C-Reactive Protein Impairs Dendritic Cell Development, Maturation, and Function: Implications for Peripheral Tolerance

A tale of two functions: C-reactive protein complement-ary structures and their role in rheumatoid arthritis

C-reactive protein (CRP) is an inflammatory biomarker with associated clinical utility in a wide number of inflammatory disorders, including rheumatoid arthritis (RA). The interaction of CRP with pro-inflammatory cytokines has been explored before, however its role in complement regulation is more subtle, where CRP is capable of both up and downregulating the complement cascade. CRP is produced in a pentameric form and can dissociate to a monomeric form in circulation which has significant implications for its ability to interact with receptors and binding partners. This dichotomy of CRP structure could have relevance in patients with RA who have significant dysfunction in their complement cascade and also widely varying CRP levels including at the time of flare. This review aims to bring together current knowledge of CRP in its various forms, its effects on complement function and how this could influence pathology in the context of RA.

C-Reactive Protein as a Predictor of Severe Respiratory Complications in Measles

Background and Objectives: Even though measles is easily prevented by vaccination, infection outbreaks are not rare. Infection carries a great risk for pulmonary complications, which are sometimes hard to predict, especially in a group of outpatients. This study aims to evaluate the association between serum CRP changes and the severity of respiratory complications in the group of inpatients treated for measles. Materials and Methods: A total of 207 patients admitted and treated at the Clinic for Infectious Diseases, University Clinical Center, Nis, for measles infection were included in the analysis. The data collected from the patients' medical records included demographic characteristics, disease duration, blood and serum biochemical analysis, general measles-associated symptoms, and disease outcome. Results: Results of the study revealed that there are almost no differences in the clinical presentation of patients with measles and those complicated with pneumonia. The examined CRP changes are found to correlate with the observable degree of pneumonia; however, they do not correspond to the changes visible in chest X-rays. Conclusions: CRP changes in the serum of patients with measles with mild clinical pictures could be a potential predictor for the development of some pulmonary complications.

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.

CRP inhibits the osteoblastic differentiation of OPCs via the up-regulation of primary cilia and repression of the Hedgehog signaling pathway

Inflammation disrupts bone metabolism and leads to bone damage. C-reactive protein (CRP) is a typical inflammation marker. Although CRP measurement has been conducted for many decades, how osteoblastic differentiation influences molecular mechanisms remains largely unknown. The present study attempted to investigate the effects of CRP on primary cultured osteoblast precursor cells (OPCs) while elucidating the underlying molecular mechanisms. OPCs were isolated from suckling Sprague-Dawleyrats. Fewer OPCs were observed after recombinant C-reactive protein treatment. In a series of experiments, CRP inhibited OPC proliferation, osteoblastic differentiation, and the OPC gene expression of the hedgehog (Hh) signaling pathway. The inhibitory effect of CRP on OPC proliferation occurred via blockade of the G1-S transition of the cell cycle. In addition, the regulation effect of proto cilium on osteoblastic differentiation was analyzed using the bioinformatics p. This revealed the primary cilia activation of recombinant CRP effect on OPCs through in vitro experiments. A specific Sonic Hedgehog signaling agonist (SAG) rescued osteoblastic differentiation inhibited by recombinant CRP. Moreover, chloral hydrate, which removes primary cilia, inhibited the Suppressor of Fused (SUFU) formation and blocked Gli2 degradation. This counteracted osteogenesis inhibition caused by CRP. Therefore, these data depict that CRP can inhibit the proliferation and osteoblastic differentiation of OPCs. The underlying mechanism could be associated with primary cilia activation and Hh pathway repression.

Prognostic Value of the Glasgow Prognostic Score in Non-Small Cell Lung Cancer Patients Receiving Immunotherapy: A Meta-Analysis

BACKGROUND

The Glasgow Prognostic Score (GPS) has proven to be a good biomarker for lung cancer prognosis. However, its usefulness in lung cancer patients receiving checkpoint inhibitor immunotherapy remains controversial. Therefore, we performed a meta-analysis to explore the prognostic value of the GPS in non-small cell lung cancer patients receiving immunotherapy.

METHODS

PubMed, Web of Science, Scopus, and Embase were systematically searched for relevant studies up to May 31, 2023, and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were merged to investigate the prognostic value of the GPS for overall survival (OS) and progression-free survival (PFS).

