Background and Purpose: Traumatic brain injury (TBI) remains a major public health concern worldwide with unmet effective treatment. Stimulator of Interferon Genes (STING) protein and its downstream type-I Interferon (IFN) signaling are now appreciated to be involved in TBI pathogenesis. Compelling evidence have shown that STING and type-I IFNs are key in mediating detrimental neuroinflammatory response after TBI, exacerbating outcome. Therefore, pharmacological inhibition of STING presents a viable therapeutic opportunity in combating the detrimental neuroinflammatory response after TBI. Experimental Approach: This study investigated the neuroprotective effects of the small-molecule STING inhibitor C-176 in the controlled-cortical impact (CCI) mouse model of TBI in 10–12-week-old male mice. 30-minutes post-CCI surgery, a single 750nmol dose of C-176 or saline (vehicle) was administered intravenously. Analysis was conducted 2h- and 24h-post TBI. Key Results: Mice administered C-176 had significantly smaller cortical lesion area when compared to vehicle-treated mice 24h post-TBI. Quantitative temporal gait analysis conducted using DigiGait™ showed C-176 administration attenuated TBI-induced impairments in gait symmetry, stride frequency and forelimb stance width. C-176-treated mice displayed a significant reduction in striatal gene expression of pro-inflammatory cytokines TNF-α, IL-1β and CXCL10 compared to their vehicle-treated counterparts 2h post-TBI. Conclusion and Implications: This study demonstrates the neuroprotective activity of C-176 in ameliorating acute neuroinflammation and preventing white matter neurodegeneration post-TBI. This study highlights the therapeutic potential of small-molecule inhibitors targeting STING for the treatment of trauma induced inflammation and neuroprotective potential.

Background and Purpose L-type amino acid (AA) transporters LAT1 (SLC7A5) and LAT2 (SLC7A8) facilitate the bidirectional transport of branched and aromatic AA across the plasma membrane. While LAT1 is overexpressed in different tumour cells and it is dedicated to deliver AA into growing cells, LAT2 facilitates the transcellular AA transport at biological barriers. Data on dynamic AA transport by LAT1/2 in physiological media are widely lacking and the impact of LAT1-selective inhibitors and mutations on the cellular metabolome is unknown. Experimental Approach The human MDST8 cell line lacking LAT1/2 expression was employed to generate transiently and stably expressing MDST8-LAT1 and MDST8-LAT2 cells. Together with the HT-29 cell line, we depicted metabolic signatures mediated by LAT1 and LAT2 using LC-ESI-MS/MS and characterized potent LAT1/2 inhibitors for their selectivity and mode of action. Moreover, LAT1 mutations associated with autism spectrum disorder (ASD) were functionally evaluated. Key Results LAT1 and LAT2 expression induced the expression of 4F2hc and facilitated differential cellular metabolomic signatures in MDST8 cells. The LAT1(A246V) mutation showed overall reduced aromatic AA uptake and profound alterations of intracellular metabolites and biochemical processes. The equipotent LAT1 inhibitors JPH203 and JX-078 showed intriguing differences on metabolomic effects, uncovering their distinct mode of action. Conclusion and Implications Our study demonstrates that SLC7A transporters mediate differential dynamic cellular AA changes under physiological conditions and reports the broad effects of one human LAT1 mutation associated with ADS. Moreover, the characterization of biased LAT1 inhibitors challenges current concepts about transporter pharmacology and has implications for drug discovery.

