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.

A brief, highly selective history of acute phase proteins as indicators of infection, inflammation and injury.

There is an array of plasma protein alterations that occur in a wide variety of species, including humans in response to trauma, inflammation and infections, seemingly irrespective of etiologic agent. In numerous species, these plasma proteins are part of the innate immune response. In addition, it appears that a number of the plasma proteins in this array can be predictive of morbidity and/or mortality. We propose that based on historic use, selected acute phase proteins should be included in ongoing and future non-clinical and clinical studies to help us better understand disease progression in chronic, as well as acute diseases. In addition to assess if there is a relationship between vaccine-induced inflammation and degree of protection from live, attenuated or synthetic vaccines.

Autoantibodies against the C-terminus of Lipopolysaccharide binding protein are elevated in young adults with psychiatric disease.

Growing evidence implies interactions between infections, the immune system and vulnerability for psychiatric disease. This study applies an affinity proteomic-based method to investigate potential disease associated autoantibody signatures in serum from patients from the "Young Adults" section of the Department of General Psychiatry at Uppsala University Hospital (n = 395) and population-based controls (n = 102). We found serum levels of antibodies against Lipopolysaccharide Binding Protein (LBP), a protein that is important for mediating innate immune responses involving the toll-like receptor-4 (TLR-4), to be higher in patients compared to controls (Mann Whitney U-test p = 5.248 × 10-10). The patients were divided into three groups based on their relative levels of autoantibodies against LBP. The distribution of autism spectra disorders (p = 2.0 × 10-4) and hospital care for an infection as adults (p = 0.036) differed between the anti-LBP groups, with low incidence in the group of patients with the highest levels of anti-LBP who were diagnosed with primarily affective and anxiety disorders. In a sub-group analysis, the controls who screened positive for current or previous psychiatric diagnosis (n = 20) had higher anti-LBP compared to non-psychiatric controls with negative screening for psychiatric disorders (Mann Whitney U-test p = 0.006). Inflammatory markers were found to differ across anti-LBP groups and several pro-inflammatory markers, including IL-1ß, were low in patients with high anti-LBP and serum LBP levels were lowest in patients with the highest levels of antibodies against LBP (p = 3.5 × 10-5). A cell-based model showed that polyclonal rabbit anti-LBP, obtained through purification via the same protein fragment used in the initial autoantibody analysis, could interfere with LBP signaling since addition of anti-LBP to the assay reduced both IL-1ß and IL-6 release from activated monocytes in response to LBP and LPS (p = 0.0001 and p = 0.02). This novel finding of antibodies against LBP, where high levels were only found in young adults with psychiatric disease, merits further study. Our results suggest that these antibodies may have relevance for TLR4 based immune responses and vulnerability for both infection and psychiatric disorders.

Phase specific suppression of neutrophil function in hibernating Syrian hamster.

Hibernation consists of alternating periods of reduced metabolism (torpor) with brief periods of metabolism similar to summer euthermia (arousal). The function of the innate immune system is reduced during hibernation, of which the underlying mechanisms are incompletely understood. Here, we studied neutrophil functionality during hibernation in Syrian hamsters. The inflammatory response to LPS-induced endotoxemia is inhibited in hibernation, partly mediated by reduced IL-6 production in early arousal. Furthermore, neutrophil pathogen binding, phagocytosis and oxidative burst is profoundly reduced in early arousal. Functionality of both summer and early arousal neutrophils was repressed in plasma from early arousal and mixed plasma from early arousal and summer euthermic, but restored by summer euthermic plasma, signifying that a plasma factor in early arousal inhibits TLR-recognition. Identification of the inhibiting factor may offer a target to modulate neutrophil function with relevance to (auto-)inflammatory diseases.

The Long Pentraxin 3 (PTX3) Suppresses Immunity to Cutaneous Leishmaniasis by Regulating CD4+ T Helper Cell Response.

