PTX3 structure determination using a hybrid cryoelectron microscopy and AlphaFold approach offers insights into ligand binding and complement activation.

Pattern recognition molecules (PRMs) form an important part of innate immunity, where they facilitate the response to infections and damage by triggering processes such as inflammation. The pentraxin family of soluble PRMs comprises long and short pentraxins, with the former containing unique N-terminal regions unrelated to other proteins or each other. No complete high-resolution structural information exists about long pentraxins, unlike the short pentraxins, where there is an abundance of both X-ray and cryoelectron microscopy (cryo-EM)-derived structures. This study presents a high-resolution structure of the prototypical long pentraxin, PTX3. Cryo-EM yielded a 2.5-Å map of the C-terminal pentraxin domains that revealed a radically different quaternary structure compared to other pentraxins, comprising a glycosylated D4 symmetrical octameric complex stabilized by an extensive disulfide network. The cryo-EM map indicated α-helices that extended N terminal of the pentraxin domains that were not fully resolved. AlphaFold was used to predict the remaining N-terminal structure of the octameric PTX3 complex, revealing two long tetrameric coiled coils with two hinge regions, which was validated using classification of cryo-EM two-dimensional averages. The resulting hybrid cryo-EM/AlphaFold structure allowed mapping of ligand binding sites, such as C1q and fibroblast growth factor-2, as well as rationalization of previous biochemical data. Given the relevance of PTX3 in conditions ranging from COVID-19 prognosis, cancer progression, and female infertility, this structure could be used to inform the understanding and rational design of therapies for these disorders and processes.

The ability of inflammatory markers to recognize infection in cancer patients with fever at admission.

Infection is one of the main causes of death in cancer patients. Accurate identification of fever caused by infection could avoid unnecessary antibiotic treatment and hospitalization. This study evaluated the diagnostic value of procalcitonin (PCT), C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-10 (IL-10), and other commonly used inflammatory markers in suspected infected adult cancer patients with fever, for better use of antibiotics. This research retrospective analyzed the clinical data of 102 adult cancer patients with fever and compared the serum levels of commonly used inflammatory markers for different fever reasons. Receiver-operating characteristic (ROC) curve and logistic regression analyses were performed. In adult cancer patients with fever, the serum PCT, CRP, IL-6, and IL-10 levels of infected patients were significantly higher than uninfected patients (median 1.19 ng/ml vs 0.14 ng/ml, 93.11 mg/l vs 56.55 mg/l, 123.74 pg/ml vs 47.35 pg/ml, 8.74 pg/ml vs 3.22 pg/ml; Mann-Whitney p = 0.000, p = 0.009, p = 0.004, p = 0.000, respectively). The ROC area under the curve(AUC) was 0.769 (95% confidence interval (CI) 0.681-0.857; p = 0.000) for PCT, 0.664 (95% CI 0.554-0.775; p = 0.009) for CRP, 0.681(95% CI 0.576-0.785; p = 0.004) for IL-6, and 0.731(95% CI 0.627-0.834; p = 0.000) for IL-10. PCT had specificity of 96.67% and positive predictive value (PPV) of 97.6%, when the cut-off value is set as 0.69 ng/ml. The serum IL-6 and IL-10 levels also had significant differences between the infected and uninfected cancer patients with advanced disease (median 128.92 pg/ml vs 36.40 pg/ml, 8.05 pg/ml vs 2.92 pg/ml; Mann-Whitney p = 0.003, p = 0.001, respectively). For the patients with neutropenia, IL-6 and IL-10 had higher AUC of 0.811 and 0.928, respectively. With a cut-off of 9.10 pg/ml, IL-10 had the highest sensitivity 83.33% and specificity 100%. In adult cancer patients, PCT had the best performance compared to CRP, IL-6, and IL-10 in differentiating infected from uninfected causes of fever, with high specificity and PPV. IL-6 and IL-10 might be useful in cancer patients with severe bloodstream infections and advanced disease. However, for patients with neutropenia, IL-10 might be more valuable than PCT in diagnosing infection.

Recognition and inhibition of SARS-CoV-2 by humoral innate immunity pattern recognition molecules.

