Fibrinogen as a damage-associated mitogenic signal for the renal fibroblast

Differential Expression of Fibrinogen Alpha and Its Potential Involvement in Osteoarthritis Pathogenesis

The deterioration of cartilage tissue and other joint components composed of synovial tissue is a defining characteristic of osteoarthritis (OA) disease. Because of the lack of understanding of the underlying cause and important molecular pathways, there are currently no effective diagnostic or treatment methods for OA. The purpose of the study is to find a specific protein biomarker with high sensitivity and specificity in order to understand the pathophysiology of the disease and the underlying molecular pathways. We examined plasma samples of matched age and sex from OA patients (n = 150) and healthy controls (HC) (n = 70) to find proteins that were differentially expressed and validated by western blotting, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and immunofluorescence. The results of western blotting demonstrated that the expression level of the fibrinogen alpha (FGA) protein was higher in plasma samples of osteoarthritis (OAPL) (p = 0.0343), and the ROC (receiver operating characteristic curve) curve supported the high sensitivity (95.22%) and specificity (74%) of FGA in OA plasma compared to healthy controls. FGA protein was detected to be deposited in the synovial tissue of OA patients (p = 0.0073). By activating the Toll-like receptor (TLR-4) receptor pathway in PBMCs (p = 0.04) and synovial tissue, FGA protein may be involved in the molecular mechanism of OA pathogenesis. Our findings collectively suggested that FGA, which is significantly expressed in OA plasma, synovial tissue, and PBMCs and is connected to the disease's advancement through the TLR-4 receptor, may serve as a diagnostic or disease-evolving tool for OA.

The Role of Epithelial Damage in the Pulmonary Immune Response

Pulmonary epithelial cells are widely considered to be the first line of defence in the lung and are responsible for coordinating the innate immune response to injury and subsequent repair. Consequently, epithelial cells communicate with multiple cell types including immune cells and fibroblasts to promote acute inflammation and normal wound healing in response to damage. However, aberrant epithelial cell death and damage are hallmarks of pulmonary disease, with necrotic cell death and cellular senescence contributing to disease pathogenesis in numerous respiratory diseases such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and coronavirus disease (COVID)-19. In this review, we summarise the literature that demonstrates that epithelial damage plays a pivotal role in the dysregulation of the immune response leading to tissue destruction and abnormal remodelling in several chronic diseases. Specifically, we highlight the role of epithelial-derived damage-associated molecular patterns (DAMPs) and senescence in shaping the immune response and assess their contribution to inflammatory and fibrotic signalling pathways in the lung.

Predictive value of combining the level of fibrinogen and antithrombin III for contrast-induced nephropathy in coronary artery disease patients undergoing percutaneous coronary intervention

Contrast-induced nephropathy (CIN) is a common adverse event in the diagnosis and treatment of coronary intervention. The current study investigated the predictive effect of preoperative fibrinogen (FIB) combined with antithrombin III (AT-III) on CIN following percutaneous coronary intervention (PCI). A total of 394 patients who underwent PCI between October 2018 and May 2019 were selected for the present study. Pre-procedural FIB levels and AT-III activity were measured before PCI. CIN was defined as a 0.5 mg/dl or 25% increase in serum creatinine levels 48 to 72 h after exposure to a radiocontrast agent. Patients were classified into CIN and non-CIN groups. CIN occurred in 48 (12.2%) patients. The serum FIB levels were significantly higher in patients who developed CIN compared with those who did not develop CIN. In addition, AT-III levels ≤89.5% were associated with higher rates of CIN. Logistical regression analysis showed that high FIB, and low AT-III and albumin levels were high-risk factors associated with CIN. For FIB, the area under the receiver operating characteristic curve (AUC) for predicting CIN was 0.653. The optimal cut-off value was 3.48 g/l with a sensitivity of 45.8% and a specificity of 79.7% [95% confidence interval (CI): 0.603-0.701; P=0.0002)]. For AT-III, the AUC was 0.711, and the optimal cut-off value was 89.5%, with a sensitivity of 81.3% and specificity of 58.2% (95% CI: 0.659-0.758; P<0.0001). When combining FIB and AT-III, the AUC was 0.747. The optimal cut-off value was 0.090424, with a diagnostic sensitivity of 93.8% and specificity of 46.6% (95% CI: 0.697-0.792; P<0.0001). The results showed that FIB combined with AT-III resulted in improved predictive accuracy of CIN (FIB vs. AT-III, AUC=0.653 vs. 0.711, P=0.292; FIB vs. FIB + AT-III, AUC=0.653 vs. 0.747, P=0.012; AT-III vs. FIB + AT-III, AUC=0.711 vs. 0.747, P=0.138). Pre-procedural levels of FIB, AT-III and albumin were independently associated with an increased risk of CIN. Furthermore, the results suggested that the combination of FIB and AT-III was a better predictor of CIN after PCI.

