C-Reactive Protein Protects Against Acetaminophen-Induced Liver Injury by Preventing Complement Overactivation

Protective effects of albiflorin on acetaminophen-induced hepatotoxicity: Regulation of blood-biliary barrier integrity by ATF3

BACKGROUND

Acetaminophen-induced hepatotoxicity remains a clinical challenge with limited targeted therapeutic options. While recent advances have identified blood‒biliary barrier disruption as a critical pathogenic mechanism, effective interventions preserving this barrier are notably lacking. Albiflorin, a key bioactive constituent of Paeonia lactiflora Pall., exhibits unique bile acid modulation along with antioxidant and anti-inflammatory activities, suggesting its potential efficacy in preventing acetaminophen-induced liver injury. However, its specific role and underlying mechanisms in alleviating acetaminophen-induced hepatotoxicity remain unclear.

OBJECTIVE

This study's objective was to examine the pharmacological effects and primary molecular mechanisms of albiflorin in alleviating acetaminophen-induced liver injury.

METHODS

An acetaminophen-induced liver injury mouse model was created using a 300 mg/kg dose of acetaminophen. The hepatoprotective effects of albiflorin were assessed through histological and biochemical analyses. Blood‒biliary barrier integrity was evaluated via Evans blue dye tests, immunofluorescence, and bile acid assays. Transcriptomic analysis, gene overexpression and interference techniques, and ChIP‒qPCR were employed to explore the molecular mechanisms underlying the protective effects of albiflorin.

RESULTS

Albiflorin significantly reduced acetaminophen-induced liver injury, as evidenced by improved biochemical profiles and hepatocyte morphology. It also prevented increases in blood‒biliary barrier permeability and bile acid levels. RNA sequencing identified 3,184 differentially expressed genes, revealing critical pathways involved in maintaining blood‒biliary barrier integrity. AF reversed the acetaminophen-induced changes in the expression of genes related to the blood‒biliary barrier, particularly occludin, claudin 5, ABCG5, and ABCG8. Albiflorin protected the blood‒biliary barrier and mitigated acetaminophen-induced liver injury by enhancing ATF3 protein stability, with ATF3 identified as a critical mediator of these protective effects.

CONCLUSION

This study provides pioneering evidence that albiflorin protects against acetaminophen-induced liver injury by interacting with ATF3 to regulate blood-biliary barrier proteins and maintain the integrity of the blood-biliary barrier. These findings deepen our understanding of the role of the blood‒biliary barrier in liver diseases and suggest a therapeutic strategy for drug overdose-induced liver injury.

Exposure to polycyclic aromatic hydrocarbons and risk of abnormal liver function: The mediating role of C-reactive protein

Polycyclic aromatic hydrocarbons (PAHs) exposure has been suggested to be linked to abnormal liver function (ALF). However, the conclusions are inconsistent, and the underlying mechanism is still unclear. In this study, a cross-sectional design including 4935 adults from the National Health and Nutrition Examination Survey (NHANES) between 2003 and 2010 was conducted to quantify the PAHs-ALF associations, and to investigate the possible mediation role of systemic inflammation. Capillary gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was utilized to detect nine urinary levels of PAH metabolites (OH-PAHs). Plasma levels of systemic inflammation biomarker, C-reactive protein (CRP), were measured by enhanced turbidimetry. ALF was diagnosed on the basis of any abnormities in albumin (ALB), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), and alanine aminotransferase (ALT). Logistic regression model and the least absolute shrinkage and selection operator (LASSO) regression models indicated positive associations between urinary 1-hydroxypyrene (1-OH-PYR), 2-hydroxyphenanthrene (2-OH-PHE), and ALF risk. Significant synergistic effect of 1-OH-PYR and 2-OH-PHE on ALF was observed via additive interaction analysis. The weighted quantile sum (WQS) analysis and the quantile-based g computation (qgcomp) were employed to investigate the mixed effect of PAHs but no significant results were found. However, these two analyses consistently showed that 2-OH-PHE and 1-OH-PYR had top dominant weights in the positive association with ALF. Furthermore, mediation analysis indicated that plasma CRP mediated 13.4 % of the association between 1-OH-PYR and ALF risk. These results enhanced our comprehension of the health effects of PAHs exposure on liver function as well as the underlying mechanism.

