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

Maternal Minocycline as Fetal Therapy in a Rat Model of Myelomeningocele

INTRODUCTION

This study aimed to investigate whether the maternal administration of minocycline, a tetracycline antibiotic known to have anti-inflammatory and neuroprotective properties in models of neural injury, reduces inflammation and neural cell death in a fetal rat model of myelomeningocele (MMC).

METHODS

E10 pregnant rats were gavaged with olive oil or olive oil + retinoic acid to induce fetal MMC. At E12, the dams were exposed to regular drinking water or water containing minocycline (range, 40-140 mg/kg/day). At E21, fetal lumbosacral spinal cords were isolated for immunohistochemistry and quantitative gene expression studies focused on microglia activity, inflammation, and apoptosis (P < 0.05).

RESULTS

There was a trend toward decreased activated Iba1+ microglial cells within the dorsal spinal cord of MMC pups following minocycline exposure when compared to water (H2O) alone (P = 0.052). Prenatal minocycline exposure was correlated with significantly reduced expression of the proinflammatory cytokine, IL-6 (minocycline: 1.75 versus H2O: 3.52, P = 0.04) and apoptosis gene, Bax (minocycline: 0.71 versus H2O: 1.04, P < 0.001) among MMC pups.

CONCLUSIONS

This study found evidence that the maternal administration of minocycline reduces selected markers of inflammation and apoptosis within the exposed dorsal spinal cords of fetal MMC rats. Further study of minocycline as a novel prenatal treatment strategy to mitigate spinal cord damage in MMC is warranted.

Boosting Mitochondrial Potential: An Imperative Therapeutic Intervention in Amyotrophic Lateral Sclerosis

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a progressive and terminal neurodegenerative disorder. Mitochondrial dysfunction, imbalance of cellular bioenergetics, electron chain transportation and calcium homeostasis are deeply associated with the progression of this disease. Impaired mitochondrial functions are crucial in rapid neurodegeneration. The mitochondria of ALS patients are associated with deregulated Ca2+ homeostasis and elevated levels of reactive oxygen species (ROS), leading to oxidative stress. Overload of mitochondrial calcium and ROS production leads to glutamatereceptor mediated neurotoxicity. This implies mitochondria are an attractive therapeutic target.

OBJECTIVE

The aim of this review is to brief the latest developments in the understanding of mitochondrial pathogenesis in ALS and emphasize the restorative capacity of therapeutic candidates.

RESULTS

In ALS, mitochondrial dysfunction is a well-known phenomenon. Various therapies targeted towards mitochondrial dysfunction aim at decreasing ROS generation, increasing mitochondrial biogenesis, and inhibiting apoptotic pathways. Some of the therapies briefed in this review may be categorized as synthetic, natural compounds, genetic materials, and cellular therapies.

CONCLUSION

The overarching goals of mitochondrial therapies in ALS are to benefit ALS patients by slowing down the disease progression and prolonging overall survival. Despite various therapeutic approaches, there are many hurdles in the development of a successful therapy due to the multifaceted nature of mitochondrial dysfunction and ALS progression. Intensive research is required to precisely elucidate the molecular pathways involved in the progression of mitochondrial dysfunctions that ultimately lead to ALS. Because of the multifactorial nature of ALS, a combination therapy approach may hold the key to cure and treat ALS in the future.

Microglial activation in the motor cortex mediated NLRP3-related neuroinflammation and neuronal damage following spinal cord injury

Spinal cord injury (SCI) is a traumatic event that can lead to neurodegeneration. Neuronal damage in the primary motor cortex (M1) can hinder motor function recovery after SCI. However, the exact mechanisms involved in neuronal damage after SCI remain incompletely understood. In this study, we found that microglia were activated in M1 after SCI, which triggered Nod-like receptor protein 3 (NLRP3) related chronic neuroinflammation and neuronal damage in vivo. Meanwhile, treatment with the microglia inhibitor minocycline reduced inflammation-induced neuronal damage in M1, protected the integrity of the motor conduction pathway, and promoted motor function recovery. Furthermore, we simulated chronic inflammation in M1 after SCI by culturing the primary neurons in primary microglia-conditioned medium, and observed that the injury to the primary neurons also occurred in vitro; however, as observed in vivo, these effects could be mitigated by minocycline treatment. Our results indicated that microglial activation in M1 mediates NLRP3-related neuroinflammation and causes the injury to M1 neurons, thereby impairing the integrity of the motor conduction pathway and inhibiting motor function recovery. These findings might contribute to the identification of novel therapeutic strategies for SCI.

