Anti-inflammatory mechanisms of apolipoprotein A-I mimetic peptide in acute respiratory distress syndrome secondary to sepsis

Synthetic Amphipathic Helical Peptide L-37pA Ameliorates the Development of Acute Respiratory Distress Syndrome (ARDS) and ARDS-Induced Pulmonary Fibrosis in Mice

In this study, we evaluated the ability of the synthetic amphipathic helical peptide (SAHP), L-37pA, which mediates pathogen recognition and innate immune responses, to treat acute respiratory distress syndrome (ARDS) accompanied by diffuse alveolar damage (DAD) and chronic pulmonary fibrosis (PF). For the modeling of ARDS/DAD, male ICR mice were used. Intrabronchial instillation (IB) of 200 µL of inflammatory agents was performed by an intravenous catheter 20 G into the left lung lobe only, leaving the right lobe unaffected. Intravenous injections (IVs) of L-37pA, dexamethasone (DEX) and physiological saline (saline) were used as therapies for ARDS/DAD. L37pA inhibited the circulating levels of inflammatory cytokines, such as IL-8, TNFα, IL1α, IL4, IL5, IL6, IL9 and IL10, by 75-95%. In all cases, the computed tomography (CT) data indicate that L-37pA reduced lung density faster to -335 ± 23 Hounsfield units (HU) on day 7 than with DEX and saline, to -105 ± 29 HU and -23 ± 11 HU, respectively. The results of functional tests showed that L-37pA treatment 6 h after ARDS/DAD initiation resulted in a more rapid improvement in the physiological respiratory lung by 30-45% functions compared with the comparison drugs. Our data suggest that synthetic amphipathic helical peptide L-37pA blocked a cytokine storm, inhibited acute and chronic pulmonary inflammation, prevented fibrosis development and improved physiological respiratory lung function in the ARDS/DAD mouse model. We concluded that a therapeutic strategy using SAHPs targeting SR-B receptors is a potential novel effective treatment for inflammation-induced ARDS, DAD and lung fibrosis of various etiologies.

HDL-based therapeutics: A promising frontier in combating viral and bacterial infections

Low levels of high-density lipoprotein (HDL) and impaired HDL functionality have been consistently associated with increased susceptibility to infection and its serious consequences. This has been attributed to the critical role of HDL in maintaining cellular lipid homeostasis, which is essential for the proper functioning of immune and structural cells. HDL, a multifunctional particle, exerts pleiotropic effects in host defense against pathogens. It functions as a natural nanoparticle, capable of sequestering and neutralizing potentially harmful substances like bacterial lipopolysaccharides. HDL possesses antiviral activity, preventing viruses from entering or fusing with host cells, thereby halting their replication cycle. Understanding the complex relationship between HDL and the immune system may reveal innovative targets for developing new treatments to combat infectious diseases and improve patient outcomes. This review aims to emphasize the role of HDL in influencing the course of bacterial and viral infections and its and its therapeutic potential.

TRENDS IN CHOLESTEROL AND LIPOPROTEINS ARE ASSOCIATED WITH ACUTE RESPIRATORY DISTRESS SYNDROME INCIDENCE AND DEATH AMONG SEPSIS PATIENTS

ABSTRACT

Objective: Compare changes in cholesterol and lipoprotein levels occurring in septic patients with and without acute respiratory distress syndrome (ARDS) and by survivorship. Methods: We reanalyzed data from prospective sepsis studies. Cholesterol and lipoprotein levels were analyzed using univariate testing to detect changes between septic patients with or without ARDS, and among ARDS survivors compared with nonsurvivors at enrollment (first 24 h of sepsis) and 48 to 72 h later. Results: 214 patients with sepsis were included of whom 48 had ARDS and 166 did not have ARDS. Cholesterol and lipoproteins among septic ARDS versus non-ARDS showed similar enrollment levels. However, 48 to 72 h after enrollment, change in median total cholesterol (48/72 h - enrollment) was significantly different between septic ARDS (-4, interquartile range [IQR] -23.5, 6.5, n = 35) and non-ARDS (0, -10.0, 17.5, P = 0.04; n = 106). When compared by ARDS survivorship, ARDS nonsurvivors (n = 14) had lower median total cholesterol levels (75.5, IQR 68.4, 93.5) compared with ARDS survivors (113.0, IQR 84.0, 126.8, P = 0.022), and lower median enrollment low-density lipoprotein cholesterol (LDL-C) levels (27, IQR 19.5-34.5) compared with ARDS survivors (43, IQR 27-67, P = 0.013; n = 33). Apolipoprotein A-I levels were also significantly lower in ARDS nonsurvivors (n = 14) (87.6, IQR 76.45-103.64) compared with ARDS survivors (130.0, IQR 73.25-165.47, P = 0.047; n = 33). At 48 to 72 h, for ARDS nonsurvivors, median levels of low-density lipoprotein cholesterol (9.0, IQR 4.3, 18.0; n = 10), LDL-C (17.0, IQR 5.0, 29.0; n = 9), and total cholesterol (59.0, 45.3, 81.5; n = 10) were significantly lower compared with ARDS survivors' (n = 25) levels of low-density lipoprotein cholesterol (20.0, IQR 12.0-39.0, P = 0.014), LDL-C (42.0, IQR 27.0-58.0, P = 0.019), and total cholesterol (105.0, IQR 91.0, 115.0, P = 0.003). Conclusions: Change in total cholesterol was different in septic ARDS versus non-ARDS. Total cholesterol, LDL-C, and apolipoprotein A-I levels were lower in ARDS nonsurvivors compared with survivors. Future studies of dysregulated cholesterol metabolism in septic ARDS patients are needed to understand biology and links to potential therapies.

A Current Update on the Role of HDL-Based Nanomedicine in Targeting Macrophages in Cardiovascular Disease

High-density lipoproteins (HDL) are complex endogenous nanoparticles involved in important functions such as reverse cholesterol transport and immunomodulatory activities, ensuring metabolic homeostasis and vascular health. The ability of HDL to interact with a plethora of immune cells and structural cells places it in the center of numerous disease pathophysiologies. However, inflammatory dysregulation can lead to pathogenic remodeling and post-translational modification of HDL, rendering HDL dysfunctional or even pro-inflammatory. Monocytes and macrophages play a critical role in mediating vascular inflammation, such as in coronary artery disease (CAD). The fact that HDL nanoparticles have potent anti-inflammatory effects on mononuclear phagocytes has opened new avenues for the development of nanotherapeutics to restore vascular integrity. HDL infusion therapies are being developed to improve the physiological functions of HDL and to quantitatively restore or increase the native HDL pool. The components and design of HDL-based nanoparticles have evolved significantly since their initial introduction with highly anticipated results in an ongoing phase III clinical trial in subjects with acute coronary syndrome. The understanding of mechanisms involved in HDL-based synthetic nanotherapeutics is critical to their design, therapeutic potential and effectiveness. In this review, we provide a current update on HDL-ApoA-I mimetic nanotherapeutics, highlighting the scope of treating vascular diseases by targeting monocytes and macrophages.

Diverse functions of apolipoprotein A-I in lung fibrosis

Apolipoprotein A-I (apoA-I) mediates reverse cholesterol transport (RCT) out of cells. In addition to its important role in the RTC, apoA-I also possesses anti-inflammatory and antioxidative functions including the ability to activate inflammasome and signal via toll-like receptors. Dysfunctional apoA-I or its low abundance may cause accumulation of cholesterol mass in alveolar macrophages, leading to the formation of foam cells. Increased numbers of foam cells have been noted in the lungs of mice after experimental exposure to cigarette smoke, silica, or bleomycin and in the lungs of patients suffering from different types of lung fibrosis, including idiopathic pulmonary fibrosis (IPF). This suggests that dysregulation of lipid metabolism may be a common event in the pathogenesis of interstitial lung diseases. Recognition of the emerging role of cholesterol in the regulation of lung inflammation and remodeling provides a challenging concept for understanding lung diseases and offers novel and exciting avenues for therapeutic development. Accordingly, a number of preclinical studies demonstrated decreased expression of inflammatory and profibrotic mediators and preserved lung tissue structure following the administration of the apoA-I or its mimetic peptides. This review highlights the role of apoA-I in lung fibrosis and provides evidence for its potential use in the treatment of this pathological condition.

