Limit Tissue Injury Research Articles

The complement system: A key player in the host response to infections.

Infections are one of the most significant healthcare and economic burdens across the world as underscored by the recent coronavirus pandemic. Moreover, with the increasing incidence of antimicrobial resistance, there is an urgent need to better understand host-pathogen interactions to design effective treatment strategies. The complement system is a key arsenal of the host defense response to pathogens and bridges both innate and adaptive immunity. However, in the contest between pathogens and host defense mechanisms, the host is not always victorious. Pathogens have evolved several approaches, including co-opting the host complement regulators to evade complement-mediated killing. Furthermore, deficiencies in the complement proteins, both genetic and therapeutic, can lead to an inefficient complement-mediated pathogen eradication, rendering the host more susceptible to certain infections. On the other hand, overwhelming infection can provoke fulminant complement activation with uncontrolled inflammation and potentially fatal tissue and organ damage. This review presents an overview of critical aspects of the complement-pathogen interactions during infection and discusses perspectives on designing therapies to mitigate complement dysfunction and limit tissue injury.

Post-resolution macrophages shape long-term tissue immunity and integrity in a mouse model of pneumococcal pneumonia

Resolving inflammation is thought to return the affected tissue back to homoeostasis but recent evidence supports a non-linear model of resolution involving a phase of prolonged immune activity. Here we show that within days following resolution of Streptococcus pneumoniae-triggered lung inflammation, there is an influx of antigen specific lymphocytes with a memory and tissue-resident phenotype as well as macrophages bearing alveolar or interstitial phenotype. The transcriptome of these macrophages shows enrichment of genes associated with prostaglandin biosynthesis and genes that drive T cell chemotaxis and differentiation. Therapeutic depletion of post-resolution macrophages, inhibition of prostaglandin E2 (PGE2) synthesis or treatment with an EP4 antagonist, MF498, reduce numbers of lung CD4+/CD44+/CD62L+ and CD4+/CD44+/CD62L-/CD27+ T cells as well as their expression of the α-integrin, CD103. The T cells fail to reappear and reactivate upon secondary challenge for up to six weeks following primary infection. Concomitantly, EP4 antagonism through MF498 causes accumulation of lung macrophages and marked tissue fibrosis. Our study thus shows that PGE2 signalling, predominantly via EP4, plays an important role during the second wave of immune activity following resolution of inflammation. This secondary immune activation drives local tissue-resident T cell development while limiting tissue injury

Pro-inflammatory cytokines stimulate CFTR-dependent anion secretion in pancreatic ductal epithelium.

Loss of CFTR-dependent anion and fluid secretion in the ducts of the exocrine pancreas is thought to contribute to the development of pancreatitis, but little is known about the impact of inflammation on ductal CFTR function. Here we used adult stem cell-derived cell cultures (organoids) obtained from porcine pancreas to evaluate the effects of pro-inflammatory cytokines on CFTR function. Organoids were cultured from porcine pancreas and used to prepare ductal epithelial monolayers. Monolayers were characterized by immunocytochemistry. Epithelial bicarbonate and chloride secretion, and the effect of IL-1β, IL-6, IFN-γ, and TNF-α on CFTR function was assessed by electrophysiology. Immunolocalization of ductal markers, including CFTR, keratin 7, and zonula occludens 1, demonstrated that organoid-derived cells formed a highly polarized epithelium. Stimulation by secretin or VIP triggered CFTR-dependent anion secretion across epithelial monolayers, whereas purinergic receptor stimulation by UTP, elicited CFTR-independent anion secretion. Most of the anion secretory response was attributable to bicarbonate transport. The combination of IL-1β, IL-6, IFN-γ, and TNF-α markedly enhanced CFTR expression and anion secretion across ductal epithelial monolayers, whereas these cytokines had little effect when tested separately. Although TNF-α triggered apoptotic signaling, epithelial barrier function was not significantly affected by cytokine exposure. Pro-inflammatory cytokines enhance CFTR-dependent anion secretion across pancreatic ductal epithelium. We propose that up-regulation of CFTR in the early stages of the inflammatory response, may serve to promote the removal of pathogenic stimuli from the ductal tree, and limit tissue injury.