C-reactive protein attenuates CCl4-induced acute liver injury by regulating complement system activation

Acute liver injury is liver dysfunction caused by multiple factors without any pre-existing liver disease. C-reactive protein (CRP) is an acute-phase protein produced by hepatocytes, serving as a marker of inflammation and tissue damage. However, its role in CCl4-induced acute liver injury has not been elucidated. Here, we report that CRP protects against CCl4-induced acute liver injury by regulating complement activation. CRP knockout exacerbates CCl4-induced acute liver injury in mice and rats, markedly enhances tissue damage, and reduces survival. Administration of exogenous CRP to CRP-knockout mice rescues the CCl4-induced liver injury phenotype. The protective effect of CRP is independent of its cellular receptor FcγR2b and early metabolic pathways. Instead, CRP suppresses the late-phase amplification of inflammation by inhibiting terminal complement pathway overactivation in injured hepatocytes via factor H recruitment. In complement C3 knockout (C3-/-) mice, the protective effect of CRP against CCl4-induced acute liver injury is lost. These results suggest that CRP can alleviate CCl4-induced acute liver injury by regulating the complement pathway, providing a theoretical basis for CRP's potential involvement and regulation of disease severity.

C-Reactive Protein Induces Immunosuppression by Activating FcγR2B in Pulmonary Macrophages to Promote Lung Metastasis

C-reactive protein (CRP) is a liver-derived acute phase reactant that is a clinical marker of inflammation associated with poor cancer prognosis. Elevated CRP levels are observed in many types of cancer and are associated with significantly increased risk of metastasis, suggesting that CRP could have prometastatic actions. In this study, we reported that CRP promotes lung metastasis by dampening the anticancer capacity of pulmonary macrophages in breast cancer and melanoma. Deletion of CRP in mice inhibited lung metastasis of breast cancer and melanoma cells without significantly impacting tumor growth compared with wild-type mice. In addition, the lungs of CRP-deficient mice were enriched for activated pulmonary macrophages, which could be reduced to the level of wild-type mice by systemic administration of human CRP. Mechanistically, CRP blocked the activation of pulmonary macrophages induced by commensal bacteria in a FcγR2B-dependent manner, thereby impairing macrophage-mediated immune surveillance to promote the formation of a premetastatic niche in the lungs of tumor-bearing mice. Accordingly, treatment with specific CRP inhibitors activated pulmonary macrophages and attenuated lung metastasis in vivo. These findings highlight the importance of CRP in lung metastasis, which may represent an effective therapeutic target for patients with advanced solid cancers in clinics. Significance: CRP maintains host-commensal tolerance by inhibiting pulmonary macrophage activation and can be targeted to remodel the premetastatic niche in the lung to lower the risk of cancer metastasis. See related commentary by Saal et al., p. 4121.

The anti-mCRP199-206 antibodies aggravate tubulointerstitial lesions in lupus nephritis

Tubulointerstitial lesions could also be prominent in lupus nephritis, and the pathogenesis of tubulointerstitial lesions may be different from glomerular lesions. Previous studies have showed that plasma antibodies against modified /monomeric C-reactive protein (mCRP) are associated with renal tubulointerstitial lesions in patients with lupus nephritis, and amino acid (aa) 199-206 was one of the major epitopes of mCRP. However, the role of anti-mCRP199-206 antibodies in the pathogenesis of tubulointerstitial lesions in lupus nephritis is unknown. A total of 95 patients with renal biopsy-proven lupus nephritis were enrolled in this study. Plasma levels of anti-mCRP199-206 antibodies were screened by enzyme-linked immunosorbent assay (ELISA). A lupus prone mouse model was immunized using peptides mCRP199-206 to explore the potential role of anti-mCRP199-206 antibodies in tubulointerstitial lesions. The mechanism of anti-mCRP199-206 antibodies damage to renal tubular epithelial cells was investigated in vitro. Plasma antibodies against mCRP199-206 were associated with renal tubulointerstitial lesions and prognosis in patients with lupus nephritis. Immunization with peptides mCRP199-206 in lupus prone mice could aggravate tubulointerstitial lesions and drive tubulointerstitial inflammation and fibrosis. Anti-mCRP 199-206 antibodies could activate the TGF-β1/Smad3 signal pathway and induce tubular damage by binding with CRP. Circulating antibodies against mCRP199-206 could be a biomarker to reveal tubulointerstitial lesion, and participate in the pathogenesis of tubulointerstitial lesions, which might provide a potential therapeutic target for lupus nephritis.