High-Density Lipoproteins: A Role in Inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is a widespread disease associated with high rates of disability and mortality. COPD is characterized by chronic inflammation in the bronchi as well as systemic inflammation, which contributes significantly to the clinically heterogeneous course of the disease. Lipid metabolism disorders are common in COPD, being a part of its pathogenesis. High-density lipoproteins (HDLs) are not only involved in lipid metabolism, but are also part of the organism's immune and antioxidant defense. In addition, HDL is a versatile transport system for endogenous regulatory agents and is also involved in the removal of exogenous substances such as lipopolysaccharide. These functions, as well as information about lipoprotein metabolism disorders in COPD, allow a broader assessment of their role in the pathogenesis of heterogeneous and comorbid course of the disease.

Plasma Proteomic Analysis Identified Proteins Associated with Faulty Neutrophils Functionality in Decompensated Cirrhosis Patients with Sepsis

Decompensated cirrhosis (DC) is susceptible to infections and sepsis. Neutrophils and monocytes provide the first line of defense to encounter infection. We aimed to evaluate proteins related to neutrophils functionality in sepsis. 70 (DC), 40 with sepsis, 30 without (w/o) sepsis and 15 healthy controls (HC) plasma was analyzed for proteomic analysis, cytokine bead array, endotoxin, cell free DNA and whole blood cells were analyzed for nCD64-mHLADR index, neutrophils-monocytes, functionality and QRT-PCR. nCD64-mHLADR index was significantly increased (p < 0.0001) with decreased HLA-DR expression on total monocytes in sepsis (p = 0.045). Phagocytic activity of both neutrophils and monocytes were significantly decreased in sepsis (p = 0.002 and p = 0.0003). Sepsis plasma stimulated healthy neutrophils, showed significant increase in NETs (neutrophil extracellular traps) and cell free DNA (p = 0.049 and p = 0.04) compared to w/o sepsis and HC. Proteomic analysis revealed upregulated- DNAJC13, TMSB4X, GPI, GSTP1, PNP, ANPEP, COTL1, GCA, APOA1 and PGAM1 while downregulated- AHSG, DEFA1,SERPINA3, MPO, MMRN1and PROS1 proteins (FC > 1.5; p < 0.05) associated to neutrophil activation and autophagy in sepsis. Proteins such as DNAJC13, GPI, GSTP1, PNP, ANPEP, COTL1, PGAM1, PROS1, MPO, SERPINA3 and MMRN1 showed positive correlation with neutrophils activity and number, oxidative burst activity and clinical parameters such as MELD, MELD Na and Bilirubin. Proteomic analysis revealed that faulty functionality of neutrophils may be due to the autophagy proteins i.e., DNAJC13, AHSG, TMSB4X, PROS1 and SERPINA3, which can be used as therapeutic targets in decompensated cirrhosis patients with sepsis.

Peptides as Therapeutic Agents for Atherosclerosis

More than three decades ago, as a test for the amphipathic helix theory, an 18 amino acid residue peptide and its analogs were designed with no sequence homology to any of the exchangeable apolipoproteins. Based on the apolipoprotein A-I (the major protein component of high density lipoproteins, HDL) mimicking properties, they were termed as ApoA-I mimicking peptides. Several laboratories around the world started studying such de novo-designed peptides for their antiatherogenic properties. The present chapter describes the efforts in bringing these peptides as therapeutic agents for atherosclerosis and several lipid-mediated disorders.

Multifaced Roles of HDL in Sepsis and SARS-CoV-2 Infection: Renal Implications

High-density lipoproteins (HDLs) are a class of blood particles, principally involved in mediating reverse cholesterol transport from peripheral tissue to liver. Omics approaches have identified crucial mediators in the HDL proteomic and lipidomic profile, which are involved in distinct pleiotropic functions. Besides their role as cholesterol transporter, HDLs display anti-inflammatory, anti-apoptotic, anti-thrombotic, and anti-infection properties. Experimental and clinical studies have unveiled significant changes in both HDL serum amount and composition that lead to dysregulated host immune response and endothelial dysfunction in the course of sepsis. Most SARS-Coronavirus-2-infected patients admitted to the intensive care unit showed common features of sepsis disease, such as the overwhelmed systemic inflammatory response and the alterations in serum lipid profile. Despite relevant advances, episodes of mild to moderate acute kidney injury (AKI), occurring during systemic inflammatory diseases, are associated with long-term complications, and high risk of mortality. The multi-faceted relationship of kidney dysfunction with dyslipidemia and inflammation encourages to deepen the clarification of the mechanisms connecting these elements. This review analyzes the multifaced roles of HDL in inflammatory diseases, the renal involvement in lipid metabolism, and the novel potential HDL-based therapies.

Current Understanding of the Immunomodulatory Activities of High-Density Lipoproteins

Lipoproteins interact with immune cells, macrophages and endothelial cells - key players of the innate and adaptive immune system. High-density lipoprotein (HDL) particles seem to have evolved as part of the innate immune system since certain HDL subspecies contain combinations of apolipoproteins with immune regulatory functions. HDL is enriched in anti-inflammatory lipids, such as sphingosine-1-phosphate and certain saturated lysophospholipids. HDL reduces inflammation and protects against infection by modulating immune cell function, vasodilation and endothelial barrier function. HDL suppresses immune cell activation at least in part by modulating the cholesterol content in cholesterol/sphingolipid-rich membrane domains (lipid rafts), which play a critical role in the compartmentalization of signaling pathways. Acute infections, inflammation or autoimmune diseases lower HDL cholesterol levels and significantly alter HDL metabolism, composition and function. Such alterations could have a major impact on disease progression and may affect the risk for infections and cardiovascular disease. This review article aims to provide a comprehensive overview of the immune cell modulatory activities of HDL. We focus on newly discovered activities of HDL-associated apolipoproteins, enzymes, lipids, and HDL mimetic peptides.

Lipid and lipoprotein predictors of functional outcomes and long-term mortality after surgical sepsis

RATIONALE

Sepsis is a life-threatening, dysregulated response to infection. Lipid biomarkers including cholesterol are dynamically regulated during sepsis and predict short-term outcomes. In this study, we investigated the predictive ability of lipid biomarkers for physical function and long-term mortality after sepsis.

METHODS

Prospective cohort study of sepsis patients admitted to a surgical intensive-care unit (ICU) within 24 h of sepsis bundle initiation. Samples were obtained at enrollment for lipid biomarkers. Multivariate regression models determined independent risk factors predictive of poor performance status (Zubrod score of 3/4/5) or survival at 1-year follow-up.

MEASUREMENTS AND MAIN RESULTS

The study included 104 patients with surgical sepsis. Enrollment total cholesterol and high-density lipoprotein (HDL-C) levels were lower, and myeloperoxidase (MPO) levels were higher for patients with poor performance status at 1 year. A similar trend was seen in comparisons based on 1-year mortality, with HDL-C and ApoA-I levels being lower and MPO levels being higher in non-survivors. However, multivariable logistic regression only identified baseline Zubrod and initial SOFA score as significant independent predictors of poor performance status at 1 year. Multivariable Cox regression modeling for 1-year survival identified high Charlson comorbidity score, low ApoA-I levels, and longer vasopressor duration as predictors of mortality over 1-year post-sepsis.

CONCLUSIONS

In this surgical sepsis study, lipoproteins were not found to predict poor performance status at 1 year. ApoA-I levels, Charlson comorbidity scores, and duration of vasopressor use predicted 1 year survival. These data implicate cholesterol and lipoproteins as contributors to the underlying pathobiology of sepsis.

