Fibrin(ogen) engagement of S. aureus promotes the host antimicrobial response and suppression of microbe dissemination following peritoneal infection.

The blood-clotting protein fibrin(ogen) plays a critical role in host defense against invading pathogens, particularly against peritoneal infection by the Gram-positive microbe Staphylococcus aureus. Here, we tested the hypothesis that direct binding between fibrin(ogen) and S. aureus is a component of the primary host antimicrobial response mechanism and prevention of secondary microbe dissemination from the peritoneal cavity. To establish a model system, we showed that fibrinogen isolated from FibγΔ5 mice, which express a mutant form lacking the final 5 amino acids of the fibrinogen γ chain (termed fibrinogenγΔ5), did not support S. aureus adherence when immobilized and clumping when in suspension. In contrast, purified wildtype fibrinogen supported robust adhesion and clumping that was largely dependent on S. aureus expression of the receptor clumping factor A (ClfA). Following peritoneal infection with S. aureus USA300, FibγΔ5 mice displayed worse survival compared to WT mice coupled to reduced bacterial killing within the peritoneal cavity and increased dissemination of the microbes into circulation and distant organs. The failure of acute bacterial killing, but not enhanced dissemination, was partially recapitulated by mice infected with S. aureus USA300 lacking ClfA. Fibrin polymer formation and coagulation transglutaminase Factor XIII each contributed to killing of the microbes within the peritoneal cavity, but only elimination of polymer formation enhanced systemic dissemination. Host macrophage depletion or selective elimination of the fibrin(ogen) ß2-integrin binding motif both compromised local bacterial killing and enhanced S. aureus systemic dissemination, suggesting fibrin polymer formation in and of itself was not sufficient to retain S. aureus within the peritoneal cavity. Collectively, these findings suggest that following peritoneal infection, the binding of S. aureus to stabilized fibrin matrices promotes a local, macrophage-mediated antimicrobial response essential for prevention of microbe dissemination and downstream host mortality.

Anti-Carbamylated Fibrinogen Antibodies Might Be Associated With a Specific Rheumatoid Phenotype and Include a Subset Recognizing In Vivo Epitopes of Its γ Chain One of Which Is Not Cross Reactive With Anti-Citrullinated Protein Antibodies.

To identify the targets recognized by anti-carbamylated protein antibodies (anti-CarP) in patients with early Rheumatoid Arthritis (RA), to study the cross-reactivity between anti-CarP and anti-citrullinated protein antibodies (ACPA) and to evaluate their prognostic value. 331 patients (184 RA and 147 other rheumatisms) from the Very Early Arthritis (VErA) French cohort were analyzed. We performed mass spectrometry analysis of RA sera displaying anti-CarP activity and epitope mapping of the carbamylated fibrinogen γ chain to identify immunodominant peptides. The specificity of these targets was studied using competition assays with the major antigens recognized by ACPA. The prognostic value of anti-carbamylated fibrinogen IgG antibodies (ACa-Fib IgG) was compared to that of anti-cyclic citrullinated peptide antibodies (anti-CCP) and anti-CarP using an in-house ELISA. Besides the α chain, the γ chain of fibrinogen, particularly one immunodominant epitope that has a specific reactivity, was identified as a circulating carbamylated target in sera. The prevalence of ACa-Fib was 37% at baseline and 10.9% for anti-CCP-negative RA. In anti-CCP-negative patients, ACa-Fib positivity was associated with a more inflammatory and erosive disease at baseline but not with rapid radiological progression, which remains strongly related to anti-CCP antibodies. Fibrinogen seems to be one of the antigens recognized in vivo by the anti-CarP response, particularly 2 epitopes of the γ chain, one of which is not cross reactive with ACPA. This specificity might be associated with a distinct clinical phenotype since ACa-Fib IgG were shown to be linked to systemic inflammation in very early RA but not to rapid radiological progression.

Fibrinogen-like protein 1 (FGL1): the next immune checkpoint target.