RESULTS

Seven studies comprising 833 patients were included in the primary analysis, and the pooled results indicated that a higher baseline GPS was associated with poorer OS and PFS in non-small cell lung cancer patients treated with immune checkpoint inhibitors (ICIs) (OS: HR = 1.95, 95% CI: 1.47-2.58, p < 0.01; PFS: HR = 1.63, 95% CI: 1.26-2.11, p < 0.01). These findings were robust after subgroup and sensitivity analyses.

CONCLUSIONS

The GPS can serve as a biomarker in non-small cell lung cancer patients receiving immunotherapy with significant prognostic value; however, these findings require more prospective evidence for validation.

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.

C-reactive protein impairs immune response of CD8+ T cells via FcγRIIb-p38MAPK-ROS axis in multiple myeloma

BACKGROUND

C-reactive protein (CRP) is a prototypical acute phase protein in humans with the function of regulating immune cells. Serum CRP levels are elevated in multiple myeloma (MM), associated with MM cell proliferation and bone destruction. However, its direct effects on T lymphocytes in MM have not been elucidated.

METHODS

Public data sets were used to explore the correlation of CRP levels with immune cell infiltration and cytotoxicity score of CD8+ T cells in MM. In vitro, repeated freeze-thaw myeloma cell lines were taken as tumor antigens to load dendritic cells (DCs) derived from HLA-A*0201-positive healthy donors. MM-specific cytotoxic T cells (MM-CTL) were obtained from T lymphocytes of the corresponding donors pulsed with these DCs. B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor (CAR)-T cells were manipulated by transfecting with lentivirus encoding an anti-BCMA single-chain variable fragment. Then T cells from healthy controls, MM-CTLs and BCMA CAR-T cells were exposed to CRP and analyzed for cell proliferation, cytotoxicity, immunophenotypes. CRP binding capacity to T cells before and after Fc gamma receptors IIb (FcγRIIb) blockage, p38 mitogen-activated protein kinase (MAPK) pathway and the downstream molecules were also detected. In vivo, both normal C57BL/6J mice and the Vk*MYC myeloma mouse models were applied to confirm the impact of CRP on T cells.

RESULTS

CRP levels were negatively correlated with cell-infiltration and cytotoxicity score of CD8+ T cells in MM. In vitro experiments showed that CRP inhibited T-cell proliferation in a dose-dependent manner, impaired the cytotoxic activity and upregulated expression of senescent markers in CD8+ T cells. In vivo results validated the suppressive role of CRP in CD8+ T cells. CRP could bind to CD8+ T cells, mainly to the naïve T subset, while the binding was dramatically decreased by FcγRIIb blockage. Furthermore, CRP resulted in increased phosphorylation of p38 MAPK, elevated levels of reactive oxygen species and oxidized glutathione in CD8+ T cells.

CONCLUSIONS

We found that CRP impaired immune response of CD8+ T cells via FcγRIIb-p38MAPK-ROS signaling pathway. The study casted new insights into the role of CRP in anti-myeloma immunity, providing implications for future immunotherapy in MM.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

The Role of NLRP3 Inflammasome in Obesity and PCOS-A Systematic Review and Meta-Analysis

Inflammasomes have recently been implicated in the pathogenesis of several chronic inflammatory disorders, such as diabetes and obesity. The aim of this meta-analysis was to investigate the possible role of the NLRP3 inflammasome in obesity and polycystic ovarian syndrome (PCOS). A comprehensive search of electronic databases was conducted to identify studies investigating NLRP3 its related components (Caspase 1, ASC and IL-1β) in adipose tissue and/or blood from obese individuals compared to non-obese controls. Another search was conducted for studies investigating NLRP3 in PCOS women and animal models. The ssearched databases included Medline, EMBASE, Cochrane Library, PubMed, Clinicaltrials.gov, the EU Clinical Trials Register and the WHO International Clinical Trials Register. The quality and risk of bias for the included articles were assessed using the modified Newcastle-Ottawa scale. Data were extracted and pooled using RevMan software for the calculation of the standardized mean difference (SMD) and 95% confidence interval (CI). Twelve eligible studies were included in the obesity systematic review and nine in the PCOS review. Of the obesity studies, nine (n = 270) were included in the meta-analysis, which showed a significantly higher adipose tissue NLRP3 gene expression in obese (n = 186) versus non-obese (n = 84) participants (SMD 1.07; 95% CI, 0.27, 1.87). Pooled analysis of adipose tissue IL-1β data from four studies showed significantly higher IL-1β gene expression levels in adipose tissue from 88 obese participants versus 39 non-obese controls (SMD 0.56; 95% CI, 0.13, 0.99). Meta-analysis of adipose tissue ASC data from four studies showed a significantly higher level in obese (n = 109) versus non-obese (n = 42) individuals (SMD 0.91, 95% CI, 0.30, 1.52). Of the nine PCOS articles, three were human (n = 185) and six were animal studies utilizing PCOS rat/mouse models. All studies apart from one article consistently showed upregulated NLRP3 and its components in PCOS women and animal models. In conclusion, obesity and PCOS seem to be associated with upregulated expression of NLRP3 inflammasome components. Further research is required to validate these findings and to elucidate the role of NLRP3 in obesity and PCOS.