Objective: Our study aimed to explore the mechanism network that TLR2/AP-1 combined with SOX10 to activate the MAPK pathway via CTGF in Dox-induced myocardial injury. Methods: Rats with Dox-induced myocardial injury were treated with a TLR2 inhibitor or CTGF silencing lentiviral vector. H9c2 cells were treated with genetic vectors or MAPK pathway activators. Cardiac function was tested using echocardiography and serum markers. H&E, sirius red, and TUNEL staining were used to detect myocardial pathological changes, collagen accumulation, and apoptosis. Western blot was used to detect proteins related to cardiac hypertrophy, fibrosis, apoptosis, and MAPK pathway. H9c2 cell injury was assessed by testing cell viability, LDH release, and mitochondrial membrane potential. Results: TLR2 and CTGF were highly expressed in patients with heart failure, and Dox treatment further increased their expression. Inhibiting TLR2 or silencing CTGF improved cardiac function and reduced myocardial fibrosis and apoptosis in Dox-treated rats. Silencing TLR2 alleviated Dox-induced H9c2 cell injury, which was nullified by CTGF overexpression. TLR2 activated AP-1, which cooperated with SOX10 to promote CTGF transcription. MAPK activation aggravated H9c2 cells against Dox-induced injury. Conclusions: TLR2 activates AP-1 which cooperates with SOX10 to promote CTGF transcription and subsequently activate the MAPK pathway, thereby stimulating Dox-induced myocardial injury.

Background and Purpose: The holotoxin A1, isolated from Apostichopus japonicus, has shown potent antifungal activities with unclear mechanism and efficacy against candidiasis. This study aimed to reveal the antifungal effects and mechanism of holotoxin A1 against Candida albicans in vitro and in candidiasis murine models for the first time. Experimental Approach: The antifungal effect of holotoxin A1 against C. albicans was tested in vitro. To explore the antifungal mechanism of holotoxin A1, the transcriptome, ROS levels, and mitochondrial function of C. albicans was evaluated. The oropharyngeal and intra-abdominal candidiasis mouse models were used to verify the effectiveness and systematic toxicity in vivo. Key Results: Holotoxin A1 was a potent fungicide against C. albicans SC5314, clinical strains and drug-resistant strains. Holotoxin A1 inhibited the oxidative phosphorylation and induced oxidative damage by increasing intracellular accumulation of ROS in C. albicans. Holotoxin A1 caused the disfunction of mitochondria by depolarizing the mitochondrial membrane potential and reducing the production of ATP. Holotoxin A1 directly inhibited the enzymatic activity of mitochondrial complex I (CI) and antagonized with the rotenone, an inhibitor of CI, against C. albicans. Meanwhile, the CI subunit NDH51 null mutants showed the decreased susceptibility to holotoxin A1. Furthermore, holotoxin A1 significantly reduced fungal burden and infections with no significant systemic toxicity in oropharyngeal and intra-abdominal candidiasis murine models. Conclusions and Implications: Holotoxin A1 was a promising candidate for the development of novel antifungal drug against both oropharyngeal and intra-abdominal candidiasis, especially caused by the drug resistant strains.

Background and purpose: Hypertension increases the risk for cognitive impairment and promotes vascular and renal inflammation. We tested if immune cell infiltration occurs in the brain during hypertension and if it is associated with cognitive impairment. Experimental approach: Male C57Bl/6 mice were administered vehicle, angiotensin II (0.7 mg/kg/d S.C.) or aldosterone (0.72 mg/kg/d S.C.) via osmotic minipumps. A subset of mice also received hydralazine (50 mg/kg) in their drinking water after minipump implantation. We measured systolic blood pressure, markers of inflammation, working memory and transcriptomic changes in the brain. Key results: Administration of angiotensin II or aldosterone increased blood pressure and promoted blood-brain barrier dysfunction, leukocyte accumulation and impairment of working memory in mice. When co-administered with angiotensin II, hydralazine prevented the development of these changes. In a separate cohort of mice in which angiotensin II-induced changes were first established, intervention with hydralazine lowered blood pressure but did not reverse brain inflammation or cognitive impairment. Finally, angiotensin II infusion altered the transcriptomic profile of the whole brain, as well as specifically within the hippocampus, and co-treatment with hydralazine modulated these changes. Conclusion and implications: Experimental hypertension leads to brain inflammation and impaired working memory. Cognitive impairment that develops during hypertension can be inhibited, but not readily reversed, by anti-hypertensive therapy.