Immune checkpoint therapy has achieved significant efficacy by blocking inhibitory pathways to release the function of T lymphocytes. In the clinic, anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) monoclonal antibodies (mAbs) have progressed to first-line monotherapies in certain tumor types. However, the efficacy of anti-PD-1/PD-L1 mAbs is still limited due to toxic side effects and de novo or adaptive resistance. Moreover, other immune checkpoint target and biomarkers for therapeutic response prediction are still lacking; as a biomarker, the PD-L1 (CD274, B7-H1) expression level is not as accurate as required. Hence, it is necessary to seek more representative predictive molecules and potential target molecules for immune checkpoint therapy. Fibrinogen-like protein 1 (FGL1) is a proliferation- and metabolism-related protein secreted by the liver. Multiple studies have confirmed that FGL1 is a newly emerging checkpoint ligand of lymphocyte activation gene 3 (LAG3), emphasizing the potential of targeting FGL1/LAG3 as the next generation of immune checkpoint therapy. In this review, we summarize the substantial regulation mechanisms of FGL1 in physiological and pathological conditions, especially tumor epithelial to mesenchymal transition, immune escape and immune checkpoint blockade resistance, to provide insights for targeting FGL1 in cancer treatment.

Soluble fibrinogen­like protein 2 levels are decreased in patients with ischemic heart failure and associated with cardiac function.

Soluble fibrinogen­like protein 2 (sFGL2), as a novel effector of regulatory T cells (Tregs), exhibits immune regulatory activity in several inflammatory diseases. Immune activation and persistent inflammation participate in the progression of ischemic heart failure (IHF). The present study aimed to determine serum sFGL2 levels in patients with IHF and explore the relationship between sFGL2 levels and cardiac function. A total of 104 patients with IHF and 32 healthy controls were enrolled. patients with IHF were further split into subgroups according to the New York Heart Association functional classification or left ventricular ejection fraction (LVEF). Serum sFGL2 levels and peripheral Tregs frequencies were analyzed by ELISA and flow cytometry, respectively. The suppressive function of Tregs was measured by proliferation and functional suppression assays. Serum levels of sFGL2 and circulating Tregs frequencies were significantly decreased in patients with IHF compared with healthy controls. In patients with IHF, sFGL2 levels and Tregs frequencies were decreased with the deterioration of cardiac function. Tregs from patients with IHF exhibited compromised ability to suppress CD4+CD25­ T cells proliferation and inflammatory cytokines secretion. Specifically, sFGL2 levels and Tregs frequencies positively correlated with LVEF, whereas negatively correlated with left ventricular end­diastolic dimension and N­terminal pro­brain natriuretic peptide. sFGL2 levels were positively correlated with Tregs frequencies. In conclusion, the reduction of serum sFGL2 levels are associated with the progression of IHF and sFGL2 could be used as a potential indicator for predicting disease severity.

Biochemical and structural characterization of a recombinant fibrinogen-related lectin from Penaeus monodon.

Fibrinogen-related lectins are carbohydrate-binding proteins of the innate immune system that recognize glycan structures on microbial surfaces. These innate immune lectins are crucial for invertebrates as they do not rely on adaptive immunity for pathogen clearance. Here, we characterize a recombinant fibrinogen-related lectin PmFREP from the black tiger shrimp Penaeus monodon expressed in the Trichoplusia ni insect cell. Electron microscopy and cross-linking experiments revealed that PmFREP is a disulfide-linked dimer of pentamers distinct from other fibrinogen-related lectins. The full-length protein binds N-acetyl sugars in a Ca2+ ion-independent manner. PmFREP recognized and agglutinated Pseudomonas aeruginosa. Weak binding was detected with other bacteria, including Vibrio parahaemolyticus, but no agglutination activity was observed. The biologically active PmFREP will not only be a crucial tool to elucidate the innate immune signaling in P. monodon and other economically important species, but will also aid in detection and prevention of shrimp bacterial infectious diseases.

Development of a nanobody-based immunoassay for the sensitive detection of fibrinogen-like protein 1.

