Minocycline: far beyond an antibiotic

Deciphering the Nexus Between Oxidative Stress and Spermatogenesis: A Compendious Overview

Oxidative stress (OS) and reactive oxygen species (ROS) are one of the main reasons for the multifactorial concern - male infertility. ROS are active components of cellular metabolism that are intrinsic to cellular functioning and are present at minimal and unreactive levels in normal cells. They are an integral component of the sperm developmental physiology, capacitation, and function. As said "anything in excess is poison," so is the case with ROS. These, when produced in excess to the antioxidants present in the seminal plasma, cause multiple malformations during the process of spermatogenesis such as lipid peroxidation, interfere with capacitation, sperm DNA fragmentation and damage to the membrane of the sperm which in turn reduces the motility of the sperm and its ability to fuse with the oocyte. Exposure of spermatozoa to oxidative stress is a major causative agent of male infertility. Thus, a delicate balance between the beneficial and detrimental effects of ROS for proper functions is of utter importance. In this chapter, the influence of ROS in OS which is a key player in male infertility along with the diagnosis, available treatment, and prevention of extensive ROS buildup within the spermatozoa are highlighted.

Systemic LPS-induced microglial activation results in increased GABAergic tone: A mechanism of protection against neuroinflammation in the medial prefrontal cortex in mice

Neuroinflammation with excess microglial activation and synaptic dysfunction are early symptoms of most neurological diseases. However, how microglia-associated neuroinflammation regulates synaptic activity remains obscure. We report here that acute neuroinflammation induced by intraperitoneal injection of lipopolysaccharide (LPS) results in cell-type-specific increases in inhibitory postsynaptic currents in the glutamatergic, but not the GABAergic, neurons of medial prefrontal cortex (mPFC), coinciding with excessive microglial activation. LPS causes upregulation in levels of GABA_AR subunits, glutamine synthetase and vesicular GABA transporter, and downregulation in brain-derived neurotrophic factor (BDNF) and its receptor, pTrkB. Blockage of microglial activation by minocycline ameliorates LPS-induced abnormal expression of GABA signaling-related proteins and activity of synaptic and network. Moreover, minocycline prevents the mice from LPS-induced aberrant behavior, such as a reduction in total distance and time spent in the centre in the open field test; decreases in entries into the open arm of elevated-plus maze and in consumption of sucrose; increased immobility in the tail suspension test. Furthermore, upregulation of GABA signaling by tiagabine also prevents LPS-induced microglial activation and aberrant behavior. This study illustrates a mode of bidirectional constitutive signaling between the neural and immune compartments of the brain, and suggests that the mPFC is an important area for brain-immune system communication. Moreover, the present study highlights GABAergic signaling as a key therapeutic target for mitigating neuroinflammation-induced abnormal synaptic activity in the mPFC, together with the associated behavioral abnormalities.

Antioxidant for Neurological Diseases and Neurotrauma and Bioengineering Approaches

Antioxidants are a class of molecules with an innate affinity to neutralize reactive oxygen species (ROS), which are known to cause oxidative stress. Oxidative stress has been associated with a wide range of diseases mediated by physiological damage to the cells. ROS play both beneficial and detrimental roles in human physiology depending on their overall concentration. ROS are an inevitable byproduct of the normal functioning of cells, which are produced as a result of the mitochondrial respiration process. Since the establishment of the detrimental effect of oxidative stress in neurological disorders and neurotrauma, there has been growing interest in exploring antioxidants to rescue remaining or surviving cells and reverse the neurological damage. In this review, we present the survey of different antioxidants studied in neurological applications including neurotrauma. We also delve into bioengineering approaches developed to deliver antioxidants to improve their cellular uptake in neurological applications.

Minocycline Mitigation of Tremor Syndrome and Defect of Cognitive and Balance Induced by Harmaline

Introduction:

Minocycline has anti-inflammatory, anti-apoptotic, and anti-oxidant effects. Preclinical data suggest that minocycline could be beneficial for treating common neurological disorders, including Parkinson disease and multiple sclerosis.

Methods:

In this study, the effects of minocycline on harmaline-induced motor and cognitive impairments were studied in male Wistar rats. The rats were divided into four groups of ten animals each. Harmaline was used for the induction of Essential Tremor (ET). Minocycline (90 mg/kg, IP) was administered 30 minutes before the saline or harmaline. Tremor intensity, spontaneous locomotor activity, passive avoidance memory, anxiety-related behaviors, and motor function were assessed in the rats.

Results:

The results showed that minocycline could recover tremor intensity and step width but failed to recuperate the motor balance. The memory impairments observed in harmaline-treated rats were somewhat reversed by administration of minocycline. The cerebellum and inferior olive nucleus were studied for neuronal degeneration using histochemistry and transmission electron microscopy techniques. Harmaline caused ultrastructural changes and neuronal cell loss in inferior olive and cerebellar Purkinje cells. Minocycline exhibited neuroprotective changes on cerebellar Purkinje cells and inferior olivary neurons.

Conclusion:

These results open new therapeutic perspectives for motor and memory impairments in ET. However, further studies are needed to clarify the exact mechanisms.

Remodeling immune microenvironment in periodontitis using resveratrol liposomes as an antibiotic-free therapeutic strategy

BACKGROUND

Periodontitis is a complicated inflammatory disease that damages the tooth-supporting tissues, with limited pharmacotherapy available. Macrophage-targeting therapy is promising for inflammatory diseases. Resveratrol (RSV), a nonflavonoid polyphenol, is known for its anti-inflammatory and immunomodulatory effects. However, its medical application is limited by its poor stability and water-solubility, as well as its low bioavailability.

RESULT

A therapeutic resveratrol-loaded liposomal system (Lipo-RSV) was developed to treat periodontitis. The physical properties of Lipo-RSV and its ability to regulate macrophages were investigated. The results showed that Lipo-RSV had good biocompatibility and could re-educate the inflammatory macrophages from M1- to M2-like phenotype through activating p-STAT3 and downregulating p-STAT1. Besides, the Lipo-RSV could scavenge ROS and inhibit the NF-κB signal and inflammasomes, thereby reducing the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α.

CONCLUSION

These results revealed that Lipo-RSV could be a potential therapeutic system for the antibiotic-free treatment for periodontal diseases.

Tetracyclines Diminish In Vitro IFN-γ and IL-17-Producing Adaptive and Innate Immune Cells in Multiple Sclerosis

Introduction

Limited data from clinical trials in multiple sclerosis (MS) reported that minocycline, a widely used antibiotic belonging to the family of tetracyclines (TCs), exerts a beneficial short-lived clinical effect A similar anti-inflammatory effect of minocycline attributed to a deviation from Th1 to Th2 immune response has been reported in experimental models of MS. Whether such an immunomodulatory mechanism is operated in the human disease remains largely unknown.

Aim

To assess the in vitro immunomodulatory effect of tetracyclines, and in particular minocycline and doxycycline, in naïve and treated patients with MS.

Material and Methods

Peripheral blood mononuclear cells from 45 individuals (35 MS patients, amongst which 15 naïve patients and 10 healthy controls, HCs) were cultured with minocycline or doxycycline and conventional stimulants (PMA/Ionomycin or IL-12/IL-18). IFN-γ and IL-17 producing T-, NK- and NKT cells were assessed by flow cytometry. The effect of TCs on cell viability and apoptosis was further assessed by flow cytometry with Annexin V staining.

Results

Both tetracyclines significantly decreased, in a dose dependent manner, IFN-γ production in NKT and CD4⁺ T lymphocytes from MS patients (naïve or treated) stimulated with IL-12/IL-18 but did not decrease IFN-γ producing CD8⁺ T cells from naive MS or treated RRMS patients. They also decreased IL-17⁺ T and NKT cells following PMA and Ionomycin-stimulation. Tetracyclines did not affect the viability of cell subsets.

Conclusion

Tetracyclines can in vitro suppress IFN-γ and IL-17- producing cells from MS patients, and this may explain their potential therapeutic effect in vivo.

Persister control by leveraging dormancy associated reduction of antibiotic efflux

Persistent bacterial infections do not respond to current antibiotic treatments and thus present a great medical challenge. These conditions have been linked to the formation of dormant subpopulations of bacteria, known as persister cells, that are growth-arrested and highly tolerant to conventional antibiotics. Here, we report a new strategy of persister control and demonstrate that minocycline, an amphiphilic antibiotic that does not require active transport to penetrate bacterial membranes, is effective in killing Escherichia coli persister cells [by 70.8 ± 5.9% (0.53 log) at 100 μg/mL], while being ineffective in killing normal cells. Further mechanistic studies revealed that persister cells have reduced drug efflux and accumulate more minocycline than normal cells, leading to effective killing of this dormant subpopulation upon wake-up. Consistently, eravacycline, which also targets the ribosome but has a stronger binding affinity than minocycline, kills persister cells by 3 logs when treated at 100 μg/mL. In summary, the findings of this study reveal that while dormancy is a well-known cause of antibiotic tolerance, it also provides an Achilles’ heel for controlling persister cells by leveraging dormancy associated reduction of drug efflux.

