Azithromycin therapy reduces cardiac inflammation and mitigates adverse cardiac remodeling after myocardial infarction: Potential therapeutic targets in ischemic heart disease

16α-OHE1 alleviates hypoxia-induced inflammation and myocardial damage via the activation of β2-Adrenergic receptor

OBJECTIVE

Myocardial injuries resulting from hypoxia are a significant concern, and this study aimed to explore potential protective strategies against such damage. Specifically, we sought to investigate the cardioprotective effects of 16α-hydroxyestrone (16α-OHE1).

METHODS

Male Sprague‒Dawley (SD) rats were subjected to hypoxic conditions simulating high-altitude exposure at 6000 m in a low-pressure chamber for 7 days. Before and during hypoxic exposure, estradiol (E2) and various doses of 16α-OHE1 were administered for 14 days. Heart weight/body weight (HW/BW), myocardial structure, Myocardial injury indicators and inflammatory infiltration in rats were measured. H9C2 cells cultured under 5% O2 conditions received E2 and varying doses of 16α-OHE1; Cell viability, apoptosis, inflammatory infiltration, and Myocardial injury indicators were determined. Expression levels of β2AR were determined in rat hearts and H9C2 cells. The β2AR inhibitor, ICI 118,551, was employed to investigate β2AR's role in 16α-OHE1's cardioprotective effects.

RESULTS

Hypoxia led to substantial myocardial damage, evident in increased heart HW, CK-MB, cTnT, ANP, BNP, structural myocardial changes, inflammatory infiltration, and apoptosis. Pre-treatment with E2 and 16α-OHE1 significantly mitigated these adverse changes. Importantly, the protective effects of E2 and 16α-OHE1 were associated with the upregulation of β2AR expression in both rat hearts and H9C2 cells. However, inhibition of β2AR by ICI 118,551 in H9C2 cells nullified the protective effect of 16α-OHE1 on myocardium.

CONCLUSION

Our findings suggest that 16α-OHE1 can effectively reduce hypoxia-induced myocardial injury in rats through β2ARs, indicating a promising avenue for cardioprotection.

Azithromycin induces neurotoxicity in zebrafish by interfering with the VEGF/Notch signaling pathway

Azithromycin (AZM) is a widely used antibiotic in both human and veterinary medicine, and its use has significantly increased during the COVID-19 pandemic. However, potential adverse effects of AZM on aquatic organisms have not been well studied. In this study, we explored the neurotoxicity of AZM in zebrafish and delved into its underlying mechanisms. Our results showed that AZM exposure resulted in a spectrum of detrimental effects in zebrafish, encompassing abnormal behaviors, damaged neuronal development, aberrant lateral line nervous system development, vascular malformations and perturbed expression of genes related to neural development. Moreover, we observed a concentration-dependent exacerbation of these neurotoxic manifestations with increasing AZM concentrations. Notably, AZM induced excessive cell apoptosis and oxidative stress damage. In addition, alterations in the expression levels of the genes involved in the VEGF/Notch signaling pathway were evident in AZM-exposed zebrafish. Consequently, we hypothesize that AZM may induce neurotoxicity by influencing the VEGF/Notch signaling pathway. To validate this hypothesis, we introduced a VEGF signaling inhibitor, axitinib, and a Notch signaling agonist, valproic acid, alongside AZM exposure. Remarkably, the administration of these rescue compounds significantly mitigated the neurotoxic effects induced by AZM. This dual verification provides compelling evidence that AZM indeed induces neurotoxicity during the early developmental stages of zebrafish, primarily through its interference with the VEGF/Notch pathway. Innovatively, our study reveals the molecular mechanism of AZM-induced neurotoxicity from the perspective of the close connection between blood vessels and nervous system. These findings provide new insights into the potential mechanisms underlying the neurotoxic effect of antibiotics and highlight the need for further investigation into the ecotoxicological effects of antibiotics on aquatic organisms and the potential risks to human health.

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.

Azithromycin alters Colony Stimulating Factor-1R (CSF-1R) expression and functional output of murine bone marrow-derived macrophages: A novel report

Antibiotic treatment may lead to side effects that require mechanistic explanation. We investigated the effect of azithromycin (AZM) treatment on bone marrow-derived macrophage (Mφ) generation, their functional output, and the subsequent effect on bacterial clearance in a mouse model of S. flexneri infection. To our fascination, AZM increased PU.1, C/EBPβ, CSF-1R/pCSF-1R expressions leading to M2-skewed in vitro BMDM generation. Altered Mφ-functions like- phagocytosis, oxidative stress generation, inflammasome-activation, cytokine release, and phenotype (pro-inflammatory-M1, anti-inflammatory-M2) even in the presence of infection were observed with AZM treatment. AZM increased CD206, egr2, arg1 (M2-marker) expression and activity while reducing CD68, inducible nitric oxide (iNOS) expression, and activity (M1-marker) in Mφs during infection. Pro-inflammatory cytokines (TNF-α, IL-12, IL-1β) were reduced and anti-inflammatory IL-10 release was augmented by AZM-treated-iMφs (aiMφs) along with decreased asc, nlrp3, aim2, nlrp1a, caspase1 expressions, and caspase3 activity signifying that aMφs/aiMφs were primed towards an anti-inflammatory phenotype. Interestingly, CSF-1R blockade increased NO, IL-12, TNF-α, IL-1β, decreased TGF-β release, and CD206 expression in aiMφs. T-cell co-stimulatory molecule cd40, cd86, and cd80 expressions were decreased in ai/aM1-Mφs and co-cultured CD8+, CD4+ T-cells had decreased proliferation, t-bet, IFN-γ, IL-17, IL-2 but increased foxp3, TGF-β, IL-4 which were rescued with CSF-1R blockade. Thus AZM affected Mφ-functions and subsequent T-cell responses independent of its antibacterial actions. This was validated in the balb/c model of S. flexneri infection. We conclude that AZM skewed BMDM generation to anti-inflammatory M2-like via increased CSF-1R expression. This warrants further investigation of AZM-induced altered-Mφ-generation during intracellular infections.