Association of C-reactive protein and complement factor H gene polymorphisms with risk of lupus nephritis in Chinese population

BACKGROUND

Complement overactivation is a major driver of lupus nephritis (LN). Impaired interactions of C-reactive protein (CRP) with complement factor H (CFH) have been shown as a pathogenic mechanism that contributes to the overactivation of complement in LN. However, genetic variations of neither CRP nor CFH show consistent influences on the risk of LN.

AIM

To examine whether genetic variations of CRP and CFH in combination can improve the risk stratification in Chinese population.

METHODS

We genotyped six CRP single nucleotide polymorphisms (SNPs) (rs1205, rs3093062, rs2794521, rs1800947, rs3093077, and rs1130864) and three CFH SNPs (rs482934, rs1061170, and rs1061147) in 270 LN patients and 303 healthy subjects.

RESULTS

No linkage was found among CRP and CFH SNPs, indicating lack of genetic interactions between the two genes. Moreover, CRP and CFH SNPs, neither individually nor in combination, are associated with the risk or clinical manifestations of LN. Given the unambiguous pathogenic roles of the two genes.

CONCLUSION

These findings suggest that the biological effects of most genetic variations of CRP and CFH on their expressions or activities are not sufficient to influence the disease course of LN.

Monomeric C-reactive protein evokes TCR Signaling-dependent bystander activation of CD4+ T cells

Bystander activation of T cells is defined as induction of effector responses by innate cytokines in the absence of cognate antigens and independent of T cell receptor (TCR) signaling. Here we show that C-reactive protein (CRP), a soluble pattern-recognition receptor assembled noncovalently by five identical subunits, can instead trigger bystander activation of CD4 + T cells by evoking allosteric activation and spontaneous signaling of TCR in the absence of cognate antigens. The actions of CRP depend on pattern ligand-binding induced conformational changes that result in the generation of monomeric CRP (mCRP). mCRP binds cholesterol in plasma membranes of CD4 + T cells, thereby shifting the conformational equilibrium of TCR to the cholesterol-unbound, primed state. The spontaneous signaling of primed TCR leads to productive effector responses manifested by upregulation of surface activation markers and release of IFN-γ. Our results thus identify a novel mode of bystander T cell activation triggered by allosteric TCR signaling, and reveal an interesting paradigm wherein innate immune recognition of CRP transforms it to a direct activator that evokes immediate adaptive immune responses.

Major alterations to monocyte and dendritic cell subsets lasting more than 6 months after hospitalization for COVID-19

Introduction

After more than two years the Coronavirus disease-19 (COVID-19) pandemic continues to burden healthcare systems and economies worldwide, and it is evident that the effects on the immune system can persist for months post-infection. The activity of myeloid cells such as monocytes and dendritic cells (DC) is essential for correct mobilization of the innate and adaptive responses to a pathogen. Impaired levels and responses of monocytes and DC to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is likely to be a driving force behind the immune dysregulation that characterizes severe COVID-19.

Methods

Here, we followed a cohort of COVID-19 patients hospitalized during the early waves of the pandemic for 6-7 months. The levels and phenotypes of circulating monocyte and DC subsets were assessed to determine both the early and long-term effects of the SARS-CoV-2 infection.

Results

We found increased monocyte levels that persisted for 6-7 months, mostly attributed to elevated levels of classical monocytes. Myeloid derived suppressor cells were also elevated over this period. While most DC subsets recovered from an initial decrease, we found elevated levels of cDC2/cDC3 at the 6-7 month timepoint. Analysis of functional markers on monocytes and DC revealed sustained reduction in program death ligand 1 (PD-L1) expression but increased CD86 expression across almost all cell types examined. Finally, C-reactive protein (CRP) correlated positively to the levels of intermediate monocytes and negatively to the recovery of DC subsets.