The long pentraxin 3 (PTX3) plays a critical role in inflammation, tissue repair, and wound healing. Here, we show that PTX3 regulates disease pathogenesis in cutaneous leishmaniasis (CL). PTX3 expression increases in skin lesions in patients and mice during CL, with higher expression correlating with severe disease. PTX3-deficient (PTX3-/-) mice are highly resistant to L. major and L. braziliensis infections. This enhanced resistance is associated with increases in Th17 and IL-17A responses. The neutralization of IL-17A abolishes this enhanced resistance, while rPTX3 treatment results in decrease in Th17 and IL-17A responses and increases susceptibility. PTX3-/- CD4+ T cells display increased differentiation to Th17 and expression of Th17-specific transcription factors. The addition of rPTX3 suppresses the expression of Th17 transcription factors, Th17 differentiation, and IL-17A production by CD4+ T cells from PTX3-/- mice. Collectively, our results show that PTX3 contributes to the pathogenesis of CL by negatively regulating Th17 and IL-17A responses.

Novel coronavirus SARS-CoV-2 (Covid-19) dynamics inside the human body.

A knowledge-based cybernetic framework model representing the dynamics of SARS-CoV-2 inside the human body has been studied analytically and in silico to explore the pathophysiologic regulations. The following modeling methodology was developed as a platform to introduce a predictive tool supporting a therapeutic approach to Covid-19 disease. A time-dependent nonlinear system of ordinary differential equations model was constructed involving type-I cells, type-II cells, SARS-CoV-2 virus, inflammatory mediators, interleukins along with host pulmonary gas exchange rate, thermostat control, and mean pressure difference. This formalism introduced about 17 unknown parameters. Estimating these unknown parameters requires a mathematical association with the in vivo sparse data and the dynamic sensitivities of the model. The cybernetic model can simulate a dynamic response to the reduced pulmonary alveolar gas exchange rate, thermostat control, and mean pressure difference under a very critical condition based on equilibrium (steady state) values of the inflammatory mediators and system parameters. In silico analysis of the current cybernetical approach with system dynamical modeling can provide an intellectual framework to help experimentalists identify more active therapeutic approaches.

C reactive protein impairs adaptive immunity in immune cells of patients with melanoma.

BACKGROUND: High C reactive protein (CRP) levels have been reported to be associated with a poor clinical outcome in a number of malignancies and with programmed cell death protein 1 immune checkpoint blockade in patients with advanced cancer. Little is known about the direct effects of CRP on adaptive immunity in cancer. Therefore, we investigated how CRP impacted the function of T cells and dendritic cells (DCs) from patients with melanoma. METHODS: The effects of CRP on proliferation, function, gene expression and phenotype of patient T cells and DCs, and expansion of MART-1 antigen-specific T cells were analyzed by multicolor flow cytometry and RNA-seq. Additionally, serum CRP levels at baseline from patients with metastatic melanoma treated on the Checkmate-064 clinical trial were assessed by a Luminex assay. RESULTS: In vitro, CRP inhibited proliferation, activation-associated phenotypes and the effector function of activated CD4+ and CD8+ T cells from patients with melanoma. CRP-treated T cells expressed high levels of interleukin-1ß, which is known to enhance CRP production from the liver. CRP also suppressed formation of the immune synapse and inhibited early events in T-cell receptor engagement. In addition, CRP downregulated the expression of costimulatory molecules on mature DCs and suppressed expansion of MART-1-specific CD8+ T cells in a dose-dependent manner by impacting on both T cells and antigen-presenting cells. High-serum CRP levels at baseline were significantly associated with a shorter survival in both nivolumab-treated and ipilimumab-treated patients. CONCLUSIONS: These findings suggest that high levels of CRP induce an immunosuppressive milieu in melanoma and support the blockade of CRP as a therapeutic strategy to enhance immune checkpoint therapies in cancer. TRIAL REGISTRATION NUMBER: NCT01783938 and NCT02983006.

Serum amyloid A exhibits pH dependent antibacterial action and contributes to host defense against Staphylococcus aureus cutaneous infection.

Serum amyloid A (SAA), one of the major highly conserved acute-phase proteins in most mammals, is predominantly produced by hepatocytes and also by a variety of cells in extrahepatic tissues. It is well-known that the expression of SAA is sharply increased in bacterial infections. However, the exact physiological function of SAA during bacterial infection remains unclear. Herein, we showed that SAA expression significantly increased in abscesses of Staphylococcus aureus cutaneous infected mice, which exert direct antibacterial effects by binding to the bacterial cell surface and disrupting the cell membrane in acidic conditions. Mechanically, SAA disrupts anionic liposomes by spontaneously forming small vesicles or micelles under acidic conditions. Especially, the N-terminal region of SAA is necessary for membrane disruption and bactericidal activity. Furthermore, we found that mice deficient in SAA1/2 were more susceptible to infection by S. aureus In addition, the expression of SAA in infected skin was regulated by interleukin-6. Taken together, these findings support a key role of the SAA in host defense and may provide a novel therapeutic strategy for cutaneous bacterial infection.