Proteomic Evidence of Biological Aging in a Child with a Compound Heterozygous ZMPSTE24 Mutation

BACKGROUND

Progeria-like syndromes offer a unique insight into aging. Here the case of a boy affected with mandibuloacral dysplasia and compound heterozygous mutations in ZMPSTE24 is presented.

METHODS

Capillary electrophoresis-mass spectroscopy is used for proteome analysis to analyze peptides previously found to be differentially regulated in chronic kidney disease (273 peptides defining the CKD273 classifier), coronary artery disease (238 peptides defining the CAD238 classifier), and aging (116 peptides defining the AGE116 classifier).

RESULTS

No evidence of renal disease is identified. Although the boy has no overt cardiovascular disease other than a raised carotid intima media thickness relative to his age, a proteomic classifier for the diagnosis of coronary artery disease is mildly raised. The biological age based on the proteomic AGE116 classifier is 24 years compared to the chronological ages of 5 and 10 years. In contrast, a control group of healthy children has a significantly lower (p < 0.0001) calculated mean age of 13.

CONCLUSION

Urinary proteomic analysis is effective in confirming advanced biological age and to identify early evidence of renal or cardiovascular damage. This case highlights the value of proteomic approaches in aging research and may represent a method for non-invasive monitoring of the effects of early aging.

Role of Elevated Fibrinogen in Burn-Induced Mitochondrial Dysfunction: Protective Effects of Glycyrrhizin

INTRODUCTION

Skeletal muscle wasting and weakness with mitochondrial dysfunction (MD) are major pathological problems in burn injury (BI) patients. Fibrinogen levels elevated in plasma is an accepted risk factor for poor prognosis in many human diseases, and is also designated one of damage-associated molecular pattern (DAMPs) proteins. The roles of upregulated fibrinogen on muscle changes of critical illness including BI are unknown. The hypothesis tested was that BI-upregulated fibrinogen plays a pivotal role in the inflammatory responses and MD in muscles, and that DAMPs inhibitor, glycyrrhizin mitigates the muscle changes.

METHODS

After third degree BI to mice, fibrinogen levels in the plasma and at skeletal muscles were compared between BI and sham-burn (SB) mice. Fibrinogen effects on inflammatory responses and mitochondrial membrane potential (MMP) loss were analyzed in C2C12 myotubes. In addition to survival, the anti-inflammatory and mitochondrial protective effects of glycyrrhizin were tested using in vivo microscopy of skeletal muscles of BI and SB mice.

RESULTS

Fibrinogen in plasma and its extravasation to muscles significantly increased in BI versus SB mice. Fibrinogen applied to myotubes evoked inflammatory responses (increased MCP-1 and TNF-α; 32.6 and 3.9-fold, respectively) and reduced MMP; these changes were ameliorated by glycyrrhizin treatment. In vivo MMP loss and superoxide production in skeletal muscles of BI mice were significantly attenuated by glycyrrhizin treatment, together with improvement of BI survival rate.

CONCLUSIONS

Inflammatory responses and MMP loss in myotubes induced by fibrinogen were reversed by glycyrrhizin. Anti-inflammatory and mitochondrial protective effect of glycyrrhizin in vivo leads to amelioration of muscle MD and improvement of BI survival rate.

Identification of ageing-associated naturally occurring peptides in human urine

To assess normal and pathological peptidomic changes that may lead to an improved understanding of molecular mechanisms underlying ageing, urinarypeptidomes of 1227 healthy and 10333 diseased individuals between 20 and 86 years of age were investigated. The diseases thereby comprised diabetes mellitus, renal and cardiovascular diseases. Using age as a continuous variable, 116 peptides were identified that significantly (p < 0.05; |ρ|≥0.2) correlated with age in the healthy cohort. The same approach was applied to the diseased cohort. Upon comparison of the peptide patterns of the two cohorts 112 common age-correlated peptides were identified. These 112 peptides predominantly originated from collagen, uromodulin and fibrinogen. While most fibrillar and basement membrane collagen fragments showed a decreased age-related excretion, uromodulin, beta-2-microglobulin and fibrinogen fragments showed an increase. Peptide-based in silico protease analysis was performed and 32 proteases, including matrix metalloproteinases and cathepsins, were predicted to be involved in ageing. Identified peptides, predicted proteases and patient information were combined in a systems biology pathway analysis to identify molecular pathways associated with normal and/or pathological ageing. While perturbations in collagen homeostasis, trafficking of toll-like receptors and endosomal pathways were commonly identified, degradation of insulin-like growth factor-binding proteins was uniquely identified in pathological ageing.

Effects of Biejia Ruangan Tablet-containing serum on matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 expression in cultured renal interstitial fibroblasts

OBJECTIVE

To investigate the effects of Biejia Ruangan Tablet ([symbol in text], BRT)-containing serum on the expression of matrix metalloproteinase (MMP-9) and tissue inhibitor of metalloproteinase (TIMP-1) in cultured renal interstitial fibroblasts.