Conclusion

By exploring the myeloid compartments, we show here that alterations in the immune landscape remain more than 6 months after severe COVID-19, which could be indicative of ongoing healing and/or persistence of viral antigens.

Inflammasomes: Cause or consequence of obesity-associated comorbidities in humans

Inflammasomes are multiprotein intracellular complexes composed of innate immune system receptors and sensors; they activate the inflammatory cascade in response to infectious microbes and/or molecules derived from host proteins. Because of cytokine secretion, inflammasomes can induce amplified systemic responses, its dysregulation can exacerbate symptoms in infectious diseases, and it has been related to the development of autoimmune diseases, inflammatory disorders, and even cancer. Obesity is associated with a chronic low-grade inflammation, in which circulating proinflammatory cytokines are elevated. Some publications describe changes in inflammation markers as a consequence of obesity, but others suggest that chronic inflammation might cause obesity (e.g., C-reactive protein): these assumptions reflect the difficulty of identifying the appropriate role of inflammation as cause or consequence of obesity and its related complications. Obesity is recognized as a clinical risk factor for developing cardiovascular diseases including atherosclerosis, metabolic syndrome, insulin resistance, and diabetes mellitus. Changes in the expression of inflammasomes are described in some of these obesity-related complications, and moreover, its modulation might exert a beneficial effect in some cases. Despite some contradictory results, most publications suggest a promising clinical effect based on in vitro and in vivo experiments. In this review, we summarized recent publications about inflammasome dysregulation in humans and its relationship with obesity-related comorbidities.

C-reactive protein levels and risk of dementia-Observational and genetic studies of 111,242 individuals from the general population

INTRODUCTION

Increased plasma levels of C-reactive protein (CRP) in midlife are associated with increased risk of Alzheimer's disease (AD), whereas in older age the opposite association is observed. Whether genetically determined CRP is associated with AD remains unclear.

METHODS

A total of 111,242 White individuals from the Copenhagen General Population Study and the Copenhagen City Heart Study were included. Plasma levels of CRP and four regulatory genetic variants in the CRP gene were determined.

RESULTS

For CRP percentile group 1 to 5 (lowest plasma CRP) versus the 50 to 75 group (reference), the hazard ratio for AD was 1.69 (95% confidence interval 1.29-2.16). Genetically low CRP was associated with increased risk of AD in individuals with body mass index ≤25 kg/m² (P = 4 × 10^-6 ).

DISCUSSION

Low plasma levels of CRP at baseline were associated with high risk of AD in individuals from the general population. These observational findings were supported by genetic studies.

Negative regulation of ATP-induced inflammasome activation and cytokine secretion by acute-phase proteins: A mini review

The expression of the acute-phase reactants C-reactive protein (CRP), α1-antitrypsin (AAT), and secretory leukocyte protease inhibitor (SLPI), is induced in response to inflammation by pro-inflammatory mediators, including interleukin-1β. It is conceivable that acute-phase proteins exert protective functions, when the integrity of an organism is challenged by pathogens or trauma, which result in uncontrolled release of endogenous damage-associated molecular patterns like Toll-like receptor agonists and ATP. Acute-phase proteins can enhance or down-modulate immunity against infections or protect the host against damage caused by over-shooting effector functions of the immune system. CRP is mainly regarded as a pro-inflammatory opsonizing agent that binds to bacteria and damaged host cells thereby contributing to their inactivation and elimination. AAT and SLPI are well known for their anti-protease activity, which protects the lung extracellular matrix against degradation by proteases that are released by activated neutrophil granulocytes. In addition, there is growing evidence, that CRP, AAT, and SLPI can control the biosynthesis, maturation, and secretion of pro-inflammatory cytokines. The purpose of this narrative mini review is to summarize these anti-inflammatory functions with a focus on the negative control of the ATP-induced, inflammasome-dependent secretion of interleukin-1β by monocytes. CRP-, AAT- and SLPI-mediated control of interleukin-1β release involves the activation of unconventional nicotinic acetylcholine receptors that inhibits the ionotropic function of the ATP receptor P2X7. Apart from other functions, CRP, AAT, and SLPI seem to be central elements of systemic negative feedback loops that protect the host against systemic hyperinflammation, barrier dysfunction, and death by multiple organ damage.

Comprehensive comparison of the prognostic value of systemic inflammation biomarkers for cancer cachexia: a multicenter prospective study

AIMS

Systemic inflammation plays an important role in cancer cachexia. However, among the systemic inflammatory biomarkers, it is unclear which has optimal prognostic value for cancer cachexia.