Bacterial persister cells are dormant phenotypic variants that are highly tolerant to most antibiotics; and thus, present a major challenge to infection control. This motivated us to develop new strategies that can specifically target the persister population. It is known that persister formation is associated with reduced membrane potential and cellular activities. Thus, we hypothesize that persister cells have reduced drug efflux compared to normal cells and accumulate more antimicrobial agents that can penetrate the membranes of persister cells. By testing this hypothesis, we developed a new set of criteria for selecting persister control agents and demonstrated effective control of Escherichia coli persister cells by minocycline, rifamycin SV, and eravacycline. Our results revealed that these agents are more effective against persister cells than normal cells and the killing occurred during persister wake-up. Collectively, these results demonstrate a new strategy for persister control by leveraging dormancy associated changes in bacterial physiology. The findings may contribute to future drug discovery and the treatment of persistent infections.

The Development of Third-Generation Tetracycline Antibiotics and New Perspectives

The tetracycline antibiotic class has acquired new valuable members due to the optimisation of the chemical structure. The first modern tetracycline introduced into therapy was tigecycline, followed by omadacycline, eravacycline, and sarecycline (the third generation). Structural and physicochemical key elements which led to the discovery of modern tetracyclines are approached. Thus, several chemical subgroups are distinguished, such as glycylcyclines, aminomethylcyclines, and fluorocyclines, which have excellent development potential. The antibacterial spectrum comprises several resistant bacteria, including those resistant to old tetracyclines. Sarecycline, a narrow-spectrum tetracycline, is notable for being very effective against Cutinebacterium acnes. The mechanism of antibacterial action from the perspective of the new compound is approached. Several severe bacterial infections are treated with tigecycline, omadacycline, and eravacycline (with parenteral or oral formulations). In addition, sarecycline is very useful in treating acne vulgaris. Tetracyclines also have other non-antibiotic properties that require in-depth studies, such as the anti-inflammatory effect effect of sarecycline. The main side effects of modern tetracyclines are described in accordance with published clinical studies. Undoubtedly, this class of antibiotics continues to arouse the interest of researchers. As a result, new derivatives are developed and studied primarily for the antibiotic effect and other biological effects.

Minocycline Extended-Release Comparison with Doxycycline for the Treatment of Rosacea: A Randomized, Head-to-Head, Clinical Trial

OBJECTIVE

Minocycline efficacy for the treatment of papulopustular rosacea (PPR) has not been evaluated in clinical trials at levels demonstrated to stay below the antimicrobial threshold. We assessed the efficacy, safety, and dose response of DFD-29, a minocycline extended-release oral capsule. Two studies are reported (NCT03340961).

METHODS

A single-center open-label, three-arm, Phase I pharmacokinetic study randomized 24 healthy subjects aged 18 to 45 years to receive 21 days of once-daily dosing with DFD-29 40 or 20mg, or doxycycline 40mg. Blood samples were collected over 24 hours on Days 1 and 21 to plot mean plasma concentration levels. A multicenter Phase II clinical trial randomized 205 subjects with mild-to-severe PPR 1:1:1:1 to receive once-daily DFD-29 40 or 20mg, doxycycline 40mg, or placebo for 16 weeks. Co-primary endpoints were the proportion of subjects achieving treatment success (IGA grade 0 or 1 and ≥2-grade improvement) at Week 16, and a reduction in total inflammatory lesion count at Week 16.

RESULTS

Pharmacokinetic analysis demonstrated that minocycline plasma levels of DFD-29 40mg were approximately half those of doxycycline 40mg after 21 days, with DFD-29 20mg even lower, demonstrating a dose response. In the Phase II trial, DFD-29 40mg met both co-primary endpoints, achieving IGA treatment success in 66.0 percent subjects versus 11.5 percent placebo (p<0.0001), 31.9 percent DFD-29 20mg (p=0.007), and 33.3 percent doxycycline 40mg (p<0.0010), and a mean reduction in lesion counts of -19.2 versus -7.3 placebo (p<0.0001), -12.6 DFD-29 20mg (p=0.0070), and -10.5 doxycycline 40mg (p=0.0004).

LIMITATIONS

MIC values and plasma concentrations shown for antibacterial threshold data are mean values; fast absorbers/slow metabolizers could exceed the threshold, causing resistance selection pressure.

CONCLUSION

DFD-29 40mg demonstrated significantly greater efficacy than placebo, DFD-29 20mg, and doxycycline 40mg at plasma concentrations predicted to be below the antimicrobial threshold for the treatment of PPR.

Ketogenic diet-induced prurigo pigmentosa: a rising association

Prurigo pigmentosa (PP) is an uncommon inflammatory dermatosis first described in 1971. It is characterized by recurrent crops of pruritic erythematous papulovesicles that resolve with a macular reticulated hyperpigmentation. The exact etiology is yet to be determined, however with the expanded application of the ketogenic diet (KD) in recent years, conditions accompanied with ketosis are more commonly being described in association with PP. Antibiotics as well as resolution of ketosis can effectively treat the dermatitis. Given the publicity and growing popularity of the ketogenic diet and numerous references to the "Keto-Rash" on social media, we reviewed the KD-induced PP cases to raise awareness of this increasingly recognized entity and provide an update to clinicians, particularly dermatologists, regarding this possible side effect of KD.

Tunable control of CAR T cell activity through tetracycline mediated disruption of protein-protein interaction

Chimeric antigen receptor (CAR) T cells are a promising form of cancer immunotherapy, although they are often associated with severe toxicities. Here, we present a split-CAR design incorporating separate antigen recognition and intracellular signaling domains. These exploit the binding between the tetracycline repressor protein and a small peptide sequence (TIP) to spontaneously assemble as a functional CAR. Addition of the FDA-approved, small molecule antibiotic minocycline, acts as an "off-switch" by displacing the signaling domain and down-tuning CAR T activity. Here we describe the optimization of this split-CAR approach to generate a CAR in which cytotoxicity, cytokine secretion and proliferation can be inhibited in a dose-dependent and reversible manner. Inhibition is effective during on-going CAR T cell activation and inhibits activation and tumor control in vivo. This work shows how optimization of split-CAR structure affects function and adds a novel design allowing easy CAR inhibition through an FDA-approved small molecule.

In vitro synergistic effect of minocycline combined with antifungals against Cryptococcus neoformans

BACKGROUND

Cryptococcus neoformans infections occur in immunocompromised patients, especially those with HIV infection, chemoradiotherapy after cancer, and organ transplantation. Infection can cause pneumonia and meningoencephalitis in severe cases with a high mortality rate if not treated. Although fluconazole and amphotericin B are the first-line treatments for cryptococcosis, the rate of fluconazole resistance has increased significantly due to long-term use. Minocycline is a derivative of tetracycline that exerts its antibacterial effect through inhibition of bacterial protein synthesis. It is also able to pass the blood-brain barrier to act on the central nervous system. The present study investigates the effects of minocycline in combination with antifungals in treating C. neoformans.

OBJECTIVE

To determine in vitro interactions of minocycline combined with itraconazole, voriconazole, posaconazole, fluconazole and amphotericin B against C. neoformans.

METHODS

The minimum inhibitory concentrations (MIC) of the antifungals were determined by the CLSI Clinical and Laboratory Standards Institute M27-A3 microdilution method. The in vitro synergistic effects of minocycline combined with itraconazole, voriconazole, posaconazole, fluconazole, and amphotericin B on C. neoformans were detected by the broth microdilution checkerboard technique and disk diffusion testing.

RESULTS AND CONCLUSION

The working concentration ranges were 0.125-4 µg/mL for itraconazole, 0.03-0.125 µg/ml for voriconazole, 0.03-1 µg/ml for posaconazole, 0.25-16 µg/ml for fluconazole, and 0.125-2 µg/ml for amphotericin B. The synergistic rates of minocycline combinations against C. neoformans were 55% with itraconazole, 10% with voriconazole, 85% with posaconazole, 20% with fluconazole, and 70% with amphotericin B. The effective MIC value of minocycline in the synergistic combination decreased to 2-32 µg/ml, while the MIC of itraconazole decreased to 0.03-0.125 µg/ml, voriconazole 0.03-0.125 µg/ml, posaconazole 0.03-0.125 µg/ml, 0.125-4 µg/ml fluconazole, and 0.06-0.50 µg/ml amphotericin B. The disk diffusion assay showed that the plates containing minocycline and antifungal drugs produced inhibition zones with diameters larger than the single drug plates. Minocycline showed no antagonistic effect in the combinations. In conclusion, the combination of minocycline and azoles or amphotericin B has synergistic effects against C. neoformans in vitro.

