Association of apolipoprotein E4 to the number of cerebral microbleeds in patients recovered from COVID-19

Background: COVID-19 has been associated with cerebral microbleeds (CMB). Previously, an association of ApoE4 with COVID-19 severity and CMBs in autopsy was found. In this study, we investigated if carrying the Apoe4 allele relates to the number of CMBs in magnetic resonance imaging (MRI) in patients recovered from COVID-19. Material(s) and Method(s): Adult patients recovered from COVID-19 and a control group without a history of COVID-19 was recruited. Exclusion criteria were major neurologic disease, developmental disability or pregnancy. The participants underwent brain MRI 6 months after infection, and a blinded neuroradiologist analyzed the findings. ApoE was genotyped using a microarray. Statistical analysis was performed using the statistical software R. A negative binomial model was chosen based on the distribution of CMBs. Result(s): Of the 216 subjects that underwent MRI, 168 consented to genetic testing, additionally 2 patients were excluded due to extensive CMBs and 1 due to diffuse axonal injury. We included 113 COVID-19 patients (49 ICU-treated, 29 ward-treated and 35 home-isolated) and 52 controls. The most prevalent comorbidities were hypertension, asthma and diabetes. CMBs was found in 47 subjects, with the number of CMBs ranging from 0 to 26. The ApoeE4 allele was carried by 37%, equally distributed among the groups. After adjustment, age (aRR = 1.06, p = 0.007) and COVID-19 (aRR = 2.59, p = 0.038) were independently associated with CMBs. The ApoE4 allele (aRR = 2.16, p = 0.07, CI = 0.94-5.10) was not significant. Conclusion(s): Age and previous COVID-19, but not possession of the ApoeE4 allele, were independently associated with the number of CMBs.

Cellular Metabolism: A Fundamental Component of Degeneration in the Nervous System.

It is estimated that, at minimum, 500 million individuals suffer from cellular metabolic dysfunction, such as diabetes mellitus (DM), throughout the world. Even more concerning is the knowledge that metabolic disease is intimately tied to neurodegenerative disorders, affecting both the central and peripheral nervous systems as well as leading to dementia, the seventh leading cause of death. New and innovative therapeutic strategies that address cellular metabolism, apoptosis, autophagy, and pyroptosis, the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), growth factor signaling with erythropoietin (EPO), and risk factors such as the apolipoprotein E (APOE-ε4) gene and coronavirus disease 2019 (COVID-19) can offer valuable insights for the clinical care and treatment of neurodegenerative disorders impacted by cellular metabolic disease. Critical insight into and modulation of these complex pathways are required since mTOR signaling pathways, such as AMPK activation, can improve memory retention in Alzheimer's disease (AD) and DM, promote healthy aging, facilitate clearance of ß-amyloid (Aß) and tau in the brain, and control inflammation, but also may lead to cognitive loss and long-COVID syndrome through mechanisms that can include oxidative stress, mitochondrial dysfunction, cytokine release, and APOE-ε4 if pathways such as autophagy and other mechanisms of programmed cell death are left unchecked.

Impact of SARS-CoV2 infection on anti-apolipoprotein A-1 IgG response in inflammatory rheumatic diseases.

Objectives: To investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection on anti-apolipoprotein A-1 IgG (AAA1) humoral response in immunosuppressed inflammatory rheumatic diseases (IRD) patients. Methods: This is a nested cohort study from the prospective Swiss Clinical Quality Management registry. A total of 368 IRD patients for which serum samples were available before and after the SARS-CoV2 pandemic were included. Autoantibodies against ApoA-1 (AAA1) and its c-terminal region (AF3L1) were measured in both samples. The exposure of interest was anti-SARS-CoV2 spike subunit 1 (S1) seropositivity measured in the second sample. The effect of SARS-CoV2 infection (anti-S1 seropositivity) on becoming AAA1 or AF3L1 positive and on the change of AAA1 or AF3L1 optical density (OD) between the two samples was tested with multivariable regressions. Results: There were 12 out of 368 IRD patients who were seroconverted against S1. The proportion of patients becoming AF3L1 seropositive was significantly higher in anti-S1-positive patients, compared with anti-S1-negative patients (66.7% versus 21.6%, p = 0.001). Adjusted logistic regression analyses indicated that anti-S1 seroconversion was associated with a sevenfold increased risk of AFL1 seropositivity (odds ratio: 7.4, 95% confidence interval (95% CI): 2.1-25.9) and predicted median increase in AF3L1 OD values (+0.17, 95% CI: 0.08-0.26). Conclusions: SARS-CoV2 infection is associated with a marked humoral response against the immunodominant c-terminal region of ApoA-1 in IRD patients. The possible clinical impact of AAA1 and AF3L1 antibodies on disease progression, cardiovascular complications, or long COVID syndrome deserves future investigations.