Background and Purpose Metabotropic Glutamate Receptors (mGlu) regulate multiple functions in the nervous systems and are involved in multiple disorders. However, selectively targeting individual mGlu subtypes with spatiotemporal precision is still an unmet need. Photopharmacology can address this concern by means of photoswitchable compounds such as Optogluram, which is a positive allosteric modulator (PAM) of mGlu4 that enables to optically control physiological responses with a high precision. However, Optogluram is not fully selective and finding mGlu4 PAMs with subtype selectivity may be complicated. Experimental Approach New photoswitchable analogues of Optogluram were synthesised with the aim of obtaining photoswitchable PAMs selective for mGlu4 receptor and with improved photoisomerization properties. The photopharmacological profiles of these new compounds were assessed using spectroscopy, functional IP and cAMP assays and computational modelling. Key Results Optogluram-2 emerged as a new photoswitchable PAM for mGlu4 receptor and offered improved photoswitching properties and was selective for mGlu4. Optogluram-2 had activity as both PAM and allosteric agonist. The π-π stacking of the thiazole ring in the allosteric pocket of mGlu6 is hypothesised to be responsible of the mGlu4 selectivity. Conclusion and Implications. The enhanced photoswitching behaviour and improved selectivity of Optogluram-2 makes it an excellent candidate to study the role of mGlu4 with a high spatiotemporal precision that only photopharmacology can offer. Indeed, the use of Optogluram-2 in tissues where mGlu4 can be co-expressed with other mGlu receptors will help to unravel the complexity of mGlu receptors in neural transmission, pinpointing the role of mGlu4 in such systems.

The GPCR signalling cascade is a key pathway responsible for the signal transduction of a multitude of physical and chemical stimuli, including light, odorants, neurotransmitters, and hormones. Understanding the structural and functional properties of the GPCR cascade requires direct observation of signalling processes in high spatial and temporal resolution with minimal perturbation to endogenous systems. Optical microscopy and spectroscopy techniques are uniquely suited to this purpose because they excel at multiple spatial and temporal scales and can be used in living objects. Here, we review recent developments in microscopy and spectroscopy technologies which enable new insights into GPCR signalling. We focus on advanced techniques with high spatial and temporal resolution, single-molecule methods, labelling strategies, and approaches suitable for endogenous systems and large living objects. This review aims to assist researchers in choosing appropriate microscopy and spectroscopy approaches for a variety of applications in the study of cellular signalling.

Inflammation is a physiological response composed by well-defined and overlapping events that can eliminate pathogens and reestablish homeostasis of tissues. Physiological systems have an elastic capacity to deal with numerous perturbations. Infection may lead to inflammation, tissue damage and disease as consequence of breakdown of tissue resilience. The resolutive phase is a sine qua non condition to achieve homeostasis after acute inflammation. Exuberant or chronic inflammation occurs in diverse infectious diseases. Pro-resolving molecules may be useful for the treatment of certain infections, as these molecules modulate the immune response and avoid the exacerbated/misplaced inflammation unleashed by microbes. Some pro-resolving molecules may also favour pathogen clearance, in addition to decreasing tissue damage. In this review, we discuss the endogenous role and the therapeutic potential of the most relevant pro-resolving molecules in the context of bacterial and viral infections.

Accumulating studies in recent years have revealed that airway remodeling is involved in the occurrence, development, and treatment sensitivity of asthma. Airway epithelial cells (AECs) regulate the activation of epithelial-mesenchymal trophic units (EMTUs) during airway remodeling through secretion of a series of signaling mediators. However, the major trigger and the intrinsic pathogenesis of airway remodeling is still obscure. Here, we show that the expression of CTSK in airway epithelia increased significantly along with the development of airway remodeling in HDM-stressed asthma model. Increased secretion of CTSK from airway epithelia induced the activation of EMTU through the activation of PAR2-mediated pathway. We found that CTSK is a potential biomarker of airway remodeling for asthma patients that can reflect the degree of airway remodeling and the severity of asthma. Blockade of CTSK inhibits EMTU activation and alleviate airway remodeling effectively that is an effective intervention target of airway remodeling. Thus, our findings provide that CTSK is a potential biomarker for airway remodeling which may also be a useful target for the targeted intervention of airway remodeling in asthma patients.