The humoral arm of innate immunity includes diverse molecules with antibody-like functions, some of which serve as disease severity biomarkers in coronavirus disease 2019 (COVID-19). The present study was designed to conduct a systematic investigation of the interaction of human humoral fluid-phase pattern recognition molecules (PRMs) with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Of 12 PRMs tested, the long pentraxin 3 (PTX3) and mannose-binding lectin (MBL) bound the viral nucleocapsid and spike proteins, respectively. MBL bound trimeric spike protein, including that of variants of concern (VoC), in a glycan-dependent manner and inhibited SARS-CoV-2 in three in vitro models. Moreover, after binding to spike protein, MBL activated the lectin pathway of complement activation. Based on retention of glycosylation sites and modeling, MBL was predicted to recognize the Omicron VoC. Genetic polymorphisms at the MBL2 locus were associated with disease severity. These results suggest that selected humoral fluid-phase PRMs can play an important role in resistance to, and pathogenesis of, COVID-19, a finding with translational implications.

Anti-SARS-CoV-2 antibody levels and kinetics of vaccine response: potential role for unresolved inflammation following recovery from SARS-CoV-2 infection.

The immune response after SARS-CoV-2 vaccine administration appears to be characterized by high inter-individual variation, even in SARS-CoV-2 positive subjects, who could have experienced different post-infection, unresolved conditions. We monitored anti-SARS-CoV-2 IgG levels and kinetics along with circulating biomarkers in a cohort of 175 healthcare workers during early immunization with COVID-19 mRNA-LNP BNT162b2 vaccine, to identify the associated factors. Subjects with a previous SARS-CoV-2 infection were characterized by higher BMI and CRP levels and lower neutrophil count with respect to naïve subjects. Baseline IgG levels resulted associated with CRP independently on BMI and inflammatory diseases. Among 137 subjects undergoing vaccination and monitored after the first and the second dose, three kinetic patterns were identified. The pattern showing a rapid growth was characterized by higher IgG levels at baseline and higher CRP and MCHC levels than negative subjects. Subjects previously exposed to SARS-CoV-2 showed higher levels of CRP, suggesting persistence of unresolved inflammation. These levels are the main determinant of IgG levels at baseline and characterized subjects belonging to the best performing, post-vaccine antibody kinetic pattern.

Hemophagocytosis, hyper-inflammatory responses, and multiple organ damages in COVID-19-associated hyperferritinemia.

Hyperferritinemia comes to light frequently in general practice. However, the characteristics of COVID-19-associated hyperferritinemia and the relationship with the prognosis were not well described. The retrospective study included 268 documented COVID-19 patients. They were divided into the hyperferritinemia group (≥ 500 µg/L) and the non-hyperferritinemia group (< 500 µg/L). The prevalence of fever and thrombocytopenia and the proportion of patients with mechanical ventilator support and in-hospital death were much higher in the hyperferritinemia group (P < 0.001). The hyperferritinemia patients showed higher median IL-6, D-dimer, and hsCRP (P < 0.001) and lowered FIB level (P = 0.036). The hyperferritinemia group had a higher proportion of patients with AKI, ARDS, and CSAC (P < 0.001). According to the multivariate analysis, age, chronic pulmonary disease, and hyperferritinemia were found to be significant independent predictors for in-hospital mortality [HR 1.041 (95% CI 1.015-1.068), P = 0.002; HR 0.427 (95% CI 0.206-0.882), P = 0.022; HR 6.176 (95% CI 2.447-15.587), P < 0.001, respectively]. The AUROC curve was 0.88, with a cut-off value of ≥ 971 µg/L. COVID-19 patients with hyperferritinemia had a high proportion of organ dysfunction, were more likely to show hyper-inflammation, progressed to hemophagocytic lymphohistiocytosis, and indicated a higher proportion of death.

Lasting Changes to Circulating Leukocytes in People with Mild SARS-CoV-2 Infections.