Inhibiting membrane rupture with NINJ1 antibodies limits tissue injury

Plasma membrane rupture (PMR) in dying cells undergoing pyroptosis or apoptosis requires the cell-surface protein NINJ11. PMR releases pro-inflammatory cytoplasmic molecules, collectively called damage-associated molecular patterns (DAMPs), that activate immune cells. Therefore, inhibiting NINJ1 and PMR may limit the inflammation that is associated with excessive cell death. Here we describe an anti-NINJ1 monoclonal antibody that specifically targets mouse NINJ1 and blocks oligomerization of NINJ1, preventing PMR. Electron microscopy studies showed that this antibody prevents NINJ1 from forming oligomeric filaments. In mice, inhibition of NINJ1 or Ninj1 deficiency ameliorated hepatocellular PMR induced with TNF plus d-galactosamine, concanavalin A, Jo2 anti-Fas agonist antibody or ischaemia–reperfusion injury. Accordingly, serum levels of lactate dehydrogenase, the liver enzymes alanine aminotransaminase and aspartate aminotransferase, and the DAMPs interleukin 18 and HMGB1 were reduced. Moreover, in the liver ischaemia–reperfusion injury model, there was an attendant reduction in neutrophil infiltration. These data indicate that NINJ1 mediates PMR and inflammation in diseases driven by aberrant hepatocellular death.

Conserved Transcriptional Signatures of Microglia in Health and Disease (P2-3.011)

<h3>Objective:</h3> To determine signatures of microglia in humans and mice in the context of central nervous system (CNS) inflammation and homeostasis. <h3>Background:</h3> Single cell profiling of gene expression has illuminated the heterogeneity of immune cells and accessible phenotypes across organs and under a myriad of conditions. These efforts—typified by recent studies aiming to identify signatures of microglia—typically entail pre-enrichment of cell populations, even from distinct species, using a limited set of surface markers or morphological traits. This step introduces potential bias and subjectivity that may alter the gene expression states that are discerned. <h3>Design/Methods:</h3> We queried the NCBI GEO for datasets of single-cell transcription within CNS tissue from healthy subjects, multiple sclerosis (MS) patients, and mice afflicted with experimental autoimmune encephalomyelitis (EAE). In total, this yielded data on over 135,000 human cells—encompassing a spectrum of lesion chronicity in patients with progressive and relapsing-remitting MS—and 12,000 murine cells. Datasets were pre-processed for quality control and harmonized according to species prior to cross-species integration. We developed classifier models of microglia using logistic regression and support vector machine frameworks. <h3>Results:</h3> Unexpectedly, markers closely linked in the literature to microglia, including Iba-1, were found to be expressed in non-microglial myeloid cells. Other markers previously ascribed to microglia in one species, such as Hexb, failed to represent useful markers in the other species. We identified intra- and inter-species signatures of microglia using machine-learning methods that form the basis of future studies. <h3>Conclusions:</h3> Whole-brain, single-cell gene expression data, unencumbered by bias introduced by prior cell enrichment, enable identification of transcriptional signatures of cell types across species. Signatures of microglia during CNS inflammation identify potentially targetable pathways to understand their role in disease and limit tissue injury. <b>Disclosure:</b> The institution of an immediate family member of Dr. Salinas has received research support from Veterans Health Administration. Navid Manouchehri has nothing to disclose. Rehana Hussain has nothing to disclose. Dr. Stuve has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. Dr. Stuve has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Stuve has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche Genentech. Dr. Stuve has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Stuve has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Stuve has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. Dr. Stuve has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for VYNE. Dr. Stuve has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Therapeutic Advances in Neurological Diseases. Dr. Stuve has received research support from US Department of Veterans Affairs. Dr. Stuve has received research support from National Multiple Sclerosis Society (US). Dr. Stuve has received research support from Exalys. Dr. Stuve has received research support from Merck KGaA.

Endothelial cells overexpressing CXCR1/2 are renoprotective in rats with acute kidney injury.