Photobiomodulation and Antiviral Photodynamic Therapy in COVID-19 Management

Coronavirus disease 2019 (COVID-19) has shocked the world by its spread and contagiousness. There is no approved vaccine and no proven treatment for this infection. Some potential treatments that have already been associated with antiviral and anti-inflammatory effects are under investigation. Photobiomodulation therapy (PBMT) is a photon-based therapy that uses light to mediate a variety of metabolic, analgesic, anti-inflammatory, and immunomodulatory effects. Antiviral photodynamic therapy (aPDT) is a branch of photodynamic therapy based on the reaction between a photosensitizing agent and a light source in the presence of oxygen, which can produce oxidative and free radical agents to damage the viral structures such as proteins and nucleic acids. This chapter aims to discuss the potential therapeutic benefit of PBMT and aPDT in the context of the novel coronavirus. Studies indicate that PBMT and aPDT could be useful in many viral and bacterial pulmonary complications like influenza, SARS-CoV, and MERS, but we found no direct study on SARS-CoV-2. With a combination of PBMT and aPDT, we may be able to combat COVID-19 with minimal interference with pharmaceutical agents. It might improve the efficacy of PBMT and aPDT by using monoclonal antibodies and preparing new photosensitizers at the nanoscale that target the lung tissue specifically. More animal and human studies would need to take place to reach an effective protocol. This chapter would encourage other scientists to work on this new platform.

Prognostic and therapeutic considerations of antibodies against c-ter apolipoprotein A-1 in the general population

Objectives

Autoantibodies against apolipoprotein A1 (anti-apoA1 IgGs) and its C-terminal region (cter apoA1) have emerged as an independent biomarker for cardiovascular disease. Cter apoA1 mimetic peptides were shown to reverse the deleterious anti-apoA1 IgG effects in vitro. We evaluated the association of anti-cter apoA1 IgGs with overall mortality in the general population and tested the ability of a cter apoA1 mimetic peptide to reverse the anti-apoA1 IgG-induced inflammatory response and mortality in vitro and in vivo, respectively.

Methods

Anti-cter apoA1 IgGs were measured in serum samples of 6386 participants of the CoLaus study of which 5220 were followed for a median duration of 5.6 years. The primary outcome was overall mortality. The peptide inhibitory concentration 50% (IC₅₀) was determined in vitro on HEK-Blue-4 and RAW cells. ApoE^-/- mice were exposed to 16 weeks of anti-apoA1IgG passive immunisation with and without peptide co-incubation.

Results

Anti-cter apoA1 IgGs were associated with higher interleukin 6 levels and independently predicted overall mortality; an increase of one standard deviation of anti-cter apoA1 IgG level was associated with an 18% increase in mortality risk (hazard ratio: 1.18, 95% confidence interval: 1.04-1.33; P = 0.009). The cterApoA1 analogue reversed the antibody-mediated inflammatory response with an IC₅₀ of 1 µm in vitro but did not rescue the significant anti-apoA1 IgG-induced mortality rate in vivo (69% vs. 23%, LogRank P = 0.02).

Conclusion

Anti-cter apoA1 IgG independently predicts overall mortality in the general population. Despite being effective in vitro, our cter apoA1 analogue did not reverse the anti-apoA1 IgG-induced mortality in mice. Our data suggest that these autoantibodies are not readily treatable through cognate peptide immunomodulation.

Probable positive effects of the photobiomodulation as an adjunctive treatment in COVID-19: A systematic review

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Photobiomodulation (PBM) can reduce lung edema, cytokines in bronchoalveolar parenchyma, neutrophil influx.

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PBM reduces TNF-α, IL-1β, IL-6, ICAM-1, MIP-2 and Reactive oxygen species.

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Transthoracic approach is the direct methods for reducing lung inflammation.

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Intravenous approach increases the oxygenation of red blood cells.

Background

COVID-19, as a newly-emerged viral infection has now spread all over the world after originating in Wuhan, China. Pneumonia is the hallmark of the disease, with dyspnea in half of the patients and acute respiratory distress syndrome (ARDS) in up to one –third of the cases. Pulmonary edema, neutrophilic infiltration, and inflammatory cytokine release are the pathologic signs of this disease. The anti-inflammatory effect of the photobiomodulation (PBM) has been confirmed in many previous studies. Therefore, this review study was conducted to evaluate the direct effect of PBM on the acute lung inflammation or ARDS and also accelerating the regeneration of the damaged tissues. The indirect effects of PBM on modulation of the immune system, increasing the blood flow and oxygenation in other tissues were also considered.

Methodology

The databases of PubMed, Cochrane library, and Google Scholar were searched to find the relevant studies. Keywords included the PBM and related terms, lung inflammation, and COVID-19 -related signs. Studies were categorized with respect to the target tissue, laser parameters, and their results.

Results

Seventeen related papers were included in this review. All of them were in animal models. They showed that the PBM could significantly decrease the pulmonary edema, neutrophil influx, and generation of pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), intracellular adhesion molecule (ICAM), reactive oxygen species (ROS), isoform of nitric oxide synthase (iNOS), and macrophage inflammatory protein 2 (MIP-2)).

Conclusion

Our findings revealed that the PBM could be helpful in reducing the lung inflammation and promoting the regeneration of the damaged tissue. PBM can increase the oxygenation indirectly in order to rehabilitate the affected organs. Thus, the infra-red lasers or light-emitting diodes (LEDs) are recommended in this regard.

Application of mesenchymal stem cell exosomes and their drug-loading systems in acute liver failure

Stem cell exosomes are nanoscale membrane vesicles released from stem cells of various origins that can regulate signal transduction pathways between liver cells, and their functions in intercellular communication have been recognized. Due to their natural substance transport properties and excellent biocompatibility, exosomes can also be used as drug carriers to release a variety of substances, which has great prospects in the treatment of critical and incurable diseases. Different types of stem cell exosomes have been used to study liver diseases. Due to current difficulties in the treatment of acute liver failure (ALF), this review will outline the potential of stem cell exosomes for ALF treatment. Specifically, we reviewed the pathogenesis of acute liver failure and the latest progress in the use of stem cell exosomes in the treatment of ALF, including the role of exosomes in inhibiting the ALF inflammatory response and regulating signal transduction pathways, the advantages of stem cell exosomes and their use as a drug‐loading system, and their pre‐clinical application in the treatment of ALF. Finally, the clinical research status of stem cell therapy for ALF and the current challenges of exosome clinical transformation are summarized.

High-Density Lipoproteins Are Bug Scavengers

Lipoproteins were initially defined according to their composition (lipids and proteins) and classified according to their density (from very low- to high-density lipoproteins—HDLs). Whereas their capacity to transport hydrophobic lipids in a hydrophilic environment (plasma) is not questionable, their primitive function of cholesterol transporter could be challenged. All lipoproteins are reported to bind and potentially neutralize bacterial lipopolysaccharides (LPS); this is particularly true for HDL particles. In addition, HDL levels are drastically decreased under infectious conditions such as sepsis, suggesting a potential role in the clearance of bacterial material and, particularly, LPS. Moreover, "omics" technologies have unveiled significant changes in HDL composition in different inflammatory states, ranging from acute inflammation occurring during septic shock to low-grade inflammation associated with moderate endotoxemia such as periodontal disease or obesity. In this review, we will discuss HDL modifications associated with exposure to pathogens including bacteria, viruses and parasites, with a special focus on sepsis and the potential of HDL therapy in this context. Low-grade inflammation associated with atherosclerosis, periodontitis or metabolic syndrome may also highlight the protective role of HDLs in theses pathologies by other mechanisms than the reverse transport of cholesterol.

Impact of the pre-illness lipid profile on sepsis mortality

PURPOSE

To determine if baseline lipid levels contribute to the relationship between lipid levels during sepsis and outcomes.

MATERIALS AND METHODS

We conducted a retrospective cohort study at a tertiary-care academic medical center. Multivariable logistic regression models were used to adjust for confounders. Both Systemic Inflammatory Response Syndrome (SIRS) and Sequential Organ Failure Assessment (SOFA) score-based definitions of sepsis were analyzed.

MEASUREMENTS AND MAIN RESULTS

After adjusting for patient characteristics and severity of illness, baseline values for both low density lipoprotein (LDL) cholesterol and triglycerides were associated with mortality (LDL cholesterol odds ratio [OR] 0.44, 95% confidence interval [CI] 0.23-0.84, p = .013; triglyceride OR 0.54, 95% CI 0.37-0.78, p = .001) using a SIRS based definition of sepsis. An interaction existed between these two variables, which resulted in increased mortality with higher baseline low density lipoprotein (LDL) cholesterol values for individuals with triglycerides below 208 mg/dL and the opposite direction of association above this level (interaction OR 1.48, 95% CI 1.02-2.16, p = .039). When using a SOFA score-based definition, only triglycerides remained associated with the mortality (OR 0.55, 95% CI 0.35-0.86, p = .008).

