by the toxin may trigger microglia, possibly leading to synergistic pro-apoptotic interaction between neuro-inflammation and toxin-induced neurotoxicity, which may further aggravate neurodegeneration. However, what molecular targets are synergistically up or downregulated during this interaction is not well understood. Here, we addressed this by co-culturing fully differentiated human SH-SY5Y cells treated with parkinsonian toxin 1-Methyl-4-phenylpyridinium (MPP⁺), with endotoxin-activated microglial cell line EOC 20 to determine how this interaction affects pro-apoptotic (p38, JNK, and bax:bcl2 ratios) and pro-survival (NF-κB, MEK1) signaling at both mRNA and protein levels. Concurrent MPP⁺ and endotoxin-treatment aggravated a decrease in SH-SY5Y cell viability and caused strong synergistic increases in the bax:bcl2 ratio, but also NF-κB and JNK signaling. These effects were attenuated by microglia inhibitor minocycline. Altogether, these data provide further molecular insights into the important role or even conditional requirement of microglia activation in the progressive neurodegenerative nature of PD.

A phenotypic Caenorhabditis elegans screen identifies a selective suppressor of antipsychotic-induced hyperphagia

Antipsychotic (AP) drugs are used to treat psychiatric disorders but are associated with significant weight gain and metabolic disease. Increased food intake (hyperphagia) appears to be a driving force by which APs induce weight gain but the mechanisms are poorly understood. Here we report that administration of APs to C. elegans induces hyperphagia by a mechanism that is genetically distinct from basal food intake. We exploit this finding to screen for adjuvant drugs that suppress AP-induced hyperphagia in C. elegans and mice. In mice AP-induced hyperphagia is associated with a unique hypothalamic gene expression signature that is abrogated by adjuvant drug treatment. Genetic analysis of this signature using C. elegans identifies two transcription factors, nhr-25/Nr5a2 and nfyb-1/NFYB to be required for AP-induced hyperphagia. Our study reveals that AP-induced hyperphagia can be selectively suppressed without affecting basal food intake allowing for novel drug discovery strategies to combat AP-induced metabolic side effects.

A randomized placebo controlled clinical trial to evaluate the efficacy and safety of minocycline in patients with Angelman syndrome (A-MANECE study)

BACKGROUND

Minocycline is an old tetracycline antibiotic that has shown antiinflammatory and antiapoptotic properties in different neurological disease mouse models. Previous single arm study in humans demonstrated benefits in individuals with Angelman Syndrome (AS); however, its efficacy in patients with Angelman Syndrome has not been assessed in a controlled trial. This was a randomized, double-blind, placebo-controlled, crossover trial in individuals with AS, aged 6 years to 30 years (n = 32, mean age 12 [SD 6·29] years). Participants were randomized to minocycline or placebo for 8 weeks and then switched to the other treatment (a subset of 22 patients) or to receive minocycline for up to 16 weeks (10 patients). After week 16, all patients entered a wash-out 8-week follow-up period.

RESULTS

Thirty-six subjects were screened and 34 were randomized. Thirty two subjects (94·1%) completed at least the first period and all of them completed the full trial. Intention-to-treat analysis demonstrated the lack of significantly greater improvements in the primary outcome, mean changes in age equivalent of the development index of the Merrill-Palmer Revised Scale after minocycline compared with placebo (1·90 ± 3·16 and 2·00 ± 3·28, respectively, p = 0·937). Longer treatment duration up to 16 weeks did not result in better treatment outcomes (1·86 ± 3·35 for 8 weeks treatment vs 1·20 ± 5·53 for 16 weeks treatment, p = 0·667). Side effects were not significantly different during minocycline and placebo treatments. No serious adverse events occurred on minocycline.

CONCLUSIONS

Minocycline treatment for up to 16 weeks in children and young adults with AS resulted in lack of significant improvements in development indexes compared to placebo treatment. Treatment with minocycline appears safe and well tolerated; even if it cannot be completely ruled out that longer trials might be required for a potential minocycline effect to be expressed, available results and lack of knowledge on the actual mechanism of action do not support this hypothesis.

TRIAL REGISTRATION

European Clinical Trial database ( EudraCT 2013-002154-67 ), registered 16th September 2013; US Clinical trials database ( NCT02056665 ), registered 6th February 2014.