Inflammation that develops with the release of chemokines and cytokines during acute kidney injury (AKI) has been shown to participate in functional renal recovery. Although a major research focus has been on the role of macrophages, the family of C-X-C motif chemokines that promote neutrophil adherence and activation also increases with kidney ischemia-reperfusion (I/R) injury. This study tested the hypothesis that intravenous delivery of endothelial cells (ECs) that overexpress (C-X-C motif) chemokine receptors 1 and 2 (CXCR1 and CXCR2, respectively) improves outcomes in kidney I/R injury. Overexpression of CXCR1/2 enhanced homing of endothelial cells to I/R-injured kidneys and limited interstitial fibrosis, capillary rarefaction, and tissue injury biomarkers (serum creatinine concentration and urinary kidney injury molecule-1) following AKI and also reduced expression of P-selectin and the rodent (C-X-C motif) chemokine cytokine-induced neutrophil chemoattractant (CINC)-2β as well as the number of myeloperoxidase-positive cells in the postischemic kidney. The serum chemokine/cytokine profile, including CINC-1, showed similar reductions. These findings were not observed in rats given endothelial cells transduced with an empty adenoviral vector (null-ECs) or a vehicle alone. These data indicate that extrarenal endothelial cells that overexpress CXCR1 and CXCR2, but not null-ECs or vehicle alone, reduce I/R kidney injury and preserve kidney function in a rat model of AKI.NEW & NOTEWORTHY Inflammation facilitates kidney ischemia-reperfusion (I/R) injury. Endothelial cells (ECs) that were modified to overexpress (C-X-C motif) chemokine receptor (CXCR)1/2 (CXCR1/2-ECs) were injected immediately following kidney I/R injury. The interaction of CXCR1/2-ECs, but not ECs transduced with an empty adenoviral vector, with injured kidney tissue preserved kidney function and reduced production of inflammatory markers, capillary rarefaction, and interstitial fibrosis. The study highlights a functional role for the C-X-C chemokine pathway in kidney damage following I/R injury.

Conjoint fascial sheath suspension with levator muscle advancement for severe blepharoptosis

In patients with severe blepharoptosis, the function of the levator muscle is usually weak. Even if a large amount of levator is resected, under-correction and recurrence often occur postoperatively. Frontalis suspension is the first choice for severe ptosis; however, the external orbital lifting force of the frontalis causes non-physiological eyelid movement. Conjoint fascial sheath (CFS) is a fibrous tissue which can provide dynamic movement of upper eyelids and has been applied for the treatment of mild and moderate blepharoptosis in recent years. This study aims to assess the efficacy and safety of CFS suspension combined with levator muscle advancement for treating severe blepharoptosis. A retrospective study included 44 patients (60 eyelids) with severe ptosis who underwent the modified technique. Preoperatively, levator muscle function and margin reflex distance 1 (MRD1) were measured. Surgical outcomes, symmetry results and complications were evaluated postoperatively. At the 12–18 months follow-up, adequate or normal correction was achieved in 56 eyelids (93.3%), and 37 patients (84.1%) presented good or fair symmetry results. The most common complication was conjunctival prolapse, which was observed in six eyelids (10.0%), followed by lid fold deformity and under-correction. No exposure keratitis was recorded. In conclusion, the modified technique can physically elevate the eyelid with limited tissue injury and is effective for the correction of severe ptosis. Both satisfactory functional and esthetic results were achieved, and severe complications (such as exposure keratitis) were not observed.

Metabolic regulation of γδ intraepithelial lymphocytes.

Elucidating the relationship between cellular metabolism and T cell function has substantially advanced our understanding of how T cells are regulated in response to activation. The metabolic profiles of circulating or peripheral T cells have been well-described, yet less is known regarding how complex local microenvironments shape or modulate the bioenergetic profile of tissue-resident T lymphocytes. Intraepithelial lymphocytes expressing the γδ T cell receptor (γδ IEL) provide immunosurveillance of the intestinal epithelium to limit tissue injury and microbial invasion; however, their activation and effector responses occur independently of antigen recognition. In this review, we will summarize the current knowledge regarding γδ T cell and IEL metabolic profiles and how this informs our understanding of γδ IEL metabolism. We will also discuss the role of the gut microbiota in shaping the metabolic profile of these sentinel lymphocytes, and in turn, how these bioenergetics contribute to regulation of γδ IEL surveillance behavior and effector function. Improved understanding of the metabolic processes involved in γδ IEL homeostasis and function may yield novel strategies to amplify the protective functions of these cells in the context of intestinal health and disease.