Background and Purpose: In major depressive disorder (MDD), exploration of biomarkers will be helpful in diagnosing the disorder as well as in choosing a treatment, and predicting the treatment response. Currently, tRNA-derived small ribonucleic acids (tsRNAs) have been established as promising non-invasive biomarker candidates that may enable a more reliable diagnosis or monitoring of various diseases. Herein, we aimed to explore tsRNA expression together with functional activities in MDD development. Experimental Approach: Serum samples were obtained from patients with MDD and healthy controls, and small RNA sequencing (RNA-Seq) was used to profile tsRNA expression. Dysregulated tsRNAs in MDD were validated by quantitative real-time polymerase chain reaction (qRT-PCR). The diagnostic utility of specific tsRNAs and the expression of these tsRNAs after antidepressant treatment was analyzed. Key Results: In total, 38 tsRNAs were significantly differentially expressed in MDD samples relative to healthy individuals (34 upregulated and 4 downregulated). qRT-PCR was used to validate the expression of six tsRNAs that were upregulated in MDD (tiRNA-1:20-chrM. Ser-GCT, tiRNA-1:33-Gly-GCC-1, tRF-1:22-chrM.Ser-GCT, tRF-1:31-Ala-AGC-4-M6, tRF-1:31-Pro-TGG-2, and tRF-1:32-chrM. Gln-TTG). Interestingly, serum tiRNA-Gly-GCC-001 levels exhibited an area under the ROC curve of 0.844. Moreover, tiRNA-Gly-GCC-001 is predicted to suppress brain-derived neurotrophic factor (BDNF) expression. Furthermore, significant tiRNA-Gly-GCC-001 downregulation was evident following an eight-week treatment course and served as a promising baseline predictor of patient response to antidepressant therapy. Conclusion and Implications: Our current work firstly found that tiRNA-Gly-GCC-001 is a promising MDD biomarker candidate that can predict patient responses to antidepressant therapy.

Decreased aortic compliance is a precursor to numerous cardiovascular diseases. Compliance is regulated by the rigidity of the aortic wall and the vascular smooth muscle cells (VSMCs) within it. Extracellular matrix stiffening, observed during ageing, reduces compliance and contributes to hypertension. In response to increased rigidity, VSMCs generate enhanced contractile forces that result in VSMC stiffening and a further reduction in compliance. Due to a lack of suitable in vitro models, the mechanisms driving VSMC response to matrix rigidity remain poorly defined. Human aortic-VSMCs were seeded onto polyacrylamide hydrogels whose rigidity mimicked either healthy or aged/diseased aortae. VSMC response to contractile agonist stimulation was measured through changes in cell area and volume. VSMCs were pre-treated with pharmacological agents prior to agonist stimulation to identify regulators of VSMC hypertrophy. VSMCs undergo a differential response to contractile agonist stimulation based on matrix rigidity. On pliable matrices, VSMCs contract, decreasing in cell area. Meanwhile, on rigid matrices VSMCs undergo a hypertrophic response, increasing in area and volume. Piezo1 mediated calcium influx drives VSMC hypertrophy by promoting microtubule destabilisation. Pharmacological stabilisation of microtubules or blocking calcium influx prevented VSMC hypertrophy on rigid matrices whilst maintaining contractility on pliable matrices. In response to extracellular matrix rigidity, VSMCs undergo a hypertrophic response driven by piezo1-mediated microtubule destabilisation. Pharmacological targeting of this response blocks matrix rigidity induced VSMC hypertrophy whilst VSMC contractility on healthy mimicking matrices is unimpeded. Through delineating this rigidity-induced mechanism, we identify novel targets whose pharmacological inhibition may prove beneficial against VSMC-driven cardiovascular disease.