CONCLUSIONS

Baseline lipid values, particularly triglyceride concentrations, are associated with hospital mortality in septic patients.

Reverse-D-4F improves endothelial progenitor cell function and attenuates LPS-induced acute lung injury

Background

Patients with acute lung injury (ALI) have increased levels of pro-inflammatory mediators, which impair endothelial progenitor cell (EPC) function. Increasing the number of EPC and alleviating EPC dysfunction induced by pro-inflammatory mediators play important roles in suppressing ALI development. Because the high density lipoprotein reverse-D-4F (Rev-D4F) improves EPC function, we hypothesized that it might repair lipopolysaccharide (LPS)-induced lung damage by improving EPC numbers and function in an LPS-induced ALI mouse model.

Methods

LPS was used to induce ALI in mice, and then the mice received intraperitoneal injections of Rev-D4F. Immunohistochemical staining, flow cytometry, MTT, transwell, and western blotting were used to assess the effect of Rev-D4F on repairment of lung impairment, and improvement of EPC numbers and function, as well as the signaling pathways involved.

Results

Rev-D4F inhibits LPS-induced pulmonary edema and decreases plasma levels of the pro-inflammatory mediators TNF-α and ET-1 in ALI mice. Rev-D4F inhibited infiltration of red and white blood cells into the interstitial space, reduced lung injury-induced inflammation, and restored injured pulmonary capillary endothelial cells. In addition, Rev-D4F increased numbers of circulating EPC, stimulated EPC differentiation, and improved EPC function impaired by LPS. Rev-D4F also acted via a PI3-kinase-dependent mechanism to restore levels of phospho-AKT, eNOS, and phospho-eNOS suppressed by LPS.

Conclusions

These findings indicate that Rev-D4F has an important vasculoprotective role in ALI by improving the EPC numbers and functions, and Rev-D4F reverses LPS-induced EPC dysfuncion partially through PI3K/AKT/eNOS signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1099-6) contains supplementary material, which is available to authorized users.

HDL inflammatory index correlates with and predicts severity of organ failure in patients with sepsis and septic shock

Objective

High density lipoprotein (HDL) is important for defense against sepsis but becomes dysfunctional (Dys-HDL) during inflammation. We hypothesize that Dys-HDL correlates with organ dysfunction (sequential organ failure assessment (SOFA) score) early sepsis.

Methods

A prospective cohort study of adult ED sepsis patients enrolled within 24 hours.

Results

Eighty eight patients were analyzed. Dys-HDL (expressed as HDL inflammatory index (HII)) correlated with SOFA at enrollment (r = 0.23, p = 0.024) and at 48 hours (r = 0.24, p = 0.026) but HII change over the first 48 hours did not correlate with change in SOFA (r = 0.06, p = 0.56). Enrollment HII was significantly different in patients with most severe organ failure (2.31, IQR 1.33–5.2) compared to less severe organ failure (1.81, IQR 1.23–2.64, p = 0.043). Change in HII over 48 hours was significantly different for in-hospital non-survivors (-0.45, IQR-2.6, -0.14 p = 0.015) and for 28-day non-survivors (-1.12, IQR -1.52, 0.12, p = 0.044). In a multivariable linear regression equation (R² = 0.13), for each unit HII increase, 48-hour SOFA increased by 0.72 (p = 0.009).

Conclusion

HII correlated with SOFA and predicted 48-hour SOFA score in early sepsis. Future studies are needed to delineate potential mechanisms.

Trial registration

NCT02370186. Registered February 24, 2015.

Preactivated and Disaggregated Shape-Changed Platelets Protected Against Acute Respiratory Distress Syndrome Complicated by Sepsis Through Inflammation Suppression

BACKGROUND

This study tested the hypothesis that preactivated and disaggregated shape-changed platelet (PreD-SCP) therapy attenuates lung injury from acute respiratory distress syndrome (ARDS) induced by 100% oxygen inhalation and complicated by sepsis through peritoneal administration of 1.5 mg/kg lipopolysaccharide (LPS).

METHODS

Adult male Sprague-Dawley rats, weighing 325 to 350 g, were randomized into group 1 (normal controls [NC]), group 2 (NC + PreD-SCP [3.0 × 10, intravenous administration]), group 3 (ARDS-LPS), and group 4 (ARDS-LPS + PreD-SCP), and sacrificed by 72 h after ARDS induction.

RESULTS

The lung injury score was significantly higher in group 3 than that in other groups, and significantly higher in group 4 than that in groups 1 and 2, whereas the numbers of alveolar sacs and oxygen saturation (%) showed a reversed pattern compared with that of lung injury score among the four groups (all P < 0.0001) without significant difference between groups 1 and 2. The expressions of proinflammatory cells (CD11+, CD14+, CD68+) and proteins (tumor necrosis factor [TNF]-α, nuclear factor [NF]-κB, interleukin [IL]-1ββ, matrix metalloproteinase [MMP]-9, inducible nitric oxide synthase, intercellular adhesion molecule-1) exhibited a pattern identical to the lung injury score. Circulating levels of white blood cell, IL-6, TNF-α, myeloperoxidase and CCL5, and pulmonary protein expressions of oxidative stress (NOX-1/NOX-2, oxidized protein), apoptotic (Bax, cleaved caspase 3/poly (ADP-ribose) polymerase), fibrotic (Smad3, transforming growth factor [TGF]-β), and DNA damage (γ-H2AX) biomarkers showed an identical pattern, whereas protein expressions of antifibrotic (Smad1/5, bone morphogenetic protein [BMP]-2) and anti-inflammatory (Bcl-2) biomarkers demonstrated an opposite pattern compared with the proinflammatory indices among the four groups (all P < 0.001).

CONCLUSIONS

PreD-SCP therapy effectively improved lung injury in ARDS complicated by sepsis.

Review of biomarkers to assess the effects of switching from cigarettes to modified risk tobacco products

Context: One approach to reducing the harm caused by cigarette smoking, at both individual and population level, is to develop, assess and commercialize modified risk alternatives that adult smokers can switch to. Studies to demonstrate the exposure and risk reduction potential of such products generally involve the measuring of biomarkers, of both exposure and effect, sampled in various biological matrices.Objective: In this review, we detail the pros and cons for using several biomarkers as indicators of effects of changing from conventional cigarettes to modified risk products.Materials and methods: English language publications between 2008 and 2017 were retrieved from PubMed using the same search criteria for each of the 25 assessed biomarkers. Nine exclusion criteria were applied to exclude non-relevant publications.Results: A total of 8876 articles were retrieved (of which 7476 were excluded according to the exclusion criteria). The literature indicates that not all assessed biomarkers return to baseline levels following smoking cessation during the study periods but that nine had potential for use in medium to long-term studies.Discussion and conclusion: In clinical studies, it is important to choose biomarkers that show the biological effect of cessation within the duration of the study.

Associations of lipoproteins with cardiovascular and infection-related outcomes in patients receiving hemodialysis

BACKGROUND

In hemodialysis (HD) patients, higher lipid levels are associated with lower mortality. Lipid-lowering therapy does not reduce all-cause mortality or cardiovascular (CV) mortality. Lipoproteins play a role in the innate immune system. Our objective was to determine whether protection from infection might counterbalance adverse CV outcomes associated with lipoproteins.

METHODS

We examined associations between serum apolipoprotein (Apo) A1, B, C2, C3, high-density lipoprotein and low-density lipoprotein (LDL) cholesterol and triglyceride levels and infectious mortality or hospitalization, CV mortality or hospitalization, and all-cause mortality in 433 prevalent HD patients. Cox models with time-varying apolipoprotein concentrations collected every 6 months for up to 2 years were used for analyses.