Toxicological risk assessment of triadimenol for human exposure, broiler health, and food safety

Triadimenol, a widely used triazole fungicide, leaves residues that pose risks to broiler health, food safety, and human health. Current studies focus on lab animals, leaving limited data regarding its impact on non-target organisms in agricultural ecosystems. Moreover, the doses in current studies often exceed typical agricultural pollution levels of triadimenol. Therefore, this study evaluates the toxic effects of triadimenol by exposing broilers to different concentrations (0.05-20 mg/kg) in their feed for 42 days, assessing growth performance, organ index, hematological parameters, histopathology, jejunum morphology, and tissue residues. The results show that triadimenol contamination at 0.05-20 mg/kg in feed does not significantly affect broiler growth performance. However, the significant changes in hematological parameters suggest the potential hematological toxicity of triadimenol in broilers. Triadimenol at 1 mg/kg or higher induces hepatotoxic and nephrotoxic effects, and significantly alters kidney organ index and histopathology in broilers. Additionally, when the triadimenol contamination level in feed exceeds 1 mg/kg, the residues in edible tissues of broilers exceed the limits set by the EU and China. Overall, our study indicates that even low-dose exposure to triadimenol poses potential risks, highlighting the need for strict regulation of its use in agriculture to protect food safety and human health.

C-Reactive Protein Is Not the Driver Factor in Ulcerative Colitis

Purpose: C-reactive protein (CRP) functions as a nonspecific marker in various inflammatory disorders, particularly in evaluating the efficacy of pharmacological treatments in patients with ulcerative colitis. The existing body of evidence does not offer adequate support for the direct implication of CRP in modulating the advancement of ulcerative colitis. Methods: Our study employed a rigorous mouse model. An ulcerative colitis mouse model was established by subjecting CRP-deficient mice to dextran sulfate sodium (DSS) treatment. The phenotype of the mice, which encompassed parameters such as body weight, colon length, and spleen weight, was meticulously evaluated. Additionally, various physiological and biochemical indicators were assessed, including colon histopathology, expression levels of inflammatory factors, and staining of the intestinal mucus layer. Results: The absence of CRP did not significantly affect the phenotype, physiological characteristics, and biochemical indices in a mouse model of ulcerative colitis compared to mice with wild-type CRP. Additionally, eliminating intestinal bacteria flora interference through antibiotic treatment revealed that mice lacking CRP did not demonstrate any notable variations in the ulcerative colitis model. Meanwhile, the survival rate of mice lacking CRP did not exhibit a statistically significant difference compared to wild-type mice. Conclusion: The results of our study suggest that CRP may not directly mediate ulcerative colitis. Instead, it is more likely to be a bystander that is present alongside with elevated inflammatory factors. Further investigation is warranted to determine the precise role of CRP in humans, given the significant limitations associated with the use of mouse models.

Efficient expression and purification of rat CRP in Pichia pastoris

C-reactive protein (CRP) plays a crucial role in the diagnosis and monitoring of the non-specific acute phase response in humans. In contrast, rat CRP (rCRP) is an atypical acute-phase protein that possesses unique features, such as a possible incapacity to trigger the complement system and markedly elevated baseline plasma concentrations. To facilitate in vitro studies on these unique characteristics, obtaining high-quality pure rCRP is essential. Here we explored various strategies for rCRP purification, including direct isolation from rat plasma and recombinant expression in both prokaryotic and eukaryotic systems. Our study optimized the recombinant expression system to enhance the secretion and purification efficiency of rCRP. Compared to traditional purification methods, we present a streamlined and effective approach for the expression and purification of rCRP in the Pichia pastoris system. This refined methodology offers significant improvements in the efficiency and effectiveness of rCRP purification, thereby facilitating further structural and functional studies on rCRP.

C-reactive protein: structure, function, regulation, and role in clinical diseases

C-reactive protein (CRP) is a plasma protein that is evolutionarily conserved, found in both vertebrates and many invertebrates. It is a member of the pentraxin superfamily, characterized by its pentameric structure and calcium-dependent binding to ligands like phosphocholine (PC). In humans and various other species, the plasma concentration of this protein is markedly elevated during inflammatory conditions, establishing it as a prototypical acute phase protein that plays a role in innate immune responses. This feature can also be used clinically to evaluate the severity of inflammation in the organism. Human CRP (huCRP) can exhibit contrasting biological functions due to conformational transitions, while CRP in various species retains conserved protective functions in vivo. The focus of this review will be on the structural traits of CRP, the regulation of its expression, activate complement, and its function in related diseases in vivo.