METHODS

The Kaplan-Meier method was used and the log-rank analysis was performed to estimate survival differences between groups. Cox proportional hazard regression analyses were conducted to assess independent risk factors for all-cause mortality.

RESULTS

The C-reactive protein-to-albumin ratio (CAR) was the optimal prognostic assessment tool for patients with cancer cachexia, with 1-, 3-, and 5-year predictive powers of 0.650, 0.658, and 0.605, respectively. Patients with a high CAR had significantly lower survival rates than those with a low CAR. Moreover, CAR can differentiate the prognoses of patients with the same pathological stage. Cox proportional risk regression analyses showed that a high CAR was an independent risk factor for cancer cachexia. For every standard deviation increase in CAR, the risk of poor prognosis for patients with cancer cachexia was increased by 20% (hazard ratio = 1.200, 95% confidence interval = 1.132-1.273, P < 0.001).

CONCLUSIONS

CAR is an effective representative of systemic inflammation and a powerful factor for predicting the life function and clinical outcome of patients with cancer cachexia.

Cell Trafficking at the Intersection of the Tumor-Immune Compartments

Migration is an essential cellular process that regulates human organ development and homeostasis as well as disease initiation and progression. In cancer, immune and tumor cell migration is strongly associated with immune cell infiltration, immune escape, and tumor cell metastasis, which ultimately account for more than 90% of cancer deaths. The biophysics and molecular regulation of the migration of cancer and immune cells have been extensively studied separately. However, accumulating evidence indicates that, in the tumor microenvironment, the motilities of immune and cancer cells are highly interdependent via secreted factors such as cytokines and chemokines. Tumor and immune cells constantly express these soluble factors, which produce a tightly intertwined regulatory network for these cells' respective migration. A mechanistic understanding of the reciprocal regulation of soluble factor-mediated cell migration can provide critical information for the development of new biomarkers of tumor progression and of tumor response to immuno-oncological treatments. We review the biophysical andbiomolecular basis for the migration of immune and tumor cells and their associated reciprocal regulatory network. We also describe ongoing attempts to translate this knowledge into the clinic.

C-reactive protein perturbs alveolar bone homeostasis: an experimental study of periodontitis and diabetes in the rat

AIMS

To explore the role of C-reactive protein (CRP) in periodontitis and diabetes and its mechanism in alveolar bone homeostasis.

MATERIALS AND METHODS

In vivo, normal and Crp knockout rats were randomly divided into: control, diabetes, periodontitis, and diabetes and periodontitis (DP) groups respectively. The diabetes model was established using a high-fat diet combined with streptozotocin (STZ) injection. The periodontitis model was established by ligature combined with lipopolysaccharide injection. Alveolar bones were analyzed using microCT, histology, and immunohistochemistry. In vitro, human periodontal ligament cells (hPDLCs) were treated with lipopolysaccharide and high glucose. CRP knockdown lentivirus or CRP overexpression adenovirus combined with a PI3K/AKT signaling inhibitor or agonist were used to explore the regulatory mechanism of CRP in osteogenesis and osteoclastogenesis of hPDLCs, as evidenced by ALP staining, WB and qPCR.

RESULTS

In periodontitis and diabetes, CRP knockout decreased the alveolar bone loss and the expression levels of osteoclastogenic markers, while increasing the expression levels of osteogenic markers. CRP constrained osteogenesis while promoting the osteoclastogenesis of hPDLCs via PI3K/AKT signaling under high glucose and pro-inflammatory conditions.

CONCLUSIONS

CRP inhibits osteogenesis and promotes osteoclastogenesis via PI3K/AKT signaling under diabetic and pro-inflammatory conditions, thus perturbing alveolar bone homeostasis. This article is protected by copyright. All rights reserved.

Photocurable Hydrogel Substrate-Better Potential Substitute on Bone-Marrow-Derived Dendritic Cells Culturing

Dendritic cells (DCs) are recognized as the most effective antigen-presenting cells at present. DCs have corresponding therapeutic effects in tumor immunity, transplantation immunity, infection inflammation and cardiovascular diseases, and the activation of T cells is dependent on DCs. However, normal bone-marrow-derived Dendritic cells (BMDCs) cultured on conventional culture plates are easy to be activated during culturing, and it is difficult to imitate the internal immune function. Here, we reported a novel BMDCs culturing with hydrogel substrate (CCHS), where we synthesized low substituted Gelatin Methacrylate-30 (GelMA-30) hydrogels and used them as a substitute for conventional culture plates in the culture and induction of BMDCs in vitro. The results showed that 5% GelMA-30 substrate was the best culture condition for BMDCs culturing. The low level of costimulatory molecules and the level of development-related transcription factors of BMDCs by CCHS were closer to that of spleen DCs and were capable of better promoting T cell activation and exerting an immune effect. CCHS was helpful to study the transformation of DCs from initial state to activated state, which contributes to the development of DC-T cell immunotherapy.