Intercellular model predicts mechanisms of inflammation-fibrosis coupling after myocardial infarction

After myocardial infarction (MI), cardiac cells work together to regulate wound healing of the infarct. The pathological response to MI yields cardiac remodelling comprising inflammatory and fibrosis phases, and the interplay of cellular dynamics that underlies these phases has not been elucidated. This study developed a computational model to identify cytokine and cellular dynamics post-MI to predict mechanisms driving post-MI inflammation, resolution of inflammation, and scar formation. Additionally, this study evaluated the interdependence between inflammation and fibrosis. Our model bypassed limitations of in vivo approaches in achieving cellular specificity and performing specific perturbations such as global knockouts of chemical factors. The model predicted that inflammation is a graded response to initial infarct size that is amplified by a positive feedback loop between neutrophils and interleukin 1β (IL-1β). Resolution of inflammation was driven by degradation of IL-1β, matrix metalloproteinase 9, and transforming growth factor β (TGF-β), as well as apoptosis of neutrophils. Inflammation regulated TGFβ secretion directly through immune cell recruitment and indirectly through upregulation of macrophage phagocytosis. Lastly, we found that mature collagen deposition was an ultrasensitive switch in response to inflammation, which was amplified primarily by cardiac fibroblast proliferation. These findings describe the relationship between inflammation and fibrosis and highlight how the two responses work together post-MI. This model revealed that post-MI inflammation and fibrosis are dynamically coupled, which provides rationale for designing novel anti-inflammatory, pro-resolving or anti-fibrotic therapies that may improve the response to MI. KEY POINTS: Inflammation and matrix remodelling are two processes involved in wound healing after a heart attack. Cardiac cells work together to facilitate these processes; this is done by secreting cytokines that then regulate the cells themselves or other cells surrounding them. This study developed a computational model of the dynamics of cardiac cells and cytokines to predict mechanisms through which inflammation and matrix remodelling is regulated. We show the roles of various cytokines and signalling motifs in driving inflammation, resolution of inflammation and fibrosis. The novel concept of inflammation-fibrosis coupling, based on the model prediction that inflammation and fibrosis are dynamically coupled, provides rationale for future studies and for designing therapeutics to improve the response after a heart attack.

Effects of a water-soluble formulation of tylvalosin on disease caused by porcine reproductive and respiratory syndrome virus alone in sows or in combination with Mycoplasma hyopneumoniae in piglets

BACKGROUND

The effect of a water-soluble formulation of tylvalosin (Aivlosin® 625 mg/g granules) on disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (Mhyop) was investigated in two animal studies. In a PRRSV challenge model in pregnant sows (n = 18), six sows received water medicated at target dose of 5 mg tylvalosin/kg body weight/day from 3 days prior to challenge until the end of gestation. Six sows were left untreated, with a third group remaining untreated and unchallenged. Sows were challenged with PRRSV-2 at approximately 85 days of gestation. Cytokines, viremia, viral shedding, sow reproductive parameters and piglet performance to weaning were evaluated. In a dual infection study (n = 16), piglets were challenged with Mhyop on days 0, 1 and 2, and with PRRSV-1 on day 14 and euthanized on day 24. From day 10 to 20, eight piglets received water medicated at target dose of 20 mg tylvalosin/kg body weight/day and eight piglets were left untreated. Cytokines, viremia, bacteriology and lung lesions were evaluated.

RESULTS

In the PRRSV challenge study in pregnant sows, tylvalosin significantly reduced the levels of serum IL-8 (P < 0.001), IL-12 (P = 0.032), TNFα (P < 0.001) and GM-CSF (P = 0.001). IL-8 (P = 0.100) tended to be lower in uterus of tylvalosin sows. All piglets from tylvalosin sows surviving to weaning were PRRSV negative in faecal swabs at weaning compared to 33.3% PRRSV positive piglets from untreated sows (P = 0.08). In the dual challenge study in piglet, tylvalosin reduced serum IL1β, IL-4, IL-6, IL-8, IL-10, IL-12, IL-1α, IL-13, IL-17A, IL-18, GM-CSF, TGFβ1, TNFα, CCL3L1, MIG, PEPCAM-1 (P < 0.001) and increased serum IFNα, IL-1ra and MIP-1b (P < 0.001). In the lungs, tylvalosin reduced IL-8, IL-10 and IL-12 compared to untreated pigs (P < 0.001) and tended to reduce TNFα (P = 0.082). Lung lavage samples from all tylvalosin treated piglets were negative for Mhyop (0 cfu/mL) compared to the untreated piglets which had mean Mhyop counts of 2.68 × 10⁴ cfu/mL (P = 0.023).

CONCLUSION

Overall, tylvalosin reduced both local and systemic proinflammatory cytokines after challenge with respiratory pathogens in sows and in piglets. Tylvalosin was effective in reducing Mhyop recovery from the lungs and may reduce virus shedding in piglets following transplacental PRRSV infection in sows.

Optimization and Characterization of a Liposomal Azithromycin Formulation for Alternative Macrophage Activation

Liposomal azithromycin (L-AZM) promotes macrophage polarization toward an M2-like phenotype in the context of myocardial infarction that results in improved cardiovascular outcomes in mice. To improve upon this formulation, we sought to identify optimized formulation, stability, and biological activity parameters necessary to enhance the immunomodulatory activity and efficacy of L-AZM. While our parent formulation contains a mixture of long-chain saturated phosphatidylcholine and phosphatidylglycerol lipids, we evaluated a series of formulations with different amounts of unsaturated lipids and cholesterol with the goal of improving the loading capacity and stability of the formulations. We also introduce fusogenic lipids to improve the cytosolic delivery to enhance the immune modulatory properties of the drug. To achieve these goals, we initially prepared a library of 24 formulations using thin film hydration and assessed the resultant liposomes for size and polydispersity. Five lead formulations were identified based on low polydispersity (<0.3) and stability over time. The lead formulations were then evaluated for stability in serum using dialysis and macrophage polarization activity in vitro as measured by decreased IL-12 expression. Collectively, our data indicate that the formulation components drive the balance between encapsulation efficiency and stability and that all the lead liposomal formulations improve in vitro alternative macrophage activation as compared to free AZM.