Minocycline attenuates excessive DNA damage response and reduces ectopic calcification in pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a hereditary ectopic calcification disorder affecting the skin, eyes and blood vessels. Recently, the DNA damage response (DDR), in particular poly(ADP-ribose) polymerase 1 (PARP1), was shown to be involved in aberrant mineralization raising the hypothesis that excessive DDR/PARP1 signaling also contributes to PXE pathogenesis. Using PXE patient and control fibroblasts, (lesional) skin tissue and abcc6a^-/- zebrafish, we performed expression analysis of DDR/PARP1 targets with QRT-PCR, western blot, immunohistochemistry and enzyme activity assays; before and after treatment with the PARP1 inhibitor minocycline. PARP1 and the ATM-p21-p53 axis was found to be significantly increased in PXE. Additionally, PARP1 downstream targets IL-6, STAT1/3, TET1 and RUNX2 were upregulated while the RUNX2-antagonist microRNA-204 was decreased. In PXE fibroblasts, DDR/PARP1 signaling increased with advancing ectopic calcification. Minocycline treatment attenuated DDR/PARP1 overexpression and reduced aberrant mineralization in PXE fibroblasts and abcc6a^-/- zebrafish. In summary, we demonstrated the involvement of excessive DDR/PARP1 signaling in PXE pathophysiology, identifying a STAT-driven cascade resulting in increased expression of the epigenetic modifier TET1 and pro-calcifying transcription factor RUNX2. Minocycline attenuated this deleterious molecular mechanism and reduced ectopic calcification both in vitro and in vivo, fueling the exciting prospect of a novel therapeutic compound for PXE.

Effects of minocycline on macrolide-unresponsive Mycoplasma pneumoniae pneumonia in children: a single-center retrospective study

BACKGROUND

Macrolide-resistant Mycoplasma pneumoniae (Mp) has become widespread in the world. We sought to determine the independently associated risk factors for refractory Mp pneumonia among macrolide-unresponsive Mp pneumonia children treated with minocycline and to investigate the effects of minocycline against macrolide-unresponsive Mp pneumonia.

METHODS

In our center, we retrospectively analyzed the data of hospitalized macrolide-unresponsive Mp pneumonia patients aged ≤18 years old who changed macrolide therapies to minocycline treatments between March 2013 and September 2018. Patient characteristics and defervescence after minocycline treatment were compared between refractory Mp pneumonia and non-refractory Mp pneumonia groups. Multivariable logistic regression analysis was performed among these macrolide-unresponsive Mp pneumonia patients.

RESULTS

Among 150 included macrolide-unresponsive Mp pneumonia children treated with minocycline; 30 cases (20.0%) were refractory Mp pneumonia. Duration of macrolide treatment before administration of minocycline (odds ratio =2.87, 95% CI: 1.79-4.61, P<0.001) and serum procalcitonin levels (odds ratio =13.50, 95% CI: 1.22-149.57, P=0.034) were independently associated with refractory Mp pneumonia. Defervescence after minocycline treatment was significantly longer among the refractory Mp pneumonia group than in the non-refractory Mp pneumonia group (median 2 vs. 1 day, P<0.001). Only one case (0.7%) suspected of a side effect of minocycline therapy was observed.

CONCLUSIONS

Two risk factors independently associated with refractory Mp pneumonia were determined. Early use of minocycline might safely prevent macrolide-unresponsive Mp pneumonia from progressing to refractory Mp pneumonia.

Neuroprotection of minocycline by inhibition of extracellular matrix metalloproteinase inducer expression following intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) is a severe neurological dysfunction and a medical emergency with a high mortality rate. Minocycline ameliorates deficits in rodent models of acute and chronic neurological diseases. However, the role of minocycline in ICH remains unclear. The extracellular matrix metalloproteinase inducer (EMMPRIN) is a key inflammatory mediator in some neurological diseases, triggering matrix metalloproteinases (MMPs) production. In this study, we aimed to use minocycline to inhibit EMMPRIN and thus the activity of MMPs. Male adult C57BL/6 mice were injected with collagenase type VII or saline into the right basal ganglia and euthanized at different time points. The minocycline was intraperitoneally injected once every 12 h for three days to block the expression of EMMPRIN from two hours after ICH. We found that breakdown of the BBB was most severe 3 days after ICH. The minocycline treatment significantly decreased EMMPRIN and MMP-9 expression, reduced zonula occludens-1 and occludin, and alleviated BBB disruption. Moreover, minocycline treatment displayed a lower brain water content, lesser neurological dysfunction, and smaller injury volume on day 3 than those of the vehicle-treated group. Minocycline also inhibited the activation of microglia/macrophages, infiltration of neutrophils, and production of inflammatory mediators, including tumor necrosis factor alpha and interleukin-1beta. The current study shows that minocycline exhibits protective roles in ICH by decreasing EMMPRIN and MMP-9 expression, alleviating BBB disruption, inhibiting neuroinflammation, areducing neuronal degeneration and death.

Local delivery strategies to restore immune homeostasis in the context of inflammation

Immune homeostasis is maintained by a precise balance between effector immune cells and regulatory immune cells. Chronic deviations from immune homeostasis, driven by a greater ratio of effector to regulatory cues, can promote the development and propagation of inflammatory diseases/conditions (i.e., autoimmune diseases, transplant rejection, etc.). Current methods to treat chronic inflammation rely upon systemic administration of non-specific small molecules, resulting in broad immunosuppression with unwanted side effects. Consequently, recent studies have developed more localized and specific immunomodulatory approaches to treat inflammation through the use of local biomaterial-based delivery systems. In particular, this review focuses on (1) local biomaterial-based delivery systems, (2) common materials used for polymeric-delivery systems and (3) emerging immunomodulatory trends used to treat inflammation with increased specificity.

Antimicrobial-induced oral dysbiosis exacerbates naturally occurring alveolar bone loss

Periodontitis-mediated alveolar bone loss is caused by dysbiotic shifts in the commensal oral microbiota that upregulate proinflammatory osteoimmune responses. The study purpose was to determine whether antimicrobial-induced disruption of the commensal microbiota has deleterious effects on alveolar bone. We administered an antibiotic cocktail, minocycline, or vehicle-control to sex-matched C57BL/6T mice from age 6- to 12 weeks. Antibiotic cocktail and minocycline had catabolic effects on alveolar bone in specific-pathogen-free (SPF) mice. We then administered minocycline or vehicle-control to male mice reared under SPF and germ-free conditions, and we subjected minocycline-treated SPF mice to chlorhexidine oral antiseptic rinses. Alveolar bone loss was greater in vehicle-treated SPF versus germ-free mice, demonstrating that the commensal microbiota drives naturally occurring alveolar bone loss. Minocycline- versus vehicle-treated germ-free mice had similar alveolar bone loss outcomes, implying that antimicrobial-driven alveolar bone loss is microbiota dependent. Minocycline induced phylum-level shifts in the oral bacteriome and exacerbated naturally occurring alveolar bone loss in SPF mice. Chlorhexidine further disrupted the oral bacteriome and worsened alveolar bone loss in minocycline-treated SPF mice, validating that antimicrobial-induced oral dysbiosis has deleterious effects on alveolar bone. Minocycline enhanced osteoclast size and interface with alveolar bone in SPF mice. Neutrophils and plasmacytoid dendritic cells were upregulated in cervical lymph nodes of minocycline-treated SPF mice. Paralleling the upregulated proinflammatory innate immune cells, minocycline therapy increased TH 1 and TH 17 cells that have known pro-osteoclastic actions in the alveolar bone. This report reveals that antimicrobial perturbation of the commensal microbiota induces a proinflammatory oral dysbiotic state that exacerbates naturally occurring alveolar bone loss.

Pharmacotherapy of schizophrenia: immunological aspects and potential role of immunotherapy

INTRODUCTION

Schizophrenia is a complex disorder owing to diversity in clinical phenotypes, overlapping symptoms, and heterogeneous clinical presentation. Even after decades of research, the exact causative mechanisms of schizophrenia are not completely known. Recent evidence indicates the role of immune dysfunction in schizophrenia pathogenesis as observed from alteration in immune cells, increased activity of complement cascade, and development of autoantibodies against neurotransmitter receptors. Immunotherapy involving immunosuppressants and cytokine-targeting drugs, have shown promising results in several clinical studies and it demands further research in this area.

AREAS COVERED

Here, the authors review the immunopathogenesis of schizophrenia, limitations of conventional, and atypical antipsychotic drugs and the potential role and limitations of immunotherapeutic drugs in schizophrenia management.