Immune checkpoint inhibition is an important strategy in cancer therapy. Blockade of CTLA-4 and PD-1/PD-L1 is well developed in clinical practice. In the last few years, LAG-3 has received much interest as an emerging novel target in immunotherapy. It was recently reported that FGL1 is a major ligand of LAG-3, which is normally secreted by the liver but is upregulated in several human cancers. FGL1 is a crucial biomarker and target for cancer immunotherapy. As the efficacy of immunotherapy is limited to specific types of patients, the subset of patients needs to be selected appropriately to receive precise treatment according to different biomarkers. To date, there is no test to accurately assess FGL1 expression levels. Nanobodies have some outstanding features, such as high stability, solubility and affinity for diagnostic and therapeutic applications. Here, we report the development and validation of a rapid, sensitive, and cost-effective nanobody-based immunoassay for the detection of FGL1 in human serum. In this study, human FGL1 recombinant protein was expressed and purified for the first time as an immunized antigen. Then, we constructed a nanobody phage display library and screened several nanobodies that bind FGL1 with high affinity. We selected two nanobodies targeting different epitopes of FGL1, one as a capture and the other conjugated with HRP as a probe. The double nanobody-based sandwich ELISA to detect the concentration of FGL1 showed a good response relationship in the range of 15.625-2000 ng/mL, and the recoveries from the spiked sample were in the range of 78% and 100%. This assay could be used as a potential approach for evaluating FGL1 expression for patient stratification and for predicting the therapeutic efficacy of targeting the LAG3/FGL1 axis.

Methylglyoxal mediated glycation leads to neo-epitopes generation in fibrinogen: Role in the induction of adaptive immune response.

In diabetes mellitus, hyperglycemia mediated non-enzymatic glycosylation of proteins results in the pathogenesis of diabetes-associated secondary complications via the generation of advanced glycation end products (AGEs). The focus of this study is to reveal the immunological aspects of methylglyoxal (MG) mediated glycation of fibrinogen protein. The induced immunogenicity of modified fibrinogen is analyzed by direct binding and inhibition ELISA. Direct binding ELISA confirmed that MG glycated fibrinogen (MG-Fib) is highly immunogenic and induces a high titer of antibodies in comparison to its native analog. Cross-reactivity and antigen-binding specificity of induced antibodies were confirmed by inhibition ELISA. The enhanced affinity of immunoglobulin G (IgG) from immunized rabbits' sera and MG glycated fibrinogen is probably the aftermath of neo-epitopes generation in the native structure of protein upon modification. Thus, we deduce that under the glycative stress, MG-mediated structural alterations in fibrinogen could induce the generation of antibodies which might serve as a potential biomarker in diabetes mellitus and its associated secondary disorders.

Transfusion management for children supported by extracorporeal membrane oxygenation.

Due to the patients' underlying illness, in combination with circuit-induced coagulopathy, as well as PLT dysfunction, children supported by ECMO are a risk of receiving large volumes of blood components. Given the increasing use of modified blood products and newer biologics, it is unknown whether these products have equal efficacy and safety, in ECMO. The majority of guidance for transfusion therapy is based on expert opinion alone, and research on indications for RBC, plasma, and PLT transfusions for children on ECMO should be a priority.

Immune Checkpoint LAG3 and Its Ligand FGL1 in Cancer.

LAG3 is the most promising immune checkpoint next to PD-1 and CTLA-4. High LAG3 and FGL1 expression boosts tumor growth by inhibiting the immune microenvironment. This review comprises four sections presenting the structure/expression, interaction, biological effects, and clinical application of LAG3/FGL1. D1 and D2 of LAG3 and FD of FGL1 are the LAG3-FGL1 interaction domains. LAG3 accumulates on the surface of lymphocytes in various tumors, but is also found in the cytoplasm in non-small cell lung cancer (NSCLC) cells. FGL1 is found in the cytoplasm in NSCLC cells and on the surface of breast cancer cells. The LAG3-FGL1 interaction mechanism remains unclear, and the intracellular signals require elucidation. LAG3/FGL1 activity is associated with immune cell infiltration, proliferation, and secretion. Cytokine production is enhanced when LAG3/FGL1 are co-expressed with PD-1. IMP321 and relatlimab are promising monoclonal antibodies targeting LAG3 in melanoma. The clinical use of anti-FGL1 antibodies has not been reported. Finally, high FGL1 and LAG3 expression induces EGFR-TKI and gefitinib resistance, and anti-PD-1 therapy resistance, respectively. We present a comprehensive overview of the role of LAG3/FGL1 in cancer, suggesting novel anti-tumor therapy strategies.