Delivering macrolide antibiotics to heal a broken heart - And other inflammatory conditions

Drug carriers to deliver macrolide antibiotics, such as azithromycin, show promise as antibacterial agents. Macrolide drug carriers have largely focused on improving the drug stability and pharmacokinetics, while reducing adverse reactions and improving antibacterial activity. Recently, macrolides have shown promise in treating inflammatory conditions by promoting a reparative effect and limiting detrimental pro-inflammatory responses, which shifts the immunologic setpoint from suppression to balance. While macrolide drug carriers have only recently been investigated for their ability to modulate immune responses, the previous strategies that deliver macrolides for antibacterial therapy provide a roadmap for repurposing the macrolide drug carriers for therapeutic interventions targeting inflammatory conditions. This review describes the antibacterial and immunomodulatory activity of macrolides, while assessing the past in vivo evaluation of drug carriers used to deliver macrolides with the intention of presenting a case for increased effort to translate macrolide drug carriers into the clinic.

Azithromycin and Major Adverse Kidney Events in Critically Ill Patients With Sepsis-Associated Acute Kidney Injury

BACKGROUND

Sepsis-associated acute kidney injury (SA-AKI) is associated with significant morbidity and mortality. Immune dysregulation is a hallmark of sepsis, with important contributions to organ dysfunction including injury and repair mechanisms in AKI. Macrolide antibiotics, such as azithromycin, have previously demonstrated in preclinical models a myriad of immunomodulatory effects that may benefit critically ill patients with SA-AKI. The aim of this study was to determine if early receipt of azithromycin in SA-AKI is associated with a reduction in major adverse kidney events (MAKE) at hospital discharge.

METHODS

This was a single center, retrospective cohort study of critically ill adult patients with SA-AKI. Early exposure to azithromycin was defined as receipt of one or more doses within 48 h of a hospital admission with SA-AKI. The primary outcome of MAKE assessed at hospital discharge was the composite of death, requirement for kidney replacement therapy, or a decline in estimated glomerular filtration rate of 25% or more. Multivariable logistic regression was used to account for potential confounders in the assessment.

RESULTS

Of 737 included patients with SA-AKI, 152 (20.6%) received azithromycin. Patients that received early azithromycin were less likely to experience MAKE at hospital discharge when compared to those patients not receiving azithromycin: 38.8% versus 48.4% (P = 0.035). In multivariable logistic regression, receipt of azithromycin was independently associated with a decreased odds of MAKE at hospital discharge (aOR 0.62, 95% CI 0.41-0.93).

CONCLUSIONS

Early exposure to azithromycin in SA-AKI is independently associated with lower odds of MAKE at hospital discharge.

Adult spiny mice (Acomys) exhibit endogenous cardiac recovery in response to myocardial infarction

Complex tissue regeneration is extremely rare among adult mammals. An exception, however, is the superior tissue healing of multiple organs in spiny mice (Acomys). While Acomys species exhibit the remarkable ability to heal complex tissue with minimal scarring, little is known about their cardiac structure and response to cardiac injury. In this study, we first examined baseline Acomys cardiac anatomy and function in comparison with commonly used inbred and outbred laboratory Mus strains (C57BL6 and CFW). While our results demonstrated comparable cardiac anatomy and function between Acomys and Mus, Acomys exhibited a higher percentage of cardiomyocytes displaying distinct characteristics. In response to myocardial infarction, all animals experienced a comparable level of initial cardiac damage. However, Acomys demonstrated superior ischemic tolerance and cytoprotection in response to injury as evidenced by cardiac functional stabilization, higher survival rate, and smaller scar size 50 days after injury compared to the inbred and outbred mouse strains. This phenomenon correlated with enhanced endothelial cell proliferation, increased angiogenesis, and medium vessel maturation in the peri-infarct and infarct regions. Overall, these findings demonstrate augmented myocardial preservation in spiny mice post-MI and establish Acomys as a new adult mammalian model for cardiac research.

The immunomodulatory effects of macrolide antibiotics in respiratory disease

Macrolide antibiotics are well known for their antibacterial properties, but extensive research in the context of inflammatory lung disease has revealed that they also have powerful immunomodulatory properties. It has been demonstrated that these drugs are therapeutically beneficial in various lung diseases, with evidence they significantly reduce exacerbations in patients with COPD, asthma, bronchiectasis and cystic fibrosis. The efficacy demonstrated in patients infected with macrolide tolerant organisms such as Pseudomonas aeruginosa supports the concept that their efficacy is at least partly related to immunomodulatory rather than antibacterial effects. Inconsistent data and an incomplete understanding of their mechanisms of action hampers the use of macrolide antibiotics as immunomodulatory therapies. Macrolides recently demonstrated no clinically relevant immunomodulatory effects in the context of COVID-19 infection. This review provides an overview of macrolide antibiotics and discusses their immunomodulatory effects and mechanisms of action in the context of inflammatory lung disease.

Lymphatic Clearance of Immune Cells in Cardiovascular Disease

Recent advances in our understanding of the lymphatic system, its function, development, and role in pathophysiology have changed our views on its importance. Historically thought to be solely involved in the transport of tissue fluid, lipids, and immune cells, the lymphatic system displays great heterogeneity and plasticity and is actively involved in immune cell regulation. Interference in any of these processes can be deleterious, both at the developmental and adult level. Preclinical studies into the cardiac lymphatic system have shown that invoking lymphangiogenesis and enhancing immune cell trafficking in ischaemic hearts can reduce myocardial oedema, reduce inflammation, and improve cardiac outcome. Understanding how immune cells and the lymphatic endothelium interact is also vital to understanding how the lymphatic vascular network can be manipulated to improve immune cell clearance. In this Review, we examine the different types of immune cells involved in fibrotic repair following myocardial infarction. We also discuss the development and function of the cardiac lymphatic vasculature and how some immune cells interact with the lymphatic endothelium in the heart. Finally, we establish how promoting lymphangiogenesis is now a prime therapeutic target for reducing immune cell persistence, inflammation, and oedema to restore heart function in ischaemic heart disease.