Analyses of the toxic properties of recombinant human Cyclophilin A in mice.

Cyclophilin A (CypA), an 18 kDa multi-functional protein with cis-trans isomerase activity, is both a ligand for cyclosporine A and a proinflammatory factor. CypA is also a chemoattractant for hemopoietic stem cells and progenitors of different lineages, and can mediate regenerative processes in an organism. Accumulated experimental data have suggested there are practical applications for this protein in the treatment of several diseases (i.e. neutralization of cyclosporine A side effects, etc.). However, the range of CypA safe doses as well as its toxic effects remain unknown. The study here investigated the acute toxicity of a single intraperitoneal (IP) or subcutaneous (SC) dosing of recombinant human CypA (rhCypA) in both female and male mice and its effect on gene expression of acute phase proteins (APP) in the female mice after IP treatment. The results showed that toxicity of rhCypA was most evident in female and male mice dosed IP with 750 mg/kg, and manifested as kidney injury and increased granulocyte/lymphocyte ratios in the blood. Enhanced expression of Sаа1 and Sаа2 genes was induced with doses of 0.1-2 mg/mouse of rhCypA. Injection of the maximal dose (750 mg/kg) significantly stimulated expression of all the APP genes studied.

Development and validation of an ELISA for the quantification of bovine ITIH4 in serum and milk.

Inter alpha trypsin inhibitor heavy chain 4 (ITIH4) is a serum protein belonging to the Inter alpha trypsin inhibitor (ITI) family, which was previously characterized by our group as a new APP in cattle. This protein was firstly described in pigs where is known to be a major acute phase protein, also denominated Pig-MAP. Increases of ITIH4 of up to 12 times the pre-infection values were previously reported in the serum of heifers with experimentally induced summer mastitis. ITIH4 was detected in the milk of cows with mastitis by western blot, but the method previously used to quantify this protein, radial immunodiffusion, was not sensitive enough to quantify it in milk samples. In this study we developed an ELISA method which allows the quantification of bovine ITIH4 in serum and milk samples. Previously developed antibodies were used to perform the assay, including anti bovine ITIH4 polyclonal antibodies and a monoclonal antibody against pig ITIH4 that also recognizes the bovine homologous protein. The ELISA developed showed an adequate precision, with inter and intra- assay coefficients of variation lower than 10% for serum and milk samples. The assay keeps linearity under dilution for both serum and milk samples. A good agreement was observed between the values measured by ELISA and radial immunodiffusion in serum samples.

Evaluation of lung parenchyma, blood vessels, and peripheral blood lymphocytes as a potential source of acute phase reactants in patients with COPD.

Background: Previous studies have shown that the arterial wall is a potential source of inflammatory markers in COPD. Here, we sought to compare the expression of acute phase reactants (APRs) in COPD patients and controls both at the local (pulmonary arteries and lung parenchyma) and systemic (peripheral blood leukocytes and plasma) compartments. Methods: Consecutive patients undergoing elective surgery for suspected primary lung cancer were eligible for the study. Patients were categorized either as COPD or control group based on the spirometry results. Pulmonary arteries and lung parenchyma sections, peripheral blood leukocytes, and plasma samples were obtained from all participants. Gene expression levels of C-reactive protein (CRP) and serum amyloid A (SAA1, SAA2, and SAA4) were evaluated in tissue samples and peripheral blood leukocytes by reverse transciption-PCR. Plasma CRP and SAA protein levels were measured by enzyme-linked immunosorbent assays. Proteins were evaluated in paraffin-embedded lung tissues by immunohistochemistry. Results: A total of 40 patients with COPD and 62 controls were enrolled. We did not find significant differences in the gene expression between COPD and control group. Both CRP and SAA were overexpressed in the lung parenchyma compared with pulmonary arteries and peripheral blood leukocytes. The expression of SAA was significantly higher in the lung parenchyma than in the pulmonary artery (2-fold higher for SAA1 and SAA4, P=0.015 and P<0.001, respectively; 8-fold higher for SAA2, P<0.001) and peripheral blood leukocytes (16-fold higher for SAA1, 439-fold higher for SAA2, and 5-fold higher for SAA4; P<0.001). No correlation between plasma levels of inflammatory markers and their expression in the lung and peripheral blood leukocytes was observed. Conclusions: The expression of SAA in lung parenchyma is higher than in pulmonary artery and peripheral blood leukocytes. Notably, no associations were noted between lung expression of APRs and their circulating plasma levels, making the leakage of inflammatory proteins from the lung to the bloodstream unlikely. Based on these results, other potential sources of systemic inflammation in COPD (eg, the liver) need further scrutiny.