Risk analysis of transfusion of cryoprecipitate without consideration of ABO group.

BACKGROUND: Transfusion medicine standards in Canada state that adult recipients can be transfused with cryoprecipitate of any ABO group, however, not all hospitals follow this guideline. There is a paucity of data on cryoprecipitate anti-A/B levels to reinforce standards. STUDY DESIGN AND METHODS: Manual tube antibody titration was performed on 7 units of group O plasma and the corresponding cryosupernatant plasma and cryoprecipitate. IgG/IgM levels were determined by nephelometry. Additionally, 10 cryoprecipitate each from groups A, B, and O were similarly assessed. From the antibody titer distribution among these samples, the probability of making a pool of cryoprecipitate with a titer ≥1:100 was calculated using bootstrap analysis. RESULTS: Anti-A/B titers in cryoprecipitate were equivalent to those in corresponding plasma; partitioning of anti-A/B activity into cryoprecipitate was not observed. Average IgM concentration was higher in cryoprecipitate than in plasma (P < .01). However, no correlation between IgM levels and anti-A/B titers was established. Among 30 cryoprecipitates from routine blood bank inventory, the median antibody titer and mode were 1:32 and 1:16, respectively. Of the samples tested, 4 of 30 and 9 of 30 had titers above 1:100 and 1:50, respectively. The probability of transfusing an adult dose of cryoprecipitate (pool of 10 cryoprecipitate) with a titer higher than 1:100 was calculated to be less than 1 in 3 million. CONCLUSIONS: This study provides strong evidence to support current Canadian transfusion medicine standards on the safety of transfusion of cryoprecipitate without the need for blood group matching in adult recipients.

Do RA associated HLA-DR molecules bind citrullinated peptides or peptides from PAD4 to help the development of RA specific antibodies to citrullinated proteins?

PURPOSE: Rheumatoid arthritis (RA) is associated with HLA-DRB1 genes encoding a five amino acid basic motive, the shared epitope SE). Each HLA-DRB1 genotype defines a genotype specific risk of developing RA. RA is preceded by the emergence of anti citrullinated protein antibodies (ACPAs). Citrullin is a neutral version of arginin, a basic amino acid, formed after post translational modification by Peptidyl Arginyl Deiminases (PADs). HLA-DRB1 genes associated with RA are also associated with ACPAs. Two models might explain this association. Here we tested both models for prediction of HLA-DRB1 genotypic risks of developing RA. METHODS: We calculated the likelihoods for the 2 HLA-DR molecules encoded by 12 common HLA-DRB1 genotypes to bind at least one randomly chosen peptide from PAD4 or fibrinogen(native or citrullinatd) and compared them with the 12 respective HLA-DRB1genotypic risks of developing RA. RESULTS: HLA-DRB1 Genotypic risks of developing RA correlate with likelihoods of binding PAD4 peptides, not citrullinated Fibrinogen peptides. Thus, the molecular basis for the association of HLA-DR and ACPA positive RA is most likely the capability for RA associated HLA-DR molecules to bind peptides(s) from PAD4.

In vitro elimination of autoreactive B cells from rheumatoid arthritis patients by universal chimeric antigen receptor T cells.