Management of inflammation in cardiovascular diseases

Cardiovascular disease is the leading cause of morbidity and mortality world-wide. Recently, the role of inflammation in the progression of diseases has significantly attracted considerable attention. In addition, various comorbidities, including diabetes, obesity, etc. exacerbate inflammation in the cardiovascular system, which ultimately leads to heart failure. Furthermore, cytokines released from specialized immune cells are key mediators of cardiac inflammation. Here, in this review article, we focused on the role of selected immune cells and cytokines (both pro-inflammatory and anti-inflammatory) in the regulation of cardiac inflammation and ultimately in cardiovascular diseases. While IL-1β, IL-6, TNFα, and IFNγ are associated with cardiac inflammation; IL-10, TGFβ, etc. are associated with resolution of inflammation and cardiac repair. IL-10 reduces cardiovascular inflammation and protects the cardiovascular system via interaction with SMAD2, p53, HuR, miR-375 and miR-21 pathway. In addition, we also highlighted recent advancements in the management of cardiac inflammation, including clinical trials of anti-inflammatory molecules to alleviate cardiovascular diseases.

Isolation Methods for Human CD34 Subsets Using Fluorescent and Magnetic Activated Cell Sorting: an In Vivo Comparative Study

INTRODUCTION

Acute myocardial infarction (AMI) and resulting cardiac damage and heart failure are leading causes of morbidity and mortality worldwide. Multiple studies have examined the utility of CD34⁺ cells for the treatment of acute and ischemic heart disease. However, the optimal strategy to enrich CD34 cells from clinical sources is not known. We examined the efficacy of fluorescence activated cell sorting (FACS) and magnetic beads cell sorting (MACS) methods for CD34 cell isolation from mobilized human mononuclear peripheral blood cells (mhPBMNCs).

METHODS

mhPBCs were processed following acquisition using FACS or MACS according to clinically established protocols. Cell viability, CD34 cell purity and characterization of surface marker expression were assessed using a flow cytometer. For in vivo characterization of cardiac repair, we conducted LAD ligation surgery on 8-10 weeks female NOD/SCID mice followed by intramyocardial transplantation of unselected mhPBMNCs, FACS or MACS enriched CD34⁺ cells.

RESULTS

Both MACS and FACS isolation methods achieved high purity rates, viability, and enrichment of CD34⁺ cells. In vivo studies following myocardial infarction demonstrated retention of CD34⁺ in the peri-infarct region for up to 30 days after transplantation. Retained CD34⁺ cells were associated with enhanced angiogenesis and reduced inflammation compared to unselected mhPBMNCs or PBS treatment arms. Cardiac scar and fibrosis as assessed by immunohistochemistry were reduced in FACS and MACS CD34⁺ treatment groups. Finally, reduced scar and augmented angiogenesis resulted in improved cardiac functional recovery, both on the global and regional function and remodeling assessments by echocardiography.

CONCLUSION

Cell based therapy using enriched CD34⁺ cells sorted by FACS or MACS result in better cardiac recovery after ischemic injury compared to unselected mhPBMNCs. Both enrichment techniques offer excellent recovery and purity and can be equally used for clinical applications.

Azithromycin inhibited oxidative stress and apoptosis of high glucose-induced podocytes by inhibiting STAT1 pathway

Azithromycin (AZM) has a therapeutic effect on diabetes, but there is no report on whether AZM has a therapeutic effect on diabetic nephropathy (DN) and its specific mechanism. Cell survival was detected by CCK-8. The expression of the inflammatory factors TNF-α, IL-1β, and IL-6 was determined by ELISA. The expression of inflammatory proteins MCP-1, NLPR3, and ASC was detected by western blot. The expression of MDA, LDH, and SOD was detected by the appropriate kit. Apoptosis was detected by flow cytometry and apoptosis-related proteins Bcl-2, Bax, Caspase-3, 6, 9, and Cleaved caspase-3, 6, 9 were detected by western blot. In addition, the expression of STAT1 was detected by western blot. AZM can increase the activity of high glucose-induced podocytes (p < .05). After high glucose induction, the expression of TNF-α, IL-1β, and IL-6 was increased and the expression of MCP-1, NLPR3, and ASC proteins was also increased (p < .001). When AZM was added, the expression of all the above-mentioned proteins was decreased (p < .001). In addition, MDA, LDH, and SOD were increased after high glucose induction, while decreased after AZM treatment (p < .001). AZM can inhibit apoptosis and the expression of Bax and Cleaved caspase-3, 6, 9, and promote the expression of Bcl-2 (p < .001). Furthermore, the expression of STAT1 was increased after high glucose induction, while the expression of STAT1 was decreased after AZM action (p < .01). By adding a STAT1 agonist IFN-γ, the effects of AZM on inflammation, oxidative stress, and apoptosis of high glucose-induced podocytes were inhibited (p < .05). AZM inhibited inflammation, oxidative stress, and apoptosis of high glucose-induced podocytes by inhibiting STAT1 pathway.

Polymer Cell Surface Coating Enhances Mesenchymal Stem Cell Retention and Cardiac Protection

Mesenchymal stem cell (MSC) therapy has been widely tested in clinical trials to promote healing post-myocardial infarction. However, low cell retention and the need for a large donor cell number in human studies remain a key challenge for clinical translation. Natural biomaterials such as gelatin are ideally suited as scaffolds to deliver and enhance cell engraftment after transplantation. A potential drawback of MSC encapsulation in the hydrogel is that the bulky matrix may limit their biological function and interaction with the surrounding tissue microenvironment that conveys important injury signals. To overcome this limitation, we adopted a gelatin methacrylate (gelMA) cell-coating technique that photocross-links gelatin on the individual cell surface at the nanoscale. The present study investigated the cardiac protection of gelMA coated, hypoxia preconditioned MSCs (gelMA-MSCs) in a murine myocardial infarction (MI) model. We demonstrate that the direct injection of gelMA-MSC results in significantly higher myocardial engraftment 7 days after MI compared to uncoated MSCs. GelMA-MSC further amplified MSC benefits resulting in enhanced cardioprotection as measured by cardiac function, scar size, and angiogenesis. Improved MSC cardiac retention also led to a greater cardiac immunomodulatory function after injury. Taken together, this study demonstrated the efficacy of gelMA-MSCs in treating cardiac injury with a promising potential to reduce the need for donor MSCs through enhanced myocardial engraftment.