A Case of COVID-Associated Nephropathy (COVAN).

Collapsing glomerulopathy is a variant of focal segmental glomerulosclerosis (FSGS) causing rapid renal failure. There has been an emergence of these cases among African American patients with COVID-19, especially those with the apolipoprotein L1 (APOL1) allele. We present a case of an African American patient with COVID-19 who tested positive for the APOL1 allele in the setting of acute renal deterioration. This provides a partial explanation for the increased burden of kidney failure in this population. As cases of COVID-19 persist, COVID-associated nephropathy (COVAN) should be suspected in patients with acute kidney injury and treatment tailored accordingly.

COVID-19 Mortality and the Cytokine Storm: An Added Value for APOE Genotyping

The new COVID-19 presents some comorbidities, such as obesity, Alzheimer's, and coronary risk, among others. We argue that the current understanding of some of these clinical conditions may illuminate the design of future COVID-19 studies to account for a bias that may be the cause of the para-doxical associations between COVID-19 mortality and cytokine storm. Given that we know some of the genetic mechanisms behind these diseases, it is possible to circumscribe these studies to some key genes that help us understand why some patients experience a cytokine storm and what the treatment strategies might be. In this paper, we discuss the role of A2M and APOE genes. A2M encodes a multifaceted protein which is highly expressed in the liver and released to the bloodstream associated with the apolipopro-tein E. This association depends on the APOE genotype. A2M has protease-clearing activity binding of a broad range of proteases, such as thrombin and Factor Xa. It also presents the ability to bind to proin-flammatory ligands, like cytokines. Further, A2M acts as chaperone of misfolded substrates, like beta-amyloid peptide. The last two molecular functions grant it a key role in regulating both inflammatory processes, as well as extracellular protein homeostasis. For these reasons, we conclude that A2M-APOE association will have prophylactic, therapeutic, and prognostic implications;and the proper understanding of the physiological role of APOE and A2M in controlling inflammatory processes can shed further light on the putative treatment of COVID-19-derived cytokine storm.Copyright © 2022 Bentham Science Publishers.

On the occasion of world kidney day 2023;renal impacts of COVID-19

World kidney day is an international campaign focused on bringing awareness to kidney health throughout the world and reducing the incidence of renal disease and its related medical complications. This mini-review sought to take a short look on the renal impact of SARS-CoV-2, with a particular focus on post-COVID-19 nephropathy as a new dilemma in the era of nephrology, which can be a new concern for nephrologists that requires more attention and particular strategies. Keywords: SARS-CoV-2 vaccine, Glomerulonephritis, Acute kidney injury, World kidney day, SARS-CoV-2, COVID-19-related nephropathy, APOL1 gene, Collapsing glomerulopathy, Podocyte.Copyright © 2023 The Author(s);Published by Society of Diabetic Nephropathy Prevention. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

BMI-Associated Anti-Apolipoprotein A-1 Positivity in Healthy Adults after mRNA-Vaccination against COVID-19.

Elevated anti-apolipoprotein A-1 (AAA1) antibody levels associated with cardiovascular risk have been observed in previously SARS-CoV-2-infected or COVID-19-vaccinated individuals. Since patient safety is generally a priority in vaccination, we sought to investigate AAA1 antibody levels in healthy adults after mRNA vaccination. We conducted a prospective cohort study in healthy adult volunteers recruited from military workers of the Transport Air Base in Prague who had received two doses of mRNA vaccines. Anti-apolipoprotein A-1 antibody levels were determined using ELISA from serum samples obtained at three and four time points after the first and second vaccine doses, respectively, within almost 17 weeks of follow-up. The transient AAA1 positivity rate achieved 24.1% (95% confidence interval CI: 15.4-34.7%), i.e., 20 out of 83 participants had at least one positive post-vaccination sample, with a repeat positivity confirmed in only 5 of them. This rate was associated with a BMI > 26 kg/m2, as documented by an adjusted odds ratio of 6.79 (95% CI: 1.53-30.01). In addition, the highest positivity rate of 46.7% (21.3-73.4%) was observed in obese subjects with >30 kg/m2. Since the incidence rate of AAA1 positivity remained unchanged after the first and second vaccine doses, any relationship between AAA1 positivity and mRNA vaccination was inconclusive. The present study showed a transient AAA1 positivity rate associated with overweight or obesity without a proven association with mRNA vaccination.