Combination of CRAFITY score with Alpha-fetoprotein response predicts a favorable outcome of atezolizumab plus bevacizumab for unresectable hepatocellular carcinoma

Immune checkpoint inhibitors (ICIs) with atezolizumab plus bevacizumab are promising agents for unresectable hepatocellular carcinoma (HCC). We tried to guide the treatment based on recent developed CRAFITY score combining with on-treatment AFP response. Eighty-nine patients who received atezolizumab plus bevacizumab regardless of as a first-line therapy or not for unresectable HCC were enrolled for analyses. Radiologic evaluation was based on modified Response Evaluation Criteria in Solid Tumors (mRECIST). The objective response rate (ORR) and disease control rate (DCR) were 25.0% and 65.5%, respectively. Multivariate analysis showed that low CRAFITY score (AFP<100 ng/ml or CRP<10 mg/l) and satisfactory AFP response at 6 weeks (≥75% decrease or ≤10% increase from baseline) were independent factors determining good overall survival (OS) (hazard ratio [HR]=0.143, P=0.002 & HR=0.337, P=0.031), progression-free survival (PFS) (HR=0.419, P=0.022 & HR=0.429, P=0.025) and good responder (odds ratio [OR]=1.763, P=0.044 & OR=3.881, P=0.011). Patients were further divided into three classes by combination of CRAFITY score and AFP response at 6 weeks [The CAR (CRAFITY score and AFP-Response) classification)]: low CRAFITY score with satisfactory AFP response at 6 weeks (class I), either high CRAFITY score or unsatisfactory AFP response at 6 weeks (class II) and high CRAFITY score together with unsatisfactory AFP response at 6 weeks (class III). ORR was 35.0%, 18.2%, and 0% in class I, II and III patients, respectively (overall P=0.034). Patients in the class I had the best OS and PFS, followed by class II and class III (median OS: not reached vs. 11.1 vs. 4.3 months, log-rank P<0.001; median PFS: 7.9 vs. 6.6 vs. 2.6 months, log-rank P=0.001). Combination CRAFITY score and AFP response at 6 weeks with AUROC predicts OS and tumor response to be 0.809 and 0.798, respectively, better than either CRAFITY score (0.771 & 0.750) or AFP response at 6 weeks (0.725 & 0.680) alone. In conclusions, the CAR classification which combining CRAFITY score and AFP response at 6 weeks provides a practical guidance for atezolizumab plus bevacizumab therapy in unresectable HCC patients.

C-Reactive Protein Levels Predict Responses to PD-1 Inhibitors in Hepatocellular Carcinoma Patients

Background

Serum C-reactive protein (CRP) is a biomarker of an acute inflammatory response and has been successfully used as a prognostic predictor for several malignancies. However, the clinicopathological significance of CRP levels in hepatocellular carcinoma (HCC) patients being treated with PD-1 inhibitors remains unclear.

Methods

Serum CRP levels were measured for a total of 101 HCC patients that had been treated with PD-1 inhibitors from July 2018 to November 2019. The clinicopathological data was retrospectively analyzed to identify any clinical implications between CRP levels and responses to PD-1 inhibitors and patients’ progression-free survival (PFS).

Results

The median PFS was 8.87 months in the CRP-low subgroup and 3.67 months in the CRP-high subgroup (P = 0.009). Univariate and multivariate Cox regression analysis demonstrated that both serum CRP and AFP levels were independent risk factors for the PFS of HCC patients treated with PD-1 inhibitors (P &lt; 0.05). Moreover, Cox regression analysis after Propensity Score Matching showed the similar results. A prognostic model combining CRP and AFP levels could significantly stratify HCC patients receiving PD-1 inhibitors into low-, intermediate-, and high-risk subgroups (P &lt; 0.001). Patients in the risk subgroups reported similar overall response rates (P = 0.625) and significantly different disease control rates (low- vs. intermediate- vs. high-risk groups: 81.6% vs. 65.1% vs. 35%, respectively, P = 0.002).