Monomeric C-reactive protein is associated with severity and prognosis of decompensated hepatitis B cirrhosis

C-reactive protein (CRP) is an acute-phase protein produced by the liver in response to infection and during chronic inflammatory disorders. Systemic inflammation is a major driver of cirrhosis progression from the compensated to the decompensated stage. Previous studies have shown that pentameric CRP (pCRP) to be a weak predictor of disease severity and prognosis in patients with decompensated hepatitis B cirrhosis, with it being only helpful for identifying patients with a higher short-term risk of death under certain conditions. Accumulating evidence indicates that pCRP dissociates to and acts primarily as the monomeric conformation (mCRP) at inflammatory loci, suggesting that mCRP may be a potentially superior disease marker with higher specificity and relevance to pathogenesis. However, it is unknown whether mCRP and anti-mCRP autoantibodies are associated with disease severity, or progression in decompensated hepatitis B cirrhosis. In this study, we evaluated the serum levels of mCRP and anti-mCRP autoantibodies in patients with decompensated cirrhosis of hepatitis B and their association with disease severity and theoretical prognosis. The results showed that patients with high mCRP and anti-mCRP autoantibody levels had more severe liver damage and that coagulation function was worse in patients with high anti-mCRP autoantibodies. Analysis of the correlation between pCRP, mCRP and anti-mCRP autoantibody levels with Model for End-Stage Liver Disease (MELD), Albumin-Bilirubin (ALBI), and Child-Turcotte-Pugh (CTP) prognostic scores showed that mCRP was the most strongly correlated with MELD score, followed by anti-mCRP autoantibodies; conversely, pCRP was not significantly correlated with prognostic score. Therefore, mCRP and anti-mCRP autoantibodies may be more advantageous clinical indicators than pCRP for evaluating the pathological state of decompensated hepatitis B cirrhosis.

Effects of N-acetyl-L-cysteine against apical periodontitis in rats with adriamycin-induced cardiomyopathy and nephropathy

AIM

This study aimed to investigate the potential protective effects of N-acetyl-L-cysteine (NAC) against apical periodontitis (AP) in rats with adriamycin (ADR)-induced kidney and heart diseases.

METHODOLOGY

Fourty-eight Wistar albino rats were divided into six groups: (1) Control group, (2) ADR group (1 mg/kg/day ip for 10 days), (3) AP Group (1st mandibular molar tooth), (4) AP + ADR Group, (5) AP + NAC group (150 mg/kg/day ip), and (6) AP + ADR + NAC group. After 3 weeks, the rats were decapitated and blood and tissue samples (heart, kidney, and jaw) were collected. Tissue samples were evaluated by biochemical (inflammatory cytokines and hemodynamic parameters) and radiological analyses. One-way anova with Tukey post hoc tests was used to compare data, considering p < .05 as statistically significant.

RESULTS

The serum levels of TNF-α, IL-1β, BUN, Creatinine, CK, and LDH were elevated in the test groups compared with the control group, and treatment with NAC reduced these levels (p < .05). Heart and kidney tissue analysis showed a higher heart-to-body weight ratio (HW/BW) and kidney-to-body weight ratio (KW/BW) in the test groups compared with the control group (p < .05). No significant differences in HW/BW and KW/BW were found between the control and AP + NAC groups. Volumetric apical bone resorption analysis showed an increase in periapical radiolucencies in AP-induced groups indicating apical periodontitis. NAC treatment reduced the total area and volume of resorption cavities (p < .05).

CONCLUSIONS

The results suggest that NAC's antioxidant and anti-inflammatory effects can reduce adriamycin-mediated heart and kidney damage and may have a positive effect on apical periodontitis in individuals with nephropathy and cardiomyopathy.

