High-density lipoprotein and the acute phase response

HDL and LDL have distinct, opposing effects on LPS-induced brain inflammation

Endotoxemia and sepsis induce neuroinflammation and increase the risk of neurodegenerative disorders although the mechanism by which peripheral infection leads to brain inflammation is not well understood. While circulating serum lipoproteins are known immunometabolites with the potential to modulate the acute phase response and cross the blood brain barrier, their contribution to neuroinflammation during systemic infection is unknown. The objective of this study was to elucidate the mechanisms by which lipoprotein subclasses modulate lipopolysaccharide (LPS)-induced neuroinflammation. Adult C57BL/6 mice were divided into 6 treatment groups, including a sterile saline vehicle control group (n = 9), an LPS group (n = 11), a premixed LPS + HDL group (n = 6), a premixed LPS + LDL group (n = 5), a HDL only group (n = 6) and an LDL only group (n = 3). In all cases injections were administered intraperitoneally. LPS was administered at 0.5 mg/kg, and lipoproteins were administered at 20 mg/kg. Behavioural testing and tissue collection was performed 6 h post-injection. The magnitude of peripheral and central inflammation was determined by qPCR of pro-inflammatory genes in fresh liver and brain. Metabolite profiles of liver, plasma and brain were determined by ¹H NMR. Endotoxin concentration in the brain was measured by the Limulus Amoebocyte Lysate (LAL) assay. Co-administration of LPS + HDL exacerbated both peripheral and central inflammation, whilst LPS + LDL attenuated this inflammation. Metabolomic analysis identified several metabolites significantly associated with LPS-induced inflammation, which were partially rescued by LDL, but not HDL. Endotoxin was detected at significantly greater concentrations in the brains of animals that received LPS + HDL compared to LPS + saline, but not those that received LPS + LDL. These results suggest that HDL may promote neuroinflammation through direct shuttling of endotoxin to the brain. In contrast, LDL was shown to have anti-neuroinflammatory properties in this study. Our results indicate that lipoproteins may be useful targets in neuroinflammation and neurodegeneration associated with endotoxemia and sepsis.

Cholesterol efflux capacity is associated with lipoprotein size and vascular health in mild to moderate psoriasis

Background and objective

Psoriasis is a systemic inflammatory condition with poor cholesterol transport measured by cholesterol efflux capacity (CEC) that is associated with a heightened risk of cardiovascular disease (CVD). In psoriasis patients, we sought to characterize the lipoprotein profile by size using a novel nuclear magnetic resonance algorithm in patients with low CEC compared to normal CEC.

Methods

Lipoprotein profile was assessed using the novel nuclear magnetic resonance LipoProfile-4 deconvolution algorithm. Aortic vascular inflammation (VI) and non-calcified burden (NCB) were characterized via positron emission tomography-computed tomography and coronary computed tomography angiography. To understand the relationship between lipoprotein size and markers of subclinical atherosclerosis, linear regression models controlling for confounders were constructed.

Results

Psoriasis patients with low CEC had higher more severe psoriasis (p = 0.04), VI (p = 0.04) and NCB (p = 0.001), concomitant with smaller high-density lipoprotein (HDL) (p < 0.001) and low-density lipoprotein (LDL) particles (p < 0.001). In adjusted models HDL size (β = -0.19; p = 0.02) and LDL size (β = -0.31; p < 0.001) associated with VI and NCB. Lastly, HDL size strongly associated with LDL size in fully adjusted models (β = -0.27; p < 0.001).

Conclusion

These findings demonstrate that in psoriasis, low CEC associates with a lipoprotein profile comprised of smaller HDL and LDL particles which correlates with vascular health and may be driving early onset atherogenesis. Further, these results demonstrate a relationship between HDL and LDL size and provide novel insights into the complexities of HDL and LDL as biomarkers of vascular health.

Hydrolysis of polyhydroxy polyunsaturated fatty acid-glycerophosphocholines by Group IIA, V, and X secretory phospholipases A2

It is widely accepted that unesterified polyunsaturated ω-6 and ω-3 fatty acids (PUFA) are converted through various lipoxygenases, cyclooxygenases, and cytochrome P450 enzymes to a range of oxygenated derivatives (oxylipins), among which the polyhydroxides of unesterified PUFA have recently been recognized as cell signaling molecules with anti-inflammatory and pro-resolving properties, known as specialized pro-resolving mediators (SPMs). This study investigates the mono-, di-, and trihydroxy 16:0/PUFA-GPCs, and the corresponding 16:0/SPM-GPC, in plasma lipoproteins. We describe the isolation and identification of mono-, di-, and trihydroxy AA, EPA, and DHA-GPC in plasma LDL, HDL, HDL3, and acute phase HDL using normal phase LC/ESI-MS, as previously reported. The lipoproteins contained variable amounts of the polyhydroxy-PUFA-GPC (0-10 nmol/mg protein), likely the product of lipid peroxidation and the action of various lipoxygenases and cytochrome P450 enzymes on both free fatty acids and the parent GPCs. Polyhydroxy-PUFA-GPC was hydrolyzed to variable extent (20%-80%) by the different secretory phospholipases A₂ (sPLA₂ s), with Group IIA sPLA₂ showing the lowest and Group X sPLA₂ the highest activity. Surprisingly, the trihydroxy-16:0/PUFA-GPC of APHDL was largely absent, while large amounts of unidentified material had migrated in the free fatty acid elution area. The free fatty acid mass spectra were consistent with that anticipated for branched chain polyhydroxy fatty acids. There was general agreement between the masses determined by LC/ESI-MS for the polyhydroxy PUFA-GPC and the masses calculated for the GPC equivalents of resolvins, protectins, and maresins using the fatty acid structures reported in the literature.

Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH

Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.

Oxidative modification of HDL by lipid aldehydes impacts HDL function

Reduced levels of high-density lipoprotein (HDL) cholesterol correlate with increased risk for atherosclerotic cardiovascular diseases and HDL performs functions including reverse cholesterol transport, inhibition of lipid peroxidation, and suppression of inflammation, that would appear critical for cardioprotection. However, several large clinical trials utilizing pharmacologic interventions that elevated HDL cholesterol levels failed to provide cardioprotection to at-risk individuals. The reasons for these unexpected results have only recently begun to be elucidated. HDL cholesterol levels and HDL function can be significantly discordant, so that elevating HDL cholesterol levels may not necessarily lead to increased functional capacity, particularly under conditions that cause HDL to become oxidatively modified, resulting in HDL dysfunction. Here we review evidence that oxidative modifications of HDL, including by reactive lipid aldehydes generated by lipid peroxidation, reduce HDL functionality and that dicarbonyl scavengers that protect HDL against lipid aldehyde modification are beneficial in pre-clinical models of atherosclerotic cardiovascular disease.

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

We investigated the immunomodulatory effect of varying levels of dietary ω6/ω3 fatty acids (FA) on Atlantic salmon (Salmo salar) antibacterial response. Two groups were fed either high-18:3ω3 or high-18:2ω6 FA diets for 8 weeks, and a third group was fed for 4 weeks on the high-18:2ω6 diet followed by 4 weeks on the high-18:3ω3 diet and termed “switched-diet”. Following the second 4 weeks of feeding (i.e., at 8 weeks), head kidney tissues from all groups were sampled for FA analysis. Fish were then intraperitoneally injected with either a formalin-killed Renibacterium salmoninarum bacterin (5 × 10⁷ cells mL⁻¹) or phosphate-buffered saline (PBS control), and head kidney tissues for gene expression analysis were sampled at 24 h post-injection. FA analysis showed that the head kidney profile reflected the dietary FA, especially for C₁₈ FAs. The qPCR analyses of twenty-three genes showed that both the high-ω6 and high-ω3 groups had significant bacterin-dependent induction of some transcripts involved in lipid metabolism (ch25ha and lipe), pathogen recognition (clec12b and tlr5), and immune effectors (znrf1 and cish). In contrast, these transcripts did not significantly respond to the bacterin in the “switched-diet” group. Concurrently, biomarkers encoding proteins with putative roles in biotic inflammatory response (tnfrsf6b) and dendritic cell maturation (ccl13) were upregulated, and a chemokine receptor (cxcr1) was downregulated with the bacterin injection regardless of the experimental diets. On the other hand, an inflammatory regulator biomarker, bcl3, was only significantly upregulated in the high-ω3 fed group, and a C-type lectin family member (clec3a) was only significantly downregulated in the switched-diet group with the bacterin injection (compared with diet-matched PBS-injected controls). Transcript fold-change (FC: bacterin/PBS) showed that tlr5 was significantly over 2-fold higher in the high-18:2ω6 diet group compared with other diet groups. FC and FA associations highlighted the role of DGLA (20:3ω6; anti-inflammatory) and/or EPA (20:5ω3; anti-inflammatory) vs. ARA (20:4ω6; pro-inflammatory) as representative of the anti-inflammatory/pro-inflammatory balance between eicosanoid precursors. Also, the correlations revealed associations of FA proportions (% total FA) and FA ratios with several eicosanoid and immune receptor biomarkers (e.g., DGLA/ARA significant positive correlation with pgds, 5loxa, 5loxb, tlr5, and cxcr1). In summary, dietary FA profiles and/or regimens modulated the expression of some immune-relevant genes in Atlantic salmon injected with R. salmoninarum bacterin. The modulation of Atlantic salmon responses to bacterial pathogens and their associated antigens using high-ω6/high-ω3 diets warrants further investigation.