EXPERT OPINION

Schizophrenia is a complex disorder and poses a challenge to the currently available treatment approaches. Nearly 30% schizophrenia patients exhibit minimal response toward conventional and atypical antipsychotic drugs. Immune system dysfunction plays an important part of schizophrenia pathophysiology and existing monoclonal antibody (mAb) drugs targeting specific components of the immune system are being repositioned in schizophrenia. The authors call upon public and private funders to facilitate urgent and rigorous research efforts in exploring potential role of immunotherapy in schizophrenia.

A Review of the Impact of Alterations in Gut Microbiome on the Immunopathogenesis of Ocular Diseases

Recent studies have highlighted the association between ocular diseases and microbiota profiles of the host intestinal tract and oral cavity. There is mounting evidence supporting the existence of a 'gut-eye axis', whereby changes in gut microbiome alter host immunity, with consequential implications for ocular health and disease. In this review, we examined recent published findings on the association between gut microbiome and ocular morbidity, based on 25 original articles published between 2011 to 2020. The review included both clinical and in vivo animal studies, with particular focus on the influence of the microbiome on host immunity and metabolism. Significant associations between altered intestinal microbiome and specific ocular diseases and pathological processes, including Behçet's syndrome, autoimmune uveitis, age-related macular degeneration, choroidal neovascularization, bacterial keratitis, and Sjögren-like lacrimal keratoconjunctivitis have been demonstrated. Furthermore, alterations in the gut microbiome resulted in quantifiable changes in the host immune response, suggesting immunopathogenesis as the basis for the link between intestinal dysbiosis and ocular disease. We also examined and compared different techniques used in the identification and quantification of gut microorganisms. With our enhanced understanding of the potential role of gut commensals in ophthalmic disease, the stage is set for further studies on the underlying mechanisms linking the gut microbiome, the host immune response, and the pathogenesis of ophthalmic disease.

Peptostreptococcus anaerobius: Pathogenicity, identification, and antimicrobial susceptibility. Review of monobacterial infections and addition of a case of urinary tract infection directly identified from a urine sample by MALDI-TOF MS

Peptostreptococcus anaerobius is a gram-positive anaerobic coccus (GPAC) found in the gastrointestinal and vaginal microbiota. The organism is mainly found in polymicrobial and scarcely in monobacterial infections such as prosthetic and native endocarditis. Anaerobic bacteria have rarely been reported as the cause of urinary tract infection (UTI). Although GPAC are susceptible to most antimicrobials used against anaerobic infections, P. anaerobius has shown to be more resistant. Herein, we report a case of UTI caused by P. anaerobius from a 62-year-old man with a history of urological disease. Surprisingly, the microorganism was directly identified by Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) from the urine sample. The isolate was successfully identified by phenotypic methods, MALDI-TOF MS, and 16S rRNA gene sequencing. P. anaerobius showed no β-lactamase-producing activity, was resistant to penicillin, ampicillin, ciprofloxacin and levofloxacin, and displayed intermediate susceptibility to ampicillin-sulbactam and amoxicillin-clavulanic acid. Successful treatment was achieved with oral amoxicillin-clavulanic acid. Antimicrobial susceptibility testing (AST) should be performed on P. anaerobius isolates due to their unpredictable AST patterns and because empirically administered antimicrobial agents may not be active. This report shows that MALDI-TOF MS, directly used in urine specimens, may be a quick option to diagnose UTI caused by P. anaerobius or other anaerobic bacteria. This review is a compilation of monobacterial infections caused by P. anaerobius published in the literature, their pathogenicity, identification, and data about the antimicrobial susceptibility of P. anaerobius.

Traumatic Brain Injury: An Age-Dependent View of Post-Traumatic Neuroinflammation and Its Treatment

Traumatic brain injury (TBI) is a leading cause of death and disability all over the world. TBI leads to (1) an inflammatory response, (2) white matter injuries and (3) neurodegenerative pathologies in the long term. In humans, TBI occurs most often in children and adolescents or in the elderly, and it is well known that immune responses and the neuroregenerative capacities of the brain, among other factors, vary over a lifetime. Thus, age-at-injury can influence the consequences of TBI. Furthermore, age-at-injury also influences the pharmacological effects of drugs. However, the post-TBI inflammatory, neuronal and functional consequences have been mostly studied in experimental young adult animal models. The specificity and the mechanisms underlying the consequences of TBI and pharmacological responses are poorly understood in extreme ages. In this review, we detail the variations of these age-dependent inflammatory responses and consequences after TBI, from an experimental point of view. We investigate the evolution of microglial, astrocyte and other immune cells responses, and the consequences in terms of neuronal death and functional deficits in neonates, juvenile, adolescent and aged male animals, following a single TBI. We also describe the pharmacological responses to anti-inflammatory or neuroprotective agents, highlighting the need for an age-specific approach to the development of therapies of TBI.

Immune treatments for alcohol use disorder: A translational framework

While the immune system is essential for survival, an excessive or prolonged inflammatory response, such as that resulting from sustained heavy alcohol use, can damage the host and contribute to psychiatric disorders. A growing body of literature indicates that the immune system plays a critical role in the development and maintenance of alcohol use disorder (AUD). As such, there is enthusiasm for treatments that can restore healthy levels of inflammation as a mechanism to reduce drinking and promote recovery. In this qualitative literature review, we provide a conceptual rationale for immune therapies and discuss progress in medications development for AUD focused on the immune system as a treatment target. This review is organized into sections based on primary signaling pathways targeted by the candidate therapies, namely: (a) toll-like receptors, (b) phosphodiesterase inhibitors, (c) peroxisome proliferator-activated receptors, (d) microglia and astrocytes, (e) other immune pharmacotherapies, and (f) behavioral therapies. As relevant within each section, we examine the basic biological mechanisms of each class of therapy and evaluate preclinical research testing the role of the therapy on mitigating alcohol-related behaviors in animal models. To the extent available, translational findings are reviewed with discussion of completed and ongoing randomized clinical trials and their findings to date. An applied and clinically focused approach is taken to identify the potential clinical applications of the various treatments reviewed. We conclude by delineating the most promising candidate treatments and discussing future directions by considering opportunities for immune treatment development and personalized medicine for AUD.

Inflammation plays a causal role in fatigue-like behavior induced by pelvic irradiation in mice

Fatigue is a persistent and debilitating symptom following radiation therapy for prostate cancer. However, it is not well-understood how radiation targeted to a small region of the body can lead to broad changes in behavior. In this study, we used targeted pelvic irradiation of healthy male mice to test whether inflammatory signaling mediates changes in voluntary physical activity levels. First, we tested the relationship between radiation dose, blood cell counts, and fatigue-like behavior measured as voluntary wheel-running activity. Next, we used oral minocycline treatments to reduce inflammation and found that minocycline reduces, but does not eliminate, the fatigue-like behavioral changes induced by radiation. We also used a strain of mice lacking the MyD88 adaptor protein and found that these mice also showed less fatigue-like behavior than the wild-type controls. Finally, using serum and brain tissue samples, we determined changes in inflammatory signaling induced by irradiation in wild-type, minocycline treated, and MyD88 knockout mice. We found that irradiation increased serum levels of IL-6, a change that was partially reversed in mice treated with minocycline or lacking MyD88. Overall, our results suggest that inflammation plays a causal role in radiation-induced fatigue and that IL-6 may be an important mediator.

Effects of adiposity on the human plasma proteome: observational and Mendelian randomisation estimates

BACKGROUND

Variation in adiposity is associated with cardiometabolic disease outcomes, but mechanisms leading from this exposure to disease are unclear. This study aimed to estimate effects of body mass index (BMI) on an extensive set of circulating proteins.

METHODS

We used SomaLogic proteomic data from up to 2737 healthy participants from the INTERVAL study. Associations between self-reported BMI and 3622 unique plasma proteins were explored using linear regression. These were complemented by Mendelian randomisation (MR) analyses using a genetic risk score (GRS) comprised of 654 BMI-associated polymorphisms from a recent genome-wide association study (GWAS) of adult BMI. A disease enrichment analysis was performed using DAVID Bioinformatics 6.8 for proteins which were altered by BMI.

RESULTS

Observationally, BMI was associated with 1576 proteins (P < 1.4 × 10-5), with particularly strong evidence for a positive association with leptin and fatty acid-binding protein-4 (FABP4), and a negative association with sex hormone-binding globulin (SHBG). Observational estimates were likely confounded, but the GRS for BMI did not associate with measured confounders. MR analyses provided evidence for a causal relationship between BMI and eight proteins including leptin (0.63 standard deviation (SD) per SD BMI, 95% CI 0.48-0.79, P = 1.6 × 10-15), FABP4 (0.64 SD per SD BMI, 95% CI 0.46-0.83, P = 6.7 × 10-12) and SHBG (-0.45 SD per SD BMI, 95% CI -0.65 to -0.25, P = 1.4 × 10-5). There was agreement in the magnitude of observational and MR estimates (R2 = 0.33) and evidence that proteins most strongly altered by BMI were enriched for genes involved in cardiovascular disease.