OBJECTIVES: Autoreactive B cells play a crucial role in the pathogenesis of rheumatoid arthritis (RA), and B cell-depleting therapies using an antibodies, such as rituximab, have been suggested to be effective in RA treatment. However, transient B cell depletion with rituximab is associated with significant safety challenges related to global suppression of the immune system and thus increases the risks of infection and cancer development. To address selective and persistent issues associated with RA therapy, we developed a customised therapeutic strategy employing universal antifluorescein isothiocyanate (FITC) chimeric antigen receptor T cells (CAR-T cells) combined with FITC-labelled antigenic peptide epitopes to eliminate autoreactive B cell subsets recognising these antigens in RA. METHODS: For a proof-of-concept study, four citrullinated peptide epitopes derived from citrullinated autoantigens, namely, citrullinated vimentin, citrullinated type II collagen, citrullinated fibrinogen and tenascin-C, and a cyclocitrulline peptide-1 were selected as ligands for targeting autoreactive B cells; Engineered T cells expressing a fixed anti-FITC CAR were constructed and applied as a universal CAR-T cell system to specifically eliminate these protein-specific autoreactive B cells via recognition of the aforementioned FITC-labelled autoantigenic peptide epitopes. RESULTS: We demonstrated that anti-FITC CAR-T cells could be specifically redirected and kill hybridoma cells generated by immunisation with antigenic peptides, and autoreactive B cell subsets from RA patients via recognition of corresponding FITC-labelled citrullinated peptide epitopes. Additionally, the cytotoxicity of the CAR-T cells was dependent on the presence of the peptides and occurred in a dose-dependent manner. CONCLUSIONS: The approach described here provides a direction for precise, customised approaches to treat RA and can likely be applied to other systemic autoimmune diseases.

T Follicular Regulatory Cell-Derived Fibrinogen-like Protein 2 Regulates Production of Autoantibodies and Induction of Systemic Autoimmunity.

T follicular regulatory (TFR) cells limit Ab responses, but the underlying mechanisms remain largely unknown. In this study, we identify Fgl2 as a soluble TFR cell effector molecule through single-cell gene expression profiling. Highly expressed by TFR cells, Fgl2 directly binds to B cells, especially light-zone germinal center B cells, as well as to T follicular helper (TFH) cells, and directly regulates B cells and TFH in a context-dependent and type 2 Ab isotype-specific manner. In TFH cells, Fgl2 induces the expression of Prdm1 and a panel of checkpoint molecules, including PD1, TIM3, LAG3, and TIGIT, resulting in TFH cell dysfunction. Mice deficient in Fgl2 had dysregulated Ab responses at steady-state and upon immunization. In addition, loss of Fgl2 results in expansion of autoreactive B cells upon immunization. Consistent with this observation, aged Fgl2-/- mice spontaneously developed autoimmunity associated with elevated autoantibodies. Thus, Fgl2 is a TFR cell effector molecule that regulates humoral immunity and limits systemic autoimmunity.

Genomic and transcriptional analysis of genes containing fibrinogen and IgSF domains in the schistosome vector Biomphalaria glabrata, with emphasis on the differential responses of snails susceptible or resistant to Schistosoma mansoni.

Achieving a deeper understanding of the factors controlling the defense responses of invertebrate vectors to the human-infecting pathogens they transmit will provide needed new leads to pursue for control. Consequently, we provide new genomic and transcriptomic insights regarding FReDs (containing a fibrinogen domain) and FREPs (fibrinogen domain and one or two IgSF domains) from the planorbid snail Biomphalaria glabrata, a Neotropical vector of Schistosoma mansoni, causative agent of human intestinal schistosomiasis. Using new bioinformatics approaches to improve annotation applied to both genome and RNA-Seq data, we identify 73 FReD genes, 39 of which are FREPs. We provide details of domain structure and consider relationships and homologies of B. glabrata FBG and IgSF domains. We note that schistosome-resistant (BS-90) snails mount complex FREP responses following exposure to S. mansoni infection whereas schistosome-susceptible (M line) snails do not. We also identify several coding differences between BS-90 and M line snails in three FREPs (2, 3.1 and 3.2) repeatedly implicated in other studies of anti-schistosome responses. In combination with other results, our study provides a strong impetus to pursue particular FREPs (2, 3.1, 3.2 and 4) as candidate resistance factors to be considered more broadly with respect to schistosome control efforts, including involving other Biomphalaria species vectoring S. mansoni in endemic areas in Africa.