Usefulness of Random Forest Algorithm in Predicting Severe Acute Pancreatitis

BACKGROUND AND AIMS

This study aimed to develop an interpretable random forest model for predicting severe acute pancreatitis (SAP).

METHODS

Clinical and laboratory data of 648 patients with acute pancreatitis were retrospectively reviewed and randomly assigned to the training set and test set in a 3:1 ratio. Univariate analysis was used to select candidate predictors for the SAP. Random forest (RF) and logistic regression (LR) models were developed on the training sample. The prediction models were then applied to the test sample. The performance of the risk models was measured by calculating the area under the receiver operating characteristic (ROC) curves (AUC) and area under precision recall curve. We provide visualized interpretation by using local interpretable model-agnostic explanations (LIME).

RESULTS

The LR model was developed to predict SAP as the following function: -1.10-0.13×albumin (g/L) + 0.016 × serum creatinine (μmol/L) + 0.14 × glucose (mmol/L) + 1.63 × pleural effusion (0/1)(No/Yes). The coefficients of this formula were utilized to build a nomogram. The RF model consists of 16 variables identified by univariate analysis. It was developed and validated by a tenfold cross-validation on the training sample. Variables importance analysis suggested that blood urea nitrogen, serum creatinine, albumin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, calcium, and glucose were the most important seven predictors of SAP. The AUCs of RF model in tenfold cross-validation of the training set and the test set was 0.89 and 0.96, respectively. Both the area under precision recall curve and the diagnostic accuracy of the RF model were higher than that of both the LR model and the BISAP score. LIME plots were used to explain individualized prediction of the RF model.

CONCLUSIONS

An interpretable RF model exhibited the highest discriminatory performance in predicting SAP. Interpretation with LIME plots could be useful for individualized prediction in a clinical setting. A nomogram consisting of albumin, serum creatinine, glucose, and pleural effusion was useful for prediction of SAP.

Metabolic Syndrome and Acute Respiratory Distress Syndrome in Hospitalized Patients With COVID-19

IMPORTANCE

Obesity, diabetes, and hypertension are common comorbidities in patients with severe COVID-19, yet little is known about the risk of acute respiratory distress syndrome (ARDS) or death in patients with COVID-19 and metabolic syndrome.

OBJECTIVE

To determine whether metabolic syndrome is associated with an increased risk of ARDS and death from COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study used data from the Society of Critical Care Medicine Discovery Viral Respiratory Illness Universal Study collected from 181 hospitals across 26 countries from February 15, 2020, to February 18, 2021. Outcomes were compared between patients with metabolic syndrome (defined as ≥3 of the following criteria: obesity, prediabetes or diabetes, hypertension, and dyslipidemia) and a control population without metabolic syndrome. Participants included adult patients hospitalized for COVID-19 during the study period who had a completed discharge status. Data were analyzed from February 22 to October 5, 2021.

EXPOSURES

Exposures were SARS-CoV-2 infection, metabolic syndrome, obesity, prediabetes or diabetes, hypertension, and/or dyslipidemia.

MAIN OUTCOMES AND MEASURES

The primary outcome was in-hospital mortality. Secondary outcomes included ARDS, intensive care unit (ICU) admission, need for invasive mechanical ventilation, and length of stay (LOS).

RESULTS

Among 46 441 patients hospitalized with COVID-19, 29 040 patients (mean [SD] age, 61.2 [17.8] years; 13 059 [45.0%] women and 15713 [54.1%] men; 6797 Black patients [23.4%], 5325 Hispanic patients [18.3%], and 16 507 White patients [57.8%]) met inclusion criteria. A total of 5069 patients (17.5%) with metabolic syndrome were compared with 23 971 control patients (82.5%) without metabolic syndrome. In adjusted analyses, metabolic syndrome was associated with increased risk of ICU admission (adjusted odds ratio [aOR], 1.32 [95% CI, 1.14-1.53]), invasive mechanical ventilation (aOR, 1.45 [95% CI, 1.28-1.65]), ARDS (aOR, 1.36 [95% CI, 1.12-1.66]), and mortality (aOR, 1.19 [95% CI, 1.08-1.31]) and prolonged hospital LOS (median [IQR], 8.0 [4.2-15.8] days vs 6.8 [3.4-13.0] days; P < .001) and ICU LOS (median [IQR], 7.0 [2.8-15.0] days vs 6.4 [2.7-13.0] days; P < .001). Each additional metabolic syndrome criterion was associated with increased risk of ARDS in an additive fashion (1 criterion: 1147 patients with ARDS [10.4%]; P = .83; 2 criteria: 1191 patients with ARDS [15.3%]; P < .001; 3 criteria: 817 patients with ARDS [19.3%]; P < .001; 4 criteria: 203 patients with ARDS [24.3%]; P < .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that metabolic syndrome was associated with increased risks of ARDS and death in patients hospitalized with COVID-19. The association with ARDS was cumulative for each metabolic syndrome criteria present.

Association between cardiometabolic risk factors and COVID-19 susceptibility, severity and mortality: a review

The novel coronavirus, which began spreading from China Wuhan and gradually spreaded to most countries, led to the announcement by the World Health Organization on March 11, 2020, as a new pandemic. The most important point presented by the World Health Organization about this disease is to better understand the risk factors that exacerbate the course of the disease and worsen its prognosis. Due to the high majority of cardio metabolic risk factors like obesity, hypertension, diabetes, and dyslipidemia among the population over 60 years old and higher, these cardio metabolic risk factors along with the age of these people could worsen the prognosis of the coronavirus disease of 2019 (COVID-19) and its mortality. In this study, we aimed to review the articles from the beginning of the pandemic on the impression of cardio metabolic risk factors on COVID-19 and the effectiveness of COVID-19 on how to manage these diseases. All the factors studied in this article, including hypertension, diabetes mellitus, dyslipidemia, and obesity exacerbate the course of Covid-19 disease by different mechanisms, and the inflammatory process caused by coronavirus can also create a vicious cycle in controlling these diseases for patients.

Probiotics act as a potent intervention in improving lipid profile: An umbrella systematic review and meta-analysis

Several meta-analysis studies have revealed improving effects of probiotics on lipid profile, while some studies have reported controversial findings. The purpose of present study was to evaluate the efficacy of probiotics on blood lipids. Relevant studies were searched in the international databases, including PubMed, Scopus, EMBASE, Web of Science, and Cochrane Central Library up to August 2021. The pooled results were calculated with the use of a random-effects model to assess the effects of probiotics on blood lipids. Overall, 38 meta-analyses were inclueded in the study. The results indicated that the probiotics supplementation was effective on reduction of total cholesterol (TC) (ES= -0.46 mg/dL; 95% CI: -0.61, -0.30, p < 0.001; I²= 83.8%, p < 0.001), triglycerides (TG) (ES= -0.13 mg/dl; 95% CI: -0.23, -0.04, p = 0.006; I²= 74.7%, p < 0.001), and low-density lipoprotein cholesterol (LDL-C)levels (ES= -0.29 mg/dL; 95% CI: -0.40, -0.19, p < 0.001; I²= 77.8%, p < 0.001). There was no significant effect of probiotics on high-density lipoprotein cholesterol (HDL-C) levels (ES= 0.02 mg/dl; 95% CI: -0.04, 0.08, p = 0.519; I²= 72.5%, p= <0.001). The results of present umbrella meta-analysis strongly support supplementation with probiotics as an influential intervention for improving lipid profile.