CONCLUSIONS

This study provides evidence for a broad impact of adiposity on the human proteome. Proteins strongly altered by BMI include those involved in regulating appetite, sex hormones and inflammation; such proteins are also enriched for cardiovascular disease-related genes. Altogether, results help focus attention onto new proteomic signatures of obesity-related disease.

Minocycline in Major Depressive Disorder: And overview with considerations on treatment-resistance and comparisons with other psychiatric disorders

Evidence on the link between the immune system and Major Depressive Disorder (MDD) has led to explore antidepressant properties of anti-inflammatory drugs. Among these, minocycline has been identified as a potential novel treatment for MDD, in particular for treatment-resistant depression. The aim of the current paper is to review current pre-clinical and clinical evidence on the antidepressant efficacy of minocycline. The review includes considerations on the role of both peripheral and central inflammation in the response to minocycline and comparisons of minocycline efficacy across different psychiatric disorders (i.e., unipolar depression, bipolar depression, and schizophrenia).

Apoptosis and its therapeutic implications in neurodegenerative diseases

Neurodegenerative disorders are characterized by progressive loss of particular populations of neurons. Apoptosis has been implicated in the pathogenesis of neurodegenerative diseases, including Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. In this review, we focus on the existing notions relevant to comprehending the apoptotic death process, including the morphological features, mediators and regulators of cellular apoptosis. We also highlight the evidence of neuronal apoptotic death in Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. Additionally, we present evidence of potential therapeutic agents that could modify the apoptotic pathway in the aforementioned neurodegenerative diseases and delay disease progression. Finally, we review the clinical trials that were conducted to evaluate the use of anti-apoptotic drugs in the treatment of the aforementioned neurodegenerative diseases, in order to highlight the essential need for early detection and intervention of neurodegenerative diseases in humans.

Microglia and BDNF at the crossroads of stressor related disorders: Towards a unique trophic phenotype

Stressors ranging from psychogenic/social to neurogenic/injury to systemic/microbial can impact microglial inflammatory processes, but less is known regarding their effects on trophic properties of microglia. Recent studies do suggest that microglia can modulate neuronal plasticity, possibly through brain derived neurotrophic factor (BDNF). This is particularly important given the link between BDNF and neuropsychiatric and neurodegenerative pathology. We posit that certain activated states of microglia play a role in maintaining the delicate balance of BDNF release onto neuronal synapses. This focused review will address how different "activators" influence the expression and release of microglial BDNF and address the question of tropomyosin receptor kinase B (TrkB) expression on microglia. We will then assess sex-based differences in microglial function and BDNF expression, and how microglia are involved in the stress response and related disorders such as depression. Drawing on research from a variety of other disorders, we will highlight challenges and opportunities for modulators that can shift microglia to a "trophic" phenotype with a view to potential therapeutics relevant for stressor-related disorders.

Cellular targets in diabetic retinopathy therapy

Despite the existence of treatment for diabetes, inadequate metabolic control triggers the appearance of chronic complications such as diabetic retinopathy. Diabetic retinopathy is considered a multifactorial disease of complex etiology in which oxidative stress and low chronic inflammation play essential roles. Chronic exposure to hyperglycemia triggers a loss of redox balance that is critical for the appearance of neuronal and vascular damage during the development and progression of the disease. Current therapies for the treatment of diabetic retinopathy are used in advanced stages of the disease and are unable to reverse the retinal damage induced by hyperglycemia. The lack of effective therapies without side effects means there is an urgent need to identify an early action capable of preventing the development of the disease and its pathophysiological consequences in order to avoid loss of vision associated with diabetic retinopathy. Therefore, in this review we propose different therapeutic targets related to the modulation of the redox and inflammatory status that, potentially, can prevent the development and progression of the disease.

[In vivo study of liposome-modified polyetheretherketone implant on bacteriostasis and osseointegration]

OBJECTIVE

To develop dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes) and apply them to improve bioinert polyetheretherketone (PEEK) surface, which could prevent post-operative bacterial contamination, enhance ossification for physiologic osseointegration, and finally reduce implant failure rates.

METHODS

Dex/Mino liposomes were covalently grafted onto the PEEK surface using polydopamine (pDA) coating as a medium. Confocal laser scanning microscopy was used to confirm the binding of fluorescently labeled liposomes onto the PEEK substrate, and a microplate reader was used to semiquantitatively measure the average fluorescence intensity of fluorescently labeled liposome-decorated PEEK surfaces. Moreover, the mouse subcutaneous infection model and the beagle femur implantation model were respectively conducted to verify the bioactivity of Dex/Mino liposome-modified PEEK in vivo, by means of micro computed tomography (micro-CT) and hematoxylin and eosin (HE) staining analysis.

RESULTS

The qualitative and quantitative results of fluorescently labeled liposomes showed that, the red fluorescence intensity of the PEEK-pDA-lipo group was stronger than that of the PEEK-NF-lipo group (P < 0.05); the liposomes were successfully and uniformly decorated on the PEEK surfaces due to the pDA coating. After mouse subcutaneous implantation of PEEKs for 24 hours, HE staining results showed that the number of inflammatory cells in the PEEK-Dex/Mino lipo group were lower than that in the inert PEEK group (P < 0.05), indicating a lower degree of infection in the test group. These results suggested that the Mino released from the liposome-functionalized surface provided an effective bacteriostasis in vivo. After beagle femoral implantation of PEEK for 8 weeks, micro-CT results showed that the PEEK-Dex/Mino lipo group newly formed more continuous bone when compared with the inert PEEK group; HE staining results showed that more new bones were formed in the PEEK-Dex/Mino lipo group than in the inert PEEK group, which were firmly bonded to the functionalized PEEK surface and extended along the PEEK interface. These results suggested that the Dex released from the liposome-functionalized surface induced effective bone regeneration in vivo.

CONCLUSION

Dex/Mino liposome modification enhanced the bioactivity of inert PEEK, the functionalized PEEK with enhanced antibacterial and osseointegrative capacity has great potential as an orthopedic/dental implant material for clinical application.

Oral Minocycline Therapy Improves Symptoms of Myalgic Encephalomyelitis, Especially in the Initial Disease Stage

Objective Central nervous system dysfunction associated with myalgic encephalomyelitis (ME) has been suggested to be the main cause of chronic fatigue syndrome. In animal models of chronic fatigue, minocycline was reported to act as a suppressor of neural inflammation. Minocycline may thus exert favorable therapeutic effects in patients with ME. Methods Oral minocycline (100 mg×2 on the first day, followed by 100 mg/day for 41 days) was administered to 100 patients with ME. The performance status score (0-9), orthostatic intolerance during the 10-min standing test, neurologic disequilibrium, and neuropathic pain were compared before and after treatment. Results After therapy completion, favorable effects were observed with a decrease in the performance status score of ≥2 points in 27 patients (27%). Before treatment, 6 of the 27 patients had orthostatic intolerance with an inability to complete the 10-min standing test; after treatment, this symptom resolved in 4 and improved in 2 patients. In addition, after treatment, postural orthostatic tachycardia resolved in five of eight patients, disequilibrium resolved in five of eight patients, and fibromyalgia or neuropathic pain was attenuated in four of five patients. The favorable effects appeared dependent on a shorter disease duration, primarily for a duration of less than three years and most frequently within six months of the disease onset. However, acute adverse effects with nausea and/or dizziness caused 38 patients (38%) to discontinue treatment in the first few days. Conclusion Oral minocycline therapy may be an effective treatment option for patients with ME, especially in the initial stage of the disease.