Survivors of severe SARS-CoV-2 infections frequently suffer from a range of post-infection sequelae. Whether survivors of mild or asymptomatic infections can expect any long-term health consequences is not yet known. Herein we investigated lasting changes to soluble inflammatory factors and cellular immune phenotype and function in individuals who had recovered from mild SARS-CoV-2 infections (n = 22), compared to those that had recovered from other mild respiratory infections (n = 11). Individuals who had experienced mild SARS-CoV-2 infections had elevated levels of C-reactive protein 1-3 months after symptom onset, and changes in phenotype and function of circulating T-cells that were not apparent in individuals 6-9 months post-symptom onset. Markers of monocyte activation, and expression of adherence and chemokine receptors indicative of altered migratory capacity, were also higher at 1-3 months post-infection in individuals who had mild SARS-CoV-2, but these were no longer elevated by 6-9 months post-infection. Perhaps most surprisingly, significantly more T-cells could be activated by polyclonal stimulation in individuals who had recently experienced a mild SARS-CoV-2, infection compared to individuals with other recent respiratory infections. These data are indicative of prolonged immune activation and systemic inflammation that persists for at least three months after mild or asymptomatic SARS-CoV-2 infections.

C-reactive protein as an effector molecule in Covid-19 pathogenesis.

The current pandemic caused by SARS-CoV-2 virus infection is known as Covid-19 (coronavirus disease 2019). This disease can be asymptomatic or can affect multiple organ systems. Damage induced by the virus is related to dysfunctional activity of the immune system, but the activity of molecules such as C-reactive protein (CRP) as a factor capable of inducing an inflammatory status that may be involved in the severe evolution of the disease, has not been extensively evaluated. A systematic review was performed using the NCBI-PubMed database to find articles related to Covid-19 immunity, inflammatory response, and CRP published from December 2019 to December 2020. High levels of CRP were found in patients with severe evolution of Covid-19 in which several organ systems were affected and in patients who died. CRP activates complement, induces the production of pro-inflammatory cytokines and induces apoptosis which, together with the inflammatory status during the disease, can lead to a severe outcome. Several drugs can decrease the level or block the effect of CRP and might be useful in the treatment of Covid-19. From this review it is reasonable to conclude that CRP is a factor that can contribute to severe evolution of Covid-19 and that the use of drugs able to lower CRP levels or block its activity should be evaluated in randomized controlled clinical trials.

Sink/Float Magnetic Immunoassays for In-Field Bioassays.

Analytical tests/devices that are used outside laboratory settings are required to have a very simple analytical protocol to get clearance by regulatory authorities. This study describes sink/float magnetic immunoassays, a new type of rapid, mix-and-observe, instrument-free tests for the detection of biomarkers in untreated biological samples that are very simple and might meet the simple-to-use criterion of authorities to be used in the field. These tests can tell whether an analyte is above or below a predetermined level within 25-45 minutes based on the sinking or floating of a mm-sized sphere on the surface of which an immunoassay that uses reporter antibodies conjugated to superparamagnetic nanoparticles is performed. This manuscript describes the theory and proof-of-concept applications of sink/float magnetic immunoassays for the detection of C-Reactive Protein, anti-Treponema pallidum antibodies and E. coli bacteria.

Anti-Monomeric C-Reactive Protein Antibody Ameliorates Arthritis and Nephritis in Mice.

Conformation-specific Ags are ideal targets for mAb-based immunotherapy. Here, we demonstrate that the monomeric form of C-reactive protein (mCRP) is a specific therapeutic target for arthritis and nephritis in a murine model. Screening of >1800 anti-mCRP mAb clones identified 3C as a clone recognizing the monomeric, but not polymeric, form of CRP. The anti-mCRP mAb suppressed leukocyte infiltration in thioglycollate-induced peritonitis, attenuated rheumatoid arthritis symptoms in collagen Ab-induced arthritis model mice, and attenuated lupus nephritis symptoms in MRL/Mp-lpr/lpr lupus-prone model mice. These data suggest that the anti-mCRP mAb 3C has therapeutic potential against rheumatoid arthritis and lupus nephritis.

C-Reactive Protein and Cancer: Interpreting the Differential Bioactivities of Its Pentameric and Monomeric, Modified Isoforms.