High density lipoprotein in atherosclerosis and coronary heart disease: Where do we stand today?

Epidemiological studies during the last five years suggest that a relation between high density lipoprotein cholesterol (HDL-C) levels and the risk for cardiovascular disease (CVD) does exist but follows rather a "U-shaped" curve with an optimal range of HDL-C concentration between 40 and 70 mg/dl for men and 50-70 mg/dl for women. Moreover, as research in the field of lipoproteins progresses it becomes increasingly apparent that HDL particles possess different attributes and depending on their structural and functional characteristics, they may be "antiatherogenic" or "proatherogenic". In light of this information, it is highly doubtful that the choice of experimental drugs and the design of respective clinical trials that put the HDL-C raising hypothesis at test, were the most suitable. Here, we compile the existing literature on HDL, providing a critical up-to-date view that focuses on key data from the biochemistry, epidemiology and pharmacology of HDL, including data from clinical trials. We also discuss the most up-to-date information on the contribution of HDL structure and function to the prevention of atherosclerosis. We conclude by summarizing important differences between mouse models and humans, that may explain why pharmacological successes in mice turn out to be failures in humans.

Alpha lipoic acid supplementation affects serum lipids in a dose and duration-dependent manner in different health status

Background: Many studies have investigated the effect of ALA supplementation on lipid profile, and different results have been obtained from these studies. The current systematic review and dose-response meta-analysis was conducted to achive a strong conclusion about the effect of ALA supplementation on lipid profile including total cholesterol (TC), low- and high-density lipoprotein cholesterol (LDL, HDL) and triglyceride (TG). Methods: A systematic search was performed in PubMed, SCOPUS, ProQuest and Embase for randomized placebo-controlled human trials that examined the effect of ALA supplementation on lipid profile up to November 2020. The dose and duration of ALA supplementation for included studies were ranged between 300-1200 mg/d and 2-16 weeks respectively. Weighted mean differences (WMD) and 95% confidence intervals (CIs) were used to evaluate the effect size. Cochran's Q and I² tests were also used to assess between-study's heterogeneity. In addition, subgroup analysis was performed to investigate potential sources of heterogeneity. Dose-response relationship was done using fractional polynomial modeling. Results: Among all eligible studies, 12 studies with a total number of 548 participants were selected. ALA caused a significant reduction on TC (WMD): -10.78 mg/dl, 95% CI: -20.81, -0.74, P=0.002), LDL (WMD: -10.88 mg/dl, 95% CI: -19.52, -2.24, P=0.014) and TG (WMD: -31.02 mg/dl, 95% CI: -49.63, -12.42, P<0.001). There was also a non-significant increaes in HDL concentrations. In addition, dose-response analysis showed a positive association between LDL (P_{non-linearity}=0.026), TG (P_{non-linearity}<0.001) and duration of intervention in a non-linear model. Conclusion: The present meta-analysis revealed the beneficial effects of ALA supplementation on TC, LDL and TG levels. Moreover, the beneficial effects of ALA supplementation on LDL and TG levels was duration-dependent.

Lipoproteins and fatty acids in chronic kidney disease: molecular and metabolic alterations

Chronic kidney disease (CKD) induces modifications in lipid and lipoprotein metabolism and homeostasis. These modifications can promote, modulate and/or accelerate CKD and secondary cardiovascular disease (CVD). Lipid and lipoprotein abnormalities - involving triglyceride-rich lipoproteins, LDL and/or HDL - not only involve changes in concentration but also changes in molecular structure, including protein composition, incorporation of small molecules and post-translational modifications. These alterations modify the function of lipoproteins and can trigger pro-inflammatory and pro-atherogenic processes, as well as oxidative stress. Serum fatty acid levels are also often altered in patients with CKD and lead to changes in fatty acid metabolism - a key process in intracellular energy production - that induce mitochondrial dysfunction and cellular damage. These fatty acid changes might not only have a negative impact on the heart, but also contribute to the progression of kidney damage. The presence of these lipoprotein alterations within a biological environment characterized by increased inflammation and oxidative stress, as well as the competing risk of non-atherosclerotic cardiovascular death as kidney function declines, has important therapeutic implications. Additional research is needed to clarify the pathophysiological link between lipid and lipoprotein modifications, and kidney dysfunction, as well as the genesis and/or progression of CVD in patients with kidney disease.

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.

Coronary heart disease risk: Low-density lipoprotein and beyond

Coronary heart disease (CHD) is the leading cause of morbidity and mortality world-wide and has been characterized as a chronic immunoinflammatory, fibroproliferative disease fueled by lipids. Great advances have been made in elucidating the complex mechanistic interactions among risk factors associated with CHD, yielding abundant success towards preventive measures and the development of pharmaceuticals to prevent and treat CHD via attenuation of lipoprotein-mediated risk. However, significant residual risk remains. Several potentially modifiable CHD risk factors ostensibly contributing to this residual risk have since come to the fore, including systemic inflammation, diabetes mellitus, high-density lipoprotein, plasma triglycerides (TG) and remnant lipoproteins (RLP), lipoprotein(a) (Lp[a]), and vascular endothelial dysfunction (ED). Herein, we summarize the body of evidence implicating each of these risk factors in residual CHD risk.

The role of high-density lipoprotein cholesterol, apolipoprotein A and paraoxonase-1 in the pathophysiology of neuroprogressive disorders

Lowered high-density lipoprotein (HDL) cholesterol has been reported in major depressive disorder, bipolar disorder, first episode of psychosis, and schizophrenia. HDL, its major apolipoprotein component, ApoA1, and the antioxidant enzyme paraoxonase (PON)1 (which is normally bound to ApoA1) all have anti-atherogenic, antioxidant, anti-inflammatory, and immunomodulatory roles, which are discussed in this paper. The paper details the pathways mediating the anti-inflammatory effects of HDL, ApoA1 and PON1 and describes the mechanisms leading to compromised HDL and PON1 levels and function in an environment of chronic inflammation. The molecular mechanisms by which changes in HDL, ApoA1 and PON1 might contribute to the pathophysiology of the neuroprogressive disorders are explained. Moreover, the anti-inflammatory actions of ApoM-mediated sphingosine 1-phosphate (S1P) signalling are reviewed as well as the deleterious effects of chronic inflammation and oxidative stress on ApoM/S1P signalling. Finally, therapeutic interventions specifically aimed at improving the levels and function of HDL and PON1 while reducing levels of inflammation and oxidative stress are considered. These include the so-called Mediterranean diet, extra virgin olive oil, polyphenols, flavonoids, isoflavones, pomegranate juice, melatonin and the Mediterranean diet combined with the ketogenic diet.

Marked Changes in Serum Amyloid A Distribution and High-Density Lipoprotein Structure during Acute Inflammation

High-density lipoprotein- (HDL-) cholesterol measurements are generally used in the diagnosis of cardiovascular diseases. However, HDL is a complicated heterogeneous lipoprotein, and furthermore, it can be converted into dysfunctional forms during pathological conditions including inflammation. Therefore, qualitative analysis of pathophysiologically diversified HDL forms is important. A recent study demonstrated that serum amyloid A (SAA) can remodel HDL and induce atherosclerosis not only over long periods of time, such as during chronic inflammation, but also over shorter periods. However, few studies have investigated rapid HDL remodeling. In this study, we analyzed HDL samples from patients undergoing orthopedic surgery inducing acute inflammation. We enrolled 13 otherwise healthy patients who underwent orthopedic surgery. Plasma samples were obtained on preoperative day and postoperative days (POD) 1-7. SAA, apolipoprotein A-I (apoA-I), and apolipoprotein A-II (apoA-II) levels in the isolated HDL were determined. HDL particle size, surface charge, and SAA and apoA-I distributions were also analyzed. In every patient, plasma SAA levels peaked on POD3. Consistently, the HDL apoA-I : apoA-II ratio markedly decreased at this timepoint. Native-polyacrylamide gel electrophoresis and high-performance liquid chromatography revealed the loss of small HDL particles during acute inflammation. Furthermore, HDL had a decreased negative surface charge on POD3 compared to the other timepoints. All changes observed were SAA-dependent. SAA-dependent rapid changes in HDL size and surface charge were observed after orthopedic surgery. These changes might affect the atheroprotective functions of HDL, and its analysis can be available for the qualitative HDL assessment.