Interorgan communication with the liver: novel mechanisms and therapeutic targets

The liver is a multifunctional organ that plays crucial roles in numerous physiological processes, such as production of bile and proteins for blood plasma, regulation of blood levels of amino acids, processing of hemoglobin, clearance of metabolic waste, maintenance of glucose, etc. Therefore, the liver is essential for the homeostasis of organisms. With the development of research on the liver, there is growing concern about its effect on immune cells of innate and adaptive immunity. For example, the liver regulates the proliferation, differentiation, and effector functions of immune cells through various secreted proteins (also known as "hepatokines"). As a result, the liver is identified as an important regulator of the immune system. Furthermore, many diseases resulting from immune disorders are thought to be related to the dysfunction of the liver, including systemic lupus erythematosus, multiple sclerosis, and heart failure. Thus, the liver plays a role in remote immune regulation and is intricately linked with systemic immunity. This review provides a comprehensive overview of the liver remote regulation of the body's innate and adaptive immunity regarding to main areas: immune-related molecules secreted by the liver and the liver-resident cells. Additionally, we assessed the influence of the liver on various facets of systemic immune-related diseases, offering insights into the clinical application of target therapies for liver immune regulation, as well as future developmental trends.

The Potential Role of C-Reactive Protein in Metabolic-Dysfunction-Associated Fatty Liver Disease and Aging

Nonalcoholic fatty liver disease (NAFLD), recently redefined as metabolic-dysfunction-associated fatty liver disease (MASLD), is liver-metabolism-associated steatohepatitis caused by nonalcoholic factors. NAFLD/MASLD is currently the most prevalent liver disease in the world, affecting one-fourth of the global population, and its prevalence increases with age. Current treatments are limited; one important reason hindering drug development is the insufficient understanding of the onset and pathogenesis of NAFLD/MASLD. C-reactive protein (CRP), a marker of inflammation, has been linked to NAFLD and aging in recent studies. As a conserved acute-phase protein, CRP is widely characterized for its host defense functions, but the link between CRP and NAFLD/MASLD remains unclear. Herein, we discuss the currently available evidence for the involvement of CRP in MASLD to identify areas where further research is needed. We hope this review can provide new insights into the development of aging-associated NAFLD biomarkers and suggest that modulation of CRP signaling is a potential therapeutic target.

C-reactive protein deficiency ameliorates experimental abdominal aortic aneurysms

Background

C-reactive protein (CRP) levels are elevated in patients with abdominal aortic aneurysms (AAA). However, it has not been investigated whether CRP contributes to AAA pathogenesis.

Methods

CRP deficient and wild type (WT) male mice were subjected to AAA induction via transient intra-aortic infusion of porcine pancreatic elastase. AAAs were monitored by in situ measurements of maximal infrarenal aortic external diameters immediately prior to and 14 days following elastase infusion. Key AAA pathologies were assessed by histochemical and immunohistochemical staining procedures. The influence of CRP deficiency on macrophage activation was evaluated in peritoneal macrophages in vitro.

Results

CRP protein levels were higher in aneurysmal than that in non-aneurysmal aortas. Aneurysmal aortic dilation was markedly suppressed in CRP deficient (aortic diameter: 1.08 ± 0.11 mm) as compared to WT (1.21 ± 0.08 mm) mice on day 14 after elastase infusion. More medial elastin was retained in CRP deficient than in WT elastase-infused mice. Macrophage accumulation was significantly less in aneurysmal aorta from CRP deficient than that from WT mice. Matrix metalloproteinase 2 expression was also attenuated in CRP deficient as compared to WT aneurysmal aortas. CRP deficiency had no recognizable influence on medial smooth muscle loss, lymphocyte accumulation, aneurysmal angiogenesis, and matrix metalloproteinase 9 expression. In in vitro assays, mRNA levels for tumor necrosis factor α and cyclooxygenase 2 were reduced in lipopolysaccharide activated peritoneal macrophages from CRP deficient as compared to wild type mice.

Conclusion

CRP deficiency suppressed experimental AAAs by attenuating aneurysmal elastin destruction, macrophage accumulation and matrix metalloproteinase 2 expression.