Cell Death Pathways: a Novel Therapeutic Approach for Neuroscientists

In the first part, the following mechanisms involved in different forms of cell death are considered, with a view to identifying potential therapeutic targets: tumour necrosis factor receptors (TNFRs) and their engagement by tumour necrosis factor-alpha (TNF-α); poly [ADP-ribose] polymerase (PARP)-1 cleavage; the apoptosis signalling kinase (ASK)-c-Jun N-terminal kinase (JNK) axis; lysosomal permeability; activation of programmed necrotic cell death; oxidative stress, caspase-3 inhibition and parthanatos; activation of inflammasomes by reactive oxygen species and the development of pyroptosis; oxidative stress, calcium dyshomeostasis and iron in the development of lysosomal-mediated necrosis and lysosomal membrane permeability; and oxidative stress, lipid peroxidation, iron dyshomeostasis and ferroptosis. In the second part, there is a consideration of the role of lethal and sub-lethal activation of these pathways in the pathogenesis and pathophysiology of neurodegenerative and neuroprogressive disorders, with particular reference to the TNF-α-TNFR signalling axis; dysregulation of ASK-1-JNK signalling; prolonged or chronic PARP-1 activation; the role of pyroptosis and chronic inflammasome activation; and the roles of lysosomal permeabilisation, necroptosis and ferroptosis. Finally, it is suggested that, in addition to targeting oxidative stress and inflammatory processes generally, neuropsychiatric disorders may respond to therapeutic targeting of TNF-α, PARP-1, the Nod-like receptor NLRP3 inflammasome and the necrosomal molecular switch receptor-interacting protein kinase-3, since their widespread activation can drive and/or exacerbate peripheral inflammation and neuroinflammation even in the absence of cell death. To this end, the use is proposed of a combination of the tetracycline derivative minocycline and N-acetylcysteine as adjunctive treatment for a range of neuropsychiatric disorders.

The independence of and associations among apoptosis, autophagy, and necrosis

Cell death is an essential biological process for physiological growth and development. Three classical forms of cell death-apoptosis, autophagy, and necrosis-display distinct morphological features by activating specific signaling pathways. With recent research advances, we have started to appreciate that these cell death processes can cross-talk through interconnecting, even overlapping, signaling pathways, and the final cell fate is the result of the interplay of different cell death programs. This review provides an insight into the independence of and associations among these three types of cell death and explores the significance of cell death under the specific conditions of human diseases, particularly neurodegenerative diseases and cancer.

Infection of Fungi and Bacteria in Brain Tissue From Elderly Persons and Patients With Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia in elderly people. The etiology of this disease remains a matter of intensive research in many laboratories. We have advanced the idea that disseminated fungal infection contributes to the etiology of AD. Thus, we have demonstrated that fungal proteins and DNA are present in nervous tissue from AD patients. More recently, we have reported that bacterial infections can accompany these mycoses, suggesting that polymicrobial infections exist in AD brains. In the present study, we have examined fungal and bacterial infection in brain tissue from AD patients and control subjects by immunohistochemistry. In addition, we have documented the fungal and bacterial species in brain regions from AD patients and control subjects by next-generation sequencing (NGS). Our results from the analysis of ten AD patients reveal a variety of fungal and bacterial species, although some were more prominent than others. The fungal genera more prevalent in AD patients were Alternaria, Botrytis, Candida, and Malassezia. We also compared these genera with those found in elderly and younger subjects. One of the most prominent genera in control subjects was Fusarium. Principal component analysis clearly indicated that fungi from frontal cortex samples of AD brains clustered together and differed from those of equivalent control subjects. Regarding bacterial infection, the phylum Proteobacteria was the most prominent in both AD patients and controls, followed by Firmicutes, Actinobacteria, and Bacteroides. At the family level, Burkholderiaceae and Staphylococcaceae exhibited higher percentages in AD brains than in control brains. These findings could be of interest to guide targeted antimicrobial therapy for AD patients. Moreover, the variety of microbial species in each patient may constitute a basis for a better understanding of the evolution and severity of clinical symptoms in each patient.

Attenuation of neuro-inflammation improves survival and neurodegeneration in a mouse model of severe neonatal hyperbilirubinemia

