Azithromycin Affords Neuroprotection in Rat Undergone Transient Focal Cerebral Ischemia

Exploring Azithromycin's Neuroprotective Role in Traumatic Brain Injury: Insights into Cognitive and Motor Recovery and Neuroinflammatory Modulation

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of mortality worldwide and often results in substantial cognitive, motor, and psychological impairments, triggering oxidative stress, neuroinflammation, and neurodegeneration. This study examined the neuroprotective effects of azithromycin (AZI) in TBI.

METHODS

TBI was induced in rats using the weight-drop method. Subsequently, rats received a daily intraperitoneal (I.P.) dose of AZI (150 mg/kg) for 28 days. Behavioral tests (Morris water maze, rotarod, and open field tests) were performed to assess cognitive and motor functions. Neurochemical analyses included oxidative stress markers (GSH, SOD, MDA, catalase), inflammatory cytokines (TNF-α, IL-1β), apoptotic markers (caspase-3, Bax, Bcl-2), mitochondrial complexes (complex I, II, III, IV, and V), and the transforming growth factor- beta (TGF-β) as a neurofilament marker. Histological evaluations focused on neuronal integrity in the cortex, hippocampus, and striatum.

RESULTS

Treatment with AZI significantly facilitated motor and cognitive function recovery in TBI-affected rats. At the molecular level, AZI effectively reduced oxidative stress markers, ameliorated neuroinflammation by decreasing TNF-α, IL-1β, and neuronal apoptosis, and differentially modulated mitochondrial complexes. Histological assessments revealed enhanced neuronal integrity and fewer pathological changes in AZI-treated rats compared to untreated TBI controls.

CONCLUSIONS

AZI was shown to interfere with several pathways involved in TBI's pathophysiology. While preclinical results are promising, further studies are necessary to establish the long-term safety and efficacy of AZI in a clinical setting. This research supports the potential re-purposing of AZI as a novel treatment strategy for TBI and related neurodegenerative disorders.

CSF-1R blockade to alleviate azithromycin mediated immunosuppression in a mouse model of intracellular infection

Colony Stimulating Factor-1 Receptor (CSF-1R) signalling plays an important role in maturation, differentiation and activation of macrophages. Apposite generation and activation of macrophage phenotypes and subsequent adaptive immune response against any infection is decisive for a positive disease outcome. Antibiotic therapy is imperative for treating bacterial infections however antibiotics have off-target effects on host immune-cells. These effects could either be contextually beneficial or harmful and could potentially aid generation of infection persistence and antimicrobial resistance (AMR) via host immunosuppression. We had recently reported the immunosuppressive-mechanism of azithromycin-induced increased CSF-1R expression on murine-macrophages and bacterial-persistence in Balb/c model of intracellular infection. We further wanted to explore the molecular-mechanism behind these observations and tested GW2580-mediated CSF-1R blockade before azithromycin treatment during S. flexneri induced intracellular infection. In the presented study, we report that the azithromycin alters the protein expression or phosphorylation of transcription-factors ERK1/2, P38, AKT1, STAT3, STAT6, and EGR2 that are involved in macrophage polarisatoin and also take part in CSF-1R signalling pathways. Intrestingly, CSF-1R blockade using GW2580 abrogated or reversed the azithromycin-induced up- or down-regulated expression or phosphorylation of ERK1/2, P38, AKT1, STAT3, STAT6, and EGR2. We further validated our results in Balb/c model of S. flexneri infection. Intrestingly, the CSF-1R blocker and azithromycin treated mice showed batter recovery than the azithromycin alone treated mice and hence we report the aftermath of GW2580 with azithromycin treatment on disease and immunological outcome of an intracellular infection caused by Shigella flexneri.

Injectable Hydrogel To Deliver Bone Mesenchymal Stem Cells Preloaded with Azithromycin To Promote Spinal Cord Repair