15-deoxy-Δ12,14-prostaglandin J2 relieved acute liver injury by inhibiting macrophage migration inhibitory factor expression via PPARγ in hepatocyte

15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) exhibited potential to alleviate liver inflammation in chronic injury but was less studied in acute injury. Acute liver injury was associated with elevated macrophage migration inhibitory factor (MIF) levels in damaged hepatocytes. This study aimed to investigate the regulatory mechanism of hepatocyte-derived MIF by 15d-PGJ2 and its subsequent impact on acute liver injury. In vivo, mouse models were established by carbon tetrachloride (CCl4) intraperitoneal injection, with or without 15d-PGJ2 administration. 15d-PGJ2 treatment reduced the necrotic areas induced by CCl4. In the same mouse model constructed using enhanced green fluorescent protein (EGFP)-labeled bone marrow (BM) chimeric mice, 15d-PGJ2 reduced CCl4 induced BM-derived macrophage (BMM, EGFP+F4/80+) infiltration and inflammatory cytokine expression. Additionally, 15d-PGJ2 down-regulated liver and serum MIF levels; liver MIF expression was positively correlated with BMM percentage and inflammatory cytokine expression. In vitro, 15d-PGJ2 inhibited Mif expression in hepatocytes. In primary hepatocytes, reactive oxygen species inhibitor (NAC) showed no effect on MIF inhibition by 15d-PGJ2; PPARγ inhibitor (GW9662) abolished 15d-PGJ2 suppressed MIF expression and antagonists (troglitazone, ciglitazone) mimicked its function. In Pparg silenced AML12 cells, the suppression of MIF by 15d-PGJ2 was weakened; 15d-PGJ2 promoted PPARγ activation in AML 12 cells and primary hepatocytes. Furthermore, the conditioned medium of recombinant MIF- and lipopolysaccharide-treated AML12 respectively promoted BMM migration and inflammatory cytokine expression. Conditioned medium of 15d-PGJ2- or siMif-treated injured AML12 suppressed these effects. Collectively, 15d-PGJ2 activated PPARγ to suppress MIF expression in injured hepatocytes, reducing BMM infiltration and pro-inflammatory activation, ultimately alleviating acute liver injury.

Biomarkers of the Complement System Activation (C3a, C5a, sC5b-9) in Serum of Patients before and after Liver Transplantation

The liver has a huge impact on the functioning of our body and the preservation of homeostasis. It is exposed to many serious diseases, which may lead to the chronic failure of this organ, which is becoming a global health problem today. Currently, the final form of treatment in patients with end-stage (acute and chronic) organ failure is transplantation. The proper function of transplanted organs depends on many cellular processes and immune and individual factors. An enormous role in the process of acceptance or rejection of a transplanted organ is attributed to, among others, the activation of the complement system. The aim of this study was the evaluation of the concentration of selected biomarkers' complement system activation (C3a, C5a, and sC5b-9 (terminal complement complex)) in the serum of patients before and after liver transplantation (24 h, two weeks). The study was conducted on a group of 100 patients undergoing liver transplantation. There were no complications during surgery and no transplant rejection in any of the patients. All patients were discharged home 2-3 weeks after the surgery. The levels of all analyzed components of the complement system were measured using the ELISA method. Additionally, the correlations of the basic laboratory parameters-C-reactive protein (CRP), hemoglobin (Hb), total bilirubin, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGTP), and albumin-with the parameters of the complement system (C3a, C5a, and sC5b-9) were determined. In our study, changes in the concentrations of all examined complement system components before and after liver transplantation were observed, with the lowest values before liver transplantation and the highest concentration two weeks after. The direct increase in components of the complement system (C3a, C5a, and sC5b-9) 24 h after transplantation likely affects liver damage after ischemia-reperfusion injury (IRI), while their increase two weeks after transplantation may contribute to transplant tolerance. Increasingly, attention is being paid to the role of C3a and CRP as biomarkers of damage and failure of various organs. From the point of view of liver transplantation, the most interesting correlation in our own research was found exactly between CRP and C3a, 24 h after the transplantation. This study shows that changes in complement activation biomarkers and the correlation with CRP in blood could be a prognostic signature of liver allograft survival or rejection.

Regulation of the Innate Immune System as a Therapeutic Approach to Supporting Respiratory Function in ALS

Amyotrophic lateral sclerosis (ALS) is a clinical diagnosis used to define a neurodegenerative process that involves progressive loss of voluntary muscle function and leads to death within 2–5 years after diagnosis, in most cases because of respiratory function failure. Respiratory vital capacity (VC) measurements are reproducible and strong predictors of survival. To understand the role of the innate immune response in progressive VC loss we evaluated ALS clinical trial and biomarker results from a 6-month phase 2 study of NP001, a regulator of innate immune function. All ALS baseline values were similar between treated and controls except for those > 65 years old who were excluded from analysis. Treated patients with plasma CRP ≥ 1.13 mg/L (high CRP) showed a 64% slower rate of VC decline compared with placebo and those with plasma CRP < 1.13 mg/L (low CRP) who showed no response. High CRP patients showed no age associated loss of VC whereas low CRP patients showed an age dependent loss of VC function. Plasma levels of serum amyloid A (SAA) were similarly elevated in high CRP patients consistent with ongoing innate immune activation. Plasma TGFB1 in high CRP treated patients was 95% higher than placebo at 6-months, confirming the activation and release of this anti-inflammatory factor by the innate immune alpha 2 macroglobulin (A2M) system. This report is the first to link a biomarker confirmed regulation of the innate immune system with a therapeutic approach for controlling VC loss in ALS patients.