All pre-term newborns and a high proportion of term newborns develop neonatal jaundice. Neonatal jaundice is usually a benign condition and self-resolves within few days after birth. However, a combination of unfavorable complications may lead to acute hyperbilirubinemia. Excessive hyperbilirubinemia may be toxic for the developing nervous system leading to severe neurological damage and death by kernicterus. Survivors show irreversible neurological deficits such as motor, sensitive and cognitive abnormalities. Current therapies rely on the use of phototherapy and, in unresponsive cases, exchange transfusion, which is performed only in specialized centers. During bilirubin-induced neurotoxicity different molecular pathways are activated, ranging from oxidative stress to endoplasmic reticulum (ER) stress response and inflammation, but the contribution of each pathway in the development of the disease still requires further investigation. Thus, to increase our understanding of the pathophysiology of bilirubin neurotoxicity, encephalopathy and kernicterus, we pharmacologically modulated neurodegeneration and neuroinflammation in a lethal mouse model of neonatal hyperbilirubinemia. Treatment of mutant mice with minocycline, a second-generation tetracycline with anti-inflammatory and neuroprotective properties, resulted in a dose-dependent rescue of lethality, due to reduction of neurodegeneration and neuroinflammation, without affecting plasma bilirubin levels. In particular, rescued mice showed normal motor-coordination capabilities and behavior, as determined by the accelerating rotarod and open field tests, respectively. From the molecular point of view, rescued mice showed a dose-dependent reduction in apoptosis of cerebellar neurons and improvement of dendritic arborization of Purkinje cells. Moreover, we observed a decrease of bilirubin-induced M1 microglia activation at the sites of damage with a reduction in oxidative and ER stress markers in these cells. Collectively, these data indicate that neurodegeneration and neuro-inflammation are key factors of bilirubin-induced neonatal lethality and neuro-behavioral abnormalities. We propose that the application of pharmacological treatments having anti-inflammatory and neuroprotective effects, to be used in combination with the current treatments, may significantly improve the management of acute neonatal hyperbilirubinemia, protecting from bilirubin-induced neurological damage and death.

Antineuroinflammation of Minocycline in Stroke

Accumulating research substantiates the statement that inflammation plays an important role in the development of stroke. Both proinflammatory and anti-inflammatory mediators are involved in the pathogenesis of stroke, an imbalance of which leads to inflammation. Anti-inflammation is a kind of hopeful strategy for the prevention and treatment of stroke. Substantial studies have demonstrated that minocycline, a second-generation semisynthetic antibiotic belonging to the tetracycline family, can inhibit neuroinflammation, inflammatory mediators and microglia activation, and improve neurological outcome. Experimental and clinical data have found the preclinical and clinical potential of minocycline in the treatment of stroke due to its anti-inflammation properties and anti-inflammation-induced pathogeneses, including antioxidative stress, antiapoptosis, inhibiting leukocyte migration and microglial activation, and decreasing matrix metalloproteinases activity. Hence, it suggests a great future for minocycline in the therapeutics of stroke that diminish the inflammatory progress of stroke.

Minocycline diminishes the rotenone induced neurotoxicity and glial activation via suppression of apoptosis, nitrite levels and oxidative stress

The study was conducted to evaluate the effect of minocycline against pesticide rotenone induced adverse effects in different rat brain regions. Assessment of oxidative stress, nitrite levels, degenerating neurons and level of cleaved caspase-3 was done in frontal cortex, mid brain, hippocampus and striatum regions of rat brain. In addition the expression profile of neuronal (MAP2), astrocytes (GFAP) and microglia (cd11b) markers was done after treatments. Rotenone induced DNA fragmentation was also assessed in all studied rat brain regions by utilizing comet assay. Rotenone administration caused significantly decreased level of glutathione along with increased level of nitrite and lipid peroxidation. Significant oxidative and nitrosative stress was also observed after rotenone administration which was considerably inhibited in minocycline treated rats in time dependent manner. Fluorojade staining and levels of cleaved caspase 3 showed the degeneration of neurons and apoptosis respectively in studied rat brain regions which were further inhibited with minocycline treatment. Rotenone administration caused significantly increased reactivity of astrocytes, microglia and altered neuronal morphology in rat brain regions which was also partially restored with minocycline treatment. In conclusion, present study showed that minocycline treatment attenuated the rotenone induced oxidative stress, nitrite level, degeneration of neurons, augmented glial reactivity and apoptosis.

Minocycline promotes the generation of dendritic cells with regulatory properties

Minocycline, which has long been used as a broad-spectrum antibiotic, also exhibits non-antibiotic properties such as inhibition of inflammation and angiogenesis. In this study, we show that minocycline significantly enhances the generation of dendritic cells (DCs) from mouse bone marrow (BM) cells when used together with GM-CSF and IL-4. DCs generated from BM cells in the presence of minocycline (Mino-DCs) demonstrate the characteristics of regulatory DCs. Compared with control DCs, Mino-DCs are resistant to subsequent maturation stimuli, impaired in MHC class II-restricted exogenous Ag presentation, and show decreased cytokine secretion. Mino-DCs also show decreased ability to prime allogeneic-specific T cells, while increasing the expansion of CD4⁺CD25⁺Foxp3⁺ T regulatory cells both in vitro and in vivo. In addition, pretreatment with MOG35-55 peptide-pulsed Mino-DCs ameliorates clinical signs of experimental autoimmune encephalitis induced by MOG peptide injection. Our study identifies minocycline as a new pharmacological agent that could be potentially used to increase the production of regulatory DCs for cell therapy to treat autoimmune disorders, allergy, and transplant rejection.