Mitochondrial Proteostasis Requires Genes Encoded in a Neurodevelopmental Syndrome Locus

Eukaryotic cells maintain proteostasis through mechanisms that require cytoplasmic and mitochondrial translation. Genetic defects affecting cytoplasmic translation perturb synapse development, neurotransmission, and are causative of neurodevelopmental disorders, such as Fragile X syndrome. In contrast, there is little indication that mitochondrial proteostasis, either in the form of mitochondrial protein translation and/or degradation, is required for synapse development and function. Here we focus on two genes deleted in a recurrent copy number variation causing neurodevelopmental disorders, the 22q11.2 microdeletion syndrome. We demonstrate that SLC25A1 and MRPL40, two genes present in the microdeleted segment and whose products localize to mitochondria, interact and are necessary for mitochondrial ribosomal integrity and proteostasis. Our Drosophila studies show that mitochondrial ribosome function is necessary for synapse neurodevelopment, function, and behavior. We propose that mitochondrial proteostasis perturbations, either by genetic or environmental factors, are a pathogenic mechanism for neurodevelopmental disorders.SIGNIFICANCE STATEMENT The balance between cytoplasmic protein synthesis and degradation, or cytoplasmic proteostasis, is required for normal synapse function and neurodevelopment. Cytoplasmic and mitochondrial ribosomes are necessary for two compartmentalized, yet interdependent, forms of proteostasis. Proteostasis dependent on cytoplasmic ribosomes is a well-established target of genetic defects that cause neurodevelopmental disorders, such as autism. Here we show that the mitochondrial ribosome is a neurodevelopmentally regulated organelle whose function is required for synapse development and function. We propose that defective mitochondrial proteostasis is a mechanism with the potential to contribute to neurodevelopmental disease.

The gut-microbiome as a target for the treatment of schizophrenia: A systematic review and meta-analysis of randomised controlled trials of add-on strategies

The gut-microbiome has been hypothesised as a novel potential target for intervention for schizophrenia. We tested this hypothesis with a systematic review and meta-analysis of studies investigating the efficacy and acceptability of add-on strategies known to affect the gut-microbiome for the treatment of schizophrenia. Following PRISMA guidelines, we searched from inception to August 2019 all the randomised double-blind controlled trials of add-on antibiotics, antimicrobials, pre/probiotics, and faecal transplant in schizophrenia. Primary outcomes were severity of negative symptoms and acceptability of treatment. Data were independently extracted by multiple observers and a random-mixed model was used for the analysis. Heterogeneity was assessed with the I² index. We identified 28 eligible trials: 21 investigated antibiotics, 4 antimicrobials (Artemisinin, Artemether, and Sodium Benzoate), 3 pre/probiotics, none faecal transplant. Results showed no effect of D-Cycloserine (10 studies; SMD, -0.16; 95% CI -0.40, 0.08; P = .20; I²: 28.2%), Minocycline (7 studies; SMD: -0.35; 95% CI -0.70, 0.00; P = .05, I²:77.7%), other antibiotics (2 studies), probiotics alone (1 study), and Artemisinin (1 study) on negative symptoms of schizophrenia when compared to placebo. Limited evidence suggests efficacy on negative symptoms for Sodium benzoate (2 studies; SMD, -0.63; 95%CI -1.03, -0.23; P < .001; I²:0%), Artemether (1 study), and probiotics combined with Vitamin D (1 study) when compared to placebo. Acceptability of intervention was similar to placebo. Negative findings were mainly led by antibiotics trials, with paucity of evidence available on pre/probiotics. There is a need of expanding our knowledge on the clinical relevance of gut-microbiome-host interaction in psychosis before engaging in further trials.

Nonantibiotic Properties of Tetracyclines in Rosacea and Their Clinical Implications

Rosacea is one of the most common inflammatory skin diseases in the United States, with a complex pathophysiology. One of the major components of the pathophysiology of rosacea is an abnormal immune detection and response to stimuli. Tetracyclines and their derivatives, including minocycline and doxycycline, have anti-inflammatory properties independent of their antibacterial activity that correlate with certain aspects of the pathophysiology, and these drugs are often used by dermatologists to treat rosacea. Biological actions of tetracyclines correlating with rosacea include anti-inflammatory and antioxidative activities, inhibitory effects on angiogenesis, and proteolysis. The objective of this review is to re-establish the current understanding of tetracyclines and their mechanism of action as they relate to the pathophysiology and treatment of rosacea for clinicians. This includes reviewing the inflammatory aspects of rosacea that correlate with the known nonantibiotic properties of tetracyclines and providing the most up-to-date clinical evidence supporting the use of tetracyclines to treat rosacea. Given the evolving and multifactorial nature of pathophysiology, this review offers clinicians a unified picture that includes research on the links between rosacea pathophysiology and clinical presentation, the nonantibiotic properties of tetracyclines that relate to pathophysiologic pathways in rosacea, and the potential for clinical application of tetracyclines in rosacea therapy.

Towards PET imaging of the dynamic phenotypes of microglia

There is increasing evidence showing the heterogeneity of microglia activation in neuroinflammatory and neurodegenerative diseases. It has been hypothesized that pro‐inflammatory microglia are detrimental and contribute to disease progression, while anti‐inflammatory microglia play a role in damage repair and remission. The development of therapeutics targeting the deleterious glial activity and modulating it into a regenerative phenotype relies heavily upon a clearer understanding of the microglia dynamics during disease progression and the ability to monitor therapeutic outcome in vivo. To that end, molecular imaging techniques are required to assess microglia dynamics and study their role in disease progression as well as to evaluate the outcome of therapeutic interventions. Positron emission tomography (PET) is such a molecular imaging technique, and provides unique capabilities for non‐invasive quantification of neuroinflammation and has the potential to discriminate between microglia phenotypes and define their role in the disease process. However, several obstacles limit the possibility for selective in vivo imaging of microglia phenotypes mainly related to the poor characterization of specific targets that distinguish the two ends of the microglia activation spectrum and lack of suitable tracers. PET tracers targeting translocator protein 18 kDa (TSPO) have been extensively explored, but despite the success in evaluating neuroinflammation they failed to discriminate between microglia activation statuses. In this review, we highlight the current knowledge on the microglia phenotypes in the major neuroinflammatory and neurodegenerative diseases. We also discuss the current and emerging PET imaging targets, the tracers and their potential in discriminating between the pro‐ and anti‐inflammatory microglia activation states.

Delayed dosing of minocycline plus N-acetylcysteine reduces neurodegeneration in distal brain regions and restores spatial memory after experimental traumatic brain injury

Multiple drugs to treat traumatic brain injury (TBI) have failed clinical trials. Most drugs lose efficacy as the time interval increases between injury and treatment onset. Insufficient therapeutic time window is a major reason underlying failure in clinical trials. Few drugs have been developed with therapeutic time windows sufficiently long enough to treat TBI because little is known about which brain functions can be targeted if therapy is delayed hours to days after injury. We identified multiple injury parameters that are improved by first initiating treatment with the drug combination minocycline (MINO) plus N-acetylcysteine (NAC) at 72 h after injury (MN72) in a mouse closed head injury (CHI) experimental TBI model. CHI produces spatial memory deficits resulting in impaired performance on Barnes maze, hippocampal neuronal loss, and bilateral damage to hippocampal neurons, dendrites, spines and synapses. MN72 treatment restores Barnes maze acquisition and retention, protects against hippocampal neuronal loss, limits damage to dendrites, spines and synapses, and accelerates recovery of microtubule associated protein 2 (MAP2) expression, a key protein in maintaining proper dendritic architecture and synapse density. These data show that in addition to the structural integrity of the dendritic arbor, spine and synapse density can be successfully targeted with drugs first dosed days after injury. Retention of substantial drug efficacy even when first dosed 72 h after injury makes MINO plus NAC a promising candidate to treat clinical TBI.

Glucagon-Like Peptide-1 Analog Exendin-4 Ameliorates Cocaine-Mediated Behavior by Inhibiting Toll-Like Receptor 4 Signaling in Mice

Exendin-4 (Ex4), a long-lasting glucagon-like peptide-1 analog, was reported to exert favourable actions on inhibiting cocaine-associated rewarding and reinforcing effects of drug in animal models of addiction. However, the therapeutic potential of different dose of GLP-1 receptor agonist Ex4 in different behavioral paradigms and the underlying pharmacological mechanisms of action are incompletely understood. Herein, we firstly investigated the effects of Ex4 on cocaine-induced condition place preference (CPP) as well as extinction and reinstatement in male C57BL/6J mice. Additionally, we sought to elucidate the underlying pharmacological mechanism of these actions of Ex4. The paradigm of cocaine-induced CPP was established using 20 mg/kg cocaine or saline alternately during conditioning, while the reinstatement paradigm was modeled using 10 mg/kg cocaine on the reinstatement day. Different dose of Ex4 was administrated intraperitoneally either during conditioning or during extinction state or only on the test day. To elucidate the molecular mechanism underlying the potential effects of Ex4 on maladaptive behaviors of cocaine, the TLR4-related inflammation within the hippocampus was observed by immunofluorescence staining, and the expression levels of toll-like receptor 4 (TLR4), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β were detected by Western blotting. As a consequence, systemic administration of different dose of Ex4 was sufficient to inhibit the acquisition and expression of cocaine-induced CPP, facilitate the extinction of cocaine-associated reward and attenuate reinstatement of cocaine-induced behavior. Furthermore, Ex4 treatment diminished expression levels of TLR4, TNF-α, and IL-1β, which were up-regulated by cocaine exposure. Altogether, our results indicated that Ex4 effectively ameliorated cocaine-induced behaviors likely through neurobiological mechanisms partly attributable to the inhibition of TLR4, TNF-α and IL-1β in mice. Consequently, our findings improved our understanding of the efficacy of Ex4 for the amelioration of cocaine-induced behavior and suggested that Ex4 may be applied as a drug candidate for cocaine addiction.