Immunomodulatory Effects of Azithromycin Revisited: Potential Applications to COVID-19

The rapid advancement of the COVID-19 pandemic has prompted an accelerated pursuit to identify effective therapeutics. Stages of the disease course have been defined by viral burden, lung pathology, and progression through phases of the immune response. Immunological factors including inflammatory cell infiltration and cytokine storm have been associated with severe disease and death. Many immunomodulatory therapies for COVID-19 are currently being investigated, and preliminary results support the premise of targeting the immune response. However, because suppressing immune mechanisms could also impact the clearance of the virus in the early stages of infection, therapeutic success is likely to depend on timing with respect to the disease course. Azithromycin is an immunomodulatory drug that has been shown to have antiviral effects and potential benefit in patients with COVID-19. Multiple immunomodulatory effects have been defined for azithromycin which could provide efficacy during the late stages of the disease, including inhibition of pro-inflammatory cytokine production, inhibition of neutrophil influx, induction of regulatory functions of macrophages, and alterations in autophagy. Here we review the published evidence of these mechanisms along with the current clinical use of azithromycin as an immunomodulatory therapeutic. We then discuss the potential impact of azithromycin on the immune response to COVID-19, as well as caution against immunosuppressive and off-target effects including cardiotoxicity in these patients. While azithromycin has the potential to contribute efficacy, its impact on the COVID-19 immune response requires additional characterization so as to better define its role in individualized therapy.

Tumour necrosis factor receptor-associated factors: interacting protein with forkhead-associated domain inhibition decreases inflammatory cell infiltration and cardiac remodelling after acute myocardial infarction

OBJECTIVES

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Post-AMI cardiac remodelling is closely related to the prognosis of AMI. The excess inflammatory responses could promote cardiac remodelling. Tumour necrosis factor receptor-associated factor-interacting protein with forkhead-associated domain (TIFA) has been identified as a nuclear factor (NF)-κB activator, which plays a key role in the activation of the NF-κB signalling pathway. The goal of this research was to investigate the expression and the underlying mechanism of TIFA in an AMI mouse model.

METHODS

The AMI mouse model was induced by ligation of the left coronary artery. TIFA and NF-κB knockdown were established by lentivirus transduction. The expression levels of associated proteins were analysed by a western blot or an enzyme-linked immunosorbent assay. Histological characteristics were evaluated by haematoxylin-eosin staining.

RESULTS

The TIFA level was elevated in our AMI mouse model. The production of interleukin-1β and tumour necrosis factor-α increased markedly in the mice with AMI. TIFA knockdown inhibited the infiltration of inflammatory cells, production of pro-inflammatory mediators (interleukin-1β and tumour necrosis factor-α), NF-κB activation and cardiac remodelling (matrix metallopeptidase 9) post-AMI. In addition, NF-κB knockdown could also alleviate cardiac remodelling after AMI.

CONCLUSIONS

The preceding results indicated that TIFA inhibition could ameliorate cardiac remodelling after AMI partly through inactivation of NF-κB. This study provides insights into further research of cardiac remodelling and AMI from bench to clinic.

Comparative Effectiveness of Anti-Inflammatory Drug Treatments in Coronary Heart Disease Patients: A Systematic Review and Network Meta-Analysis

Methods

We conducted a network meta-analysis of randomized controlled trials that studied the effects of anti-inflammatory medications on cardiovascular outcomes of coronary artery disease patients. We searched the electronic database until March 2020 for relevant studies.

Results

Nineteen trials examining the efficacy of eight anti-inflammatory medications (pexelizumab, anakinra, colchicine, darapladib, varespladib, canakinumab, inclacumab, and losmapimod) were selected for analysis. Overall, there is no statistically significant difference in all-cause mortality, cardiovascular mortality, revascularization, and major cardio and cerebrovascular events (MACCE) with the use of anti-inflammatory drugs. However, we found the use of colchicine significantly reduces the odds of developing stroke by approximately 75% (OR 0.26, CI 0.10-0.63). Colchicine use was also associated with a lower risk of revascularization and MACCE compared to the other agents. Our subgroup analyses comparing the timing of medication initiation (within 7 days vs. >7 days) and clinical presentation (ACS vs. non-ACS) revealed a significant reduction in the risk of recurrent MI in the group that received medication after seven days (OR 0.92, CI 0.86-0.99) and the non-ACS group (OR 0.88, CI 0.80-0.98).

Conclusion

Although many anti-inflammatory medications have failed to reduce adverse cardiovascular outcomes in the CAD population, selected medications show promise among subgroups of patients without ACS or after the first week following an acute ischemic event. Future studies examining the proper timing and targetable anti-inflammatory pathways are warranted.

Baicalin regulates macrophages polarization and alleviates myocardial ischaemia/reperfusion injury via inhibiting JAK/STAT pathway

CONTEXT

Baicalin is an active compound which demonstrates cardioprotection effects against myocardial ischaemia/reperfusion injury (MI/RI).

OBJECTIVE

To investigate how baicalin protects against myocardial injury and to explore its potential mechanism. We hypothesized that baicalin-modulated macrophages change from M1 (pro-inflammatory subset) to M2 (anti-inflammatory subset) under I/R stress.

MATERIALS AND METHODS

We established an ischaemia/reperfusion (I/R) model using Sprague Dawley (SD) rat, then baicalin was intragastric administration (20, 60 or 120 mg/kg) for 24 h. The rats were randomly divided into five groups (n = 10): control, I/R, I/R + baicalin (20 mg/kg), I/R + baicalin (60 mg/kg) and I/R + baicalin (120 mg/kg). Cardiac function was detected by echocardiography, HE staining and ELISA, respectively. Macrophage phenotype was examined by flow cytometry. Furthermore, IHC, qRT-PCR and WB were employed to analyse the related mechanisms.