RESULTS

Median follow-up time for all-cause mortality was 2.7 years (25th-75th percentile range: 2.2-3.4 years). One hundred seventy-nine (41%) patients had an infection-related event. In multivariable models, higher Apo B and LDL were associated with lower risks of infection-related outcomes (hazard ratio Apo B 0.92 [95% confidence interval 0.86-0.99 per 10 mg/dL, P = .03]; hazard ratio LDL 0.93 [95% confidence interval 0.87-1.00 per 10 mg/dL, P = .05]). Sixty-three (15%) participants had a CV-related event. No significant associations were observed between lipoproteins and CV outcomes. Eighty-seven (20%) participants died. Higher Apo A1, Apo B, and Apo C3 were associated with lower risks of all-cause mortality. There was no interaction between the use of lipid-lowering medication and any of the outcomes.

CONCLUSION

Associations of lipoproteins with lower risk of serious infection accompanied by no significant association with CV events may help to explain the paradoxical association between lipids and survival and lack of benefit of lipid-lowering therapies in HD.

A New Proposal for the Pathogenic Mechanism of Non-Coeliac/Non-Allergic Gluten/Wheat Sensitivity: Piecing Together the Puzzle of Recent Scientific Evidence

Non-coeliac/non-allergic gluten/wheat sensitivity (NCG/WS) is a gluten-related disorder, the pathogenesis of which remains unclear. Recently, the involvement of an increased intestinal permeability has been recognized in the onset of this clinical condition. However, mechanisms through which it takes place are still unclear. In this review, we attempt to uncover these mechanisms by providing, for the first time, an integrated vision of recent scientific literature, resulting in a new hypothesis about the pathogenic mechanisms involved in NCG/WS. According to this, the root cause of NCG/WS is a particular dysbiotic profile characterized by decreased butyrate-producing-Firmicutes and/or Bifidobacteria, leading to low levels of intestinal butyrate. Beyond a critical threshold of the latter, a chain reaction of events and vicious circles occurs, involving other protagonists such as microbial lipopolysaccharide (LPS), intestinal alkaline phosphatase (IAP) and wheat α-amylase trypsin inhibitors (ATIs). NCG/WS is likely to be a multi-factor-onset disorder, probably transient and preventable, related to quality and balance of the diet, and not to the presence of gluten in itself. If future studies confirm our proposal, this would have important implications both for the definition of the disease, as well as for the prevention and therapeutic-nutritional management of individuals with NCG/WS.

Exploring the Predictive Ability of Dysfunctional High-Density Lipoprotein for Adverse Outcomes in Emergency Department Patients with Sepsis: A Preliminary Investigation

BACKGROUND

High density lipoprotein (HDL) can be readily oxidized in inflammatory conditions and exhibit pro-inflammatory and dysfunctional (Dys-HDL) characteristics. We hypothesize that Dys-HDL may predict adverse outcomes and correlate with inflammatory cytokines in sepsis.

METHODS

Emergency department (ED) patients with sepsis were enrolled. Blood was drawn at enrollment and after 48 h. Dys-HDL, expressed as HDL inflammatory index (HII), and cytokines were measured. Multivariable logistic regression was used to determine the predictive ability of Dys-HDL for adverse outcomes (death, discharge to hospice, or nursing home).

RESULTS

Thirty-five patients were included in the study. HII was not significantly different at baseline or 48 h between patients with adverse outcomes versus those without. However, there was a significant difference in change in HII over the first 48 h between those with adverse outcomes (+0.21, 95% CI -0.13 to 0.31) versus those without (-0.11, 95% CI -1 to 0.11) (P = 0.025). Logistic regression revealed increasing HII to be an independent predictor of adverse outcomes (OR 5.2, 95% CI 1.1-25.1 P = 0.040). Of the 24 patents with cytokine measurements at both time points, significant inverse correlations between change in HII and change in GRO (rs = -0.52, P = 0.0088) and monocyte chemotactic protein-1 (rs = -0.61, P = 0.0014) concentrations over 48 h were observed.

CONCLUSION

Increasing Dys-HDL concentrations in the first 48 h of sepsis are associated with an ongoing inflammatory response and adverse clinical outcomes. Early changes in HII may be a potential biomarker in ED patients admitted with sepsis.

Apolipoprotein A-I mimetic peptide 4F suppresses tumor-associated macrophages and pancreatic cancer progression

Pancreatic cancer is an aggressive malignancy that is unresponsive to conventional radiation and chemotherapy. Therefore, development of novel immune therapeutic strategies is urgently needed. L-4F, an Apolipoprotein A-I (ApoA-I) mimetic peptide, is engineered to mimic the anti-inflammatory and anti-oxidative functionalities of ApoA-I. In this work, H7 cells were orthotopically implanted in C57BL/6 mice and treated with L-4F. Then, pancreatic cancer progression and the inflammatory microenvironment were investigated in vivo. The cytotoxicity of L-4F toward H7 cells was assessed in vitro. Furthermore, we investigated the effects of L-4F on macrophage polarization by analyzing the polarization and genes of mouse bone marrow-derived macrophages in vitro. The results show that L-4F substantially reduced the tumorigenicity of H7 cells. L-4F inhibited inflammation by reducing the accumulation of inflammatory cells, such as IL-17A-, IL-4-, GM-CSF-, IL-1β-, and IL-6-producing cells and Th1 and Th17. Notably, L-4F also decreased the percentage of macrophages in tumor tissues, especially M2 macrophages (CD11b⁺F4/80⁺CD206⁺), which was also confirmed in vitro. Additionally, the expression of the M2 marker genes Arg1, MRC1, and CCL22 and the inflammatory genes IL-6, iNOS, and IL-12 was decreased by L-4F, indicating that L-4F prevents M2 type macrophage polarization. However, L-4F could not directly attenuate H7 cell invasion or proliferation and did not induce apoptosis. In addition, L-4F potently down-regulated STAT3, JNK and ERK signaling pathways but not affects the phosphorylation of p38 in RAW 264.7 cells. These results suggest that L-4F exhibits an effective therapeutic effect on pancreatic cancer progression by inhibiting tumor-associated macrophages and inflammation.

Emerging Roles of Apolipoprotein E and Apolipoprotein A-I in the Pathogenesis and Treatment of Lung Disease

Emerging roles are being recognized increasingly for apolipoproteins in the pathogenesis and treatment of lung diseases on the basis of their ability to suppress inflammation, oxidative stress, and tissue remodeling, and to promote adaptive immunity and host defense. Apolipoproteins, such as apolipoprotein E (apoE) and apolipoprotein A-I (apoA-I), are important components of lipoprotein particles that facilitate the transport of cholesterol, triglycerides, and phospholipids between plasma and cells. ApoE-containing lipoprotein particles are internalized into cells by low-density lipoprotein receptors (LDLRs), whereas apoA-I can interact with the ATP-binding cassette subfamily A member 1 (ABCA1) transporter to efflux cholesterol and phospholipids out of cells. ApoE and apoA-I also mediate receptor-independent effects, such as binding to and neutralizing LPS. Both apoE and apoA-I are expressed by lung cells, which allows apoE/LDLR- and apoA-I/ABCA1-dependent pathways to modulate normal lung health and the pathogenesis of respiratory diseases, including asthma, acute lung injury, cancer, emphysema, pulmonary fibrosis, and pulmonary hypertension. Data from human studies and research using experimental murine model systems have shown that both apoE and apoA-I pathways play primarily protective roles in lung biology and respiratory disease. Furthermore, apolipoprotein mimetic peptides, corresponding to the LDLR-binding domain of apoE or the class A amphipathic α-helical structure of apoA-I, have antiinflammatory and antioxidant effects that attenuate the severity of lung disease in murine models. Thus, the development of inhaled apolipoprotein mimetic peptides as a novel treatment paradigm could represent a significant advance for patients with respiratory disease who do not respond to current therapies.

High density lipoprotein promoting proliferation and migration of type II alveolar epithelial cells during inflammation state

BACKGROUND

To investigate the effect and mechanism of high density lipoprotein (HDL) on type II alveolar epithelial cells during inflammation state.