Unconjugated bilirubin induces pyroptosis in cultured rat cortical astrocytes

Background

Bilirubin-induced neurological dysfunction (BIND), a severe complication of extreme neonatal hyperbilirubinemia, could develop into permanent neurodevelopmental impairments. Several studies have demonstrated that inflammation and nerve cell death play important roles in bilirubin-induced neurotoxicity; however, the underlying mechanism remains unidentified.

Methods

The present study was intended to investigate whether pyroptosis, a highly inflammatory form of programmed cell death, participated in the bilirubin-mediated toxicity on cultured rat cortical astrocytes. Further, VX-765, a potent and selective competitive drug, was used to inhibit the activation of caspase-1. The effects of VX-765 on astrocytes treated with bilirubin, including the cell viability, morphological changes of the cell membrane and nucleus, and the production of pro-inflammation cytokines, were observed.

Results

Stimulation of the astrocytes with unconjugated bilirubin (UCB) at the conditions mimicking those of jaundiced newborns significantly increased the activation of caspase-1. Further, caspase-1 activation was inhibited by treatment with VX-765. Compared with UCB-treated astrocytes, the relative cell viability of VX-765-pretreated astrocytes was improved; meanwhile, the formation of plasma membrane pores was prevented, as measured by lactate dehydrogenase release, trypan blue staining, and ethidium bromide (EtBr) uptake. Moreover, DNA fragmentation was partly attenuated and the release of IL-1β and IL-18 was apparently decreased.

Conclusion

Pyroptosis is involved in the process of UCB-induced rat cortical astrocytes’ injury in vitro and may be the missing link of cell death and inflammatory response exacerbating UCB-related neurotoxicity. More importantly, the depression of caspase-1 activation, the core link of pyroptosis, attenuated UCB-induced cellular dysfunction and cytokine release, which might shed light on a new therapeutic approach to BIND.

Antimanic activity of minocycline in a GBR12909-induced model of mania in mice: Possible role of antioxidant and neurotrophic mechanisms

BACKGROUND

Mania/hypomania is the cardinal feature of bipolar disorder. Recently, single administration of the dopamine transporter (DAT) inhibitor, GBR12909, was related to mania-like alterations. In the present study we aimed at testing behavioral and brain oxidant/neurotrophic alterations induced by the repeated administration of GBR12909 and its prevention/reversal by the mood stabilizing drugs, lithium (Li) and valproate (VAL) as well as by the neuroprotective drug, minocycline (Mino).

METHODS

Adult Swiss mice were submitted to 14 days protocols namely prevention and reversal. In the reversal protocol mice were given GBR12909 or saline and between days 8 and 14 received Li, VAL, Mino (25 or 50mg/kg) or saline. In the prevention treatment, mice were pretreated with Li, VAL, Mino or saline prior to GBR12909.

RESULTS

GBR12909 repeated administration induced hyperlocomotion and increased risk taking behavior that were prevented and reversed by the mood stabilizers and both doses of Mino. Li, VAL or Mino were more effective in the reversal of striatal GSH alterations induced by GBR12909. Regarding lipid peroxidation Mino was more effective in the prevention and reversal of lipid peroxidation in the hippocampus whereas Li and VAL prevented this alteration in the striatum and PFC. Li, VAL and Mino25 reversed the decrease in BDNF levels induced by GBR12909.

CONCLUSION

GBR12909 repeated administration resembles manic phenotype. Similarly to classical mood-stabilizing agents, Mino prevented and reversed GBR12909 manic-like behavior in mice. Thus, our data provide preclinical support to the design of trials investigating Mino's possible antimanic effects.

Neuroinflammatory reactions in sickness behavior induced by bacterial infection: Protective effect of minocycline

The neurological changes elicited by bacterial infection are called sickness behavior. Minocycline (MIN) is neuroprotective with a remarkable brain tissue penetration. MIN was orally administered at a dose 90 mg/kg for 3 days, whereas Escherichia coli was given as a single intraperitoneal injection (0.2 mL of 24 h growth) on the third day. After 24 h of bacterial infection, behavioral tests namely open field and forced swimming were carried out, then animals were decapitated. Rats infected with E. coli displayed reduced struggling time in forced swimming test, as well as, exploration and locomotion in open field test with reduction in neurotransmitters (norepinephrine, dopamine, and serotonin) versus elevation in the inflammatory (tumor necrosis factor-alpha, interferon-gamma) and oxidative stress (thiobarbituric acid reactive substance, reduced glutathione) biomarkers. Inflammatory infiltrates of nuclear cells were observed in brains of infected rats. MIN administration prevented the deleterious effects of E. coli infection, thus protects against sickness behavior possibly via defending from neuroinflammation.