C-reactive protein (CRP) was first recognized in the 1940s as a protein that appeared in blood during acute episodes of infectious disease. Its presence and pharmacodynamics were found in essentially all diseases that involved tissue damage and inflammation. Identified as a major component of the innate, unlearned immunity, it became a useful diagnostic marker for the extent of inflammation during disease exacerbation or remission. Efforts to define its true biological role has eluded clear definition for over a half-century. Herein, a unifying concept is presented that explains both pro-inflammatory and anti-inflammatory activities of CRP. This concept involves the recognition and understanding that CRP can be induced to undergo a pronounced, non-proteolytic reorganization of its higher-level protein structures into conformationally distinct isomers with distinctive functional activities. This process occurs when the non-covalently associated globular subunits of the pentameric isoform ("pCRP") are induced to dissociate into a monomeric isoform ("mCRP"). mCRP consistently and potently provides pro-inflammatory activation and amplification activities. pCRP provides weak anti-inflammatory activities consistent with low-level chronic inflammation. mCRP can spontaneously form in purified pCRP reagents in ways that are not immediately recognized during purification and certification analyses. By now understanding the factors that influence pCRP dissociate into mCRP, many published reports investigating CRP as a biological response modifier of host defense can be reevaluated to include a discussion of how each CRP isoform may have affected the generated results. Specific attention is given to in vitro and in vivo studies of CRP as an anti-cancer agent.

Evaluation of circulating CD34+ stem cells in peripheral venous blood in patients with varying degrees of periodontal disease.

INTRODUCTION: Periodontal disease presents a challenge for modern medicine, and research on the use of stem cells as a treatment is currently underway. MATERIAL AND METHODS: The study included 45 patients who were given a thorough physical examination. Additionally, an evaluation of their medical history of the disease, degree of progression of periodontal disease, and the level of CRP in the blood was carried out. Patients were divided into 4 groups: 4 patients were in the first group with no periodontal disease, 8 patients in the second group with a moderate level, 20 patients in the third group with an advanced level, and 13 patients in the fourth group were toothless. For each group, the use of stem cells as a treatment of antibody-labeled CD34+ stem cells, lymphocytes, and leukocytes was conducted. RESULTS: A statistically significant positive correlation was observed in CD34+ stem cells in proportion to lymphocytes in the moderate (0.80), in the advanced (0.75), and in the toothless groups (0.70). The ratio of CD34+ stem cells to leukocytes was statistically significant in the toothless group (0.92) and in the advanced group (0.91). A statistically significant increase was noted in the level of CRP in the previously mentioned groups of patients, and the highest concentration of CD34+ stem cells in the advanced group. CONCLUSIONS: The highest concentration of CD34+ cells was observed in the group of patients with advanced periodontal disease.

Serum C-Reactive Protein and Periodontitis: A Systematic Review and Meta-Analysis.

Periodontitis has been associated with low-grade inflammation as assessed by C-reactive protein (CRP) levels and its treatment can decrease CRP serum levels. The aim of this systematic review was to critically appraise the evidence comparing CRP serum levels (standard and high-sensitivity [hs]) of otherwise healthy patients suffering from periodontitis when compared to controls. The impact of intensive and non-intensive nonsurgical periodontal treatment (NSPT) on hs-CRP was also investigated. Four electronic databases (Pubmed, The Cochrane Central Register of Controlled Trials [CENTRAL], EMBASE and Web of Science) were searched up to February 2021 and the review was completed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO No. CRD42020167454). Observational and intervention studies that: 1) evaluated CRP and hs-CRP serum levels in patients with and without periodontitis, and; 2) hs- CRP levels after NSPT were included. Following risk of bias appraisal, both qualitative and quantitative analyses were performed. Pooled estimates were rendered through ratio of means (RoM) random-effects meta-analyses. After screening 485 studies, 77 case-control studies and 67 intervention trials were included. Chronic and aggressive periodontitis diagnoses were consistently associated with higher levels of CRP and hs-CRP (p<0.001). Patients with aggressive periodontitis exhibited on average more than 50% higher levels of CRP (RoM [95% confidence interval [CI]]: 1.56 [1.15; 2.12], p=0.0039) than patients with chronic periodontitis. Intensive NSPT induced an immediate increase of hs-CRP followed by a progressive decrease whilst non-intensive NSPT consistently decreased hs-CRP after treatment up to 180 days (p<0.001). These findings provide robust evidence that periodontitis is associated with systemic inflammation as measured by serum CRP levels. Periodontitis treatment induces a short-term acute inflammatory increase when performed in an intensive session, whilst a progressive reduction up to 6 months was demonstrated when performed in multiple visits.