Congenital dysfibrinogenaemia presented with preterm premature rupture of the membranes and vaginal bleeding.

A 26-year-old woman was found to have congenital dysfibrinogenaemia after presenting to our hospital with premature rupture of the membranes and vaginal bleeding. Given the absence of clear guidelines for the management of pregnancy complicated by dysfibrinogenaemia, we followed expert consensus that exists among published works, with some modifications. This case was managed by a multidisciplinary team of obstetrics-gynaecology, haematology and paediatric haematology. Here we review how the patient presented, the investigations that led to the diagnosis and the treatment options.

Identification of integrative molecular and clinical profiles of Fibrinogen-like protein 2 in gliomas using 1323 samples.

BACKGROUND: Fibrinogen-like protein 2 (FGL2), a member of the fibrinogen superfamily, has been described to augment immunosuppression in gliomas. However, the precise clinical molecular features and the prognostic relevance of FGL2 in gliomas remain unclear. Therefore, a comprehensive analysis of the role of FGL2 in gliomas would provide insights into the therapeutic implications for this disease. METHODS: Totally, 1323 glioma samples with RNA-seq and microarray data from TCGA and CGGA databases were used to clarify the clinical significance and molecular profile of FGL2 in glioma. The findings were further validated through immunohistochemistry (IHC). RESULTS: The transcriptional level of FGL2 was positively associated with tumor grade in gliomas, which was confirmed at the protein level through IHC staining. Consistently, FGL2 was significantly enriched in isocitrate dehydrogenase wild-type tumors and the mesenchymal subtype of gliomas. We also demonstrated FGL2 expression correlated with high immune scores and infiltration of immune cell populations, including T cells, macrophages and B cells. Pearson's correlation analysis revealed that FGL2-related genes correlated with inflammatory-immune responses, particularly T cell-mediated immune response. Additionally, FGL2 expression was found tightly associated with immune checkpoints PD-L1 and PD-L2. Clinically, patients with high FGL2 expression exhibited unfavorable overall survival. CONCLUSION: Our results provide the integrative molecular and clinical profiles of FGL2 in gliomas and emphasize the importance of prospective studies on the FGL2-related immune-inflammatory network.

Fungal recognition by mammalian fibrinogen-related proteins.

Fungi are ubiquitous eukaryotic micro-organisms present in virtually all environmental habitats. Although rarely pathogenic to the healthy population, many fungal species are capable of causing human disease in immunocompromised individuals. Thus, fungal infections remain a significant cause of morbidity and mortality, with rising prevalence accompanying the worldwide increase in immunosuppression-based therapies. Therefore, better understanding of the mutual interactions between the protective host mechanisms and the invading fungi remains of critical importance. The innate immune system constitutes the first line of defence against exogenous insults. The innate antifungal immunity is mediated through recognition of specific pathogen-associated molecular patterns (PAMPs) by a broad panel of host pattern recognition receptors (PRRs), responsible for mounting adequate protective responses. In this review, we describe fungal PAMPs as well as a selection of PRRs able to recognize them. We focus on the members of the fibrinogen-related domain (FReD) protein family that have been shown to recognize fungi-derived molecules: ficolins, fibrinogen C domain containing 1 (FIBCD1) and tenascin-C. We describe their structure, their binding targets and their established as well as putative biological functions related to fungal recognition and immunity.

Autoantibodies against a novel citrullinated fibrinogen peptide related to smoking status, disease activity and therapeutic response to methotrexate in cuban patients with early rheumatoid arthritis.