High-Density Lipoprotein Modifications: A Pathological Consequence or Cause of Disease Progression?

High-density lipoprotein (HDL) is well-known for its cardioprotective effects, as it possesses anti-inflammatory, anti-oxidative, anti-thrombotic, and cytoprotective properties. Traditionally, studies and therapeutic approaches have focused on raising HDL cholesterol levels. Recently, it became evident that, not HDL cholesterol, but HDL composition and functionality, is probably a more fruitful target. In disorders, such as chronic kidney disease or cardiovascular diseases, it has been observed that HDL is modified and becomes dysfunctional. There are different modification that can occur, such as serum amyloid, an enrichment and oxidation, carbamylation, and glycation of key proteins. Additionally, the composition of HDL can be affected by changes to enzymes such as cholesterol ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), and phospholipid transfer protein (PLTP) or by modification to other important components. This review will highlight some main modifications to HDL and discuss whether these modifications are purely a consequential result of pathology or are actually involved in the pathology itself and have a causal role. Therefore, HDL composition may present a molecular target for the amelioration of certain diseases, but more information is needed to determine to what extent HDL modifications play a causal role in disease development.

Different value of HDL-C in predicting outcome of ARDS secondary to bacterial and viral pneumonia: A retrospective observational study

BACKGROUND

High density lipoprotein-cholesterol (HDL-C) concentration decreases in septic patients and the low level of HDL-C is associated with poor prognosis. However, no study has yet analyzed its prognostic implication specifically in pneumonia-ARDS cohort.

OBJECTIVES

To evaluate the prognostic value of HDL-C levels in ARDS patients secondary to bacterial and viral pneumonia.

METHODS

This was a retrospective observational study on 108 pneumonia-ARDS patients in RICU from 2017 to 2019. These patients were stratified into bacterial ARDS group (56) and viral ARDS group (52). The primary outcome was the association between HDL-C levels and 28-day mortality.

RESULTS

HDL-C levels were statistically lower in bacterial ARDS patients than those in viral ARDS patients (p<0.001). There were statistic negative correlations between HDL-C and APACHE II/SOFA score in bacterial ARDS patients (r=-0.284, p = 0.034 and r=-0.369, p = 0.005), but not in viral ARDS patients (r=-0.103, p = 0.469 and r=-0.225, p = 0.108). ROC analysis demonstrated that HDL-C had superior prediction value for 28-day mortality and identified HDL-C < 0.42 mmol/L was significantly associated with adverse outcomes in bacterial ARDS patients. The low HDL-C was an independent risk factor for death of bacterial ARDS patients (OR 0.027, 95% CI [0.001-0.905], P = 0.044).

CONCLUSIONS

HDL-C might be a valuable marker to assess the 28-d mortality for bacterial ARDS patients rather than viral ARDS patients.

Post-inflammatory behavioural despair in male mice is associated with reduced cortical glutamate-glutamine ratios, and circulating lipid and energy metabolites

Post-inflammatory behaviours in rodents are widely used to model human depression and to test the efficacy of novel anti-depressants. Mice injected with lipopolysaccharide (LPS) display a depressive-like phenotype twenty-four hours after endotoxin administration. Despite the widespread use of this model, the mechanisms that underlie the persistent behavioural changes after the transient peripheral inflammatory response remain elusive. The study of the metabolome, the collection of all the small molecule metabolites in a sample, combined with multivariate statistical techniques provides a way of studying biochemical pathways influenced by an LPS challenge. Adult male CD-1 mice received an intraperitoneal injection of either LPS (0.83 mg/kg) or saline, and were assessed for depressive-like behaviour 24 h later. In a separate mouse cohort, pro-inflammatory cytokine gene expression and 1H nuclear magnetic resonance (NMR) metabolomics measurements were made in brain tissue and blood. Statistical analyses included Independent Sample t-tests for gene expression data, and supervised multi-variate analysis using orthogonal partial least squares discriminant analysis for metabolomics. Both plasma and brain metabolites in male mice were altered following a single peripheral LPS challenge that led to depressive-like behaviour in the forced swim test. The plasma metabolites altered by LPS are involved in energy metabolism, including lipoproteins, glucose, creatine, and isoleucine. In the brain, glutamate, serine, and N-acetylaspartate (NAA) were reduced after LPS, whereas glutamine was increased. Serine-modulated glutamatergic signalling and changes in bioenergetics may mediate the behavioural phenotype induced by LPS. In light of other data supporting a central imbalance of glutamate-glutamine cycling in depression, our results suggest that aberrant central glutaminergic signalling may underpin the depressive-like behaviours that result from both inflammation and non-immune pathophysiology. Normalising glutaminergic signalling, rather than seeking to increase serotonergic signalling, might prove to be a more coherent approach to the development of new treatments for mood disorder.

Metabolic Syndrome and COVID-19 Mortality Among Adult Black Patients in New Orleans

OBJECTIVE

Coronavirus disease 2019 (COVID-19) mortality is high in patients with hypertension, obesity, and diabetes. We examined the association between hypertension, obesity, and diabetes, individually and clustered as metabolic syndrome (MetS), and COVID-19 outcomes in patients hospitalized in New Orleans during the peak of the outbreak.

RESEARCH DESIGN AND METHODS

Data were collected from 287 consecutive patients with COVID-19 hospitalized at two hospitals in New Orleans, LA from 30 March to 5 April 2020. MetS was identified per World Health Organization criteria.

RESULTS

Among 287 patients (mean age 61.5 years; female, 56.8%; non-Hispanic black, 85.4%), MetS was present in 188 (66%). MetS was significantly associated with mortality (adjusted odds ratio [aOR] 3.42 [95% CI 1.52-7.69]), intensive care unit (ICU) (aOR 4.59 [CI 2.53-8.32]), invasive mechanical ventilation (IMV) (aOR 4.71 [CI 2.50-8.87]), and acute respiratory distress syndrome (ARDS) (aOR 4.70 [CI 2.25-9.82]) compared with non-MetS. Multivariable analyses of hypertension, obesity, and diabetes individually showed no association with mortality. Obesity was associated with ICU (aOR 2.18 [CI, 1.25-3.81]), ARDS (aOR 2.44 [CI 1.28-4.65]), and IMV (aOR 2.36 [CI 1.33-4.21]). Diabetes was associated with ICU (aOR 2.22 [CI 1.24-3.98]) and IMV (aOR 2.12 [CI 1.16-3.89]). Hypertension was not significantly associated with any outcome. Inflammatory biomarkers associated with MetS, CRP, and lactate dehydrogenase (LDH) were associated with mortality (CRP [aOR 3.66] [CI 1.22-10.97] and LDH [aOR 3.49] [CI 1.78-6.83]).

CONCLUSIONS

In predominantly black patients hospitalized for COVID-19, the clustering of hypertension, obesity, and diabetes as MetS increased the odds of mortality compared with these comorbidities individually.

Quantitative analysis of proteins related to chemoresistance to paclitaxel and carboplatin in human SiHa cervical cancer cells via iTRAQ

Objective

This study aimed to identify proteins related to paclitaxel and carboplatin chemoresistance in cervical cancer.

Methods

Quantitative proteomic analysis was performed on normal SiHa cells and those treated with paclitaxel and carboplatin for 14 days, with isobaric tags for relative and absolute quantitation (iTRAQ) analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to identify related processes and differentially expressed proteins.

Results

A total of 67 and 96 differentially expressed proteins were identified in the paclitaxel- and carboplatin- treated groups, respectively. GO and KEGG enrichment analyses identified 53 (43 upregulated and 10 downregulated) and 85 differentially expressed proteins (70 upregulated and 15 downregulated) in the paclitaxel- and carboplatin-treated groups, respectively. The cell counting kit-8 results revealed that APOA1 was overexpressed in both the paclitaxel- and carboplatin- resistant SiHa cells compared with the control cells. Immunohistochemistry showed that APOA1 was highly expressed in the paclitaxel- and carboplatin- resistant squamous cell carcinoma of the cervix.

Conclusion

This study is the first to use iTRAQ to identify paclitaxel- and carboplatin- resistance proteins in cervical cells. We identified several proteins previously unassociated with paclitaxel and carboplatin resistance in cervical cancer, thereby expanding our understanding of paclitaxel and carboplatin resistance mechanisms. Moreover, these findings indicate that the APOA1 protein could serve as a potential marker for monitoring and predicting paclitaxel and carboplatin resistance levels.