METHODS

The original generation of type II alveolar epithelial cells were separated in rats and treated with PBS/LPS/HDL/HDL + LPS. To observe the proliferation and migration of type II alveolar epithelial cells with bromodeoxyuridine(BrdU) assay, transwell assay and wound healing experiments. In addition, western blot detected the expression of TP-binding cassette transporter A1 (ABCA1), cystic fibrosis transmembrane conductance regulator (CFTR) and the phosphorylation of AKT/extracellular signal-regulated kinase(ERK)/mitogen-activated protein kinase(MAPK). Enzyme-linked immunosorbent assay (ELISA) tested the secretion of tumor necrosis factor a(TNF-a)/interleukin 1a(IL-1a)/IL-6.

RESULTS

HDL promoted the proliferation (↑17%, p < 0.001 HDL+ LPS vs. LPS) and migration (wounding healing: ↑93%, p < 0.001 HDL+ LPS vs. LPS; transwell migration: ↑154%, p < 0.001 HDL+ LPS vs. LPS) of type II alveolar epithelial cells. Furthermore, HDL increased the phosphorylation of MAPK, but not AKT/ERK. And HDL decreased the secretion of TNF-a (↓46%, p < 0.01 HDL+ LPS vs. LPS) and IL-1a (↓45%, p < 0.001 HDL+ LPS vs. LPS), but not IL-6. In addition, HDL up-regulated the expression of ABCAI (↑99%, p < 0.001 HDL vs. CON) and down-regulated the expression of CFTR (↓25%, p < 0.05 HDL vs. CON) in type II alveolar epithelial cells.

CONCLUSIONS

HDL increases the phosphorylation of MAPK, which promotes the proliferation and migration of type II alveolar epithelial cells. And it decreased the secretion of TNF-a/IL-1a and the expression of CFTR. All these suggest that HDL plays an important role in anti-inflammatory effect in inflammation state of lung.

Influence of route of administration and lipidation of apolipoprotein A-I peptide on pharmacokinetics and cholesterol mobilization

apoA-I, apoA-I mimetic peptides, and their lipid complexes or reconstituted high-density lipoprotein (HDL) have been studied as treatments for various pathologies. However, consensus is lacking about the best method for administration, by intravenous (IV) or intraperitoneal (IP) routes, and formulation, as an HDL particle or in a lipid-free form. The objective of this study was to systematically examine peptide plasma levels, cholesterol mobilization, and lipoprotein remodeling in vivo following administration of lipid-free apoA-I peptide (22A) or phospholipid reconstituted 22A-sHDL by IV and IP routes. The mean circulation half-life was longer for 22A-sHDL (T1/2 = 6.27 h) than for free 22A (T1/2 = 3.81 h). The percentage of 22A absorbed by the vascular compartment after the IP dosing was ∼50% for both 22A and 22A-sHDL. The strongest pharmacologic response came from IV injection of 22A-sHDL, specifically a 5.3-fold transient increase in plasma-free cholesterol (FC) level compared with 1.3- and 1.8-fold FC increases for 22A-IV and 22A-sHDL-IP groups. Addition of either 22A or 22A-sHDL to rat plasma caused lipoprotein remodeling and appearance of a lipid-poor apoA-I. Hence, both the route of administration and the formulation of apoA-I peptide significantly affect its pharmacokinetics and pharmacodynamics.

High-Density Lipoprotein (HDL) Counter-Regulates Serum Amyloid A (SAA)-Induced sPLA2-IIE and sPLA2-V Expression in Macrophages

Human serum amyloid A (SAA) has been demonstrated as a chemoattractant and proinflammatory mediator of lethal systemic inflammatory diseases. In the circulation, it can be sequestered by a high-density lipoprotein, HDL, which carries cholesterol, triglycerides, phospholipids and apolipoproteins (Apo-AI). The capture of SAA by HDL results in the displacement of Apo-AI, and the consequent inhibition of SAA’s chemoattractant activities. It was previously unknown whether HDL similarly inhibits SAA-induced sPLA₂ expression, as well as the resultant HMGB1 release, nitric oxide (NO) production and autophagy activation. Here we provided compelling evidence that human SAA effectively upregulated the expression and secretion of both sPLA₂-IIE and sPLA₂-V in murine macrophages, which were attenuated by HDL in a dose-dependent fashion. Similarly, HDL dose-dependently suppressed SAA-induced HMGB1 release, NO production, and autophagy activation. In both RAW 264.7 cells and primary macrophages, HDL inhibited SAA-induced secretion of several cytokines (e.g., IL-6) and chemokines (e.g., MCP-1 and RANTES) that were likely dependent on functional TLR4 signaling. Collectively, these findings suggest that HDL counter-regulates SAA-induced upregulation and secretion of sPLA₂-IIE/V in addition to other TLR4-dependent cytokines and chemokines in macrophage cultures.

High-density Lipoproteins and Apolipoprotein A-I: Potential New Players in the Prevention and Treatment of Lung Disease

Apolipoprotein A-I (apoA-I) and high-density lipoproteins (HDL) mediate reverse cholesterol transport out of cells. Furthermore, HDL has additional protective functions, which include anti-oxidative, anti-inflammatory, anti-apoptotic, and vasoprotective effects. In contrast, HDL can become dysfunctional with a reduction in both cholesterol efflux and anti-inflammatory properties in the setting of disease or the acute phase response. These paradigms are increasingly being recognized to be active in the pulmonary system, where apoA-I and HDL have protective effects in normal lung health, as well as in a variety of disease states, including acute lung injury (ALI), asthma, chronic obstructive pulmonary disease, lung cancer, pulmonary arterial hypertension, pulmonary fibrosis, and viral pneumonia. Similar to observations in cardiovascular disease, however, HDL may become dysfunctional and contribute to disease pathogenesis in respiratory disorders. Furthermore, synthetic apoA-I mimetic peptides have been shown to have protective effects in animal models of ALI, asthma, pulmonary hypertension, and influenza pneumonia. These findings provide evidence to support the concept that apoA-I mimetic peptides might be developed into a new treatment that can either prevent or attenuate the manifestations of lung diseases, such as asthma. Thus, the lung is positioned to take a page from the cardiovascular disease playbook and utilize the protective properties of HDL and apoA-I as a novel therapeutic approach.

HDL-c levels predict the presence of pleural effusion and the clinical outcome of community-acquired pneumonia

Objectives

To investigate if HDL cholesterol (HDL-c) could be a biomarker of the degree of severity according to prognostic prediction scores in community-acquired pneumonia (CAP) or the development of clinical complications such as pleural effusion.

Methods

We included in a retrospective study 107 patients admitted to the hospital that fulfilled diagnostic criteria for CAP between the 30th October 2011 and 1st September 2012. HDL-c levels at admission, CAP prognosis scores (PSI and CURB65) and clinical outcomes were recorded for the study.

Results

Basal HDL-c levels were not statistically different according to prognostics scores neither PSI nor CURB-65. Significantly lower levels of HDL-c were also associated to the development of septic shock and admission to the intensive care unit. HDL-c were inversely correlated with acute phase reactants CRP (r = −0.585, P < 0.001), ESR (r = −0.477, P < 0.001), and leukocytes cell count (r = −0.254, P < 0.009). Patients with pleural effusion showed significant lower levels of HDL-c [28.9 (15.5) mg/dl vs. 44.6 (21.1) mg/dl]; P = 0.007. HDL-c is a good predictor of the presence of pleural effusion in multivariate analyses and using ROC analyses [AUC = 0.712 (0.591–0.834), P = 0.006]. HDL-c levels of 10 mg/dl showed a sensitivity of 97.6 % and a specificity of 82.4 % for the presence of pleural effusion.

Conclusion

Monitoring HDL-c in CAP is an useful serum marker of acute phase response, clinical outcome and the presence of pleural effusion.