Low Levels of Factor H Family Proteins During Meningococcal Disease Indicate Systemic Processes Rather Than Specific Depletion by Neisseria meningitidis.

Neisseria meningitidis, the causative agent of meningococcal disease (MD), evades complement-mediated clearance upon infection by ‘hijacking’ the human complement regulator factor H (FH). The FH protein family also comprises the homologous FH-related (FHR) proteins, hypothesized to act as antagonists of FH, and FHR-3 has recently been implicated to play a major role in MD susceptibility. Here, we show that the circulating levels of all FH family proteins, not only FH and FHR-3, are equally decreased during the acute illness. We did neither observe specific consumption of FH or FHR-3 by N. meningitidis, nor of any of the other FH family proteins, suggesting that the globally reduced levels are due to systemic processes including dilution by fluid administration upon admission and vascular leakage. MD severity associated predominantly with a loss of FH rather than FHRs. Additionally, low FH levels associated with renal failure, suggesting insufficient protection of host tissue by the active protection by the FH protein family, which is reminiscent of reduced FH activity in hemolytic uremic syndrome. Retaining higher levels of FH may thus limit tissue injury during MD.

Metabolic Reprogramming and Host Tolerance: A Novel Concept to Understand Sepsis-Associated AKI.

Acute kidney injury (AKI) is a frequent complication of sepsis that increases mortality and the risk of progression to chronic kidney disease. However, the mechanisms leading to sepsis-associated AKI are still poorly understood. The recognition that sepsis induces organ dysfunction in the absence of overt necrosis or apoptosis has led to the consideration that tubular epithelial cells (TEC) may deploy defense mechanisms to survive the insult. This concept dovetails well with the notion that the defense against infection does not only depend on the capacity of the immune system to limit the microbial load (known as resistance), but also on the capacity of cells and tissues to limit tissue injury (known as tolerance). In this review, we discuss the importance of TEC metabolic reprogramming as a defense strategy during sepsis, and how this cellular response is likely to operate through a tolerance mechanism. We discuss the fundamental role of specific regulatory nodes and of mitochondria in orchestrating this response, and how this opens avenues for the exploration of targeted therapeutic strategies to prevent or treat sepsis-associated AKI.

IL-13 deficiency exacerbates lung damage and impairs epithelial-derived type 2 molecules during nematode infection.

IL-13 is implicated in effective repair after acute lung injury and the pathogenesis of chronic diseases such as allergic asthma. Both these processes involve matrix remodelling, but understanding the specific contribution of IL-13 has been challenging because IL-13 shares receptors and signalling pathways with IL-4. Here, we used Nippostrongylus brasiliensis infection as a model of acute lung damage comparing responses between WT and IL-13-deficient mice, in which IL-4 signalling is intact. We found that IL-13 played a critical role in limiting tissue injury and haemorrhaging in the lung, and through proteomic and transcriptomic profiling, identified IL-13-dependent changes in matrix and associated regulators. We further showed a requirement for IL-13 in the induction of epithelial-derived type 2 effector molecules such as RELM-α and surfactant protein D. Pathway analyses predicted that IL-13 induced cellular stress responses and regulated lung epithelial cell differentiation by suppression of Foxa2 pathways. Thus, in the context of acute lung damage, IL-13 has tissue-protective functions and regulates epithelial cell responses during type 2 immunity.

Arthroscopic Ankle Arthrodesis: A Review of Current Concepts and Technique

Background: Open ankle arthrodesis (OAA) has traditionally been the gold standard for improving pain and function in ankle osteoarthritis patients. With advances in arthroscopic technology and improved instrumentation, arthroscopic ankle arthrodesis (AAA) has become more popular among orthopedic surgeons with equivalent or better outcomes compared with OAA. Recent studies have shown that, with increasing experience, AAA can even be suitable for large deformities, which has been traditional viewed as a relative contraindication. A review of literature and concepts with expert opinion. AAA has been shown in the literature to have equivalent fusion rates, decreased hospital length of stay, and better short-term and long-term function when compared with OAA. Arthroscopy advantages include faster time to union, decreased morbidity, decreased blood loss, and accelerated rehabilitation. Advanced arthroscopic techniques and instrumentation facilitate joint preparation with limited soft tissue injury, creating a favorable environment for fusion. Arthroscopic techniques lead to better short-term and long-term outcomes and decreased complications compared with open arthrodesis. The technique has been shown to be successful and reproducible within the literature, and can be employed to ultimately reduce overall hospital care costs and improve patient outcomes. Level of Evidence: Diagnostic Level V. See Instructions for Authors for a complete description of levels of evidence.