Background and Purpose Asthma is characterized by airway inflammation, mucus hypersecretion and airway hyperresponsiveness (AHR). The activation of cholinergic anti‐inflammatory pathway (CAP) through nicotinic agents has been shown to control experimental asthma. Yet, the effects of vagus nerve stimulation (VNS)-induced CAP on allergic inflammation remain unknown. Experimental Approach BALB/c mice were sensitized and challenged with house dust mite (HDM) extract, and treated with active VNS (5Hz, 0.5 ms, 0.1 mA). Bronchoalveolar lavage (BAL) fluid was assessed for total and differential cell counts and cytokine levels. Lungs were examined by histopathology and electron microscopy. AHR in response to methacholine was also measured. Key Results In the HDM mouse asthma model, active but not sham VNS reduced BAL fluid total and differential cell counts, blocked mucus hypersecretion and suppressed choline acetyltransferase (ChAT) expression in bronchial epithelial cells. Besides, active VNS also abated HDM-induced elevation of type 2 cytokines IL-4 and IL-5. Furthermore, goblet cell hyperplasia and collagen deposition were diminished in VNS-treated mice. Mechanistically, VNS was found to block the phosphorylation of transcription factor STAT6 and the level of IRF4 in total lung lysates. Finally, VNS abrogated methacholine-induced AHR in asthma mice. Therapeutic effects of VNS were abolished by prior administration with α-bungarotoxin, a specific inhibitor of α7 nicotinic receptors (α7nAChR). Conclusion Our data revealed the protective effects of VNS on various clinical features in allergic airway inflammation model. VNS, a clinically approved therapy for depression and epilepsy, appears to be a promising new strategy for controlling allergic asthma through α7nAChR.

Background and Purpose: Aristolochic acid nephropathy (AAN) is a progressive kidney disease caused by using herbal medicines. Currently, no therapies are available to treat or prevent AAN. Histone deacetylase (HDAC) plays a crucial role in the development and progression of renal disease. We tested whether HDAC inhibitors could prevent AAN and determined the underlying mechanism. Experimental Approach: HDACs expression in the kidneys was examined. Mouse kidney and renal tubular epithelial cell damage were assessed after exposure to HDAC1 and HDAC2 blockade (FK-228). Conditional knock-in of Proline-serine-threonine-phosphatase-interacting protein 2 (PSTPIP2) in the kidney and knockdown of PSTPIP2 expression in PSTPIP2-knockin mice, pathological parameters, and kidney injuries were assessed. Key Results: Aristolochic acid upregulated the expression of HDAC1 and HDAC2 in the kidneys. Notably, the HDAC1 and -2 specific inhibitor, romidepsin (FK228, Depsipeptide), suppressed aristolochic acid-induced kidney injury, epithelial cell pyroptosis, apoptosis, and necroptosis (PANoptosis). Moreover, romidepsin upregulated PSTPIP2 in renal tubular epithelial cells, which was enhanced by aristolochic acid treatment. Conditional knock-in of PSTPIP2 in the kidney protected against AAN. In contrast, the knockdown of PSTPIP2 expression in PSTPIP2-knockin mice restored kidney damage and PANoptosis. PSTPIP2 function was determined in vitro using PSTPIP2 knockdown or overexpression in mTEC. Additionally, PSTPIP2 was found to regulate Caspase-8 in Aristolochic acid nephropathy. Conclusion and Implications: HDAC-mediated silencing of PSTPIP2 may contribute to aristolochic acid nephropathy. Hence, HDAC1 and -2 specific inhibitors or PSTPIP2 could be valuable therapeutic agents for the prevention of aristolochic acid nephropathy.

Investigating the intricate mechanisms of G protein-coupled receptor (GPCR) signalling in living cells is far from trivial. Over the last 20 years, the rise of genetically encoded resonance energy transfer (RET) sensors has shed new light onto the mechanisms of GPCR signalling. Such findings have challenged classical views on GPCR signalling and enhanced our understanding of the spatiotemporal dimensions of GPCR activity, leading to the discovery of endosomal GPCR signalling. This review highlights the use of RET sensors to monitor GPCR signalling in real-time and in live cells, focusing on GPCR activation and trafficking, and second messenger activity. It explores the physiological relevance of illustrative cases of endosomal signalling and discusses potential avenues to improve RET approaches to further explore endogenous GPCR activity in physiologically relevant contexts.