METHODS

Different BRT-containing sera were prepared by gastric gavages to rats with the high-dose (7 g/kg), mid-dose (3.5 g/kg), and low-dose (1.75 g/kg) BRT respectively. The expression of extracellular matrix in NRK-49F cells was induced by treatment with human transforming growth factor-β1 (recombined human TGF-β1), and BRT-containing serum. Western blotting and Northern blotting were used to measure type I and III procollagen, MMP-9, and TIMP-1.

RESULTS

The high dose BRT-containing serum could decrease the type I and III procollagen gene expression which boosted by TGF-β1, at the same time cut down TIMP-1 protein and gene expression which increased by TGF-β1 (P <0.05). Treatment of cells with recombined human TGF-β1 had no significant effect on MMP-9 expression and BRT-containing serum also had no effect on MMP-9 expression.

CONCLUSIONS

High dose BRT has anti-fibrosis effects in NRK-49F cells, as indicated by its inhibition of type I and III procollagen and TIMP-1 expression.

Pharmacological and genetic depletion of fibrinogen protects from kidney fibrosis

Fibrinogen (Fg) has been implicated in the pathogenesis of several fibrotic disorders by acting as a profibrotic ligand for a variety of cellular surface receptors and by modulating the provisional fibrin matrix formed after injury. We demonstrated increased renal Fg expression after unilateral ureteral obstruction and folic acid (FA) nephropathy in mice, respectively. Urinary Fg excretion was also increased in FA nephropathy. Using in vitro and in vivo approaches, our results suggested that IL-6 mediates STAT3 activation in kidney fibrosis and that phosphorylated (p)STAT3 binds to Fgα, Fgβ, and Fgγ promoters in the kidney to regulate their transcription. Genetically modified Fg heterozygous mice (∼75% of normal plasma Fg levels) exhibited only 3% kidney interstitial fibrosis and tubular atrophy after FA nephropathy compared with 24% for wild-type mice. Fibrinogenolysis through Ancrod administration after FA reduced interstitial fibrosis more than threefold compared with vehicle-treated control mice. Mechanistically, we show that Fg acts synergistically with transforming growth factor (TGF)-β1 to induce fibroblast proliferation and activates TGF-β1/pSMAD2 signaling. This study offers increased understanding of Fg expression and molecular interactions with TGF-β1 in the progression to kidney fibrosis and, importantly, indicates that fibrinogenolytics like Ancrod present a treatment opportunity for a yet intractable disease.

Danger signals - damaged-self recognition across the tree of life

Multicellular organisms suffer injury and serve as hosts for microorganisms. Therefore, they require mechanisms to detect injury and to distinguish the self from the non-self and the harmless non-self (microbial mutualists and commensals) from the detrimental non-self (pathogens). Danger signals are "damage-associated molecular patterns" (DAMPs) that are released from the disrupted host tissue or exposed on stressed cells. Seemingly ubiquitous DAMPs are extracellular ATP or extracellular DNA, fragmented cell walls or extracellular matrices, and many other types of delocalized molecules and fragments of macromolecules that are released when pre-existing precursors come into contact with enzymes from which they are separated in the intact cell. Any kind of these DAMPs enable damaged-self recognition, inform the host on tissue disruption, initiate processes aimed at restoring homeostasis, such as sealing the wound, and prepare the adjacent tissues for the perception of invaders. In mammals, antigen-processing and -presenting cells such as dendritic cells mature to immunostimulatory cells after the perception of DAMPs, prime naïve T-cells and elicit a specific adaptive T-/B-cell immune response. We discuss molecules that serve as DAMPs in multiple organisms and their perception by pattern recognition receptors (PRRs). Ca(2+)-fluxes, membrane depolarization, the liberation of reactive oxygen species and mitogen-activated protein kinase (MAPK) signaling cascades are the ubiquitous molecular mechanisms that act downstream of the PRRs in organisms across the tree of life. Damaged-self recognition contains both homologous and analogous elements and is likely to have evolved in all eukaryotic kingdoms, because all organisms found the same solutions for the same problem: damage must be recognized without depending on enemy-derived molecules and responses to the non-self must be directed specifically against detrimental invaders.

Damaged-self recognition as a general strategy for injury detection

Plants perceive endogenous molecules or their fragments as signals of danger when these appear at increased concentrations in the extracellular space, and they respond with increased endogenous levels of jasmonic acid. The wound hormone jasmonic acid represents a central player in the induced resistance of plants to herbivore feeding and infection by necrotrophic pathogens. This 'damaged self recognition' mechanism of plants exhibits astonishing similarities to the perception of 'damage-associated molecular patterns' (DAMPs) by the human immune system: endogenous cell constituents, or their fragments, that can be released into the extracellular milieu during states of cellular stress or damage function as 'stress signals' and trigger inflammatory and other immunity-related responses. Multicellular organisms use endogenous molecules as danger signals to mount adequate healing and resistance-related responses without depending on exogenous signals and to place exogenous, enemy-derived molecular signals into the adequate functional context.