A Quick Guide to Small-Molecule Inhibitors of Eukaryotic Protein Synthesis

Eukaryotic ribosome and cap-dependent translation are attractive targets in the antitumor, antiviral, anti-inflammatory, and antiparasitic therapies. Currently, a broad array of small-molecule drugs is known that specifically inhibit protein synthesis in eukaryotic cells. Many of them are well-studied ribosome-targeting antibiotics that block translocation, the peptidyl transferase center or the polypeptide exit tunnel, modulate the binding of translation machinery components to the ribosome, and induce miscoding, premature termination or stop codon readthrough. Such inhibitors are widely used as anticancer, anthelmintic and antifungal agents in medicine, as well as fungicides in agriculture. Chemicals that affect the accuracy of stop codon recognition are promising drugs for the nonsense suppression therapy of hereditary diseases and restoration of tumor suppressor function in cancer cells. Other compounds inhibit aminoacyl-tRNA synthetases, translation factors, and components of translation-associated signaling pathways, including mTOR kinase. Some of them have antidepressant, immunosuppressive and geroprotective properties. Translation inhibitors are also used in research for gene expression analysis by ribosome profiling, as well as in cell culture techniques. In this article, we review well-studied and less known inhibitors of eukaryotic protein synthesis (with the exception of mitochondrial and plastid translation) classified by their targets and briefly describe the action mechanisms of these compounds. We also present a continuously updated database (http://eupsic.belozersky.msu.ru/) that currently contains information on 370 inhibitors of eukaryotic protein synthesis.

Minocycline Treatment Reduces Mass and Force Output From Fast-Twitch Mouse Muscles and Inhibits Myosin Production in C2C12 Myotubes

Minocycline, a tetracycline-class of antibiotic, has been tested with mixed effectiveness on neuromuscular disorders such as amyotrophic lateral sclerosis, autoimmune neuritis and muscular dystrophy. The independent effect of minocycline on skeletal muscle force production and signalling remain poorly understood. Our aim here is to investigate the effects of minocycline on muscle mass, force production, myosin heavy chain abundance and protein synthesis. Mice were injected with minocycline (40 mg/kg i.p.) daily for 5 days and sacrificed at day six. Fast-twitch EDL, TA muscles and slow-twitch soleus muscles were dissected out, the TA muscle was snap-frozen and the remaining muscles were attached to force transducer whilst maintained in an organ bath. In C2C12 myotubes, minocycline was applied to the media at a final concentration of 10 μg/mL for 48 h. In minocycline treated mice absolute maximal force was lower in fast-twitch EDL while in slow-twitch soleus there was an increase in the time to peak and relaxation of the twitch. There was no effect of minocycline treatment on the other contractile parameters measured in isolated fast- and slow-twitch muscles. In C2C12 cultured cells, minocycline treatment significantly reduced both myosin heavy chain content and protein synthesis without visible changes to myotube morphology. In the TA muscle there was no significant changes in myosin heavy chain content. These results indicate that high dose minocycline treatment can cause a reduction in maximal isometric force production and mass in fast-twitch EDL and impair protein synthesis during myogenesis in C2C12 cultured cells. These findings have important implications for future studies investigating the efficacy of minocycline treatment in neuromuscular or other muscle-atrophy inducing conditions.

Rosacea: New Concepts in Classification and Treatment

Rosacea is a chronic inflammatory dermatosis mainly affecting the cheeks, nose, chin, and forehead. Rosacea is characterized by recurrent episodes of flushing or transient erythema, persistent erythema, phymatous changes, papules, pustules, and telangiectasia. The eyes may also be involved. Due to rosacea affecting the face, it has a profound negative impact on quality of life, self-esteem, and well-being. In addition to general skin care, there are several approved treatment options available for addressing these features, both topical and systemic. For some features, intense pulse light, laser, and surgery are of value. Recent advances in fundamental scientific research have underscored the roles of the innate and adaptive immune systems as well as neurovascular dysregulation underlying the spectrum of clinical features of rosacea. Endogenous and exogenous stimuli may initiate and aggravate several pathways in patients with rosacea. This review covers the new phenotype-based diagnosis and classification system reflecting pathophysiology, and new and emerging treatment options and approaches. We address new topical and systemic formulations, as well as recent evidence on treatment combinations. In addition, ongoing studies investigating novel therapeutic interventions will be summarized.

Aiding and Abetting Anhedonia: Impact of Inflammation on the Brain and Pharmacological Implications

Exogenous administration of inflammatory stimuli to humans and laboratory animals and chronic endogenous inflammatory states lead to motivational deficits and ultimately anhedonia, a core and disabling symptom of depression present in multiple other psychiatric disorders. Inflammation impacts neurotransmitter systems and neurocircuits in subcortical brain regions including the ventral striatum, which serves as an integration point for reward processing and motivational decision-making. Many mechanisms contribute to these effects of inflammation, including decreased synthesis, release and reuptake of dopamine, increased synaptic and extrasynaptic glutamate, and activation of kynurenine pathway metabolites including quinolinic acid. Neuroimaging data indicate that these inflammation-induced neurotransmitter effects manifest as decreased activation of ventral striatum and decreased functional connectivity in reward circuitry involving ventral striatum and ventromedial prefrontal cortex. Neurocircuitry changes in turn mediate nuanced effects on motivation that include decreased willingness to expend effort for reward while maintaining the ability to experience reward. Taken together, the data reveal an inflammation-induced pathophysiologic phenotype that is agnostic to diagnosis. Given the many mechanisms involved, this phenotype represents an opportunity for development of novel and/or repurposed pharmacological strategies that target inflammation and associated cellular and systemic immunometabolic changes and their downstream effects on the brain. To date, clinical trials have failed to capitalize on the unique nature of this transdiagnostic phenotype, leaving the field bereft of interpretable data for meaningful clinical application. However, novel trial designs incorporating established targets in the brain and/or periphery using relevant outcome variables (e.g., anhedonia) are the future of targeted therapy in psychiatry. SIGNIFICANCE STATEMENT: Emerging understanding of mechanisms by which peripheral inflammation can affect the brain and behavior has created unprecedented opportunities for development of pharmacological strategies to treat deficits in motivation including anhedonia, a core and disabling symptom of depression well represented in multiple psychiatric disorders. Mechanisms include inflammation and cellular and systemic immunometabolism and alterations in dopamine, glutamate, and kynurenine metabolites, revealing a target-rich environment that nevertheless has yet to be fully exploited by current clinical trial designs and drugs employed.

Emerging Gene and Small Molecule Therapies for the Neurodevelopmental Disorder Angelman Syndrome

Angelman syndrome (AS) is a rare (~1:15,000) neurodevelopmental disorder characterized by severe developmental delay and intellectual disability, impaired communication skills, and a high prevalence of seizures, sleep disturbances, ataxia, motor deficits, and microcephaly. AS is caused by loss-of-function of the maternally inherited UBE3A gene. UBE3A is located on chromosome 15q11-13 and is biallelically expressed throughout the body but only maternally expressed in the brain due to an RNA antisense transcript that silences the paternal copy. There is currently no cure for AS, but advancements in small molecule drugs and gene therapies offer a promising approach for the treatment of the disorder. Here, we review AS and how loss-of-function of the maternal UBE3A contributes to the disorder. We also discuss the strengths and limitations of current animal models of AS. Furthermore, we examine potential small molecule drug and gene therapies for the treatment of AS and associated challenges faced by the therapeutic design. Finally, gene therapy offers the opportunity for precision medicine in AS and advancements in the treatment of this disorder can serve as a foundation for other single-gene neurodevelopmental disorders.

The effects of minocycline in improving of methamphetamine withdrawal syndrome in male mice

Methamphetamine (METH) is a potent psychostimulant drug with an increasing rate of abuse over recent years. Depressive-like behaviors are one of the major symptoms patients in the METH withdrawal period experience. There is limited evidence regarding the METH withdrawal treatment, and conventional managements are not completely effective. Furthermore, extensive promising literature supports minocycline, a well-known antibiotic with anti-oxidant, anti-inflammatory properties, to treat depressive-like behaviors. Therefore, we hypothesized that administration of minocycline might mitigate the methamphetamine (METH) induced depression in male mice. Administration of METH (2 mg/kg) to mice two times a day for 14 constitutive days was done to induce the METH-induced withdrawal syndrome model. Animals were divided into 10 groups (n = 10 in each group), and three doses of minocycline (2.5, 5 and 10 mg/kg) were daily administered to male albino mice for 10 days. Following the behavioral test, the animals were scarified, their hippocampus were dissected to measure oxidative stress parameters. Our data revealed that chronic administration of minocycline provoked antidepressant effects in behavioral tests, such as forced swim test (FST), tail suspension test (TST) and splash test. Additionally, minocycline was able to improve oxidative stresses and neuronal damage in the hippocampus and restore the body's antioxidant system by increasing glutathione (GSH) and the cellular energy (ATP) and reducing the malondialdehyde (MDA) level. According to our promising results of minocycline on targeting mitochondria and its performance, we suggest minocycline as a new therapeutic option in clinical trials of depression treatment.