Synergy between serum amyloid A and secretory phospholipase A2

Serum amyloid A (SAA) is an evolutionally conserved enigmatic biomarker of inflammation. In acute inflammation, SAA plasma levels increase ~1,000 fold, suggesting that this protein family has a vital beneficial role. SAA increases simultaneously with secretory phospholipase A₂ (sPLA₂), compelling us to determine how SAA influences sPLA₂ hydrolysis of lipoproteins. SAA solubilized phospholipid bilayers to form lipoproteins that provided substrates for sPLA₂. Moreover, SAA sequestered free fatty acids and lysophospholipids to form stable proteolysis-resistant complexes. Unlike albumin, SAA effectively removed free fatty acids under acidic conditions, which characterize inflammation sites. Therefore, SAA solubilized lipid bilayers to generate substrates for sPLA₂ and removed its bioactive products. Consequently, SAA and sPLA₂ can act synergistically to remove cellular membrane debris from injured sites, which is a prerequisite for tissue healing. We postulate that the removal of lipids and their degradation products constitutes a vital primordial role of SAA in innate immunity; this role remains to be tested in vivo.

Cell boundaries are made up of fatty substances known as lipids. When cells get severely damaged, their lipid membranes break apart. These broken fragments of membrane become highly toxic, and must be removed as soon as possible to allow the tissue to heal. A small protein called serum amyloid A, SAA for short, was recently proposed to play a pivotal role in this process. In humans, SAA levels in the blood rapidly spike to over a thousand times their normal level following inflammation, injury or infection. Combined with the fact SAA has been conserved for over 500 million years, this suggests that SAA must be important for survival. But, it is not entirely clear how this protein works.

One clue for how SAA works is its relationship to another ancient protein called secretory phospholipase A₂. This protein, also known as sPLA₂, is part of a big family of enzymes that break down lipids in the cell membrane. Notably, sPLA₂ levels rise at the same time and place as SAA during inflammation. This led Jayaraman et al. to ask whether SAA and sPLA₂ might be working together to clean up the cell membrane debris.

To find out, Jayaraman et al. mixed mouse SAA with vesicles of membrane lipids, and then added sPLA₂. This revealed that SAA reshapes the lipid membrane into smaller ‘nanoparticles’ with tightly curved surfaces that are easier for sPLA₂ to break down. As the sPLA₂ breaks up these particles, SAA then gathers up and gets rid of the leftover toxic fragments. This suggests that SAA has two roles: helping sPLA₂ break down the membrane, and removing any toxic debris.

Clearing debris after injury is essential for proper healing. So, understanding how it works is crucial to find new ways to treat inflammation. Further work to understand SAA and sPLA₂ could improve our understanding of how to treat acute and chronic inflammation and its life-threatening complications.

Dyslipidaemia among Ghanaian migrants in three European countries and their compatriots in rural and urban Ghana: The RODAM study

BACKGROUND AND AIMS

African populations have a favourable lipid profile compared to European populations. However, the extent to which they differ between rural and urban settings in Africa and upon migration to Europe is unknown. We assessed the lipid profiles of Ghanaians living in rural- and urban-Ghana and Ghanaian migrants living in three European countries.

METHODS

We used data from a multi-centre, cross-sectional study among Ghanaian adults residing in rural- and urban-Ghana and London, Amsterdam and Berlin (n = 5482). Dyslipidaemias were defined using the 2012 European Guidelines on Cardiovascular Prevention. Comparisons between groups were made using age-standardised prevalence and prevalence ratios (PRs) with adjustments for important covariates.

RESULTS

In both sexes, the age-standardised prevalence of high total cholesterol (TC) and LDL-cholesterol (LDL-C) was lower in rural- than in urban-Ghana and Ghanaian migrants in Europe. Adjusted PRs of high TC and LDL-C were higher in urban-Ghana (TC PR = 2.15, 95%confidence interval 1.69-2.73) and Ghanaian migrant men (TC PR = 2.03 (1.56-2.63)) compared to rural-Ghana, but there was no difference between rural- and Ghanaian migrant women (TC PR = 1.01 (0.84-1.22)). High triglycerides levels were as prevalent in rural-Ghana (11.6%) as in urban-Ghana (12.8%), but were less prevalent in Ghanaian migrant women (2.0%). In both sexes, low HDL-cholesterol was most prevalent in rural-Ghana (50.1%) and least prevalent in Europe (12.9%).

CONCLUSION

The lipid profile varied among ethnically homogeneous African populations living in different geographical locations in Africa and Europe. Additional research is needed to identify factors driving these differential risks to assist prevention efforts.

Plasma proteome correlates of lipid and lipoprotein: biomarkers of metabolic diversity and inflammation in children of rural Nepal

Proteins involved in lipoprotein metabolism can modulate cardiovascular health. While often measured to assess adult metabolic diseases, little is known about the proteomes of lipoproteins and their relation to metabolic dysregulation and underlying inflammation in undernourished child populations. The objective of this population study was to globally characterize plasma proteins systemically associated with HDL, LDL, and triglycerides in 500 Nepalese children. Abnormal lipid profiles characterized by elevated plasma triglycerides and low HDL-cholesterol (HDL-C) concentrations were common, especially in children with subclinical inflammation. Among 982 proteins analyzed, the relative abundance of 11, 12, and 52 plasma proteins was correlated with LDL-cholesterol (r = −0.43∼0.70), triglycerides (r = −0.39∼0.53), and HDL-C (r = −0.49∼0.79) concentrations, respectively. These proteins included apolipoproteins and numerous unexpected intracellular and extracellular matrix binding proteins, likely originating in hepatic and peripheral tissues. Relative abundance of two-thirds of the HDL proteome varied with inflammation, with acute phase reactants higher by 4∼40%, and proteins involved in HDL biosynthesis, cholesterol efflux, vitamin transport, angiogenesis, and tissue repair lower by 3∼20%. Untargeted plasma proteomics detects comprehensive sets of both known and novel lipoprotein-associated proteins likely reflecting systemic regulation of lipoprotein metabolism and vascular homeostasis. Inflammation-altered distributions of the HDL proteome may be predisposing undernourished populations to early chronic disease.

Anti-Inflammatory Effects of HDL in Mice With Rheumatoid Arthritis Induced by Collagen

Objective

To investigate the anti-inflammatory effects of high-density lipoprotein (HDL) in mice with rheumatoid arthritis (RA) induced by collagen.

Methods

Male DBA/1 mice (8-week-old) were divided into three groups: control (treated with saline), collagen-induced arthritis (CIA), and CIA + HDL. CIA was induced with bovine type II collagen, and after the injection of bovine type II collagen, the CIA + HDL group received an injection of HDL on day 28 followed by HDL injections four times every 3 days. Mice were weighed, the paws were scored, and paw thickness was measured beginning on day 21. Additionally, the levels of tumor necrosis factor-alpha (TNF-α) and IL-6 were measured by ELISA kits, tissue sections of paws were stained with hematoxylin and eosin, and the inflammatory signaling pathway was analyzed by western blotting.

Results

We found that the production of pro-inflammatory cytokines TNF-α and IL-6 in mice which received HDL decreased 45.14 and 35.02%, respectively. And we also found that HDL could significantly decrease the level of anti-type-II-collagen IgG2a and inhibit the neutrophil infiltration and cell proliferation and protect the ankle joint from type II collage-induced injury. Western blot analysis indicated that HDL could also inhibit the activation of the NF-κB, MAPK, and ERK signaling pathways in RA mice.

Conclusion

HDL can inhibit the inflammation induced by bovine type II collagen and the development of RA.

Early prediction of persistent organ failure by serum apolipoprotein A-I and high-density lipoprotein cholesterol in patients with acute pancreatitis

BACKGROUND

Early identification of acute pancreatitis (AP) patients at high-risk of developing persistent organ failure (persistent OF) is a vital clinical goal. This research intends to assess the ability of apolipoprotein A-I (APO A-I) and high-density lipoprotein cholesterol (HDL-C) to predict persistent OF.

METHODS

Between January 2011 and September 2016, a total of 102 adult AP patients with organ failure, local complications or deterioration of former comorbidities disease during hospitalization were included in this study retrospectively. Serum lipids were tested and computed the correlation with clinical outcomes or scoring systems. The AUCs to predict persistent OF were also calculated and compared with each other.