Treatment recommendations of early rheumatoid arthritis (RA) suggest differential management of patients on the basis of prognostic factors. In this study we aimed to investigate the relationship between autoantibodies against a novel citrullinated fibrinogen peptide (anti-CFP), smoking status, clinical activity and therapeutic response in Cuban patients with early RA, receiving treatment with methotrexate in comparison to rheumatoid factor (RF), anti-cyclic citrullinated peptide of second generation (anti-CCP2) and anti-mutated citrullinated vimentin (anti-MCV). A 6-month prospective observational study was performed in 60 early RA patients at baseline and 6 months after receiving methotrexate. Baseline and outcome measures included disease activity score of 28 joints (DAS 28), simplified disease activity index (SDAI), anti-CFP antibodies, RF, anti-CCP2 and anti-MCV. Therapeutic response was determined using 20/50/70 American College of Rheumatology (ACR) response rates. DAS28 (p < 0.0001), SDAI (p < 0.0001) as well as titres of anti-CFP (p = 0.0481), anti-CCP2 (p = 0.0082), RF IgM (p = 0.0187) and RF IgA (p = 0.0252) decreased under therapy. Multivariate analyses showed association of final anti-CFP values with sex and smoking status (p = 0.0296). It is of note that anti-CFP antibodies were one of predictors for DAS 28 (p = 0.0072) SDAI (p < 0.0001) and ACR response (p = 0.0003) in multivariate models. Anti-CFP antibodies decrease in correspondence with clinical improvement after 6-month therapy and are associated with sex and smoking status. Moreover, baseline anti-CFP antibodies, using in combination with sex, smoking status and autoantibodies (anti-CCP2, anti-MCV or RF) seems to have clinical relevance for predicting clinical activity and therapeutic response.

The Diagnostic Value of Antibodies Against Citrullinated or Carbamylated Fibrinogen in Rheumatoid Arthritis.

BACKGROUND: This study aimed to evaluate the overall diagnostic value of citrullinated or carbamylated fibrinogen antibodies in patients with rheumatoid arthritis (RA). METHODS: Serum samples collected from 114 patients with established RA, 143 patients with non-RA diseases, and 200 healthy controls were tested by ELISA for citrullinated fibrinogen (Cit-fib), carbamylated fibrinogen (Ca-fib), and chimeric fibrinogen a/b chain citrullinated peptides (CFABCP). Diagnostic indexes and correlations with titers were calculated, cross reactivities of Cit-fib, Ca-fib, and CFABCP were assessed by competition experiments. RESULTS: With a cutoff ensuring 98% specificity for RA patients versus healthy controls, the sensitivities of Cit-fib and Ca-fib are 66.67% and 24.6%, respectively, while the sensitivity of CFABCP was 74.56%. Cit-fib, Ca-fib, and CFABCP can inhibit reciprocally in competition experiments. As for non-RA patients, the positive rate of Ca-fib was higher than that of Cit-fib and CFABCP. CONCLUSIONS: Citrullination and carbamylation of fibrinogen both have a role in RA diagnosing, but citrullination is better. The recombination of peptides, CFABCP, has high specificity and considerable sensitivity for diagnosis for RA patients.

The differential role of CR3 (CD11b/CD18) and CR4 (CD11c/CD18) in the adherence, migration and podosome formation of human macrophages and dendritic cells under inflammatory conditions.

CR3 and CR4, the leukocyte specific ß2-integrins, involved in cellular adherence, migration and phagocytosis, are often assumed to have similar functions. Previously however, we proved that under physiological conditions CR4 is dominant in the adhesion to fibrinogen of human monocyte-derived macrophages (MDMs) and dendritic cells (MDDCs). Here, using inflammatory conditions, we provide further evidence that the expression and function of CR3 and CR4 are not identical in these cell types. We found that LPS treatment changes their expression differently on MDMs and MDDCs, suggesting a cell type specific regulation. Using mAb24, specific for the high affinity conformation of CD18, we proved that the activation and recycling of ß2-integrins is significantly enhanced upon LPS treatment. Adherence to fibrinogen was assessed by two fundamentally different approaches: a classical adhesion assay and a computer-controlled micropipette, capable of measuring adhesion strength. While both receptors participated in adhesion, we demonstrated that CR4 exerts a dominant role in the strong attachment of MDDCs. Studying the formation of podosomes we found that MDMs retain podosome formation after LPS activation, whereas MDDCs lose this ability, resulting in a significantly reduced adhesion force and an altered cellular distribution of CR3 and CR4. Our results suggest that inflammatory conditions reshape differentially the expression and role of CR3 and CR4 in macrophages and dendritic cells.