Spinal cord injury is a disease that causes severe damage to the central nervous system. Currently, there is no cure for spinal cord injury. Azithromycin is commonly used as an antibiotic, but it can also exert anti-inflammatory effects by down-regulating M1-type macrophage genes and up-regulating M2-type macrophage genes, which may make it effective for treating spinal cord injury. Bone mesenchymal stem cells possess tissue regenerative capabilities that may help promote the repair of the injured spinal cord. In this study, our objective was to explore the potential of promoting repair in the injured spinal cord by delivering bone mesenchymal stem cells that had internalized nanoparticles preloaded with azithromycin. To achieve this objective, we formulated azithromycin into nanoparticles along with a trans-activating transcriptional activator, which should enhance nanoparticle uptake by bone mesenchymal stem cells. These stem cells were then incorporated into an injectable hydrogel. The therapeutic effects of this formulation were analyzed in vitro using a mouse microglial cell line and a human neuroblastoma cell line, as well as in vivo using a rat model of spinal cord injury. The results showed that the formulation exhibited anti-inflammatory and neuroprotective effects in vitro as well as therapeutic effects in vivo. These results highlight the potential of a hydrogel containing bone mesenchymal stem cells preloaded with azithromycin and trans-activating transcriptional activator to mitigate spinal cord injury and promote tissue repair.

Azithromycin preserves adult hippocampal neurogenesis and behavior in a mouse model of sepsis

The mammalian hippocampus can generate new neurons throughout life. Known as adult hippocampal neurogenesis (AHN), this process participates in learning, memory, mood regulation, and forgetting. The continuous incorporation of new neurons enhances the plasticity of the hippocampus and contributes to the cognitive reserve in aged individuals. However, the integrity of AHN is targeted by numerous pathological conditions, including neurodegenerative diseases and sustained inflammation. In this regard, the latter causes cognitive decline, mood alterations, and multiple AHN impairments. In fact, the systemic administration of Lipopolysaccharide (LPS) from E. coli to mice (a model of sepsis) triggers depression-like behavior, impairs pattern separation, and decreases the survival, maturation, and synaptic integration of adult-born hippocampal dentate granule cells. Here we tested the capacity of the macrolide antibiotic azithromycin to neutralize the deleterious consequences of LPS administration in female C57BL6J mice. This antibiotic exerted potent neuroprotective effects. It reversed the increased immobility time during the Porsolt test, hippocampal secretion of pro-inflammatory cytokines, and AHN impairments. Moreover, azithromycin promoted the synaptic integration of adult-born neurons and functionally remodeled the gut microbiome. Therefore, our data point to azithromycin as a clinically relevant drug with the putative capacity to ameliorate the negative consequences of chronic inflammation by modulating AHN and hippocampal-related behaviors.

Preventive and therapeutic effects of azithromycin on acrylamide-induced neurotoxicity in rats

BACKGROUND

Acrylamide (ACR) can induce neurotoxicity through different pathways, including oxidative stress and apoptosis. Azithromycin is well-known for its antioxidant and anti-apoptotic properties.

OBJECTIVE

To evaluate the potential neuroprotective effect of azithromycin in an in vivo model of ACR-induced neurotoxicity, by investigating its impact on oxidative stress and apoptosis pathways.

METHODS

Male rats were divided into eleven groups at random (n = 6). 1:control (vehicle), 2:ACR (50 mg/kg, 11 days, I.P.), 3-7:ACR+ azithromycin (3.1, 6.25, 12.5, 25, 50 mg/kg, 11 days, I.P.), 8-9:ACR+ azithromycin (3.1, 6.25 mg/kg, from day 3-11), 10: ACR+ vitamin E (200 mg/kg, every other day, I.P.), 11. Azithromycin (50 mg/kg). Following the treatment period, a gait score examination was performed, and malondialdehyde (MDA), glutathione (GSH), Bcl-2-associated X protein (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and caspase-3 levels in the cerebral cortex were measured.

RESULTS

Gait abnormality, a drop in GSH, and an increase in lipid peroxidation, Bax/Bcl-2 ratio, and caspase-3 levels were all significantly triggered by ACR in the cerebral cortex versus the control group. Azithromycin 3.1 and 6.25 mg/kg with ACR and azithromycin 6.25 mg/kg with ACR from day 3-11 ameliorated movement disorders caused by ACR. Azithromycin in all doses and both protocols along with ACR decreased the MDA level. Azithromycin (3.1, 6.25 mg/kg) along with ACR in both protocols increased the level of GSH, reduced the Bax/Bcl-2 ratio and caspase-3 amounts in the brain tissue versus the ACR group.

CONCLUSIONS

Administration of azithromycin had both preventive and therapeutic effects on ACR-induced neurotoxicity through its antioxidant and antiapoptotic properties.