Hepatoprotective and immunomodulatory effects of copper-nicotinate complex against fatty liver in rat model.

Aim:The current study was designed to evaluate the potential hepatoprotective and immunomodulatory effects of copper-nicotinate complex (CNC) against methionine- and choline-deficient diet (MCDD)-induced fatty liver in rats.Materials and Methods:Forty male Wistar rats were randomly allocated into one of four equal-sized groups (G1-G4). The G1 group was fed a balanced diet and kept under normal conditions; the G2 group received CNC orally at a dose of 0.043 mg/kg body weight, 3 times/week for 4 weeks, and a balanced diet; the G3 group was fed an MCDD for 4 weeks; and the G4 group was fed an MCDD and administered CNC at the same dose and route as G2. Blood samples were collected for the determination of serum enzyme activity. After 4 weeks of treatment, liver specimens were collected for the evaluation of the oxidative/antioxidative markers, cytokine gene expression, and histopathological examination.Results:CNC improved MCDD-induced liver dysfunctions by recovering serum alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase activities to their normal levels. The glutathione (GSH) level and superoxide dismutase (SOD) activity significantly decreased, while lipid peroxidation (as reflected by malondialdehyde [MDA]) markedly increased in the liver tissue of the MCDD group. After cotreatment with MCDD and CNC, the GSH level and SOD activity markedly increased and the MDA level significantly decreased to return to normal levels. After cotreatment with MCDD and CNC, significant downregulation of the mRNA expression of hepatic interleukin (IL)-1β, IL-4, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 genes was found. Moreover, CNC reduced fatty liver complications by reducing the number of hepatic vacuolations, degenerative changes in the hepatocytes, and hemorrhage.Conclusion:CNC has the potential to limit tissue injury and possibly prevent the progression to severe liver disease caused by an MCDD.

Autophagy genes in myeloid cells counteract IFNγ-induced TNF-mediated cell death and fatal TNF-induced shock

Host inflammatory responses must be tightly regulated to ensure effective immunity while limiting tissue injury. IFN gamma (IFNγ) primes macrophages to mount robust inflammatory responses. However, IFNγ also induces cell death, and the pathways that regulate IFNγ-induced cell death are incompletely understood. Using genome-wide CRISPR/Cas9 screening, we identified autophagy genes as central mediators of myeloid cell survival during the IFNγ response. Hypersensitivity of autophagy gene-deficient cells to IFNγ was mediated by tumor necrosis factor (TNF) signaling via receptor interacting protein kinase 1 (RIPK1)- and caspase 8-mediated cell death. Mice with myeloid cell-specific autophagy gene deficiency exhibited marked hypersensitivity to fatal systemic TNF administration. This increased mortality in myeloid autophagy gene-deficient mice required the IFNγ receptor, and mortality was completely reversed by pharmacologic inhibition of RIPK1 kinase activity. These findings provide insight into the mechanism of IFNγ-induced cell death via TNF, demonstrate a critical function of autophagy genes in promoting cell viability in the presence of inflammatory cytokines, and implicate this cell survival function in protection against mortality during the systemic inflammatory response.

Targeting the HIV-infected brain to improve ischemic stroke outcome

HIV-associated cerebrovascular events remain highly prevalent even in the current era of antiretroviral therapy (ART). We hypothesize that low-level HIV replication and associated inflammation endure despite antiretroviral treatment and affect ischemic stroke severity and outcomes. Using the EcoHIV infection model and the middle cerebral artery occlusion as the ischemic stroke model in mice, we present in vivo analysis of the relationship between HIV and stroke outcome. EcoHIV infection increases infarct size and negatively impacts tissue and functional recovery. Ischemic stroke also results in an increase in EcoHIV presence in the affected regions, suggesting post-stroke reactivation that magnifies pro-inflammatory status. Importantly, ART with a high CNS penetration effectiveness (CPE) is more beneficial than low CPE treatment in limiting tissue injury and accelerating post-stroke recovery. These results provide potential insight for treatment of HIV-infected patients that are at risk of developing cerebrovascular disease, such as ischemic stroke.