Plasma Apolipoprotein Concentrations Are Highly Altered in Severe Intensive Care Unit COVID-19 Patients: Preliminary Results from the LIPICOR Cohort Study.

SARS-CoV-2 infection goes beyond acute pneumonia, as it also impacts lipid metabolism. Decreased HDL-C and LDL-C levels have been reported in patients with COVID-19. The lipid profile is a less robust biochemical marker than apolipoproteins, components of lipoproteins. However, the association of apolipoprotein levels during COVID-19 is not well described and understood. The objective of our study is to measure plasma levels of 14 apolipoproteins in patients with COVID-19 and to evaluate the relationships between apolipoprotein levels, severity factors and patient outcomes. From November to March 2021, 44 patients were recruited on admission to the intensive care unit because of COVID-19. Fourteen apolipoproteins and LCAT were measured by LC-MS/MS in plasma of 44 COVID-19 patients on admission to the ICU and 44 healthy control subjects. Absolute apolipoprotein concentrations were compared between COVID-19 patients and controls. Plasma apolipoproteins (Apo) A (I, II, IV), C(I, II), D, H, J and M and LCAT were lower in COVID-19 patients, whereas Apo E was higher. COVID-19 severity factors such as PaO2/FiO2 ratio, SO-FA score and CRP were correlated with certain apolipoproteins. Lower Apo B100 and LCAT levels were observed in non-survivors of COVID-19 versus survivors. To conclude, in this study, lipid and apolipoprotein profiles are altered in COVID-19 patients. Low Apo B100 and LCAT levels may be predictive of non-survival in COVID-19 patients.

The bidirectional interaction of COVID-19 infections and lipoproteins.

COVID-19 infections decrease total cholesterol, LDL-C, HDL-C, and apolipoprotein A-I, A-II, and B levels while triglyceride levels may be increased or inappropriately normal for the poor nutritional status. The degree of reduction in total cholesterol, LDL-C, HDL-C, and apolipoprotein A-I are predictive of mortality. With recovery lipid/lipoprotein levels return towards pre-infection levels and studies have even suggested an increased risk of dyslipidemia post-COVID-19 infection. The potential mechanisms for these changes in lipid and lipoprotein levels are discussed. Decreased HDL-C and apolipoprotein A-I levels measured many years prior to COVID-19 infections are associated with an increased risk of severe COVID-19 infections while LDL-C, apolipoprotein B, Lp (a), and triglyceride levels were not consistently associated with an increased risk. Finally, data suggest that omega-3-fatty acids and PCSK9 inhibitors may reduce the severity of COVID-19 infections. Thus, COVID-19 infections alter lipid/lipoprotein levels and HDL-C levels may affect the risk of developing COVID-19 infections.

APOL1 Risk Variants and Acute Kidney Injury in Black Americans with COVID-19.

BACKGROUND AND OBJECTIVES: Black Americans have a higher incidence of kidney disease compared with populations that do not have recent African ancestry. Two risk variants in the APOL1 are responsible for a portion of this higher risk. We sought to assess the odds of AKI conferred by APOL1 risk alleles in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Black Americans who tested positive for coronavirus disease 2019 (COVID-19) were genotyped to determine APOL1 risk allele status. We assessed the incidence of AKI, persistent AKI, and AKI requiring KRT within 21 days of the PCR-based diagnosis. Outcomes were adjusted for age, sex, body mass index, hypertension, eGFR, and use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker. RESULTS: In total, 126 cases of SARS-CoV-2 infection were included within a 5-month period, with 16 (13%) and 110 (87%) cases with two and zero/one APOL1 high-risk alleles, respectively. AKI occurred in 11 (69%) patients with two APOL1 high-risk alleles and 39 (35%) patients with zero/one high-risk alleles (adjusted odds ratio, 4.41; 95% confidence interval, 1.11 to 17.52; P=0.04). Persistent AKI occurred in eight (50%) patients with two APOL1 high-risk alleles and 21 (19%) of those with zero/one high-risk alleles (adjusted odds ratio, 3.53; 95% confidence interval, 1.8 to 11.57; P=0.04). AKI KRT occurred in four (25%) of those with two APOL1 high-risk alleles and eight (7%) of those with zero/one high-risk alleles (adjusted odds ratio, 4.99; 95% confidence interval, 1.02 to 24.4, P=0.05). CONCLUSIONS: APOL1 high-risk alleles are associated with greater odds of AKI in Black American patients with COVID-19.