Macrophage-Targeted Sodium Chlorite (NP001) Slows Progression of Amyotrophic Lateral Sclerosis (ALS) through Regulation of Microbial Translocation

Amyotrophic lateral sclerosis (ALS) is a heterogeneous, progressive, and universally fatal neurodegenerative disease. A subset of ALS patients has measurable plasma levels of lipopolysaccharide (LPS) and C-reactive protein (CRP) consistent with low-grade microbial translocation (MT). Unless interrupted, MT sets up a self-perpetuating loop of inflammation associated with systemic macrophage activation. To test whether MT contributed to ALS progression, blood specimens from a phase 2 study of NP001 in ALS patients were evaluated for changes in activity in treated patients as compared to controls over the 6-month study. In this post hoc analysis, plasma specimens from baseline and six-month timepoints were analyzed. Compared with baseline values, biomarkers related to MT were significantly decreased (LPS, LPS binding protein (LBP), IL-18, Hepatocyte growth factor (HGF), soluble CD163 (sCD163)) in NP001-treated patients as compared to controls, whereas wound healing and immunoregulatory factors were increased (IL-10, Epidermal growth factor (EGF), neopterin) by the end of study. These biomarker results linked to the positive clinical trial outcome confirm that regulation of macrophage activation may be an effective approach for the treatment of ALS and, potentially, other neuroinflammatory diseases related to MT.

Deficiency of C-reactive protein or human C-reactive protein transgenic treatment aggravates influenza A infection in mice

C-reactive protein (CRP) has been shown to be a potential candidate target in the immunotherapy of severe influenza A infection. However, it is unclear on the pathogenesis associated with CRP in influenza infections. Here, we used influenza A H1N1 CA04 to infect human CRP transgenic mice (KI), CRP knockout mice (KO), and wild-type mice (WT), respectively, and compared the viral pathogenicity and associated immune response in those mice. The results showed that CA04 infection resulted in 100%, 80%, and 60% death in KO, KI, and WT mice, respectively. Compared to WT mice, CA04 infection resulted in higher TCID50 in lungs on day 3 after infection but lowered HI antibody titers in sera of survivors on day 21 after infection in KI mice. ELISA assay showed that IFN-γ concentration was significantly increased in sera of WT, KI, or KO mice on day 7 after infection, and IL-17 was remarkably increased in sera of WT mice but decreased in sera of KI mice while no significant change in sera of KO mice on day 3 or 7 after infection. Quantitative RT-PCR showed that the relative expression levels of immune checkpoint CTLA-4, LAIR-1, GITR, BTLA, TIM-3, or PD-1 mRNA in the lung presented decreased levels on day 3 or 7 after infection in KI or KO mice. The correlation analysis showed that mRNA expression levels of the 6 molecules positively correlated with viral TICD50 in WT mice but negatively correlated with viral TCID50 in KI or KO mice. However, only LAIR-1 presented a significant correlation in each lung tissue of WT, KI, or KO mice with CA07 infection statistically. IHC results showed that LAIR-1 positive cells could be found in WT, KO, or KI mice lung tissues with CA04 infection, and the positive cells were mainly distributed in an inflammatory dense area. Our results suggested that deficiency of CRP or human CRP transgenic treatment aggravates influenza A virus infection in mice. CRP is a double sword in immune regulation of influenza infection in which IL-17 and immune checkpoint may be involved.