RelB controls adaptive responses of astrocytes during sterile inflammation.

In response to brain injury or infections, astrocytes become reactive, undergo striking morphological and functional changes, and secrete and respond to a spectrum of inflammatory mediators. We asked whether reactive astrocytes also display adaptive responses during sterile IL-1β-induced neuroinflammation, which may limit tissue injury associated with many disorders of the central nervous system. We found that astrocytes display days-to-weeks long specific tolerance of cytokine genes, which is coordinated by NF-κB family member, RelB. However, in contrast to innate immune cells, astrocytic tolerance does not involve epigenetic silencing of the cytokine genes. Establishment of tolerance depends on persistent higher levels of RelB in tolerant astrocytes and its phosphorylation on serine 472. Mechanistically, this phosphorylation prevents efficient removal of RelB from cytokine promoters by IκBα and helps to establish tolerance. Importantly, ablation of RelB from astrocytes in mice abolishes tolerance during experimental neuroinflammation in vivo.

Determination of the Role of LOX‐1 during Escherichia coli Pneumonia

Pneumonia is primarily caused by infection from bacteria, virus, and/or fungi and results in an acute lower respiratory tract inflammation. It is responsible for severe morbidity and mortality worldwide. Pneumonia is the foremost cause of children's hospitalizations in the United States and accounts for more than 935,000 deaths globally. In mice with severe bacterial pneumonia it is known that the pathophysiology of pneumonia is due to the overt activation and recruitment of host innate immune cells. Data generated in our lab has shown that there is an induction of the OLR1 gene that expresses lectin‐like oxidized low‐density lipoprotein receptor 1 (LOX‐1) in the lungs of mice during pneumonia. LOX‐1 is a receptor that is expressed in many cells, including host innate immune cells and it is commonly associated with atherosclerosis and inflammation. Herein, we aim to understand the role LOX‐1 plays during Gram‐negative bacterial pneumonia. Our recent results indicate that local neutralization of LOX‐1 within the lungs during pneumonia caused a significant increase in total tissue injury and inflammatory cytokines, indicating that LOX‐1 may have a protective effect.To determine the effect of LOX‐1 inhibition systemically, an intraperitoneal injection with 10 μg of anti‐LOX‐1 antibody was administered to neutralize LOX‐1 in C57BL/6J mice that were subsequently infected with Escherichia coli. Mice were euthanized 24 hours after infection and bronchoalveolar lavage fluid (BALF) samples were collected. In an ex vivo system, mouse lung epithelial (MLE‐12) cells were similarly treated with anti‐LOX‐1 antibody to observe the effect of neutralizing LOX‐1 on epithelial cell death. BALF from infected and uninfected mice was also added in the ex vivo model to more accurately recreate the conditions of the alveolar space. Total protein from MLE‐12 cells was then collected 24 hours after stimulation for analysis and characterization.Overall, the systemic neutralization of LOX‐1 in C57BL/6J mice during bacterial pneumonia did not significantly affect leukocyte recruitment or lung injury. In addition, ex vivo LOX‐1 neutralization in MLE‐12 cells did not affect apoptosis as measured by cleaved caspase‐3 on a western blot. In contrast with local inhibition of LOX‐1 in the lungs, systemic inhibition of LOX‐1 did not significantly limit tissue injury in mice with pneumonia. Blockade of LOX‐1 in ex vivo model did not remarkably affect epithelial cell death or apoptosis. Further studies involving measurement of resistance and resilience of lung tissue are underway and will more completely characterize the role of LOX‐1 during pneumonia.Support or Funding InformationNIH grants R01‐HL111449, R01‐GM120060, and T32‐HL007035.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Lactococcus Lactis Subsp. cremoris Is an Efficacious Beneficial Bacterium that Limits Tissue Injury in the Intestine

SummaryThe use of beneficial bacteria to promote health is widely practiced. However, experimental evidence corroborating the efficacy of bacteria promoted with such claims remains limited. We address this gap by identifying a beneficial bacterium that protects against tissue damage and injury-induced inflammation in the gut. We first employed the Drosophila animal model to screen for the capacity of candidate beneficial bacteria to protect the fly gut against injury. From this screen, we identified Lactococcus lactis subsp. cremoris as a bacterium that elicited potent cytoprotective activity. Then, in a murine model, we demonstrated that the same strain confers powerful cytoprotective influences against radiological damage, as well as anti-inflammatory activity in a gut colitis model. In summary, we demonstrate the positive salutary effects of a beneficial bacterium, namely, L. lactis subsp. cremoris on intestinal tissue and propose the use of this strain as a therapeutic to promote intestinal health.