Acute Phase Proteins in Marine Mammals: State of Art, Perspectives and Challenges.

The term "acute phase response" (APR) is referred to a nonspecific and complex reaction of an organism that occurs shortly after any tissue damage, such as infection, trauma, neoplasia, inflammation, and stress. The APR can be identified and monitored with some laboratory tests, such as the concentration of several plasma proteins, the acute phase proteins (APPs). The APPs are components of the non-specific innate immune response, and their plasma concentration is proportional to the severity and/or the extent of tissue damage. The evaluation of health status of marine mammals is difficult because the classical clinical signs of illness used for human and domestic animals are difficult to recognize and understand. For this reason, in the past years, several efforts were done to identify laboratory markers of disease in these animals. The APPs have demonstrated their role as early markers of inflammation in veterinary medicine, thus several APPs were tested in marine mammals, such as C-reactive protein (CRP), serum amyloid-A (SAA), and Haptoglobin (Hp). However, the difficulty to extrapolate the knowledge about APPs in one species to another, the lack of specie-specific reagents, the absence of data about negative APPs have hampered their extent use in marine mammals. Herein, the state of art of APPs in marine mammals is reviewed, with particular attention to pre-analytical and analytical factors that should be taken into account in validation and interpretation of APPs assays. Moreover, the current application, potential utility and the future developments of APPs in marine mammals is highlighted and discussed.

The Long Pentraxin PTX3 Is of Major Importance Among Acute Phase Proteins in Chickens.

The expression level of acute phase proteins (APPs) mirrors the health status of an individual. In human medicine, C-reactive protein (CRP), and other members of the pentraxin family are of significant relevance for assessing disease severity and prognosis. In chickens, however, which represent the most common livestock species around the world, no such marker has yet gained general acceptance. The aim of this study was therefore, to characterize chicken pentraxin 3 (chPTX3) and to evaluate its applicability as a general marker for inflammatory conditions. The mammalian and chicken PTX3 proteins were predicted to be similar in sequence, domain organization and polymeric structure. Nevertheless, some characteristics like certain sequence sections, which have varied during the evolution of mammals, and species-specific glycosylation patterns, suggest distinct biological functions. ChPTX3 is constitutively expressed in various tissues but, interestingly, could not be found in splenic tissue samples without stimulation. However, upon treatment with lipopolysaccharide (LPS), PTX3 expression in chicken spleens increased to 95-fold within hours. A search for PTX3 reads in various publicly available RNA-seq data sets of chicken spleen and bursa of Fabricius also showed that PTX3 expression increases within days after experimental infection with viral and bacterial pathogens. An experimental infection with avian pathogenic E.coli and qPCR analysis of spleen samples further established a challenge dose-dependent significant up-regulation of chPTX3 in subclinically infected birds of up to over 150-fold as compared to untreated controls. Our results indicate the potential of chPTX3 as an APP marker to monitor inflammatory conditions in poultry flocks.

Chronic inflammation in adult familial Mediterranean fever patients: underlying causes and association with amyloidosis.

Background: Chronic inflammation, as determined by persistently elevated acute-phase reactants in attack-free periods, can occasionally be observed in patients with familial Mediterranean fever (FMF) and is suggested to be a risk factor for the development of amyloidosis. We aimed to investigate the underlying causes of chronic inflammation in FMF patients and its association with amyloidosis in long-term follow-up. Method: Electronic medical records of FMF patients who had regular follow-up for ≥ 5 years in our cohort were utilized. As part of routine evaluation, detailed history, physical examination, and pertinent laboratory and radiographic investigations were performed in all patients to determine potential causes of elevated C-reactive protein (CRP) levels. Results: The study included 146 FMF patients who had no evidence of amyloidosis at baseline and had regular follow-up for ≥ 5 years. Thirty-seven patients (25.3%) were found to have chronic inflammation in the disease course. Twenty-five (67.5%) of them had either very frequent attacks or chronic manifestations of disease. In the entire study group, amyloidosis developed in five patients (3.42%) during the 5 year follow-up, four in the FMF with chronic inflammation group (10.8%), and only one of the 109 patients without chronic inflammation (odds ratio 13.09, 95% confidence interval 1.41-121.2). Conclusions: The results suggest that persistently high CRP levels during the attack-free periods may be a strong risk factor for the development of amyloidosis in patients with FMF. The vast majority of FMF patients with chronic inflammation had active FMF.