Changes in Cerebrospinal Fluid Balance of TNF and TNF Receptors in Naïve Multiple Sclerosis Patients: Early Involvement in Compartmentalised Intrathecal Inflammation.

An imbalance of TNF signalling in the inflammatory milieu generated by meningeal immune cell infiltrates in the subarachnoid space in multiple sclerosis (MS), and its animal model may lead to increased cortical pathology. In order to explore whether this feature may be present from the early stages of MS and may be associated with the clinical outcome, the protein levels of TNF, sTNF-R1 and sTNF-R2 were assayed in CSF collected from 122 treatment-naïve MS patients and 36 subjects with other neurological conditions at diagnosis. Potential correlations with other CSF cytokines/chemokines and with clinical and imaging parameters at diagnosis (T0) and after 2 years of follow-up (T24) were evaluated. Significantly increased levels of TNF (fold change: 7.739; p < 0.001), sTNF-R1 (fold change: 1.693; p < 0.001) and sTNF-R2 (fold change: 2.189; p < 0.001) were detected in CSF of MS patients compared to the control group at T0. Increased TNF levels in CSF were significantly (p < 0.01) associated with increased EDSS change (r = 0.43), relapses (r = 0.48) and the appearance of white matter lesions (r = 0.49). CSF levels of TNFR1 were associated with cortical lesion volume (r = 0.41) at T0, as well as with new cortical lesions (r = 0.56), whilst no correlation could be found between TNFR2 levels in CSF and clinical or MRI features. Combined correlation and pathway analysis (ingenuity) of the CSF protein pattern associated with TNF expression (encompassing elevated levels of BAFF, IFN-γ, IL-1ß, IL-10, IL-8, IL-16, CCL21, haptoglobin and fibrinogen) showed a particular relationship to the interaction between innate and adaptive immune response. The CSF sTNF-R1-associated pattern (encompassing high levels of CXCL13, TWEAK, LIGHT, IL-35, osteopontin, pentraxin-3, sCD163 and chitinase-3-L1) was mainly related to altered T cell and B cell signalling. Finally, the CSF TNFR2-associated pattern (encompassing high CSF levels of IFN-ß, IFN-λ2, sIL-6Rα) was linked to Th cell differentiation and regulatory cytokine signalling. In conclusion, dysregulation of TNF and TNF-R1/2 pathways associates with specific clinical/MRI profiles and can be identified at a very early stage in MS patients, at the time of diagnosis, contributing to the prediction of the disease outcome.

Cell Population Data and Serum Polyclonal Immunoglobulin Free Light Chains in the Assessment of COVID-19 Severity.

Distinguishing between severe and nonsevere COVID-19 to ensure adequate healthcare quality and efficiency is a challenge for the healthcare system. The aim of this study was to assess the usefulness of CBC parameters together with analysis of FLC serum concentration in risk stratification of COVID-19. MATERIALS AND METHODS: CBC was analyzed in 735 COVID ICU, COVID non-ICU, and non-COVID ICU cases. FLC concentration was analyzed in 133 of them. RESULTS: COVID ICU had neutrophils and lymphocytes with the greatest size, granularity, and nucleic acid content. Significant differences in concentrations of κ and λ FLCs were shown between COVID ICU and COVID non-ICU. However, no difference was found in the κ/λ ratio between these groups, and the ratio stayed within the reference value, which indicates the presence of polyclonal FLCs. FLC κ measurement has significant power to distinguish between severe COVID-19 and nonsevere COVID-19 (AUC = 0.7669), with a sensitivity of 86.67% and specificity of 93.33%. The κ coefficients' odds ratio of 3.0401 was estimated. CONCLUSION: It can be concluded that the results obtained from the measure of free light immunoglobulin concentration in serum are useful in distinguishing between severe and nonsevere COVID-19.