The Cholesterol-Binding Sequence in Monomeric C-Reactive Protein Binds to the SARS-CoV-2 Spike Receptor-Binding Domain and Blocks Interaction With Angiotensin-Converting Enzyme 2

The receptor-binding domain (RBD) of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the human angiotensin-converting enzyme 2 (ACE2) receptor, which is a prerequisite for the virus to enter the cell. C-reactive protein (CRP) is an important marker of inflammation and is a putative soluble pattern recognition receptor. Clinical elevation of CRP levels in patients with COVID-19 is one of the characteristics of the disease; however, whether CRP is involved in COVID-19 pathogenesis is unknown. Here, we report that monomeric CRP (mCRP) can bind to the SARS-CoV-2 spike RBD and competitively inhibit its binding to ACE2. Furthermore, truncated mutant peptide competition assays and surface plasmon resonance binding experiments showed that the cholesterol-binding sequence (CBS, amino acids 35-47) in mCRP was critical for mediating the binding of mCRP to spike RBD. In a cell model of spike RBD and ACE2 interaction, the CBS motif effectively reduced the binding of spike RBD to ACE2 overexpressed on the cell surface. Thus, this study highlights the pattern recognition function of mCRP in innate immunity and provides a preliminary theoretical basis for the development of the CBS motif in mCRP into a functional peptide with both diagnostic significance and potential therapeutic capabilities.

Identification of a distal enhancer that determines the expression pattern of acute phase marker C-reactive protein

C-reactive protein (CRP) is a major acute phase protein and inflammatory marker, the expression of which is largely liver specific and highly inducible. Enhancers are regulatory elements critical for the precise activation of gene expression, yet the contributions of enhancers to the expression pattern of CRP have not been well defined. Here, we identify a constitutively active enhancer (E1) located 37.7 kb upstream of the promoter of human CRP in hepatocytes. By using chromatin immunoprecipitation, luciferase reporter assay, in situ genetic manipulation, CRISPRi, and CRISPRa, we show that E1 is enriched in binding sites for transcription factors STAT3 and C/EBP-β and is essential for the full induction of human CRP during the acute phase. Moreover, we demonstrate that E1 orchestrates with the promoter of CRP to determine its varied expression across tissues and species through surveying activities of E1-promoter hybrids and the associated epigenetic modifications. These results thus suggest an intriguing mode of molecular evolution wherein expression-changing mutations in distal regulatory elements initiate subsequent functional selection involving coupling among distal/proximal regulatory mutations and activity-changing coding mutations.

Targeting innate immune responses to attenuate acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) hepatotoxicity is an important cause of acute liver failure, resulting in massive deaths in many developed countries. Currently, the metabolic process of APAP in the body has been well studied. However, the underlying mechanism of APAP-induced liver injury remains elusive. Increasing clinical and experimental evidences indicate that the innate immune responses are involved in the pathogenesis of APAP-induced acute liver injury (AILI), in which immune cells have dual roles of inducing inflammation to exacerbate hepatotoxicity and removing dead cells and debris to help liver regeneration. In this review, we summarize the latest findings of innate immune cells involved in AILI, particularly emphasizing the activation of innate immune cells and their different roles during the injury and repair phases. Moreover, current available treatments are discussed according to the different roles of innate immune cells in the development of AILI. This review aims to update the knowledge about innate immune responses in the pathogenesis of AILI, and provide potential therapeutic interventions for AILI.

3'mRNA sequencing reveals pro-regenerative properties of c5ar1 during resolution of murine acetaminophen-induced liver injury

Murine acetaminophen-induced acute liver injury (ALI) serves as paradigmatic model for drug-induced hepatic injury and regeneration. As major cause of ALI, acetaminophen overdosing is a persistent therapeutic challenge with N-acetylcysteine clinically used to ameliorate parenchymal necrosis. To identify further treatment strategies that serve patients with poor N-acetylcysteine responses, hepatic 3′mRNA sequencing was performed in the initial resolution phase at 24 h/48 h after sublethal overdosing. This approach disclosed 45 genes upregulated (≥5-fold) within this time frame. Focusing on C5aR1, we observed in C5aR1-deficient mice disease aggravation during resolution of intoxication as evidenced by increased liver necrosis and serum alanine aminotransferase. Moreover, decreased hepatocyte compensatory proliferation and increased caspase-3 activation at the surroundings of necrotic cores were detectable in C5aR1-deficient mice. Using a non-hypothesis-driven approach, herein pro-regenerative/-resolving effects of C5aR1 were identified during late acetaminophen-induced ALI. Data concur with protection by the C5a/C5aR1-axis during hepatectomy and emphasize the complex role of inflammation during hepatic regeneration and repair.