Synthetic Amphipathic Helical Peptides Targeting CD36 Attenuate Lipopolysaccharide-Induced Inflammation and Acute Lung Injury

Synthetic amphipathic helical peptides (SAHPs) designed as apolipoprotein A-I mimetics are known to bind to class B scavenger receptors (SR-Bs), SR-BI, SR-BII, and CD36, receptors that mediate lipid transport and facilitate pathogen recognition. In this study, we evaluated SAHPs, selected for targeting human CD36, by their ability to attenuate LPS-induced inflammation, endothelial barrier dysfunction, and acute lung injury (ALI). L37pA, which targets CD36 and SR-BI equally, inhibited LPS-induced IL-8 secretion and barrier dysfunction in cultured endothelial cells while reducing lung neutrophil infiltration by 40% in a mouse model of LPS-induced ALI. A panel of 20 SAHPs was tested in HEK293 cell lines stably transfected with various SR-Bs to identify SAHPs with preferential selectivity toward CD36. Among several SAHPs targeting both SR-BI/BII and CD36 receptors, ELK-B acted predominantly through CD36. Compared with L37pA, 5A, and ELK SAHPs, ELK-B was most effective in reducing the pulmonary barrier dysfunction, neutrophil migration into the lung, and lung inflammation induced by LPS. We conclude that SAHPs with relative selectivity toward CD36 are more potent at inhibiting acute pulmonary inflammation and dysfunction. These data indicate that therapeutic strategies using SAHPs targeting CD36, but not necessarily mimicking all apolipoprotein A-I functions, may be considered a possible new treatment approach for inflammation-induced ALI and pulmonary edema.

HDL-cholesterol and cardiovascular disease: rethinking our approach

PURPOSE OF REVIEW

A low level of plasma high density lipoprotein cholesterol (HDL-C) is a strong and independent risk factor for atherosclerotic cardiovascular disease (ASCVD). However, several large studies recently revealed that pharmacologic interventions that increase HDL-C concentration have not improved cardiovascular outcomes when added to standard therapy. In addition, specific genetic variants that raise HDL-C levels are not clearly associated with reduced risk of coronary heart disease. These observations have challenged the 'HDL hypothesis' that HDL-C is causally related to ASCVD and that intervention to raise HDL-C will reduce ASCVD events. This article will present the current data on the HDL hypothesis and provide a revised paradigm of considering HDL in the atherosclerotic pathway.

RECENT FINDINGS

Recent evidence has shed light on the complex nature of HDL-C metabolism and function. There are compelling data that the ability of HDL to promote cholesterol efflux from macrophages, the first step in the 'reverse cholesterol transport' (RCT) pathway, is inversely associated with risk for ASCVD even after controlling for HDL-C. This has led to the 'HDL flux hypothesis' that therapeutic intervention that targets macrophage cholesterol efflux and RCT may reduce risk. Preclinical studies of such interventions show promise and early phase clinical studies, though small, are encouraging.

SUMMARY

The role of HDL-C in modulating atherosclerotic disease is as yet uncertain. However, new findings and therapies targeting HDL-C show early promise and may provide an important intervention in attenuating the burden of ASCVD in the future.

Advances in high-density lipoprotein physiology: surprises, overturns, and promises

Emerging evidence strongly supports that changes in the HDL metabolic pathway, which result in changes in HDL proteome and function, appear to have a causative impact on a number of metabolic disorders. Here, we provide a critical review of the most recent and novel findings correlating HDL properties and functionality with various pathophysiological processes and disease states, such as obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, inflammation and sepsis, bone and obstructive pulmonary diseases, and brain disorders.

L-4F inhibits lipopolysaccharide-mediated activation of primary human neutrophils

Human apolipoprotein A-I (apoA-I) mimetic L-4F inhibits acute inflammation in endotoxemic animals. Since neutrophils play a crucial role in septic inflammation, we examined the effects of L-4F, compared to apoA-I, on lipopolysaccharide (LPS)-mediated activation of human neutrophils. We performed bioassays in human blood, isolated human neutrophils (incubated in 50 % donor plasma), and isolated human leukocytes (incubated in 5 and 50 % plasma) in vitro. In whole blood, both L-4F and apoA-I inhibited LPS-mediated elevation of TNF-α and IL-6. In LPS-stimulated neutrophils, L-4F and apoA-I (40 μg/ml) also decreased myeloperoxidase and TNF-α levels; however, L-4F tended to be superior in inhibiting LPS-mediated increase in IL-6 levels, membrane lipid rafts abundance and CD11b expression. In parallel experiments, when TNF-α and IL-8, instead of LPS, was used for cell stimulation, L-4F and/or apoA-I revealed only limited efficacy. In LPS-stimulated leukocytes, L-4F was as effective as apoA-I in reducing superoxide formation in 50 % donor plasma, and more effective in 5 % donor plasma (P<0.05). Limulus ambocyte lysate (LAL) and surface plasmon resonance assays showed that L-4F neutralizes LAL endotoxin activity more effectively than apoA-I (P<0.05) likely due to avid binding to LPS. We conclude that (1) direct binding/neutralization of LPS is a major mechanism of L-4F in vitro; (2) while L-4F has similar efficacy to apoA-I in anti-endotoxin effects in whole blood, it demonstrates superior efficacy to apoA-I in aqueous solutions and fluids with limited plasma components. This study rationalizes the utility of L-4F in the treatment of inflammation that is mediated by endotoxin-activated neutrophils.

The pleiotropic role of HDL in autoimmune diseases

As is widely known, the classic function of HDL is reverse cholesterol transport (RCT), thus removing cholesterol from peripheral tissues. Early epidemiological studies, such as Framingham's, stated that increased HDL levels were associated with a significant decrease in relative risk for cardiovascular disease (CVD) mortality. However, those with heightened expectations in recent years for the development of therapeutic targets to increase HDL levels have been disappointed, because efforts have demonstrated the opposite effect on cardiovascular and global mortality. However, in contrast, studies have highlighted the complexity and the intriguing role of HDL in different pathological conditions, such as infections, neoplasms, and autoimmune diseases. In this review an attempt is made to summarize some biological pathways that link HDL function with the immune system, and its possible clinical repercussions in autoimmune diseases.

Apolipoprotein A-I mimetics

PURPOSE OF REVIEW

To summarize recent publications in the field of apolipoprotein mimetics.

RECENT FINDINGS

Apolipoprotein mimetic peptides continue to show efficacy in a number of animal models of disease and demonstrate properties that make them attractive as potential therapeutic agents. A number of new apolipoprotein mimetics have been described recently. A major site of action of apolipoprotein mimetic peptides was found to be in the small intestine in which they decrease the levels of proinflammatory bioactive lipids. A major problem related to the use of apolipoprotein mimetic peptides is their cost, particularly those that need to be generated by solid phase synthesis with chemical addition of end-blocking groups. Novel approaches to apolipoprotein mimetic therapy have emerged recently that show promise in overcoming these barriers.

SUMMARY

Despite the recent failure of therapies designed to raise HDL-cholesterol in humans, an approach to therapy using mimetics of HDL and its components continues to show promise.

Palmitoleic acid (n-7) attenuates the immunometabolic disturbances caused by a high-fat diet independently of PPARα

Palmitoleic acid (PMA) has anti-inflammatory and antidiabetic activities. Here we tested whether these effects of PMA on glucose homeostasis and liver inflammation, in mice fed with high-fat diet (HFD), are PPAR-α dependent. C57BL6 wild-type (WT) and PPAR-α-knockout (KO) mice fed with a standard diet (SD) or HFD for 12 weeks were treated after the 10th week with oleic acid (OLA, 300 mg/kg of b.w.) or PMA 300 mg/kg of b.w. Steatosis induced by HFD was associated with liver inflammation only in the KO mice, as shown by the increased hepatic levels of IL1-beta, IL-12, and TNF-α; however, the HFD increased the expression of TLR4 and decreased the expression of IL1-Ra in both genotypes. Treatment with palmitoleate markedly attenuated the insulin resistance induced by the HFD, increased glucose uptake and incorporation into muscle in vitro, reduced the serum levels of AST in WT mice, decreased the hepatic levels of IL1-beta and IL-12 in KO mice, reduced the expression of TLR-4 and increased the expression of IL-1Ra in WT mice, and reduced the phosphorylation of NF 𝜅B (p65) in the livers of KO mice. We conclude that palmitoleate attenuates diet-induced insulin resistance, liver inflammation, and damage through mechanisms that do not depend on PPAR-α.