Case Report: C-Reactive Protein Apheresis in a Patient With COVID-19 and Fulminant CRP Increase.

Background: Plasma levels of C-reactive protein (CRP), induced by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) triggering COVID-19, can rise surprisingly high. The increase of the CRP concentration as well as a certain threshold concentration of CRP are indicative of clinical deterioration to artificial ventilation. In COVID-19, virus-induced lung injury and the subsequent massive onset of inflammation often drives pulmonary fibrosis. Fibrosis of the lung usually proceeds as sequela to a severe course of COVID-19 and its consequences only show months later. CRP-mediated complement- and macrophage activation is suspected to be the main driver of pulmonary fibrosis and subsequent organ failure in COVID-19. Recently, CRP apheresis was introduced to selectively remove CRP from human blood plasma. Case Report: A 53-year-old, SARS-CoV-2 positive, male patient with the risk factor diabetes type 2 was referred with dyspnea, fever and fulminant increase of CRP. The patient's lungs already showed a pattern enhancement as an early sign of incipient pneumonia. The oxygen saturation of the blood was ≤ 89%. CRP apheresis using the selective CRP adsorber (PentraSorb® CRP) was started immediately. CRP apheresis was performed via peripheral venous access on 4 successive days. CRP concentrations before CRP apheresis ranged from 47 to 133 mg/l. The removal of CRP was very effective with up to 79% depletion within one apheresis session and 1.2 to 2.14 plasma volumes were processed in each session. No apheresis-associated side effects were observed. It was at no point necessary to transfer the patient to the Intensive Care Unit or to intubate him due to respiratory failure. 10 days after the first positive SARS-CoV-2 test, CRP levels stayed below 20 mg/l and the patient no longer exhibited fever. Fourteen days after the first positive SARS-CoV-2 test, the lungs showed no sign of pneumonia on X-ray. Conclusion: This is the first report on CRP apheresis in an early COVID-19 patient with fulminant CRP increase. Despite a poor prognosis due to his diabetes and biomarker profile, the patient was not ventilated, and the onset of pneumonia was reverted.

Peroxidase-mimicking nanozyme with surface-dispersed Pt atoms for the colorimetric lateral flow immunoassay of C-reactive protein.

Platinum-containing nanozymes with peroxidase-mimicking activity (PMA) have found a broad application in bioanalytical methods and are potentially able to compete with enzymes as the labels. However, traditionally used methods for the synthesis of nanozymes result in only a small fraction of surface-exposed Pt atoms, which participate in catalysis. To overcome this limitation, we propose a new approach for the synthesis of nanozymes with the efficient dispersion of Pt atoms on particles' surfaces. The synthesis of nanozymes includes three steps: the synthesis of gold nanoparticles (Au NPs), the overgrowth of a silver layer over Au NPs (Au@Ag NPs, 6 types of NPs with different thicknesses of Ag shell), and the galvanic replacement of silver with PtCl62- leading to the formation of trimetallic Au@Ag-Pt NPs with uniformly deposited catalytic sites and high Pt-utilization efficiency. Au@Ag-Pt NPs (23 types of NPs with different concentrations of Pt) with various sizes, morphology, optical properties, and PMA were synthesized and comparatively tested. Using energy-dispersive spectroscopy mapping, we confirm the formation of core@shell Au@Ag NPs and dispersion of surface-exposed Pt. The selected Au@Ag-Pt NPs were conjugated with monoclonal antibodies and used as the colorimetric and catalytic labels in lateral flow immunoassay of the inflammation biomarker: C-reactive protein (CRP). The colorimetric signal enhancement was achieved by the oxidation of 3,3'-diaminobenzidine by H2O2 catalyzed by Au@Ag-Pt NPs directly on the test strip. The use of Au@Ag-Pt NPs as the catalytic label produces a 65-fold lower limit of CRP detection in serum (15 pg mL-1) compared with Au NPs and ensures the lowest limit of detection for equipment-free lateral flow immunoassays. The assay shows a high correlation with data of enzyme-linked immunosorbent assay (R2 = 0.986) and high recovery (83.7-116.2%) in serum and plasma. The assay retains all the benefits of lateral flow immunoassay as a point-of-care method.