Background and Purpose: Traumatic brain injury (TBI) remains a leading cause of mortality and morbidity in young adults. The role of iron in potentiating neurodegeneration following TBI has gained recent interest since iron deposition has been detected in the injured brain in the weeks to months post-TBI, in both the preclinical and clinical setting. A failure in iron homeostasis can lead to oxidative stress, inflammation and excitotoxicity; and whether this is a cause or consequence of the long-term effects of TBI remains unknown. Experimental approach: We investigated the role of iron, and the effect of therapeutic intervention using a brain-permeable iron chelator, deferiprone, in a controlled cortical impact mouse model of TBI. An extensive assessment of cognitive, motor and anxiety/depressive outcome measures were examined, and neuropathological and biochemical changes, over a 3-month period post-TBI. Key Results: Lesion volume was significantly reduced at 3 months, which was preceded by a reduction in astrogliosis and a preservation of neurons in the injured brain at 2 weeks and/or 1-month post-TBI in mice receiving oral deferiprone. Deferiprone treatment showed significant improvements in neurological severity scores and locomotor/gait performance, and cognitive function, and attenuated anxiety-like symptoms post-TBI. Deferiprone reduced iron levels, oxidative stress and altered expression of neurotrophins in the injured brain over this period. Conclusion and Implications: Our findings support a detrimental role of iron in the injured brain and suggest that deferiprone (or similar iron chelators) may be promising therapeutic approaches to improve survival, functional outcomes and quality of life following TBI.

Background and Purpose: Peptides derived from retroviral envelope proteins have been shown to possess a wide range of immunosuppressive and anti-inflammatory activities. We have previously reported identification of such a peptide derived from the envelope protein coded by a human endogenous retrovirus (HERV). In this study we assessed effects of this peptide treatment on inhibition of immune response in the DSS-induced mice model of colitis. Furthermore, we identified that in vitro the peptide inhibits the KCa3.1 potassium channel, a potential target for therapy of immune diseases. Experimental Approach: We characterized an immunosuppressive peptide ENV59, from a specific HERV envelope protein, in vivo effects on inflammation control in acute colitis mice model and in vitro on the production of pro-inflammatory cytokines. Furthermore, we described in vitro ENV59-GP3 effects with respect to potency of inhibition on KCa3.1 channels and calcium influx. Key Results: ENV59-GP3 peptide treatment showed reduction of the disease score in the DSS-induced acute colitis mice model, which was comparable to effects of the KCa3.1 channel blocker NS6180. Analysis of cytokine production from DSS-mice model treated animals revealed equipotent inhibitory effects of the ENV59-GP3 and NS6180 compounds on the production of IL-6, TNF-α, IL-1β. Patch clamp studies show that the peptide ENV59-GP3 is a blocker of the potassium channel KCa3.1. Conclusion and Implications: Env59-GP3 represents KCa3.1 channel inhibitor underlining the implications of using virus derived channel blockers for treatment of autoimmune diseases. There are no drugs with a similar mechanism of action currently on the market.

Background and Purpose: The Covid-19 is a viral infection classified as a pandemic by the World Health Organization. There is not currently therapy against the Sars-cov-2. We aimed to assess the best drug therapy approach for the management of Covid-19. Experimental Approach: We did a systematic review and meta-analysis of randomized controlled trials of drugs used in patients with Covid-19. We performed research in the PubMed and the Medrxiv. The trials were included if the patients were over 12 years old, diagnosed through the rt-PCR test and who assessed as primary outcomes or decreased mortality, or time to clinical improvement, or hospitalization time. Random-effects meta-analysis was used to pool individual studies. Heterogeneity was assessed using I². The review has been registered on PROSPERO, number 179879. Key Results: Nine trials were included for analysis. Remdesivir, mainly early after the onset of symptoms, led to a reduction in mortality (OR, 0·85; 95% CI, 0·05 to 0·98; P=0·045). Although this meta-analysis did not observe a reduction using dexamethasone, the Recovery Trial indicates that it can be an option for a patient that needs oxygen support. Our study did not demonstrate the efficacy of any treatment to minimize the effects of Covid-19 related to large hospital stay or time to clinical improvement. Conclusion and Implications: Remdesivir is the only drug that can change the course of Covid-19, reducing mortality rates. Despite this result, other studies must evaluate the effectiveness of this and other drugs in the management of Covid-19 mainly studies with robust methods.