RESULTS

Serum APO A-I and HDL-C levels were negatively associated with scoring systems. Meanwhile, serum lipids were negatively correlated with poor clinical outcomes. The AUCs of APO A-I, HDL-C, the combination of APO A-I and BISAP, or the combination of APO A-I and MCTSI to predict persistent OF among Moderately severe acute pancreatitis (MSAP) and Severe acute pancreatitis (SAP) patients were 0.886, 0.811, 0.912, and 0.900 or among those with organ failure were 0.915, 0.859, 0.933, and 0.933, respectively.

CONCLUSIONS

The concentrations of APO A-I, HDL-C, and the combinations of APO A-I and scoring systems have high predictive value to predict persistent OF.

Plasma cholesterol homeostasis, HDL remodeling and function during the acute phase reaction

Acute phase reaction (APR) is a systemic inflammation triggered by several conditions associated with lipid profile alterations. We evaluated whether APR also associates with changes in cholesterol synthesis and absorption, HDL structure, composition, and cholesterol efflux capacity (CEC). We analyzed 59 subjects with APR related to infections, oncologic causes, or autoimmune diseases and 39 controls. We detected no difference in markers of cholesterol synthesis and absorption. Conversely, a significant reduction of LpA-I- and LpAI:AII-containing HDL (-28% and -44.8%, respectively) and of medium-sized HDL (-10.5%) occurred in APR. Total HDL CEC was impaired in APR subjects (-18%). Evaluating specific CEC pathways, we found significant reductions in CEC by aqueous diffusion and by the transporters scavenger receptor B-I and ABCG1 (-25.5, -41.1 and -30.4%, respectively). ABCA1-mediated CEC was not affected. Analyses adjusted for age and gender provided similar results. In addition, correcting for HDL-cholesterol (HDL-C) levels, the differences in aqueous diffusion total and ABCG1-CEC remained significant. APR subjects displayed higher levels of HDL serum amyloid A (+20-folds; P = 0.003). In conclusion, APR does not associate with cholesterol synthesis and absorption changes but with alterations of HDL composition and a marked impairment of HDL CEC, partly independent of HDL-C serum level reduction.

Transcriptomic and Proteomic Profiling Provides Insight into Mesangial Cell Function in IgA Nephropathy

IgA nephropathy (IgAN), the most common GN worldwide, is characterized by circulating galactose-deficient IgA (gd-IgA) that forms immune complexes. The immune complexes are deposited in the glomerular mesangium, leading to inflammation and loss of renal function, but the complete pathophysiology of the disease is not understood. Using an integrated global transcriptomic and proteomic profiling approach, we investigated the role of the mesangium in the onset and progression of IgAN. Global gene expression was investigated by microarray analysis of the glomerular compartment of renal biopsy specimens from patients with IgAN (n=19) and controls (n=22). Using curated glomerular cell type-specific genes from the published literature, we found differential expression of a much higher percentage of mesangial cell-positive standard genes than podocyte-positive standard genes in IgAN. Principal coordinate analysis of expression data revealed clear separation of patient and control samples on the basis of mesangial but not podocyte cell-positive standard genes. Additionally, patient clinical parameters (serum creatinine values and eGFRs) significantly correlated with Z scores derived from the expression profile of mesangial cell-positive standard genes. Among patients grouped according to Oxford MEST score, patients with segmental glomerulosclerosis had a significantly higher mesangial cell-positive standard gene Z score than patients without segmental glomerulosclerosis. By investigating mesangial cell proteomics and glomerular transcriptomics, we identified 22 common pathways induced in mesangial cells by gd-IgA, most of which mediate inflammation. The genes, proteins, and corresponding pathways identified provide novel insights into the pathophysiologic mechanisms leading to IgAN.

Relapsing-remitting multiple sclerosis patients display an altered lipoprotein profile with dysfunctional HDL

Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease multiple sclerosis (MS), reports on lipoprotein level alterations are inconsistent and it is unclear whether lipoprotein function is affected. Using nuclear magnetic resonance (NMR) spectroscopy, we analysed the lipoprotein profile of relapsing-remitting (RR) MS patients, progressive MS patients and healthy controls (HC). We observed smaller LDL in RRMS patients compared to healthy controls and to progressive MS patients. Furthermore, low-BMI (BMI ≤ 23 kg/m²) RRMS patients show increased levels of small HDL (sHDL), accompanied by larger, triglyceride (TG)-rich VLDL, and a higher lipoprotein insulin resistance (LP-IR) index. These alterations coincide with a reduced serum capacity to accept cholesterol via ATP-binding cassette (ABC) transporter G1, an impaired ability of HDL₃ to suppress inflammatory activity of human monocytes, and modifications of HDL₃’s main protein component ApoA-I. In summary, lipoprotein levels and function are altered in RRMS patients, especially in low-BMI patients, which may contribute to disease progression in these patients.

Differences in GlycA and lipoprotein particle parameters may help distinguish acute kawasaki disease from other febrile illnesses in children

Background

Glycosylation patterns of serum proteins, such as α1-acid glycoprotein, are modified during an acute phase reaction. The response of acute Kawasaki disease (KD) patients to IVIG treatment has been linked to sialic acid levels on native IgG, suggesting that protein glycosylation patterns vary during the immune response in acute KD. Additionally, the distribution and function of lipoprotein particles are altered during inflammation. Therefore, the aim of this study was to explore the potential for GlycA, a marker of protein glycosylation, and the lipoprotein particle profile to distinguish pediatric patients with acute KD from those with other febrile illnesses.

Methods

Nuclear magnetic resonance was used to quantify GlycA and lipoprotein particle classes and subclasses in pediatric subjects with acute KD (n = 75), post-treatment subacute (n = 36) and convalescent (n = 63) KD, as well as febrile controls (n = 48), and age-similar healthy controls (n = 48).

Results

GlycA was elevated in acute KD subjects compared to febrile controls with bacterial or viral infections, IVIG-treated subacute and convalescent KD subjects, and healthy children (P <0.0001). Acute KD subjects had increased total and small low density lipoprotein particle numbers (LDL-P) (P <0.0001) and decreased total high density lipoprotein particle number (HDL-P) (P <0.0001) compared to febrile controls. Consequently, the ratio of LDL-P to HDL-P was higher in acute KD subjects than all groups tested (P <0.0001). While GlycA, CRP, erythrocyte sedimentation rate, LDL-P and LDL-P/HDL-P ratio were able to distinguish patients with KD from those with other febrile illnesses (AUC = 0.789–0.884), the combinations of GlycA and LDL-P (AUC = 0.909) or GlycA and the LDL-P/HDL-P ratio (AUC = 0.910) were best at discerning KD in patients 6–10 days after illness onset.

Conclusions

High levels of GlycA confirm enhanced protein glycosylation as part of the acute phase response in KD patients. When combined with common laboratory tests and clinical characteristics, GlycA and NMR-measured lipoprotein particle parameters may be useful for distinguishing acute KD from bacterial or viral illnesses in pediatric patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0688-5) contains supplementary material, which is available to authorized users.

Acute phase proteins as promising biomarkers: Perspectives and limitations for human and veterinary medicine

Acute phase proteins (APPs) are highly conserved plasma proteins that are increasingly secreted by the liver in response to a variety of injuries, independently of their location and cause. APPs favor the systemic regulation of defense, coagulation, proteolysis, and tissue repair. Various APPs have been applied as general diagnostic parameters for a long time. Through proteomic techniques, more and more APPs have been discovered to be differentially altered. Since they are not consistently explainable by a stereotypic hepatic expression of sets of APPs, most of these results have unfortunately been neglected or attributed to the nonspecificity of the acute phase reaction. Moreover, it appears that various extrahepatic tissues are also able to express APPs. These extrahepatic APPs show focally specific roles in tissue homeostasis and repair and are released primarily into interstitial and distal fluids. Since these focal proteins might leak into the circulatory system, mixtures of hepatic and extrahepatic APP species can be expected in blood. Hence, a selective alteration of parts of APPs might be expected. There are several hints on multiple molecular forms and fragments of tissue-derived APPs. These differences offer the chance for multiple selective determinations. Thus, specific proteoforms might indeed serve as tissue-specific disease indicators.