Native Low-Density Lipoproteins Act in Synergy with Lipopolysaccharide to Alter the Balance of Human Monocyte Subsets and Their Ability to Produce IL-1 Beta, CCR2, and CX3CR1 In Vitro and In Vivo: Implications in Atherogenesis.

Increasing evidence has demonstrated that oxidized low-density lipoproteins (oxLDL) and lipopolysaccharide (LPS) enhance accumulation of interleukin (IL)-1 beta-producing macrophages in atherosclerotic lesions. However, the potential synergistic effect of native LDL (nLDL) and LPS on the inflammatory ability and migration pattern of monocyte subpopulations remains elusive and is examined here. In vitro, whole blood cells from healthy donors (n = 20) were incubated with 100 µg/mL nLDL, 10 ng/mL LPS, or nLDL + LPS for 9 h. Flow cytometry assays revealed that nLDL significantly decreases the classical monocyte (CM) percentage and increases the non-classical monocyte (NCM) subset. While nLDL + LPS significantly increased the number of NCMs expressing IL-1 beta and the C-C chemokine receptor type 2 (CCR2), the amount of NCMs expressing the CX3C chemokine receptor 1 (CX3CR1) decreased. In vivo, patients (n = 85) with serum LDL-cholesterol (LDL-C) >100 mg/dL showed an increase in NCM, IL-1 beta, LPS-binding protein (LBP), and Castelli's atherogenic risk index as compared to controls (n = 65) with optimal LDL-C concentrations (≤100 mg/dL). This work demonstrates for the first time that nLDL acts in synergy with LPS to alter the balance of human monocyte subsets and their ability to produce inflammatory cytokines and chemokine receptors with prominent roles in atherogenesis.

Systematic Review of Antiphospholipid Antibodies in COVID-19 Patients: Culprits or Bystanders?

PURPOSE OF REVIEW: COVID-19 patients have a procoagulant state with a high prevalence of thrombotic events. The hypothesis of an involvement of antiphospholipid antibodies (aPL) has been suggested by several reports. Here, we reviewed 48 studies investigating aPL in COVID-19 patients. RECENT FINDINGS: Prevalence of Lupus Anticoagulant (LA) ranged from 35% to 92% in ICU patients. Anti-cardiolipin (aCL) IgG and IgM were found in up to 52% and up to 40% of patients respectively. Anti-ß2-glycoprotein I (aß2-GPI) IgG and IgM were found in up to 39% and up to 34% of patients respectively. Between 1% and 12% of patients had a triple positive aPL profile. There was a high prevalence of aß2-GPI and aCL IgA isotype. Two cohort studies found few persistent LA but more persistent solid phase assay aPL over time. aPL determination and their potential role is a real challenge for the treatment of this disease.

Differential immune responses in pregnant patients recovered from COVID-19.

Pregnant women are generally more susceptible to viral infection. Although the impact of SARS-CoV-2 in pregnancy remains to be determined, evidence indicates that the risk factors for severe COVID-19 are similar in pregnancy to the general population. Here we systemically analyzed the clinical characteristics of pregnant and non-pregnant female COVID-19 patients who were hospitalized during the same period and found that pregnant patients developed marked lymphopenia and higher inflammation evident by higher C-reactive protein and IL-6. To elucidate the pathways that might contribute to immunopathology or protective immunity against COVID-19 during pregnancy, we applied single-cell mRNA sequencing to profile peripheral blood mononuclear cells from four pregnant and six non-pregnant female patients after recovery along with four pregnant and three non-pregnant healthy donors. We found normal clonal expansion of T cells in the pregnant patients, heightened activation and chemotaxis in NK, NKT, and MAIT cells, and differential interferon responses in the monocyte compartment. Our data present a unique feature in both innate and adaptive immune responses in pregnant patients recovered from COVID-19.