RESULTS

The study showed that baicalin (20, 60 or 120 mg/kg) significantly improved cardiac function and impeded cardiac apoptosis in rats. In addition, the repair of myocardial morphology (reduced neutrophil infiltration) further confirmed its cardiacprotective effect. Moreover, baicalin effectively decreased iNOS, IL-1β and IL-6, and up-regulated Arg-1, IL-10 and TGF-β via changing the macrophage phenotype (from M1 towards M2). Notably, treatment with baicalin also inhibited the phosphorylation levels of JAK2 and STAT3. Discussion and conclusions: It was confirmed that baicalin alleviated post-I/R myocardial injury and reduced inflammation via JAK/STAT pathway, and baicalin treatment might be recommended as a new approach for myocardial ischaemic complications.

Liposomal delivery of azithromycin enhances its immunotherapeutic efficacy and reduces toxicity in myocardial infarction

A growing body of evidence shows that altering the inflammatory response by alternative macrophage polarization is protective against complications related to acute myocardial infarction (MI). We have previously shown that oral azithromycin (AZM), initiated prior to MI, reduces inflammation and its negative sequelae on the myocardium. Here, we investigated the immunomodulatory role of a liposomal AZM formulation (L-AZM) in a clinically relevant model to enhance its therapeutic potency and avoid off-target effects. L-AZM (40 or 10 mg/kg, IV) was administered immediately post-MI and compared to free AZM (F-AZM). L-AZM reduced cardiac toxicity and associated mortality by 50% in mice. We observed a significant shift favoring reparatory/anti-inflammatory macrophages with L-AZM formulation. L-AZM use resulted in a remarkable decrease in cardiac inflammatory neutrophils and the infiltration of inflammatory monocytes. Immune cell modulation was associated with the downregulation of pro-inflammatory genes and the upregulation of anti-inflammatory genes. The immunomodulatory effects of L-AZM were associated with a reduction in cardiac cell death and scar size as well as enhanced angiogenesis. Overall, L-AZM use enhanced cardiac recovery and survival after MI. Importantly, L-AZM was protective from F-AZM cardiac off-target effects. We demonstrate that the liposomal formulation of AZM enhances the drug’s efficacy and safety in an animal model of acute myocardial injury. This is the first study to establish the immunomodulatory properties of liposomal AZM formulations. Our findings strongly support clinical trials using L-AZM as a novel and clinically relevant therapeutic target to improve cardiac recovery and reduce heart failure post-MI in humans.

Autotaxin inhibition reduces cardiac inflammation and mitigates adverse cardiac remodeling after myocardial infarction

OBJECTIVE

Acute myocardial infarction (AMI) initiates pathological inflammation which aggravates tissue damage and causes heart failure. Lysophosphatidic acid (LPA), produced by autotaxin (ATX), promotes inflammation and the development of atherosclerosis. The role of ATX/LPA signaling nexus in cardiac inflammation and resulting adverse cardiac remodeling is poorly understood.

APPROACH AND RESULTS

We assessed autotaxin activity and LPA levels in relation to cardiac and systemic inflammation in AMI patients and C57BL/6 (WT) mice. Human and murine peripheral blood and cardiac tissue samples showed elevated levels of ATX activity, LPA, and inflammatory cells following AMI and there was strong correlation between LPA levels and circulating inflammatory cells. In a gain of function model, lipid phosphate phosphatase-3 (LPP3) specific inducible knock out (Mx1-Plpp3^Δ) showed higher systemic and cardiac inflammation after AMI compared to littermate controls (Mx1-Plpp3^fl/fl); and a corresponding increase in bone marrow progenitor cell count and proliferation. Moreover, in Mx1- Plpp3^Δ mice, cardiac functional recovery was reduced with corresponding increases in adverse cardiac remodeling and scar size (as assessed by echocardiography and Masson's Trichrome staining). To examine the effect of ATX/LPA nexus inhibition, we treated WT mice with the specific pharmacological inhibitor, PF8380, twice a day for 7 days post AMI. Inhibition of the ATX/LPA signaling nexus resulted in significant reduction in post-AMI inflammatory response, leading to favorable cardiac functional recovery, reduced scar size and enhanced angiogenesis.

CONCLUSION

ATX/LPA signaling nexus plays an important role in modulating inflammation after AMI and targeting this mechanism represents a novel therapeutic target for patients presenting with acute myocardial injury.

Monocyte recruitment and fate specification after myocardial infarction

Monocytes are critical mediators of the inflammatory response following myocardial infarction (MI) and ischemia-reperfusion injury. They are involved in both initiation and resolution of inflammation and play an integral role in cardiac repair. The antagonistic nature of their function is dependent on their subset heterogeneity and biphasic response following injury. New advancements in single-cell transcriptomics and mass cytometry have allowed us to identify smaller, transcriptionally distinct clusters that may have functional relevance in disease and homeostasis. Additionally, recent insights into the spatiotemporal dynamics of monocytes following ischemic injury and their subsequent interactions with the endothelium and other immune cells reveal a complex interplay between monocytes and the cardiac milieu. In this review, we highlight recent findings on monocyte functional heterogeneity, present new mechanistic insight into monocyte recruitment and fate specification following MI, and discuss promising therapeutic avenues targeting monocytes for the treatment of ischemic heart disease.