Aging mesenchymal stem cells fail to protect because of impaired migration and antiinflammatory response

RATIONALE

Aging is characterized by functional impairment and reduced capacity to respond appropriately to environmental stimuli and injury. With age, there is an increase in the incidence and severity of chronic and acute lung diseases. However, the relationship between age and the lung's reduced ability to repair is far from established and necessitates further research in the field.

OBJECTIVES

Little is currently known about age-related phenomena in mesenchymal stem cells (MSCs). On account of their ability to protect the endothelium and the alveolar epithelium through multiple paracrine mechanisms, we looked for adverse effects that aging might cause in MSC biology. Such age-related changes might partly account for the increased susceptibility of the aging lung to injury.

MEASUREMENTS AND MAIN RESULTS

We demonstrated that old mice have more inflammation in response to acute lung injury. To investigate the causes, we compared the global gene expression of aged and young bone marrow-derived MSCs (B-MSCs). Our results revealed that the expression levels of inflammatory response genes depended on the age of the B-MSCs. We demonstrated that the age-dependent decrease in expression of several cytokine and chemokine receptors is important for the migration and activation of B-MSCs. Finally, we showed by adoptive transfer of aged B-MSCs to young endotoxemic mice that aged cells lacked the antiinflammatory protective effect of their young counterparts.

CONCLUSIONS

Taken together, the decreased expression of cytokine and chemokine receptors in aged B-MSCs compromises their protective role by perturbing the potential of B-MSCs to become activated and mobilize to the site of injury.

Low level laser therapy reduces acute lung inflammation in a model of pulmonary and extrapulmonary LPS-induced ARDS

The present study aimed to investigate the effects low level laser therapy (LLLT) in a LPS-induced pulmonary and extrapulmonary acute respiratory distress syndrome (ARDS) in BALB/c mice. Laser (830nm laser, 9J/cm(2), 35mW, 80s per point, 3 points per application) was applied in direct contact with skin, 1h after LPS administration. Mice were distributed in control (n=6; PBS), ARDS IT (n=7; LPS orotracheally 10μg/mouse), ARDS IP (n=7; LPS intra-peritoneally 100μg/mouse), ARDS IT+Laser (n=9; LPS intra-tracheally 10μg/mouse), ARDS IP+Laser (n=9; LPS intra-peritoneally 100μg/mouse). Twenty-four hours after last LPS administration, mice were studied for pulmonary inflammation by total and differential cell count in bronchoalveolar lavage (BAL), cytokines (IL-1beta, IL-6, KC and TNF-alpha) levels in BAL fluid and also by quantitative analysis of neutrophils number in the lung parenchyma. LLLT significantly reduced pulmonary and extrapulmonary inflammation in LPS-induced ARDS, as demonstrated by reduced number of total cells (p<0.001) and neutrophils (p<0.001) in BAL, reduced levels of IL-1beta, IL-6, KC and TNF-alpha in BAL fluid and in serum (p<0.001), as well as the number of neutrophils in lung parenchyma (p<0.001). LLLT is effective to reduce pulmonary inflammation in both pulmonary and extrapulmonary model of LPS-induced ARDS.

Comparison of anti-endotoxin activity of apoE and apoA mimetic derivatives of a model amphipathic peptide 18A

Endotoxemia is a major cause of chronic inflammation, and is an important pathogenic factor in the development of metabolic syndrome and atherosclerosis. Human apolipoprotein E (apoE) and apoA-I are protein components of high-density lipoprotein, which have strong anti-endotoxin activity. Here, we compared anti-endotoxin activity of Ac-hE18A-NH2 and 4F peptides, modified from model amphipathic helical 18A peptide, to mimic, respectively, apoE and apoA-I properties. Ac-hE18A-NH2, stronger than 4F, inhibited endotoxin activity and disaggregated Escherichia coli 055:B5 (wild smooth serotype). Ac-hE18A-NH2 and 4F inhibited endotoxin activity of E. coli 026:B6 (rough-like serotype) to a similar degree. This suggests that Ac-hE18A-NH2 as a dual-domain molecule might interact with both the lipid A and headgroup of smooth LPS, whereas 4F binds lipid A. In C57BL/6 mice, Ac-hE18A-NH2 was superior to 4F in inhibiting the inflammatory responses mediated by E. coli 055:B5, but not E. coli 026:B6. However, in THP-1 cells, isolated human primary leukocytes, and whole human blood, Ac-hE18A-NH2 reduced responses more strongly than 4F to both E. coli serotypes either when peptides were pre-incubated or co-incubated with LPS, indicating that Ac-hE18A-NH2 also has strong anti-inflammatory effects independent of endotoxin-neutralizing properties. In conclusion, Ac-hE18A-NH2 is more effective than 4F in inhibiting LPS-mediated inflammation, which opens prospective clinical applications for Ac-hE18A-NH2.

Quantitative proteomic analysis by iTRAQ for identification of candidate biomarkers in plasma from acute respiratory distress syndrome patients

Acute respiratory distress syndrome (ARDS) is a major cause of morbidity and mortality in critical patients. Proteomic analysis of plasma from individuals with ARDS could elucidate new biomarkers for diagnosis and pathophysiology and identify potential ARDS treatment targets. In this study, we recruited 26 patients (15 controls, 11 ARDS). The ARDS group was subdivided into two groups depending on the type of injury: (1) direct lung injury (AD) and (2) indirect lung injury (AI). Using iTRAQ (isobaric tags for relative and absolute quantitation) analysis, we identified 2429 peptides representing 132 plasma proteins. Among these, 16 were differentially expressed in ARDS patients, including 11 overlapping proteins between the AI and AD group and 5 AI-specific proteins. Protein annotation revealed that lipid transport and complement activation were significantly enriched in the biological process category, and lipid transporter, transporter, and serine-type peptidase activities were significantly enriched in the molecular function category. IPA (Ingenuity Pathway Analysis) signaling pathways revealed that the overlapping proteins were involved in a variety of signaling pathways, including those underlying acute phase response; liver X receptor/retinoid X receptor (LXR/RXR) and farnesoid X (FXR)/RXR activation; clathrin-mediated endocytosis; atherosclerosis; interleukin (IL)-12; complement system; and cytokine, nitric oxide, and reactive oxygen species production in macrophages. We present the first proteomic analysis of ARDS plasma using the iTRAQ approach. Our data provide new biomarker candidates and shed light on potential pathological mechanisms underlying ARDS.

Cationic peptide mR18L with lipid lowering properties inhibits LPS-induced systemic and liver inflammation in rats

The cationic single domain peptide mR18L has demonstrated lipid-lowering and anti-atherogenic properties in different dyslipidemic mouse models. Lipopolysaccharide (LPS)-mediated inflammation is considered as one of the potential triggers for atherosclerosis. Here, we evaluated anti-inflammatory effects of mR18L peptide against LPS-mediated inflammation. First, we tested the efficacy and tolerance of 1, 2.5 and 5mg/kg mR18L in normolipidemic rats stimulated with 5mg/kg LPS. LPS and then mR18L were injected in different intraperitoneal regions. By 2h post LPS, mR18L inhibited LPS-mediated plasma TNF-α elevation at all doses, with the effect being stronger for 2.5mg/kg (P<0.05 vs. 1mg/kg, non-significant vs. 5mg/kg). In a similar model, 2.5mg/kg mR18L reduced LPS-mediated inflammation in the liver, as assessed by microscopic examination of liver sections and measurements of iNOS expression in the liver tissue. In plasma, 2.5mg/kg mR18L decreased levels of TNF-α and IL-6, decreased endotoxin activity and enhanced HDL binding to LPS. In another similar experiment, mR18L administered 1h post LPS, prevented elevation of plasma triglycerides by 6h post LPS and increased plasma activity of anti-oxidant enzyme paraoxonase 1, along with noted trends in reducing plasma levels of endotoxin and IL-6. Surface plasmon resonance study revealed that mR18L readily binds LPS. We conclude that mR18L exerts anti-endotoxin activity at least in part due to direct LPS-binding and LPS-neutralizing effects. We suggest that anti-endotoxin activity of mR18L is an important anti-inflammatory property, which may increase anti-atherogenic potential of this promising orally active lipid-lowering peptide.