APOE4: A Culprit for the Vulnerability of COVID-19 in Alzheimer's Patients.

Apolipoprotein E4 (APOE4) is one of the primary genetic risk factors for late-onset of Alzheimer's disease (AD). While its primary function is to transport cholesterol, it also regulates metabolism, aggregation, and deposition of amyloid-ß (Aß) in the brain. The disruption in the generation and removal of Aß in the brain is the primary cause of memory and cognitive loss and thus plays a significant role in the development of AD. In several prior genetic investigations, the APOE4 allele has been linked to higher susceptibility to severe acute respiratory syndrome (SARSCoV- 2) infection and COVID-19 mortality. However, information on the involvement of APOE4 in the underlying pathology and clinical symptoms is limited. Due to the high infection and mortality rate of COVID-19 in AD individuals, challenges have been identified in the management of AD patients during the COVID-19 pandemic. In order to provide evidence-based, more effective healthcare, it is critical to identify underlying concerns and, preferably, biomarkers. The risk variant APOE4 imparts enhanced infectivity by the underlying coronavirus SARS-CoV-2 at a cellular level, genetic level, and route level. Here we review existing advances in clinical and basic research on the AD-related gene APOE, as well as the role of APOE in AD pathogenesis, using neurobiological evidence. Moreover, the role of APOE in severe COVID-19 in Alzheimer's patients has also been reviewed.

Relation between apolipoprotein e in alzheimer's disease and sars-cov-2 and their treatment strategy: A review.

COVID-19, which primarily affects the pulmonary system, turned out to be a global pandemic, whereas the effects on other systems are still unknown. SARS-CoV-2, binds to angiotensin-converting enzyme 2 (ACE2) receptors in the lungs, causing pneumonia-like symptoms. The same ACE receptors are also present in organs other than the lungs. Therefore, there is a need to study the impact of coronavirus on other human body organs. Recently, UK Biobank reports on the genetic risk factor of the virus attack. A double mutation in the apolipoprotein E (APOE4) allele has shown a significant role in COVID-19. The same APOE4 mutation has already been proven to hold a key role in developing early-onset Alzheimer's disease (EOAD). Despite this data, Alzheimer's disease is believed to be a comorbidity of COVID-19. Previous virus attacks on the same viral family, Coronaviridae, produced neurological effects like neurodegeneration, neuronal inflammation, and other central nervous system-related dysfunctions. Since the long-term implications of COVID-19 are unknown, more research into the impact of the virus on the central nervous system is needed. Both COVID-19 and AD share a common genetic factor, so that AD patients may have a greater risk of SARS-CoV-2. Here, in this review, we have briefly discussed the role of APOE4 in the pathogenesis of AD and SARS-CoV-2, along with their treatment strategy, current scenario, and possible future directions.

Lung health after covid . . . and other stories

Among 3000 people with hypertension inadequately controlled by medication, who were treated with renal denervation, there were sustained reductions in systolic blood pressure and fewer major cardiovascular events over 36 months of follow-up (J Am Coll Cardiol doi:10.1016/j.jacc.2022.08.802). PACE labels Ten worksite cafeterias in England were randomised in the order in which they introduced labels containing information about physical activity calorie equivalents (PACE labels) on selected food and drinks. Experiments in transgenic mice and in cell culture now link the APOE gene with faulty lipid processing in oligodendrocytes.

An APOL1 genotype associated with adverse Covid- 19 outcomes: UK-Biobank data, September 2021