Carnosic acid protects against pressure overload-induced cardiac remodelling by inhibiting the AKT/GSK3β/NOX4 signalling pathway

Oxidative stress and apoptosis serve an important role in the development of pressure overload-induced cardiac remodelling. Carnosic acid (CA) has been found to exert antioxidant and anti-apoptotic effects. The present study investigated the underlying mechanism of CA protection and whether this effect was exerted against pressure overload-induced cardiac remodelling. Aortic banding (AB) surgery was performed to induce cardiac remodelling. Mice were randomly divided into four groups (n=15/group): i) Sham + vehicle; ii) sham + CA; iii) AB + vehicle; and iv) AB + CA. After 2 days of AB, 50 mg kg CA was administered orally for 12 days. Echocardiography, histological analysis and molecular biochemistry techniques were performed to evaluate the roles of CA. CA treatment decreased cardiac hypertrophy, fibrosis, oxidative stress and apoptosis in mice challenged with pressure overload. CA also decreased the cross-sectional area of cardiomyocytes and the mRNA and protein expression levels of hypertrophic markers. Furthermore, CA treatment decreased collagen deposition, α-smooth muscle actin expression and the mRNA and protein expression of various fibrotic markers. Additionally, CA reversed the AB-mediated increase in NAPDH oxidase (NOX) 2, NOX4 and 4-hydroxynonenal levels. The number of apoptotic cells was decreased following CA treatment following under conditions of pressure overload. CA also suppressed the activation of AKT and glycogen synthase kinase 3 β (GSK3β) in mice challenged with AB. The present results suggested that CA could inhibit pressure overload-induced cardiac hypertrophy and fibrosis by suppressing the AKT/GSK3β/NOX4 signalling pathway. Therefore, CA may be a promising therapy for cardiac remodelling.

Hydroxychloroquine is protective to the heart, not harmful: a systematic review

Hydroxychloroquine (HCQ) has been shown to be at least somewhat effective in treating patients with coronavirus disease 2019 (COVID-19). Recently the US Food and Drug Administration and Centers for Disease Control and Prevention warnings of fatal cardiac toxicity from torsades de pointes (TDP) arrhythmia from HCQ receipt have been made, notwithstanding the long safe provision of HCQ to treat lupus and rheumatoid arthritis. This has resulted in restricted access of HCQ for COVID-19 treatment. We hypothesized that HCQ and azithromycin have not been reported to cause significant acute cardiac arrhythmic mortality. We performed a literature search for the effects of HCQ and azithromycin on the heart. No TDP or related deaths were found to have been reported as a result of HCQ and azithromycin receipt in the peer-reviewed literature. On the contrary, HCQ and azithromycin were both found to substantially reduce cardiac mortality and also decrease thrombosis, arrhythmia and cholesterol in treated patients in recent peer-reviewed studies and meeting presentations. HCQ and azithromycin do not cause TDP cardiac mortality; rather, HCQ decreases cardiac events. HCQ should not be restricted in COVID-19 patients out of fear of cardiac mortality.

LncRNA promoted inflammatory response in ischemic heart failure through regulation of miR-455-3p/TRAF6 axis

OBJECTIVES

Ischemic heart failure (IHF) is the most common cause of death globally. Growing evidence shows abnormal expression of long non-coding RNAs in heart failure patients. This study aims to investigate the effect of sex-determining region Y-box 2 (SOX2) overlapping transcript (SOX2-OT) on the regulation of the inflammatory response in ischemic heart failure.

METHODS

IHF rat and oxygen and glucose deprivation (OGD) cell models were established. qRT-PCR was employed to investigate the expression of SOX2-OT. ELISA, western blot and cell viability/apoptosis assays were performed to assess the effects of SOX2-OT. Online software program was used to identify miRNAs that target SOX2-OT, followed by validation using RNA pull-down. Potential targets of miRNAs were searched, and examined by immunoblotting, qRT-PCR and luciferase reporter assay.

RESULTS

SOX2-OT was up-regulated in IHF and OGD. Knockdown of SOX2-OT promoted cell proliferation, decreased apoptosis rate and cell oxidative damage, and ameliorated inflammatory response. SOX2-OT contains binding sites for miR-455-3p, miR-5586-3p and miR-1252-5p. RNA pull-down confirmed the binding ability between SOX2-OT and miR-455-3p. TRAF6 is a direct target of miR-455-3p. Moreover, the regulatory activity of SOX2-OT on inflammatory response was partially through its negative regulation of miR-455-3p, which directly regulates TRAF6. Down-regulation of SOX2-OT improved myocardial dysfunction in IHF rat.

CONCLUSIONS

Our results reveal that SOX2-OT may be a driver of IHF through repression of miR-455-3p, and miR-455-3p alleviates IHF by targeting TRAF6. Therefore, SOX2-OT/miR-455-3p/TRAF6 may be a potential target for advanced therapeutic strategy for IHF.

Adhesive stem cell coatings for enhanced retention in the heart tissue

Injection into the heart tissue is a direct route for optimally placing mesenchymal stem cells (MSC) to regulate local inflammation following a heart attack. The retention of MSCs at the injection site is severely limited by the fluid flows that rapidly wash cells away and minimize their capacity to modulate cardiac inflammation. To prevent this loss of MSCs and their function, antibody coatings were designed for the surface of MSCs to enhance their adhesion to the inflamed tissue. MSCs were biotinylated, and biotinylated antibodies against intercellular cell adhesion molecules were conjugated to the cell surface through an intermediate layer of streptavidin. MSC surfaces were modified with ~7,000 biotin/μm² and ~23 antibodies/μm². The heart tissue injection of antibody-coated MSCs offered a 3-fold increase of cell retention in an infarcted heart over the injection of uncoated MSCs. We supported the mechanism of adhesion through analysis of MSC adhesion to inflamed endothelial cells and also surfaces of purified adhesion molecules on glass under microfluidic shear flow.

Effects of tetracycline on myocardial infarct size in obese rats with chemically-induced colitis

Background

Recent evidence suggests that antibiotic-induced changes in the composition of intestinal microflora, as well as the systemic immunoendocrine effects that result from them, can modulate myocardial tolerance to ischemia-reperfusion injury. The aim of this study was to investigate the effects of tetracycline (TTC) on myocardial infarct size in the isolated hearts obtained from obese rats with chemically-induced colitis (CIC). The association between TTC-induced changes in infarct size and intestinal microbiome composition as well as plasma levels of cytokines and short-chain fatty acids (SCFAs) was also studied.