Hypothesized neuroprotective effect of minocycline against COVID-19-induced stroke and neurological dysfunction: possible role of matrix metalloprotease signaling pathway

Severe Acute Respiratory Syndrome Coronavirus-2 (COVID-19) is a respiratory disease that causes dysfunction in respiration. Since late 2019, this virus has infected and killed millions of people around the world and imposed many medical and therapeutic problems in the form of a pandemic. According to recent data, COVID-19 disease can increase the risk of stroke, which can be deadly or cause many neurological disorders after the disease. During the last two years, many efforts have been made to introduce new therapies for management of COVID-19-related complications, including stroke. To achieve this goal, several conventional drugs have been investigated for their possible therapeutic roles. Minocycline, a broad-spectrum, long-acting antibiotic with anti-inflammatory and antioxidant properties, is one such conventional drug that should be considered for treating COVID-19-related stroke, as indirect evidence indicates that it exerts neuroprotective effects, can modulate stroke occurrence, and can play an effective and strategic role in management of the molecular signals caused by stroke and its destructive consequences. The matrix metalloprotease (MMP) signaling pathway is one of the main signaling pathways involved in the occurrence and exacerbation of stroke; however, its role in COVID-19-induced stroke and the possible role of minocycline in the management of this signaling pathway in patients with COVID-19 is unclear and requires further investigation. Based on this concept, we hypothesize that minocycline might act via MMP signaling as a neuroprotective agent against COVID-19-induced neurological dysfunction, particularly stroke.

The human dental apical papilla promotes spinal cord repair through a paracrine mechanism

Traumatic spinal cord injury is an overwhelming condition that strongly and suddenly impacts the patient's life and her/his entourage. There are currently no predictable treatments to repair the spinal cord, while many strategies are proposed and evaluated by researchers throughout the world. One of the most promising avenues is the transplantation of stem cells, although its therapeutic efficiency is limited by several factors, among which cell survival at the lesion site. In our previous study, we showed that the implantation of a human dental apical papilla, residence of stem cells of the apical papilla (SCAP), supported functional recovery in a rat model of spinal cord hemisection. In this study, we employed protein multiplex, immunohistochemistry, cytokine arrays, RT- qPCR, and RNAseq technology to decipher the mechanism by which the dental papilla promotes repair of the injured spinal cord. We found that the apical papilla reduced inflammation at the lesion site, had a neuroprotective effect on motoneurons, and increased the apoptosis of activated macrophages/ microglia. This therapeutic effect is likely driven by the secretome of the implanted papilla since it is known to secrete an entourage of immunomodulatory or pro-angiogenic factors. Therefore, we hypothesize that the secreted molecules were mainly produced by SCAP, and that by anchoring and protecting them, the human papilla provides a protective niche ensuring that SCAP could exert their therapeutic actions. Therapeutic abilities of the papilla were demonstrated in the scope of spinal cord injury but could very well be beneficial to other types of tissue.

Spinal Nrf2 translocation may inhibit neuronal NF-κB activation and alleviate allodynia in a rat model of bone cancer pain

Bone cancer pain (BCP) is a clinical pathology that urgently needs to be solved, but research on the mechanism of BCP has so far achieved limited success. Nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) has been shown to be involved in pain, but its involvement in BCP and the specific mechanism have yet to be examined. This study aimed to test the hypothesis that BCP induces the transfer of Nrf2 from the cytoplasm to the nucleus and further promotes nuclear transcription to activate heme oxygenase-1 (HO-1) and inhibit the activation of nuclear factor-kappa B (NF-κB) signalling, ultimately regulating the neuroinflammatory response. Von-Frey was used for behavioural analysis in rats with BCP, whereas western blotting, real-time quantitative PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect molecular expression changes, and immunofluorescence was used to detect cellular localization. We demonstrated that BCP induced increased Nrf2 nuclear protein expression with decreased cytoplasmic protein expression in the spinal cord. Further increases in Nrf2 nuclear protein expression can alleviate hyperalgesia and activate HO-1 to inhibit the expression of NF-κB nuclear protein and inflammatory factors. Strikingly, intrathecal administration of the corresponding siRNA reversed the above effects. In addition, the results of double immune labelling revealed that Nrf2 and NF-κB were coexpressed in spinal cord neurons of rats with BCP. In summary, these findings suggest that the entry of Nrf2 into the nucleus promotes the expression of HO-1, inhibiting activation of the NF-κB signalling pathway, reducing neuroinflammation and ultimately exerting an anti-nociceptive effect.