Perinatal Azithromycin Provides Limited Neuroprotection in an Ovine Model of Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Hypoxic-ischemic brain injury/encephalopathy affects about 1.15 million neonates per year, 96% of whom are born in low- and middle-income countries. Therapeutic hypothermia is not effective in this setting, possibly because injury occurs significantly before birth. Here, we studied the pharmacokinetics, safety, and efficacy of perinatal azithromycin administration in near-term lambs following global ischemic injury to support earlier treatment approaches.

METHODS

Ewes and their lambs of both sexes (n=34, 141-143 days) were randomly assigned to receive azithromycin or placebo before delivery as well as postnatally. Lambs were subjected to severe global hypoxia-ischemia utilizing an acute umbilical cord occlusion model. Outcomes were assessed over a 6-day period.

RESULTS

While maternal azithromycin exhibited relatively low placental transfer, azithromycin-treated lambs recovered spontaneous circulation faster following the initiation of cardiopulmonary resuscitation and were extubated sooner. Additionally, peri- and postnatal azithromycin administration was well tolerated, demonstrating a 77-hour plasma elimination half-life, as well as significant accumulation in the brain and other tissues. Azithromycin administration resulted in a systemic immunomodulatory effect, demonstrated by reductions in proinflammatory IL-6 (interleukin-6) levels. Treated lambs exhibited a trend toward improved neurodevelopmental outcomes while histological analysis revealed that azithromycin supported white matter preservation and attenuated inflammation in the cingulate and parasagittal cortex.

CONCLUSIONS

Perinatal azithromycin administration enhances neonatal resuscitation, attenuates neuroinflammation, and supports limited improvement of select histological outcomes in an ovine model of hypoxic-ischemic brain injury/encephalopathy.

Neuroprotective strategies for neonatal hypoxic-ischemic brain damage: Current status and challenges

Neonatal hypoxic-ischemic brain damage (HIBD) is a prominent contributor to both immediate mortality and long-term impairment in newborns. The elusive nature of the underlying mechanisms responsible for neonatal HIBD presents a significant obstacle in the effective clinical application of numerous pharmaceutical interventions. This comprehensive review aims to concentrate on the potential neuroprotective agents that have demonstrated efficacy in addressing various pathogenic factors associated with neonatal HIBD, encompassing oxidative stress, calcium overload, mitochondrial dysfunction, endoplasmic reticulum stress, inflammatory response, and apoptosis. In this review, we conducted an analysis of the precise molecular pathways by which these drugs elicit neuroprotective effects in animal models of neonatal hypoxic-ischemic brain injury (HIBD). Our objective was to provide a comprehensive overview of potential neuroprotective agents for the treatment of neonatal HIBD in animal experiments, with the ultimate goal of enhancing the feasibility of clinical translation and establishing a solid theoretical foundation for the clinical management of neonatal HIBD.

A bioinformatic investigation of proteasome and autophagy expression in the central nervous system

The ubiquitin proteasome system (UPS) and autophagy lysosome pathway (ALP) are crucial in the control of protein quality. However, data regarding the relative significance of UPS and ALP in the central nervous system (CNS) are limited. In the present study, using publicly available data, we computed the quantitative expression status of UPS- and ALP-related genes and their products in the CNS as compared with that in other tissues and cells. We obtained human and mouse gene expression datasets from the reference expression dataset (RefEx) and Genevestigator (a tool for handling curated transcriptomic data from public repositories) as well as human proteomics data from the proteomics database (ProteomicsDB). The expression levels of genes and proteins in four categories-ubiquitin, proteasome, autophagy, and lysosome--in the cells and tissues were assessed. Perturbation of the gene expression by drugs was also analyzed for the four categories. Compared with that for ubiquitin, autophagy, and lysosome, gene expression for proteasome was consistently lower in the CNS of mice but was more pronounced in humans. Neural stem cells and neurons showed low proteasome gene expression as compared with embryonic stem cells. Proteomic analyses, however, did not show trends similar to those observed in the gene expression analyses. Perturbation analyses revealed that azithromycin and vitamin D3 upregulated the expression of both UPS and ALP. Gene and proteomic expression data could offer a fresh perspective on CNS pathophysiology. Our results indicate that disproportional expression of UPS and ALP might affect CNS disorders and that this imbalance might be redressed by several therapeutic candidates.