Marciano Lee1, Elise Anderson1, Ali Farooq1, Mohammed Yasin1, Yazan Alkawaleet1, Frank Annie2Charleston Area Medical Center, Department of Cardiology, 3200 MacCorkle Ave. SE,Charleston, WV 25304CAMC Health Education and Research Institute, 3200 MacCorkle Ave. SE,Charleston, WV 25304Corresponding:Frank Annie MA; MPA; PhDResearch Scientist (Department of Cardiology)CAMC Health Education and Research Institute3200 MacCorkle Ave. SE,Charleston, WV 25304Cell 304 -395 – 3830Phone 304-388-9921Fax: 304-388-9921Email: [email protected]:COVID-19, GEMFIBROZIL, IMMUNE MODULATING TREATMENTAbstract:The current Covid-19 viral infection has been declared a pandemic causing significant global morbidity and mortality predominantly from the manifestation of severe acute respiratory syndrome (SARS). It has been designated as SARS-CoV 2. Epidemiological studies show predilection in patients with associated chronic medical conditions including those with cardiovascular disease. Exaggerated host immune response known as cytokine storm syndrome (CSS) leading to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is the proposed mechanism for the development of SARS in Covid-19 infection. Gemfibrozil has proven benefits in patients with cardiovascular disease. More importantly, it has established anti-inflammatory, anti-oxidative, and anti-migratory properties. Gemfibrozil has shown survival benefits as immune modulation of ALI/ARDS from viral pathogens. This article reviews the potential of gemfibrozil as adjuntive immue modulating therapy for SARS associated with Covid-19 infected patients who have associated cardiovascular disease.Introduction:The severe acute respiratory syndrome (SARS) seen in Covid-19 infection share similarities with previous coronavirus epidemics, particularly SARS-CoV 1 and the Middle East Respiratory Syndrome (MERS-CoV). (1) It has been designated SARS-CoV 2. Acute lung injury (ALI) with subsequent development of acute respiratory distress syndrome (ARDS) from robust host hyper-immune response is the proposed pathophysiological mechanism. This so called ”cytokine storm” may be independent of viral load and replication. (2) Thus, the rationale for adding immune modulating strategies on top of antiviral/antimicrobial therapies is warranted to prevent this complication and hopefully improve survival. The development of ALI/ARDS amplifies mortality in Covid-19 infection, more so in patients with associated chronic medical conditions including cardiovascular disease. (3)Gemfibrozil, a drug discovered over 40 years ago, have beneficial effects and safety profile in both primary and secondary prevention of cardiovascular disease. (4) In addition to its lipid lowering ability, it has important immune modulating properties that inhibit pro-inflammatory factors involved in cytokine storms.(5) It is a peroxisome proliferators-activated receptor (PPAR) agonist known to reduce the release of inflammatory cytokines including interleukin-6 (IL-6), tumor necrosing factors (TNF) and interferon-gamma (IFN-g).IL-6 elevation have been reported as an important marker of severity with Covid-19 infection. (3) Together with other markers for inflammation such as CRP, the degree of IL-6 elevation correlates with increased morbidity and mortality.Gemfibrozil has shown survival benefits by attenuating ALI/ARDS development from viral etiologies. (6) Since gemfibrozil is currently indicated for patients with cardiovascular disease, its adjunctive use does not have to be repurposed for SARS associated with Covid-19 infection. Therefore, Gemfibrozil’s potential as an immune modulating strategy to prevent ALI/ARDS cannot be ignored.Immune Modulating Targets for Gemfibrozil in Covid-19 SARS pathogenesis:Gemfibrozil has been shown to attenuate pro-inflammatory effects of disease states through its immune-modulating, anti-inflammatory and anti-migratory properties. (5). It belongs to the fibrate family of drugs used to lower plasma lipds and cholesterol. They are one of several known synthetic lignads acting as agonists to the PPARs. (7) Their action in turn decrease serum levels of TNF, IFN-g and IL-6. (8,9)As an an anti-inflammatory, gemfibrozil reduces superoxide production and expression of nuclear factor kB (NF-kB). (10) Moreover, it inhibits astrocyte production of TNF, IL-1b, IL-6 and nitric oxide (NO) production. (11) Gemfibrozil also promotes the production of anti-inflammatory cytokine IL-4. (12) It reduces the production of C-reactive protein (CRP), TNF-a and IL-6 in peripheral blood mononuclear cells. It inhibits