Introduction/ Background: The risk of hospitalisation/death from Covid-19 in the UK is disproportionately high in black populations. In people of African ancestry, variants of the APOL1 gene (G1 and G2) are associated with risk of noncommunicable diseases, and sleeping sickness. We hypothesise that adverse Covid-19 outcomes are also associated with these variants. Methods: The UK Biobank contains genetic, lifestyle, and health information from 7,643 individuals who self-report as being of black ethnicity. Within this cohort there had been 142 hospitalisations and 36 deaths attributed to Covid-19 as of September 2021. Taking risk factors previously associated with poor Covid-19 outcomes (age, sex, chronic kidney disease, atrial fibrillation, hypertension, depression, chronic obstructive pulmonary disease, dementia, type 2 diabetes, obesity, and Townsend deprivation index) as covariates, we used Firth's Bias Reduced Logistic Regression in R to identify APOL1 genotypes that were associated with hospitalisation and death. Results: Individuals who are heterozygous for variants at both the G1 and the G2 loci are termed G1/G2 compound heterozygotes. G1/G2 compound heterozygosity was associated with hospitalisation (odds ratio = 2.4, 95% confidence interval: 1.2-4.5, p = 0.010) and death (odds ratio = 5.4, 95% confidence interval: 1.8-15.4, p = 0.004). This association has not previously been detected in genome wide association studies, as they usually examine individual loci separately rather than considering combinations of loci. Impact: This has implications at the individual and population level by identifying those at higher risk of severe Covid-19 who would benefit from early vaccination and treatment. This is especially relevant to geographical regions where APOL1 G1 and G2 variants are common, such as West and Central Africa and their diaspora. Conclusion: This data supports hypotheses proposing APOL1 genotype (and specifically G1/G2 compound heterozygosity) as a significant contributory factor in the increased rates of poor Covid-19 outcomes observed in people of African ancestry.

Presentation and Variability of APOL1-Related Kidney Disease

Inheritance of the APOL1 G1 or G2 risk alleles in the homozygous or compound heterozygous state, are associated with a ~7-30X increased risk of development of chronic kidney disease (CKD), and with collapsing glomerulopathies in individuals with viral infections including COVID-19 or HIV. Identification of APOL1 high risk genotypes (HRG) can impact patient treatment, prognosis and kidney donor selection. Approximately 13% of African Americans (AA) have an APOL1 HRG, indicating genetic testing in this population can identify those at-risk for CKD development, leading to appropriate patient counseling and management. Here we sought to understand the clinical presentation and variability among patients with APOL1 HRGs, following the implementation of genetic testing for kidney disease with a broad panel at a Louisiana Nephrology clinic. Clinical genetic testing of patient samples was performed using a >380 kidney gene panel (the RenasightTM test, Natera, Inc.) A retrospective review of clinical data for individuals positive for an APOL1 HRG (G1/G1, G2/G2, G1/G2) was performed. We identified 12 patients that were positive for an APOL1 HRG, with all genotypes represented: G1/G1 (n=8), G1/G2 (n=3), and G2/G2 (n=1). Among this cohort, 100% (12/12) were of AA descent. At the time of testing 91% (11/12) of the patients were diagnosed with CKD or ESRD with proteinuria. Biopsy confirmed focal segmental glomerulosclerosis (FSGS) in two patients and collapsing glomerulopathy in one patient. The most common comorbidities among this cohort were hypertension (9/12) and diabetes mellitus (2/12). Four patients had a history of infection with COVID-19 (n=3) or HIV (n=1), three of whom had renal involvement (acute kidney injury or CKD and proteinuria). Use of a broad kidney gene panel enabled the identification of APOL1 HRGs in individuals for which hypertension or diabetes may have otherwise been attributed as the primary cause of CKD. APOL1 HRGs could also provide context for the renal involvement seen in the patients with COVID-19 or HIV infection. Broad panel genetic testing provides an accessible tool for nephrology clinics to help identify individuals at risk for positivity for an APOL1 HRG, including those of AA descent with hypertensive, proteinuric CKD.

Cholesterol and obesity: A marker for Alzheimer's disease

Modern lifestyle and fast-food consumption nature increase the cholesterol consumption and deposition in our body. It is becoming one of the key risk factors in AD development. Several genes and receptors play crucial roles in such developments. Consumption of high-fat diet and absence of physical activity can lead to obesity. Higher BMI is the indicator of obesity. Higher BMI accelerates AD development due to brain atrophy, neuroinflammation, and oxidative stress in the hippocampus. Obesity in childhood and adolescence leads to dementia and AD in later life. COVID harmfully affects Alzheimer's patients, and it is also reported that COVID related dementia and neurodegeneration is one of the prominent post-COVID complications. This review summarises the role of cholesterol in Alzheimer's disease development and the importance of genes, receptors, and diet behind this.