High-density lipoprotein and inflammation in cardiovascular disease

Great advances are being made at the mechanistic level in the understanding of the structural and functional diversity of high-density lipoprotein (HDL). HDL particle subspecies of different sizes are now known to differ in the protein and lipid cargo they transport, conferring on them the ability to perform different functions that in aggregate would be expected to provide protection against the development of atherosclerosis and its downstream clinical consequences. Exacerbating what is already a very complex system is the finding that inflammation, via alteration of the proteomic and lipidomic composition of HDL subspecies, can modulate at least some of their functional activities. In contrast to the progress being made at the mechanistic level, HDL epidemiologic research has lagged behind, largely because the simple HDL biomarkers used (mainly just HDL cholesterol) lack the needed complexity. To address this deficiency, analyses will need to use multiple HDL subspecies and be conducted in such a way as to eliminate potential sources of confounding. To help account for the modulating influence of inflammation, effective use must also be made of inflammatory biomarkers including searching systematically for HDL-inflammation interactions. Using nuclear magnetic resonance (NMR)-measured HDL subclass data and a novel NMR-derived inflammatory biomarker, GlycA, we offer a case study example of the type of analytic approach considered necessary to advance HDL epidemiologic understanding.

Thermal transitions in serum amyloid A in solution and on the lipid: implications for structure and stability of acute-phase HDL

Serum amyloid A (SAA) is an acute-phase protein that circulates mainly on plasma HDL. SAA interactions with its functional ligands and its pathogenic deposition in reactive amyloidosis depend, in part, on the structural disorder of this protein and its propensity to oligomerize. In vivo, SAA can displace a substantial fraction of the major HDL protein, apoA-I, and thereby influence the structural remodeling and functions of acute-phase HDL in ways that are incompletely understood. We use murine SAA1.1 to report the first structural stability study of human plasma HDL that has been enriched with SAA. Calorimetric and spectroscopic analyses of these and other SAA-lipid systems reveal two surprising findings. First, progressive displacement of the exchangeable fraction of apoA-I by SAA has little effect on the structural stability of HDL and its fusion and release of core lipids. Consequently, the major determinant for HDL stability is the nonexchangeable apoA-I. A structural model explaining this observation is proposed, which is consistent with functional studies in acute-phase HDL. Second, we report an α-helix folding/unfolding transition in SAA in the presence of lipid at near-physiological temperatures. This new transition may have potentially important implications for normal functions of SAA and its pathogenic misfolding.

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.

The development of diet-induced obesity and glucose intolerance in C57BL/6 mice on a high-fat diet consists of distinct phases

High-fat (HF) diet-induced obesity and insulin insensitivity are associated with inflammation, particularly in white adipose tissue (WAT). However, insulin insensitivity is apparent within days of HF feeding when gains in adiposity and changes in markers of inflammation are relatively minor. To investigate further the effects of HF diet, C57Bl/6J mice were fed either a low (LF) or HF diet for 3 days to 16 weeks, or fed the HF-diet matched to the caloric intake of the LF diet (PF) for 3 days or 1 week, with the time course of glucose tolerance and inflammatory gene expression measured in liver, muscle and WAT. HF fed mice gained adiposity and liver lipid steadily over 16 weeks, but developed glucose intolerance, assessed by intraperitoneal glucose tolerance tests (IPGTT), in two phases. The first phase, after 3 days, resulted in a 50% increase in area under the curve (AUC) for HF and PF mice, which improved to 30% after 1 week and remained stable until 12 weeks. Between 12 and 16 weeks the difference in AUC increased to 60%, when gene markers of inflammation appeared in WAT and muscle but not in liver. Plasma proteomics were used to reveal an acute phase response at day 3. Data from PF mice reveals that glucose intolerance and the acute phase response are the result of the HF composition of the diet and increased caloric intake respectively. Thus, the initial increase in glucose intolerance due to a HF diet occurs concurrently with an acute phase response but these effects are caused by different properties of the diet. The second increase in glucose intolerance occurs between 12-16 weeks of HF diet and is correlated with WAT and muscle inflammation. Between these times glucose tolerance remains stable and markers of inflammation are undetectable.

Investigation into the effect of hepatitis B virus on apoliprotein A1 expression and its mechanism

Background

Hepatitis B virus (HBV) infection poses a serious threat to human health, with China being one of the highly affected countries. However, the pathogenesis of chronic hepatitis B (CHB) is still unclear. Apolipoprotein A1 (ApoA1) which represents the major protein component of high-density lipoprotein is normally secreted by hepatocytes. When hepatocytes are infected with HBV may lead to the disruption of ApoA1 secretion. In this study, we investigated the effect of HBV on ApoA1 expression and preliminarily explored its molecular mechanism of regulation for revealing the pathogenesis of CHB.

Methods

The expression of mRNA and protein of ApoA1 in Human HepG2 hepatoblastoma cells and subline HepG2.2.15 cells were performed by reverse transcription-polymerase chain reaction (RT-PCR) and Western-blot. The serum ApoA1, by the immune turbidimetric test, and high-density lipoprotein cholesterol (HDL-C) in CHB patients and healthy controls, based on the enzymatic method, were measured with autobiochemical analyzer. The statistical difference was analyzed by SPSS 13.0. HBV infectious clone, pHBV1.3, and ApoA1 gene promoter were co-transfected into HepG2, and the luciferase activity was determined. The changes of ApoA1 mRNA and protein expression were detected by RT-PCR and Western-blot method, after HepG2 cells were transfected with pHBV1.3.

Results

The expression of ApoA1 mRNA and protein in HepG2.2.15 were lower than those in HepG2, and when compared with healthy controls, serum levels of ApoA1 and HDL-C in CHB patients were lower (P < 0.05). pHBV1.3 in HepG2 cells restrained the activity of ApoA1 promoter, mRNA and protein expression.

Conclusions

HBV could inhibit the expression of ApoA1 in vitro and in vivo.

Identification of ApoA1, HPX and POTEE genes by omic analysis in breast cancer

Breast cancer is the most common cancer among women and accounts for 23% of all female types of cancers. It is well recognized that breast cancer represents a heterogeneous group of tumors, and the molecular events involved in the progression to cancer remain undetermined. Moreover, available prognostic and predictive markers are not sufficient for the accurate determination of the risk for many breast cancer patients. Thus, it is necessary to discover new molecular markers for accurate prediction of clinical outcome and individualized therapy. In the present study, we performed omics-based whole-genome trancriptomic and whole proteomic profiling with network and pathway analyses of breast tumors to identify gene expression patterns related to clinical outcome. A total of 20 samples from tumors and 14 normal appearing breast tissues were analyzed using both gene expression microarrays and LC-MS/MS. We identified 585 downregulated and 413 upregulated genes by gene expression microarrays. Among these genes, HPX, POTEE and ApoA1 were the most significant genes correlated with the proteomic profile. Our data revealed that these identified genes are closely related to breast cancer and may be involved in robust detection of disease progression.

Dusty punch cards and an eternal enigma: high-density lipoproteins and atherosclerosis

Epidemiological, clinical, and experimental evidence has accumulated during the last decades suggesting that high-density lipoproteins (HDLs) may protect from atherosclerosis and its clinical consequences. However, more than 55 years after the first description of the link between HDL and heart attacks, many facets of the biochemistry, function, and clinical significance of HDL remain enigmatic. This applies particularly to the completely unexpected results that became available from some recent clinical trials of nicotinic acid and of inhibitors of cholesteryl ester transfer protein (CETP). The concept that raising HDL cholesterol by pharmacological means would decrease the risk of vascular disease has therefore been challenged.

Serum lipid levels are associated with the severity of acute pancreatitis

BACKGROUND/AIMS

Serum lipid concentrations react during acute disease. We sought to measure changes in the serum lipid profile during acute pancreatitis and ascertain whether these changes were associated with the severity of the disease.

METHODS

A total of 233 patients (71% male, median age 48 years) hospitalized for acute pancreatitis were included in the study. The most common etiology for acute pancreatitis was alcohol (n = 131, 56%), followed by biliary (n = 48, 21%) and idiopathic pancreatitis (n = 36, 16%). Serum lipid levels were measured enzymatically. We analyzed samples obtained during the first days of hospitalization and later follow-up samples to measure changes during the course of the disease.

RESULTS

We report profound changes in the serum lipid concentrations during acute pancreatitis. Serum total cholesterol, high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol concentrations measured within 2 days of admission (n = 203) were significantly lower in patients who developed severe pancreatitis (3.20 vs. 3.80 mmol/l, p = 0.001; 0.72 vs. 1.05 mmol/l, p < 0.000, and 1.60 vs. 2.14 mmol/l, p < 0.000, respectively). Low serum total cholesterol, HDL cholesterol and LDL cholesterol concentrations were moreover associated with in-hospital mortalities and longer hospitalization (p < 0.05). In the subgroup analysis, the findings remained statistically significant in patients with alcohol-induced acute pancreatitis.