the production of cyclooxygenase-2 (COX-2) and prostaglandins. (13)As an immune-modulating agent, gemfibrozil attenuates pro-inflammatory transcription factor activation. This includes IFN-g regulatory factor 1 (IRF-1)bidning to gamma activation site (GAS), nuclear factor-kB (NF-kB), activator protein 1 (AP-1), and CCAT/enhancer binding protein beta (C/EBPb). (5) It also promotes switching of T helper (Th) cells from the pro-inflammatory Th1 to anti-inflammatory Th2. Production of Th2-specific cytokines is amplified including IL-4, IL-5 and IL-10. (14)As an anti-oxidant, gemfibrozil not only prevents low density lipoprotein (LDL) peroxidation but also acts on other signals of inflammation. Reactive oxygen species (ROS) have emerged as important signaling molecules during inflammatory conditions. Excessive ROS generation results in damage to most cellular components of the living organism. Gemfibrozil is known to inhibit ROS-mediated inflammation. (15) It has free radical scavenging ability as well. Its para-hydroxyl metabolite has been shown to reduce the burden of ROS. (16)As an anti-migratory agent, gemfibrozil affects the expression of cell-surface adhesion molecules icluding intracellular adhesion molecule 1 (ICAM-1), VCAM-1 and selectins inhibiting trans endothelial migration of mononuclear cells and macrophages. (17) It also down-regulates the expression of chemokines including monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1 (MIP-1), monokines induced by IFN-g (MIG) and IL-8. The expression of IL-8 induces inflammation, monocyte/macrophage recruitment, angiogenesis and vascular smooth muscle migration. Thus, gemfibrozil can function as an anti-migratory factor by down-regulating the expression of different soluble chemokines and inhibit the expression of different cell surface proteins and selectins.Discussion:Over the years, viral pathogens including Influenzas and Coronaviruses cause ALI/ARDS from excessive release of pro-inflammatory cytokines and chemokines described in cytokine storm syndromes. They induce much higher transcription and up regulation of TNF genes including TNF related aptoptosis-inducing lignad and TNF-mRNA in human monocyte-derived macrophages. (18) This macrophage activation syndrome (MAS) seen with the current SARS-CoV 2 may be a dysregulated host response to Covid-19 viral induced immunosuppression and lymphopenia leading to unintended ALI/ARDS consequences at the site of infection. (19) The development of ALI/ARDS and the need for ventilator support portends to increased mortality rates. Markers of inflammation including CRP and IL-6 have been used as surrogates for MAS, and their degree of elevation have correlated well with disease severity. (3)Experiments with SARS-CoV indicate that MAS induced cytokine storms result more from amplification of gene related inflammatory signals regardless of viral load. In one model, immune modulation of receptor sites or alteration of recruitment signals resulted in dramatic improvement in host survival with viral load remaining constant. (20) This suggests that immune modulating therapy may have as important a role in addition to antiviral therapy in altering the course of Covid-19 infection. Reports of clinical improvement have been reported with the adjuvant use of IL-6 antagonists including tocilizumab. However, cost and repurposing use of these medications may be limiting factors.Gemfibrozil has been in clinical use for patients with cardiovascular disease and has achieved generic status. In addition, it has vital immune modulating properties against cytokine storms that mitigate the development of ALI/ARDS from both viral and nonviral pathogens. (21). It not only reduces the levels of IL-6, TNF and IFN-g. But it has also been shown to attneuate gene recruiting signals of inflammation utlizing human equivalent dosing. In one animal study, the adjuvant use of gemfibrozil resulted in enhanced host survival that developed ALI/ARDS from viral pathogens. (6) Enhanced survival is seen even after exposure to the virus. This implies that gemfibrozil has the potential to be a treatment rather than a preventive therapy in human disease.Therefore, the potential of gemfibrozil as adjunct immune modulating therapy in conjunction with antiviral treatment for SARS associated with Covid-19 infection in patients with associated cardiovascular disease is emphasized.References:1. Petrosillo N, Vicenconte G, et al. Covid-19, SARS and MERS: are they closely related? JCMI. 20202. 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