Neutrophil-Initiated Myocardial Inflammation and Its Modulation by B-Type Natriuretic Peptide: A Potential Therapeutic Target

Activation of neutrophils is a critically important component of the innate immune response to bacterial and chemical stimuli, and culminates in the “neutrophil burst”, which facilitates neutrophil phagocytosis via the release of superoxide anion radical (O2−) from NADPH oxidase. Excessive and/or prolonged neutrophil activation results in substantial tissue injury and increases in vascular permeability—resulting in sustained tissue infiltration with neutrophils and monocytes, and persistent vasomotor dysfunction. Cardiovascular examples of such changes include acute and chronic systolic and diastolic heart failure (“heart failure with preserved ejection fraction”), and the catecholamine-induced inflammatory disorder takotsubo syndrome. We have recently demonstrated that B-type natriuretic peptide (BNP), acting via inhibition of activation of neutrophil NADPH oxidase, is an important negative modulator of the “neutrophil burst”, though its effectiveness in limiting tissue injury is partially lost in acute heart failure. The potential therapeutic implications of these findings, regarding the development of new means of treating both acute and chronic cardiac injury states, are discussed.

Novel Chitohexaose Compounds to Treat Abdominal Peritonitis Leading to Sepsis

Gastrointestinal perforation and appendicitis are the common cause of leakage of alimentary contents into the peritoneal cavity, leading to sepsis with a mortality rate between 14.7% and 29.9%. Besides its clinical challenge, the treatment of sepsis and its complications impose an enormous economic burden on health care systems worldwide. In sepsis caused by gram-negative bacteria, the bacterial endotoxin, lipopolysaccharide (LPS), activates the immune system through signaling the MD2-toll like receptor 4 complex (TLR4) to initiate the infection process for production of inflammatory cytokines (TNF-α, IL-1β, IL-6) that are responsible for hyperinflammation. Thus, development of antagonists that block these receptors either by inhibition of activation of TLRs or downstream signaling pathways would be beneficial in ameliorating the hyperinflammation if introduced early in the therapy. At AyuVis Research, we have designed a series of dual-acting small molecules (AVR-25, 48) that block TLR4 receptor, which inhibits the production of proinflammatory cytokines; stimulate production of macrophages leading to organ protection; and limit tissue injury. Our lead compound, AVR-25, has efficaciously demonstrated survival, organ protection, downregulation of inflammatory cytokines, and upregulation of M2 biomarkers and cytokines such as arginase-1 and IL-10 in vivo in a cecal ligation and puncture (CLP) sepsis mouse model via intravenous (IV) dosing. Our published and unpublished in silico modeling experiment has demonstrated that our compounds have a unique binding mode where they either bind to the dimerization site or to the middle of the TLR4 protein restricting the dimerization of protein, which is a critical step in downstream signaling. In our CLP model of both young and aged mice, compounds AVR-45 and AVR-48 efficaciously protected them against CLP-induced death and organ dysfunction at a 10-mg/kg (q8h) IV dose. These compounds also possess modest antibacterial activities against both gram-positive and gram-negative bacteria, as well as synergistic/additive activity in combination with standard of care antibiotics such as primaxin (PRM, Imipenem + cilastatin), indicating good potential for adjuvant antimicrobial therapy. We are the first and only key investigator team to observe the effects of AVR-25 and AVR-48 natural oligosaccharide-derived small molecules in preventing sepsis-induced death in the murine CLP-induced peritonitis model. We believe that development of this class of compounds will lead to a paradigm shift and could become a very high-gain project in the treatment management of inflammation and organ dysfunction in intra-abdominal sepsis. These significant research capabilities will open a new facet to combination therapy with antibiotic and standard antihypotensive agents for critically ill patients.