Beyond the lesion site: minocycline augments inflammation and anxiety-like behavior following SCI in rats through action on the gut microbiota

Background

Minocycline is a clinically available synthetic tetracycline derivative with anti-inflammatory and antibiotic properties. The majority of studies show that minocycline can reduce tissue damage and improve functional recovery following central nervous system injuries, mainly attributed to the drug’s direct anti-inflammatory, anti-oxidative, and neuroprotective properties. Surprisingly the consequences of minocycline’s antibiotic (i.e., antibacterial) effects on the gut microbiota and systemic immune response after spinal cord injury have largely been ignored despite their links to changes in mental health and immune suppression.

Methods

Here, we sought to determine minocycline’s effect on spinal cord injury-induced changes in the microbiota-immune axis using a cervical contusion injury in female Lewis rats. We investigated a group that received minocycline following spinal cord injury (immediately after injury for 7 days), an untreated spinal cord injury group, an untreated uninjured group, and an uninjured group that received minocycline. Plasma levels of cytokines/chemokines and fecal microbiota composition (using 16s rRNA sequencing) were monitored for 4 weeks following spinal cord injury as measures of the microbiota-immune axis. Additionally, motor recovery and anxiety-like behavior were assessed throughout the study, and microglial activation was analyzed immediately rostral to, caudal to, and at the lesion epicenter.

Results

We found that minocycline had a profound acute effect on the microbiota diversity and composition, which was paralleled by the subsequent normalization of spinal cord injury-induced suppression of cytokines/chemokines. Importantly, gut dysbiosis following spinal cord injury has been linked to the development of anxiety-like behavior, which was also decreased by minocycline. Furthermore, although minocycline attenuated spinal cord injury-induced microglial activation, it did not affect the lesion size or promote measurable motor recovery.

Conclusion

We show that minocycline’s microbiota effects precede its long-term effects on systemic cytokines and chemokines following spinal cord injury. These results provide an exciting new target of minocycline as a therapeutic for central nervous system diseases and injuries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02123-0.

Repurposing of Antimicrobial Agents for Cancer Therapy: What Do We Know?

The substantial costs of clinical trials, the lengthy timelines of new drug discovery and development, along the high attrition rates underscore the need for alternative strategies for finding quickly suitable therapeutics agents. Given that most approved drugs possess more than one target tightly linked to other diseases, it encourages promptly testing these drugs in patients. Over the past decades, this has led to considerable attention for drug repurposing, which relies on identifying new uses for approved or investigational drugs outside the scope of the original medical indication. The known safety of approved drugs minimizes the possibility of failure for adverse toxicology, making them attractive de-risked compounds for new applications with potentially lower overall development costs and shorter development timelines. This latter case is an exciting opportunity, specifically in oncology, due to increased resistance towards the current therapies. Indeed, a large body of evidence shows that a wealth of non-cancer drugs has beneficial effects against cancer. Interestingly, 335 drugs are currently being evaluated in different clinical trials for their potential activities against various cancers (Redo database). This review aims to provide an extensive discussion about the anti-cancer activities exerted by antimicrobial agents and presents information about their mechanism(s) of action and stage of development/evaluation.

A Characterization of the Effects of Minocycline Treatment During Adolescence on Structural, Metabolic, and Oxidative Stress Parameters in a Maternal Immune Stimulation Model of Neurodevelopmental Brain Disorders

BACKGROUND

Minocycline (MIN) is a tetracycline with antioxidant, anti-inflammatory, and neuroprotective properties. Given the likely involvement of inflammation and oxidative stress (IOS) in schizophrenia, MIN has been proposed as a potential adjuvant treatment in this pathology. We tested an early therapeutic window, during adolescence, as prevention of the schizophrenia-related deficits in the maternal immune stimulation (MIS) animal model.

METHODS

On gestational day 15, Poly I:C or vehicle was injected in pregnant Wistar rats. A total 93 male offspring received MIN (30 mg/kg) or saline from postnatal day (PND) 35-49. At PND70, rats were submitted to the prepulse inhibition test. FDG-PET and T2-weighted MRI brain studies were performed at adulthood. IOS markers were evaluated in frozen brain tissue.

RESULTS

MIN treatment did not prevent prepulse inhibition test behavioral deficits in MIS offspring. However, MIN prevented morphometric abnormalities in the third ventricle but not in the hippocampus. Additionally, MIN reduced brain metabolism in cerebellum and increased it in nucleus accumbens. Finally, MIN reduced the expression of iNOS (prefrontal cortex, caudate-putamen) and increased the levels of KEAP1 (prefrontal cortex), HO1 and NQO1 (amygdala, hippocampus), and HO1 (caudate-putamen).

CONCLUSIONS

MIN treatment during adolescence partially counteracts volumetric abnormalities and IOS deficits in the MIS model, likely via iNOS and Nrf2-ARE pathways, also increasing the expression of cytoprotective enzymes. However, MIN treatment during this peripubertal stage does not prevent sensorimotor gating deficits. Therefore, even though it does not prevent all the MIS-derived abnormalities evaluated, our results suggest the potential utility of early treatment with MIN in other schizophrenia domains.

A phase Ib/IIa trial of 9 repurposed drugs combined with temozolomide for the treatment of recurrent glioblastoma: CUSP9v3

Background

The dismal prognosis of glioblastoma (GBM) may be related to the ability of GBM cells to develop mechanisms of treatment resistance. We designed a protocol called Coordinated Undermining of Survival Paths combining 9 repurposed non-oncological drugs with metronomic temozolomide—version 3—(CUSP9v3) to address this issue. The aim of this phase Ib/IIa trial was to assess the safety of CUSP9v3.

Methods

Ten adults with histologically confirmed GBM and recurrent or progressive disease were included. Treatment consisted of aprepitant, auranofin, celecoxib, captopril, disulfiram, itraconazole, minocycline, ritonavir, and sertraline added to metronomic low-dose temozolomide. Treatment was continued until toxicity or progression. Primary endpoint was dose-limiting toxicity defined as either any unmanageable grade 3–4 toxicity or inability to receive at least 7 of the 10 drugs at ≥ 50% of the per-protocol doses at the end of the second treatment cycle.

Results

One patient was not evaluable for the primary endpoint (safety). All 9 evaluable patients met the primary endpoint. Ritonavir, temozolomide, captopril, and itraconazole were the drugs most frequently requiring dose modification or pausing. The most common adverse events were nausea, headache, fatigue, diarrhea, and ataxia. Progression-free survival at 12 months was 50%.

Conclusions

CUSP9v3 can be safely administered in patients with recurrent GBM under careful monitoring. A randomized phase II trial is in preparation to assess the efficacy of the CUSP9v3 regimen in GBM.

A Review of Systemic Minocycline Side Effects and Topical Minocycline as a Safer Alternative for Treating Acne and Rosacea

Resistance of Cutibacterium acnes to topical antibiotics historically used to treat acne (topical erythromycin and clindamycin and, more recently, topical azithromycin and clarithromycin) has been steadily increasing and new topical antibiotics are needed. Minocycline is a semisynthetic tetracycline-derived antibiotic currently used systemically to treat a wide range of infections caused by Gram-negative and Gram-positive bacteria. In addition to its antibiotic activity, minocycline possesses anti-inflammatory properties, such as the downregulation of proinflammatory cytokine production, suppression of neutrophil chemotaxis, activation of superoxide dismutase, and inhibition of phagocytosis, among others. These characteristics make minocycline a valuable agent for treatment of dermatological diseases such as acne vulgaris and papulopustular rosacea. However, more frequent or serious adverse effects have been observed upon the systemic administration of minocycline than with other tetracyclines. Examples of serious adverse effects include hypersensitivity syndrome reaction, drug-induced lupus, idiopathic intracranial hypertension, and other autoimmune syndromes that may cause death. Here, we review adverse effects and drug–drug interactions observed with oral administration of minocycline and contrast this with topical minocycline formulations recently approved or under development for effectively treating dermatological disorders with fewer adverse effects and less drug interaction.