Bone Marrow Mesenchymal Stem Cell-Derived Dermcidin-Containing Migrasomes enhance LC3-Associated Phagocytosis of Pulmonary Macrophages and Protect against Post-Stroke Pneumonia

Pneumonia is one of the leading causes of death in patients with acute ischemic stroke (AIS). Antibiotics fail to improve prognosis of patients with post-stroke pneumonia, albeit suppressing infection, due to adverse impacts on the immune system. The current study reports that bone marrow mesenchymal stem cells (BM-MSC) downregulate bacterial load in the lungs of stroke mice models. RNA-sequencing of the lung from BM-MSC-treated stroke models indicates that BM-MSC modulates pulmonary macrophage activities after cerebral ischemia. Mechanistically, BM-MSC promotes the bacterial phagocytosis of pulmonary macrophages through releasing migrasomes, which are migration-dependent extracellular vesicles. With liquid chromatography-tandem mass spectrometry (LC-MS/MS), the result shows that BM-MSC are found to load the antibacterial peptide dermcidin (DCD) in migrasomes upon bacterial stimulation. Besides the antibiotic effect, DCD enhances LC3-associated phagocytosis (LAP) of macrophages, facilitating their bacterial clearance. The data demonstrate that BM-MSC is a promising therapeutic candidate against post-stroke pneumonia, with dual functions of anti-infection and immunol modulation, which is more than a match for antibiotics treatment.

Azithromycin and Sildenafil May Have Protective Effects on Retinal Ganglion Cells via Different Pathways: Study in a Rodent Microbead Model

Decreased blood flow to the optic nerve (ON) and neuroinflammation are suggested to play an important role in the pathophysiology of glaucoma. This study investigated the potential neuroprotective effect of azithromycin, an anti-inflammatory macrolide, and sildenafil, a selective phosphodiesterase-5 inhibitor, on retinal ganglion cell survival in a glaucoma model, which was induced by microbead injection into the right anterior chamber of 50 wild-type (WT) and 30 transgenic toll-like receptor 4 knockout (TLR4KO) mice. Treatment groups included intraperitoneal azithromycin 0.1 mL (1 mg/0.1 mL), intravitreal sildenafil 3 µL, or intraperitoneal sildenafil 0.1 mL (0.24 μg/3 µL). Left eyes served as controls. Microbead injection increased intraocular pressure (IOP), which peaked on day 7 in all groups and on day 14 in azithromycin-treated mice. Furthermore, the retinas and ON of microbead-injected eyes showed a trend of increased expression of inflammatory- and apoptosis-related genes, mainly in WT and to a lesser extent in TLR4KO mice. Azithromycin reduced the BAX/BCL2 ratio, TGFβ, and TNFα levels in the ON and CD45 expression in WT retina. Sildenafil activated TNFα-mediated pathways. Both azithromycin and sildenafil exerted a neuroprotective effect in WT and TLR4KO mice with microbead-induced glaucoma, albeit via different pathways, without affecting IOP. The relatively low apoptotic effect observed in microbead-injected TLR4KO mice suggests a role of inflammation in glaucomatous damage.

Effect of Azithromycin on Sciatic Nerve Injury in the Wistar Rats

After a severe peripheral nerve injury, complete functional recovery is rare. Modulating the inflammatory response could be an effective way to enhance peripheral nerve regeneration. The present study aimed to determine the effect of azithromycin on functional recovery following sciatic nerve crush in Wistar rats. 40 male Wistar rats were used in four groups, including: the negative control, sham, and two groups of azithromycin (15 and 150 mg/kg/day) (n = 10).The rats' right sciatic nerve was crushed using a non-serrated clamp. In experimental groups, animals were treated with azithromycin (15 and 150 mg/kg/day) for 7 days. Then, sensory-motor functions were evaluated over eight weeks. Real-time PCR was used to measure the expression of NGF and BDNF genes. At the end of the 4th week, the sensory recovery accelerated in the azithromycin-treated rats so that the reaction times in the groups treated with 15 mg/kg and 150 mg/kg doses of azithromycin reached 5.14 s and 6.61 s, respectively, which were significantly lower than the 12 s in the negative control group (P < 0.05).Eventually, the mean SFI values in the negative control and both azithromycin-treated groups recovered to preoperative levels in the 8th week, with no significant difference between the sciatic lesion groups. Findings showed a seven-day course of azithromycin administered immediately after a sciatic nerve crush could accelerate regeneration and improve motor and sensory function recovery compared to negative controls. These significant effects were observed in both the azithromycin 15 mg/kg and the azithromycin 150 mg/kg treatment groups. Azithromycin treatment upregulated the expression of NGF and BDNF genes in crushed sciatic nerve. Our findings suggest that a seven-day treatment of azithromycin after a sciatic nerve injury could accelerate the regeneration process and improve functional recovery.