Sulforaphane alleviates hyperalgesia and enhances analgesic potency of morphine in rats with cancer-induced bone pain

Due to the efficacy and tolerability of the available drugs, the current treatment for cancer-induced bone pain (CIBP) is not considered ideal, and new drugs are required for better treatment results. This study investigated whether intrathecal injection of sulforaphane (SFN) can modulates the noxious behavior associated with CIBP and enhances the analgesic effects of morphine and the possible mechanisms related to these effects were investigated. Walker256 breast cancer cells were injected into the bone marrow cavity of rats to establish the CIBP model. When CIBP rats began to exhibit painful behavior (CIBP 6 days), SFN was injected intrathecally for 7 days. The results showed that SFN alleviated the painful behavioral hypersensitivity caused by cancer, accompanied by nuclear factor, erythroid 2 like 2 (Nrf2), Haem oxygenase 1 (HO-1) activation, nuclear factor kappa B (NF-κB) inhibition and inflammation-related factors (tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-β), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) reduction. In addition, SFN treatment inhibited the proliferation of Walker 256 cells in a dose-dependent manner, promoted mu-opioid receptor (MOR) expression in SH-SY5Y cells and enhanced the antihyperalgesic effects of morphine on CIBP rats by restoring the downregulation of MOR expression in the spinal cord. Interestingly, the antihyperalgesic effects of SFN were partially blocked by opioid receptor antagonists. This study showed that SFN combined with morphine might be a new way to treat CIBP.

The influence of adalimumab treatment on the systemic gene expression in patients with psoriatic arthritis - preliminary report

INTRODUCTION

The primary goal of psoriasis treatment is to reduce the inflammatory response and associated complications. In severe cases of psoriasis that are resistant to local treatment (e.g., keratolytic preparations) and at least two types of general treatment methods (e.g., retinoids and cyclosporine A), biological therapy is used. This study aimed to assess the systemic effects of adalimumab at a given stage of treatment in patients with psoriatic arthritis and evaluate how the drug can improve the clinical condition of the patients.

MATERIAL AND METHODS

The study group consisted of patients with diagnosed psoriatic arthritis, while the control group consisted of individuals from whom peripheral blood mononuclear cells were obtained. The effects of the administration of adalimumab were assessed by analyzing the gene expression using oligonucleotide microarrays.

RESULT

The apoptosis process was found to be one of the overrepresented categories (the PANTHER classification system 13.1 program, overrepresentation test, p < 0.05). The dermatological indexes decreased, indicating an improvement in the clinical conditions of the patients 3 months after the first dose of adalimumab.

CONCLUSIONS

We found that adalimumab affects apoptosis, which is crucial in the development and course of psoriasis. The differential gene expression in peripheral blood mononuclear cells of patients with psoriatic arthritis indicated the potential systemic effects of adalimumab therapy. The analyses of dermatological (the Psoriasis Area and Severity Index, body surface area and Dermatology Life Quality Index) and inflammatory (Biernacki's reaction) parameters revealed the effectiveness of the therapy.

Emerging Therapeutic Strategies for Traumatic Spinal Cord Injury

Spinal cord injury (SCI) is a debilitating neurologic condition with tremendous socioeconomic impact on affected individuals and the health care system. The treatment of SCI principally includes surgical treatment and marginal pharmacologic and rehabilitation therapies targeting secondary events with minor clinical improvements. This unsuccessful result mainly reflects the complexity of SCI pathophysiology and the diverse biochemical and physiologic changes that occur in the injured spinal cord. Once the nervous system is injured, cascades of cellular and molecular events are triggered at varying times. Although the cascade of tissue reactions and cell injury develops over a period of days or weeks, the most extensive cell death in SCI occurs within hours of trauma. This situation suggests that early intervention is likely to be the most promising approach to rescue the cord from further and irreversible cell damage. Over the past decades, a wealth of research has been conducted in preclinical and clinical studies with the hope to find new therapeutic strategies. Researchers have identified several targets for the development of potential therapeutic interventions (e.g., neuroprotection, replacement of cells lost, removal of inhibitory molecules, regeneration, and rehabilitation strategies to induce neuroplasticity). Most of these treatments have passed preclinical and initial clinical evaluations but have failed to be strongly conclusive in the clinical setting. This narrative review provides an update of the many therapeutic interventions after SCI, with an emphasis on the underlying pathophysiologic mechanisms.