Conclusions

The results of this study support the association between high serum CRP levels with the response and PFS for HCC patients receiving PD-1 inhibitors. Furthermore, the levels of both CRP and AFP in an HCC patient before treatment initiation show great potential for determining the efficacy of PD-1 inhibitors.

Hematopoiesis, Inflammation and Aging-The Biological Background and Clinical Impact of Anemia and Increased C-Reactive Protein Levels on Elderly Individuals

Anemia and systemic signs of inflammation are common in elderly individuals and are associated with decreased survival. The common biological context for these two states is then the hallmarks of aging, i.e., genomic instability, telomere shortening, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion and altered intercellular communication. Such aging-associated alterations of hematopoietic stem cells are probably caused by complex mechanisms and depend on both the aging of hematopoietic (stem) cells and on the supporting stromal cells. The function of inflammatory or immunocompetent cells is also altered by aging. The intracellular signaling initiated by soluble proinflammatory mediators (e.g., IL1, IL6 and TNFα) is altered during aging and contributes to the development of both the inhibition of erythropoiesis with anemia as well as to the development of the acute-phase reaction as a systemic sign of inflammation with increased CRP levels. Both anemia and increased CRP levels are associated with decreased overall survival and increased cardiovascular mortality. The handling of elderly patients with inflammation and/or anemia should in our opinion be individualized; all of them should have a limited evaluation with regard to the cause of the abnormalities, but the extent of additional and especially invasive diagnostic evaluation should be based on an overall clinical evaluation and the possible therapeutic consequences.

Intersection of FcγRIIB, the microbiome, and checkpoint inhibitors in antitumor immunity

Fc receptors (FcRs) and the microbiome are both known to have an effect on the development and progression of cancers. Checkpoint inhibitors are a novel class of therapeutics which are used to combat cancer and are integrally linked to both FcRs and the microbiome. The use of checkpoint inhibitors has grown exponentially over the past decade, although many host factors affect both the efficacy and the safety of these therapeutics. Some of these host factors, including the microbiome and the expression of FcRs, are currently being investigated. Here we discuss the current understanding of FcRs (particularly the inhibitory FcγRIIB) and the microbiome in context of T cell immunity, inflammation, cancer, and checkpoint inhibition.

An evaluation of the recognised systemic inflammatory biomarkers of chronic sub-optimal inflammation provides evidence for inflammageing (IFA) during multiple sclerosis (MS)

The pathogenesis of the human demyelinating disorder multiple sclerosis (MS) involves the loss of immune tolerance to self-neuroantigens. A deterioration in immune tolerance is linked to inherent immune ageing, or immunosenescence (ISC). Previous work by the author has confirmed the presence of ISC during MS. Moreover, evidence verified a prematurely aged immune system that may change the frequency and profile of MS through an altered decline in immune tolerance. Immune ageing is closely linked to a chronic systemic sub-optimal inflammation, termed inflammageing (IFA), which disrupts the efficiency of immune tolerance by varying the dynamics of ISC that includes accelerated changes to the immune system over time. Therefore, a shifting deterioration in immunological tolerance may evolve during MS through adversely-scheduled effects of IFA on ISC. However, there is, to date, no collective proof of ongoing IFA during MS. The Review addresses the constraint and provides a systematic critique of compelling evidence, through appraisal of IFA-related biomarker studies, to support the occurrence of a sub-optimal inflammation during MS. The findings justify further work to unequivocally demonstrate IFA in MS and provide additional insight into the complex pathology and developing epidemiology of the disease.

C-Reactive Protein Suppresses the Th17 Response Indirectly by Attenuating the Antigen Presentation Ability of Monocyte Derived Dendritic Cells in Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a classical murine model for Multiple Sclerosis (MS), a human autoimmune disease characterized by Th1 and Th17 responses. Numerous studies have reported that C-reactive protein (CRP) mitigates EAE severity, but studies on the relevant pathologic mechanisms are insufficient. Our previous study found that CRP suppresses Th1 response directly by receptor binding on naïve T cells; however, we did not observe the effect on Th17 response at that time; thus it remains unclear whether CRP could regulate Th17 response. In this study, we verified the downregulation of Th17 response by a single-dose CRP injection in MOG-immunized EAE mice in vivo while the direct and indirect effects of CRP on Th17 response were differentiated by comparing its actions on isolated CD4⁺ T cells and splenocytes in vitro, respectively. Moreover, the immune cell composition was examined in the blood and CNS (Central Nervous System), and a blood (monocytes) to CNS (dendritic cells) infiltration pathway is established in the course of EAE development. The infiltrated monocyte derived DCs (moDCs) were proved to be the only candidate antigen presenting cells to execute CRP’s function. Conversely, the decrease of Th17 responses caused by CRP disappeared in the above in vivo and in vitro studies with FcγR2B^−/− mice, indicating that FcγR2B expressed on moDCs mediates CRP function. Furthermore, peripheral blood monocytes were isolated and induced to establish moDCs, which were used to demonstrate that the antigen presenting ability of moDCs was attenuated by CRP through FcγR2B, and then NF-κB and ERK signaling pathways were manifested to be involved in this regulation. Ultimately, we perfected and enriched the mechanism studies of CRP in EAE remission, so we are more convinced that CRP plays a key role in protecting against EAE development, which may be a potential therapeutic target for the treatment of MS in human.