Primary data analyses of MAESTRO-NAFLD-1 a 52 week double-blind placebo-controlled phase 3 clinical trial of resmetirom in patients with NAFLD

Background and aims: Approval of a drug therapy for NASH requires a very good safety/tolerability profile and acceptable therapeutic index. MAESTRO-NAFLD-1 (NCT04197479) is a randomized doubleblind (DB) Phase 3 clinical trial of placebo (PBO) versus resmetirom (RES), a once-a-day oral selective thyroid hormone receptor β agonist, in >1100 patients with NAFLD with safety as the primary end point. Method: Enrollment was Dec 2019 to Oct 2020 at 79 US sites. Requirements included 3 metabolic risk factors, fibroscan (FS) ≥5.5 kPa/CAP≥280 dBm, MRI-PDFF≥8%. Randomization was 1:1:1:1 to 3 DB arms, PBO, 80 or 100 mg RES (n = 972) or an 100 mg open label (OL) arm (n = 171). The primary objective was to evaluate the safety and tolerability of 80 or 100 mg RES versus PBO measured by the incidence of adverse events (AEs). Results: At baseline the DB safety population (n = 969) was age 55.9 (11.8);female, 54.4%, white 88.6%;hispanic 34.7%;BMI 35.3 (6.0) type 2 diabetes 49%, hypertension 76.1%, dyslipidemia 87.9%;FS 7.4 (4.7) kPa. Discontinuations (22.5%) did not differ by treatment, most patient decision (pandemic related). DB compliancewas impacted by COVID drug kit delays. AE withdrawals were 80 mg, 2.4%;100 mg, 2.8%;PBO, 1.3%. The primary objective was met. TEAEs were 80 mg, 88.4%;100 mg, 86.1%;PBO, 81.8%. TEAEs ≥grade 3 severity were 80 mg, 7.6%;100 mg, 9.0%;PBO, 9.1%. AEs in excess of PBOwere grade 1–2 AEs of diarrhea (80 mg, 23.5%;100 mg, 31.2%;PBO, 13.8%) and nausea (80 mg, 11.9%;100 mg, 18.2%;PBO, 7.9%), in the first few weeks. ALT increases ≥3XULN were 80 mg, 0.61%;100 mg, 0.31%;PBO,1.6%. Therewere no changes in bodyweight or HR. BP decreased by 2–3 mmHg in the RES arms. Key 2o end points were met (Table). Comparative mean reduction in FS VCTE was not significant;a responder analysis of FS and MRE showed significant reductions with RES treatment. Conclusion: RES achieved the primary safety end point in this 52- week Phase 3 NAFLD clinical trial that identified patients by metabolic risk and non-invasive imaging. Key 2o end points were met including LDL-C, ApoB, triglycerides, MRI-PDFF, FS (CAP).(Table Presented) 1MRE combined RES groups.

Human Serum Amyloid a Impaired Structural Stability of High-Density Lipoproteins (HDL) and Apolipoprotein (Apo) A-I and Exacerbated Glycation Susceptibility of ApoA-I and HDL.

Human serum amyloid A (SAA) is an exchangeable apolipoprotein (apo) in high-density lipoprotein (HDL) that influences HDL quality and functionality, particularly in the acute phase of inflammation. On the other hand, the structural and functional correlations of HDL containing SAA and apoA-I have not been reported. The current study was designed to compare the change in HDL quality with increasing SAA content in the lipid-free and lipid-bound states in reconstituted HDL (rHDL). The expressed recombinant human SAA1 (13 kDa) was purified to at least 98% and characterized in the lipid-free and lipid-bound states with apoA-I. The dimyristoyl phosphatidylcholine (DMPC) binding ability of apoA-I was impaired severely by the addition of SAA, while SAA alone could not bind with DMPC. The recombinant human SAA1 was incorporated into the rHDL (molar ratio 95:5:1, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC): cholesterol: apoA-I) with various apoA-I:SAA molar ratios from 1:0 to 1:0.5, 1:1 and 1:2. With increasing SAA1 content, the rHDL particle size was reduced from 98 Å to 93 Å, and the α-helicity of apoA-I:SAA was decreased from 73% to 40% for (1:0) and (1:2), respectively. The wavelength maximum fluorescence (WMF) of tryptophan in rHDL was red-shifted from 339 nm to 345 nm for (1:0) and (1:2) of apoA-I:SAA, respectively, indicating that the addition of SAA to rHDL destabilized the secondary structure of apoA-I. Upon denaturation by urea treatment from 0 M to 8 M, SAA showed only a 3 nm red-shift in WMF, while apoA-I showed a 16 nm red-shift in WMF, indicating that SAA is resistant to denaturation and apoA-I had higher conformational flexibility than SAA. The glycation reaction of apoA-I in the presence of fructose was accelerated up to 1.8-fold by adding SAA in a dose-dependent manner than that of apoA-I alone. In conclusion, the incorporation of SAA in rHDL impaired the structural stability of apoA-I and exacerbated glycation of HDL and apoA-I.