CONCLUSION

Levels of serum total cholesterol, HDL cholesterol and LDL cholesterol are significantly lower in patients with severe acute pancreatitis and are associated with longer hospitalization.

Proteolysis of apolipoprotein A-I by secretory phospholipase A₂: a new link between inflammation and atherosclerosis

In the acute phase of the inflammatory response, secretory phospholipase A2 (sPLA2) reaches its maximum levels in plasma, where it is mostly associated with high density lipoproteins (HDL). Overexpression of human sPLA2 in transgenic mice reduces both HDL cholesterol and apolipoprotein A-I (apoA-I) plasma levels through increased HDL catabolism by an unknown mechanism. To identify unknown PLA2-mediated activities on the molecular components of HDL, we characterized the protein and lipid products of the PLA2 reaction with HDL. Consistent with previous studies, hydrolysis of HDL phospholipids by PLA2 reduced the particle size without changing its protein composition. However, when HDL was destabilized in the presence of PLA2 by the action of cholesteryl ester transfer protein or by guanidine hydrochloride treatment, a fraction of apoA-I, but no other proteins, dissociated from the particle and was rapidly cleaved. Incubation of PLA2 with lipid-free apoA-I produced similar protein fragments in the range of 6-15 kDa, suggesting specific and direct reaction of PLA2 with apoA-I. Mass spectrometry analysis of isolated proteolytic fragments indicated at least two major cleavage sites at the C-terminal and the central domain of apoA-I. ApoA-I proteolysis by PLA2 was Ca(2+)-independent, implicating a different mechanism from the Ca(2+)-dependent PLA2-mediated phospholipid hydrolysis. Inhibition of proteolysis by benzamidine suggests that the proteolytic and lipolytic activities of PLA2 proceed through different mechanisms. Our study identifies a previously unknown proteolytic activity of PLA2 that is specific to apoA-I and may contribute to the enhanced catabolism of apoA-I in inflammation and atherosclerosis.

Activation of paraoxonase 1 is associated with HDL remodeling ex vivo

BACKGROUND

We hypothesize that during high density lipoprotein (HDL) remodeling PON1 reaches an optimal distribution in HDL subclasses by which it achieves maximum activity. We conducted this study to gain insight on PON1 fate and activation during short-term HDL remodeling ex vivo.

METHODS

Serum from 8 healthy volunteers was either frozen at -80°C (time 0) or incubated under sterile conditions for up to 48h at 37°C or at 4°C. Aliquots were taken at 3, 6, 9, 24 and 48 h and immediately frozen at -80°C. PON1 activities were measured, as well as PON1 and apolipoprotein distributions in HDL subclasses by gradient gel electrophoresis.

RESULTS

The first novel finding in our study is the evidence provided for a significant activation of both lactonase and arylesterase activities of PON1 that ensues in a very short time frame of incubation of serum ex vivo at 37°C. All subjects studied displayed these changes, the activation was apparent in <3h, peaked at 6h and amounted to >20%. This is associated with a temperature and time-dependent redistribution of PON1 activity in HDL subclasses, with an increase in activity in both very large HDL2 and small HDL3 in the first phase (3-9h), followed by a progressive transfer of PON1 to very large HDL2 as the particles mature. These changes are paralleled by the appearance of weak, but apparent PON1 activity at subspecies that correspond to sdLDL. During the first phase of PON1 activation and shifts, a parallel shift of apoE can be evidenced: at 3-9h, apoE increases in sdLDL, after that time it is lost from HDL and also from sdLDL and stays in VLDL at the origin of the run. ApoA-I shifts towards larger particles, which parallels the change in PON1. As HDL matures there is a progressive shift of apoA-II towards larger HDL. Low levels of apoA-IV at the initiation of the incubation are followed by time dependent quick disappearance of apoA-IV in HDL which parallels the changes in PON1, apoE and A-II.

CONCLUSION

Short, ex vivo incubation of serum leads to quick activation of PON1 associated with transfers to HDL3c, large HDL and sdLDL. The process is blocked by CETP and LCAT inhibitors. The data suggest that HDL maturation optimizes PON1 activity. These findings may be of interest for future studies aimed at modulating PON-1 activity for its cardioprotective effects and suggest a new mechanism whereby CETP inhibitors failed in clinical trials.

Proteomic diversity of high density lipoproteins: our emerging understanding of its importance in lipid transport and beyond

Recent applications of mass spectrometry technology have dramatically increased our understanding of the proteomic diversity of high density lipoproteins (HDL). Depending on the method of HDL isolation, upwards of 85 proteins have been identified, and the list continues to grow. In addition to proteins consistent with traditionally accepted roles in lipid transport, HDL carries surprising constituents, such as members of the complement pathway, protease inhibitors involved in hemostasis, acute-phase response proteins, immune function mediators, and even metal-binding proteins. This compositional diversity fits well with hundreds of studies demonstrating a wide functional pleiotrophy, including roles in lipid transport, oxidation, inflammation, hemostasis, and immunity. This review summarizes the progression of our understanding of HDL proteomic complexity and points out key experimental observations that reinforce the functional diversity of HDL. The possibility of specific HDL subspecies with distinct functions, the evidence supporting this concept, and some of the best examples of experimentally defined HDL subspecies are also discussed. Finally, key challenges facing the field are highlighted, particularly the need to identify and define the function of HDL subspecies to better inform attempts to pharmacologically manipulate HDL for the benefit of cardiovascular disease and possibly other maladies.

Some acute phase reactants and cholesterol levels in serum of patient with Crimean-Congo haemorrhagic fever

The purpose of this study is to determine erythrocyte sedimentation rate (ESR), C - reactive protein (CRP), serum amyloid-A (SAA) and cholesterol levels in patients with Crimean-Congo Hemorrhagic Fever (CCHF) and determine the relationship of these parameters with the severity of disease. By polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) method 40 patients were diagnosed as CCHF and 39 volunteer without any systemic disease whose blood were taken and their serum separated. SAA, CRP and ESR were measured with ELISA, nephelometry and Mix-Rate x100 vital diagnostic device, respectively, in serum samples. High density lipoprotein (HDL), low density lipoprotein (LDL) and total cholesterol levels were determined by using autoanalyzer HDL, LDL and total cholesterol kit (Syncron LX20). Statistically significant difference was determined between patients and controls in terms of the levels of SAA, CRP, HDL, LDL and total cholesterol (p<0.05). However, there was no significant difference between the groups in terms of the levels of ESR. In addition, neither SAA, CRP, ESR nor HDL, LDL and total cholesterol levels varied with the severity of disease in the cases assessed (p>0.05). Using of CRP and SAA together might increase the sensitivity of diagnosis of CCHF infection. However, none of the parameters investigated in this study were found to be a proper marker of the prognosis in CCHF. Cholesterol levels were significantly decreased in patients with CCHF, which was suggested to be associated with the increased serum levels of SAA in the patient group.

High density lipoproteins down-regulate transcriptional expression of pro-inflammatory factors and oxidative burst in head kidney leukocytes from rainbow trout, Oncorhynchus mykiss

Teleosts are the first group of vertebrates possessing an acquired immune system; however, it is less developed than in mammals and is highly influenced by environmental changes. Therefore, innate immunity effectors play a more critical role in survival of pathogen-challenged fish. In a previous study we showed that trout high density lipoprotein (HDL), and its major apolipoprotein (ApoA-I) are widely expressed in primary defense barriers and other immune-relevant tissues, displaying important antibacterial activity in vitro. Here we show that trout HDL inhibits both basal and LPS-induced transcript expression of pro-inflammatory cytokines such as TNF-α and IL-1β, and the acute phase protein serum amyloid A (A-SAA), in head kidney leukocytes (HLK) from rainbow trout. In addition, trout HDL was able to block the respiratory burst of PMA-stimulated HKL, at physiological concentrations and in a dose dependent manner. Moreover, this effect was only partially mimicked by supra-physiologic concentrations of the HDL-transported carotenoid, astaxanthin. These results constitute the first data suggesting that in addition to its antimicrobial activity, HDL would have a relevant immunomodulatory role in salmonid fish.