Advances in Antibody-Based Therapeutics for Cerebral Ischemia

Cerebral ischemia is an acute disorder characterized by an abrupt reduction in blood flow that results in immediate deprivation of both glucose and oxygen. The main types of cerebral ischemia are ischemic and hemorrhagic stroke. When a stroke occurs, several signaling pathways are activated, comprising necrosis, apoptosis, and autophagy as well as glial activation and white matter injury, which leads to neuronal cell death. Current treatments for strokes include challenging mechanical thrombectomy or tissue plasminogen activator, which increase the danger of cerebral bleeding, brain edema, and cerebral damage, limiting their usage in clinical settings. Monoclonal antibody therapy has proven to be effective and safe in the treatment of a variety of neurological disorders. In contrast, the evidence for stroke therapy is minimal. Recently, Clone MTS510 antibody targeting toll-like receptor-4 (TLR4) protein, ASC06-IgG1 antibody targeting acid sensing ion channel-1a (ASIC1a) protein, Anti-GluN1 antibodies targeting N-methyl-D-aspartate (NMDA) receptor associated calcium influx, GSK249320 antibody targeting myelin-associated glycoprotein (MAG), anti-High Mobility Group Box-1 antibody targeting high mobility group box-1 (HMGB1) are currently under clinical trials for cerebral ischemia treatment. In this article, we review the current antibody-based pharmaceuticals for neurological diseases, the use of antibody drugs in stroke, strategies to improve the efficacy of antibody therapeutics in cerebral ischemia, and the recent advancement of antibody drugs in clinical practice. Overall, we highlight the need of enhancing blood-brain barrier (BBB) penetration for the improvement of antibody-based therapeutics in the brain, which could greatly enhance the antibody medications for cerebral ischemia in clinical practice.

Potential of Antibiotics for the Treatment and Management of Parkinson Disease: An Overview

Evidences have emerged over the last 2 decades to ascertain the proof of concepts viz. mitochondrial dysfunction, inflammation-derived oxidative damage and cytokine-induced toxicity that play a significant role in Parkinson's disease (PD). The available pharmacotherapies for PD are mainly symptomatic and typically indications of L-DOPA to restrain dopamine deficiency and their consequences. In the 21st century, the role of the antibiotics has emerged at the forefront of medicine in health and human illness. There are several experimental and pre-clinical evidences that supported the potential use of antibiotic as neuroprotective agent. The astonishing effects of antibiotics and their neuroprotective properties against neurodegeneration and neuro-inflammation would be phenomenal for the development of effective therapy against PD. Antibiotics are also testified as useful not only to prevent the formation of alpha-synuclein but also act on mitochondrial dysfunction and neuro-inflammation. Thus, the possible therapy with antibiotics in PD would impact both the pathways leading to neuronal cell death in substantia nigra and pars compacta in midbrain. Moreover, the antibiotic based pharmacotherapy will open a scientific research passageway to add more to the evidence based and rational use of antibiotics for the treatment and management of PD and other neurodegenerative disorders.

Infection as a Stroke Risk Factor and Determinant of Outcome After Stroke

Understanding the relationship between infection and stroke has taken on new urgency in the era of the coronavirus disease 2019 (COVID-19) pandemic. This association is not a new concept, as several infections have long been recognized to contribute to stroke risk. The association of infection and stroke is also bidirectional. Although infection can lead to stroke, stroke also induces immune suppression which increases risk of infection. Apart from their short-term effects, emerging evidence suggests that poststroke immune changes may also adversely affect long-term cognitive outcomes in patients with stroke, increasing the risk of poststroke neurodegeneration and dementia. Infections at the time of stroke may also increase immune dysregulation after the stroke, further exacerbating the risk of cognitive decline. This review will cover the role of acute infections, including respiratory infections such as COVID-19, as a trigger for stroke; the role of infectious burden, or the cumulative number of infections throughout life, as a contributor to long-term risk of atherosclerotic disease and stroke; immune dysregulation after stroke and its effect on the risk of stroke-associated infection; and the impact of infection at the time of a stroke on the immune reaction to brain injury and subsequent long-term cognitive and functional outcomes. Finally, we will present a model to conceptualize the many relationships among chronic and acute infections and their short- and long-term neurological consequences. This model will suggest several directions for future research.