Methods

Obesity was induced in Wistar rats by feeding them a high-fat, high-carbohydrate diet for five weeks. A single rectal administration of 3% acetic acid (2 mL) to the rats resulted in CIC. Healthy rats as well as obese rats with CIC received TTC (15 mg daily for 3 days) via gavage. The rats were euthanized, after which isolated heart perfusion with simulated global ischemia and reperfusion was performed. Infarct size was determined histochemically. Lipopolysaccharide (LPS) and cytokine levels in plasma were measured by enzyme-linked immunosorbent assay, whereas SCFA levels in plasma were measured by gas chromatography/mass spectrometry. The intestinal microbiome was analyzed using reverse transcription polymerase chain reaction.

Results

The treatment with TTC resulted in significant infarct size limitation (50 ± 7 vs. 62 ± 4% for the control mice, p < 0.05) in the hearts from intact animals. However, infarct size was not different between the control rats and the obese rats with CIC. Furthermore, infarct size was significantly larger in TTC-treated obese rats with CIC than it was in the control animals (77 ± 5%, p < 0.05). The concentrations of proinflammatory cytokines and LPS in serum were elevated in the obese rats with CIC. Compared to the control rats, the rats with both obesity and CIC had lower counts of Lactobacillus and Bifidobacterium spp. but higher counts of Escherichia coli. The effects of TTC on infarct size were not associated with specific changes in SCFA levels.

Conclusions

TTC reduced infarct size in the healthy rats. However, this effect was reversed in the obese animals with CIC. Additionally, it was associated with specific changes in gut microbiota and significantly elevated levels of cytokines and LPS.

Azithromycin Polarizes Macrophages to an M2 Phenotype via Inhibition of the STAT1 and NF-κB Signaling Pathways

Azithromycin is effective at controlling exaggerated inflammation and slowing the long-term decline of lung function in patients with cystic fibrosis. We previously demonstrated that the drug shifts macrophage polarization toward an alternative, anti-inflammatory phenotype. In this study we investigated the immunomodulatory mechanism of azithromycin through its alteration of signaling via the NF-κB and STAT1 pathways. J774 murine macrophages were plated, polarized (with IFN-γ, IL-4/-13, or with azithromycin plus IFN-γ) and stimulated with LPS. The effect of azithromycin on NF-κB and STAT1 signaling mediators was assessed by Western blot, homogeneous time-resolved fluorescence assay, nuclear translocation assay, and immunofluorescence. The drug's effect on gene and protein expression of arginase was evaluated as a marker of alternative macrophage activation. Azithromycin blocked NF-κB activation by decreasing p65 nuclear translocation, although blunting the degradation of IκBα was due, at least in part, to a decrease in IKKβ kinase activity. A direct correlation was observed between increasing azithromycin concentrations and increased IKKβ protein expression. Moreover, incubation with the IKKβ inhibitor IKK16 decreased arginase expression and activity in azithromycin-treated cells but not in cells treated with IL-4 and IL-13. Importantly, azithromycin treatment also decreased STAT1 phosphorylation in a concentration-dependent manner, an effect that was reversed with IKK16 treatment. We conclude that azithromycin anti-inflammatory mechanisms involve inhibition of the STAT1 and NF-κB signaling pathways through the drug's effect on p65 nuclear translocation and IKKβ.

Effect of paeoniflorin on cardiac remodeling in chronic heart failure rats through the transforming growth factor β1/Smad signaling pathway

Background

Cardiac remodeling is an important mechanism for the occurrence and development of chronic heart failure (CHF). Paeoniflorin (Pae) is the main active ingredient of Chinese herbaceous peony and has novel anti-inflammatory effect. This study was conducted to assess the effects and mechanisms of Pae on cardiac remodeling in CHF rats.

Methods

A cardiac remodeling rat model was induced by isoprenaline (Iso). Pae (20 µg/kg/d) was administrated to CHF rats for six weeks. Cardiac ultrasound was used to assess the structure and function of CHF rats. Collagen volume fraction (CVF) and perivascular collagen volume area of myocardial tissues were calculated. With real-time polymerase chain reaction and Western blot, the protein and mRNA levels of transforming growth factor β1 (TGF-β1) and Smad3 were detected.

Results

Compared to Iso group, Pae can alleviate cardiac remodeling and improve cardiac function in CHF rats. The levels of CVF and perivascular collagen volume area reduced in Pae group (P<0.05). The expression of TGF-β1 and Smad3 protein decreased in Pae and Cap group (P<0.05). Further, the expression of TGF-β1 and Smad3 mRNA also decreased markedly in the Pae group (P<0.05).

Conclusions

Pae could attenuate cardiac remodeling and improve cardiac function in CHF rats. The potential mechanism for the cardioprotective effect of Pae may be highly associated with the down-regulating of TGF-β1/Smad signaling pathway.

Sexual Dimorphism of Pain Control: Analgesic Effects of Pioglitazone and Azithromycin in Chronic Spinal Cord Injury

Central neuropathic pain develops in greater than 75% of individuals suffering a spinal cord injury (SCI). Increasingly, sex is recognized as an important biological variable in the development and treatment of peripheral neuropathic pain, but much less is known about the role of sex in central neuropathic pain and its pharmacological inhibition. To test the hypothesis that efficacy of analgesic therapies differs between males and females in SCI, we used a mouse model of SCI pain to determine the analgesic efficacy of pioglitazone (PIO), U.S. Food and Drug Administration–approved drug for the treatment of diabetes, and azithromycin (AZM), a commonly prescribed macrolide antibiotic with immunomodulatory properties. Male and female mice received moderate-severe T9 contusion SCI (75-kdyn). A robust heat hyperalgesia developed similarly between male and female mice by 4 weeks post-injury and lasted throughout the duration of the study (14 weeks). Three months after SCI, mice were treated with PIO (10 mg/kg, intraperitoneal) or AZM (160 mg/kg, oral). We observed a sex-specific effect of PIO with significant antihyperalgesic effects in females, but not males. In contrast, AZM was effective in both sexes. Our data support the use of PIO and AZM as novel therapies for SCI pain and highlight the importance of considering sex as a biological variable in clinical and experimental SCI pain research.