Molecular identification and function analysis of bactericidal permeability-increasing protein/LPS-binding protein 1 (BPI/LBP1) from turbot (Scophthalmus maximus).

Bactericidal permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) play important roles in host antimicrobial defense. In the present study, we identified one isoform of BPI/LBP gene from turbot (Scophthalmus maximus), designated as SmBPI/LBP1. The full-length cDNA sequence of SmBPI/LBP1 was 1826 bp, which encoding one secreted protein with 480 amino acid residues. Structurally, the SmBPI/LBP1 showed high similarity to its homologs from other vertebrates or invertebrates, which all contained a signal peptide, a BPI/LBP/CETP N-terminal with a LPS-binding domain, and a BPI/LBP/CETP C-terminal domain. The deduced amino acid sequences of SmBPI/LBP1 shared significant similarity to BPI/LBP of Seriola lalandi dorsalis (71%) and Paralichthys olivaceus (69%). Phylogentic analysis further supported that SmBPI/LBP1 act as a new member of vertebrate BPI/LBP family. SmBPI/LBP1 was ubiquitously expressed in all tested tissues, with the highest expression level in spleen tissue. The mRNA expression of SmBPI/LBP1 in spleen and kidney were significantly up-regulated after Vibrio vulnificus challenge. Finally, the recombinant SmBPI/LBP1 showed high affinity to lipopolysaccharide, followed by peptidoglycan and lipoteichoic acid, which is the ubiquitous component of Gram-negative or Gram-positive bacteria. These results indicated that SmBPI/LBP1 probably played important roles in immune response against bacteria infection.

One-step production of bioactive human lipopolysaccharide binding protein from LPS-eliminated E. coli.

Human lipopolysaccharide (LPS) binding protein (LBP) is a ∼60 kDa glycosylated protein that mediates potent innate immune against invading Gram-negative bacteria by recognition of LPS in their outer membranes. To date, there is no method for efficient production of bioactive LPS-free LBP at sufficient amounts through prokaryotic expression system. Here we present a simple approach for rapid preparation of human LBP from a LPS-eliminated E. coli strain named ClearColi BL21 (DE)3. Combined with the usage of an ultra-high-affinity CL7/Im7 purification system, we achieved one-step purification of recombinant human LBP with over 90% purity at a yield of ∼4 mg/L when using LB culture medium. The produced LBP retains full LPS binding activity which was validated by fluorescence spectroscopy and isothermal titration calorimetry (ITC). Collectively, we develop a valid method that can be applied to cost-effectively produce and purify LPS-free proteins.

Immunophenotyping lymphocyte and acute phase proteins in canine X-linked muscular dystrophy.

Duchenne Muscular Dystrophy (DMD) is the most common X-linked muscular disease affecting humans. The Golden Retriever Muscular Dystrophy model (GRMD) is considerthe most suitable for several studies. This assay aims to quantify lymphocyte subpopulations CD4, CD5, and CD8, and standardize, the serum electrophoretic profile, to understand their contribution to the pathologic process in normal Golden Retriever dogs (GR group) and dystrophic´s (GRMD group), through the umbilical cord blood, in dogs aged from 2 to 3 months (GR II and GRMD II), and in dogs over 1 year of age (GR III and GRMD III). No significant differences were observed between the CD8+ lymphocyte subpopulations of the groups studied. The CD4+ and CD5+ lymphocyte subpopulations were significantly higher in the GRMD III group compared to the GR III group. Twenty-two different proteins in the gel were identified. The serum concentrations of the proteins belonging to the GR I and GRMD I groups were significantly lower than those of the other groups. We show that expression of acute phase proteins are worst during the aging of the dogs. We hope to expand knowledge to better understand the GRMD model and the translational data.