Regulatory Dendritic Cells, T Cell Tolerance, and Dendritic Cell Therapy for Immunologic Disease

Dendritic cells (DC) are antigen-presenting cells that can communicate with T cells both directly and indirectly, regulating our adaptive immune responses against environmental and self-antigens. Under some microenvironmental conditions DC develop into anti-inflammatory cells which can induce immunologic tolerance. A substantial body of literature has confirmed that in such settings regulatory DC (DCreg) induce T cell tolerance by suppression of effector T cells as well as by induction of regulatory T cells (Treg). Many in vitro studies have been undertaken with human DCreg which, as a surrogate marker of antigen-specific tolerogenic potential, only poorly activate allogeneic T cell responses. Fewer studies have addressed the abilities of, or mechanisms by which these human DCreg suppress autologous effector T cell responses and induce infectious tolerance-promoting Treg responses. Moreover, the agents and properties that render DC as tolerogenic are many and varied, as are the cells’ relative regulatory activities and mechanisms of action. Herein we review the most current human and, where gaps exist, murine DCreg literature that addresses the cellular and molecular biology of these cells. We also address the clinical relevance of human DCreg, highlighting the outcomes of pre-clinical mouse and non-human primate studies and early phase clinical trials that have been undertaken, as well as the impact of innate immune receptors and symbiotic microbial signaling on the immunobiology of DCreg.

Therapeutic Lowering of C-Reactive Protein

In the blood of healthy individuals C-reactive protein (CRP) is typically quite scarce, whereas its blood concentration can rise robustly and rapidly in response to tissue damage and inflammation associated with trauma and infectious and non-infectious diseases. Consequently, CRP plasma or serum levels are routinely monitored in inpatients to gauge the severity of their initial illness and injury and their subsequent response to therapy and return to health. Its clinical utility as a faithful barometer of inflammation notwithstanding, it is often wrongly concluded that the biological actions of CRP (whatever they may be) are manifested only when blood CRP is elevated. In fact over the last decades, studies done in humans and animals (e.g. human CRP transgenic and CRP knockout mice) have shown that CRP is an important mediator of biological activities even in the absence of significant blood elevation, i.e. even at baseline levels. In this review we briefly recap the history of CRP, including a description of its discovery, early clinical use, and biosynthesis at baseline and during the acute phase response. Next we overview evidence that we and others have generated using animal models of arthritis, neointimal hyperplasia, and acute kidney injury that baseline CRP exerts important biological effects. In closing we discuss the possibility that therapeutic lowering of baseline CRP might be a useful way to treat certain diseases, including cancer.

Modeling of the immune response in the pathogenesis of solid tumors and its prognostic significance

BACKGROUND

Tumor initiation and subsequent progression are usually long-term processes, spread over time and conditioned by diverse aspects. Many cancers develop on the basis of chronic inflammation; however, despite dozens of years of research, little is known about the factors triggering neoplastic transformation under these conditions. Molecular characterization of both pathogenetic states, i.e., similarities and differences between chronic inflammation and cancer, is also poorly defined. The secretory activity of tumor cells may change the immunophenotype of immune cells and modify the extracellular microenvironment, which allows the bypass of host defense mechanisms and seems to have diagnostic and prognostic value. The phenomenon of immunosuppression is also present during chronic inflammation, and the development of cancer, due to its duration, predisposes patients to the promotion of chronic inflammation. The aim of our work was to discuss the above issues based on the latest scientific insights. A theoretical mechanism of cancer immunosuppression is also proposed.

CONCLUSIONS

Development of solid tumors may occur both during acute and chronic phases of inflammation. Differences in the regulation of immune responses between precancerous states and the cancers resulting from them emphasize the importance of immunosuppressive factors in oncogenesis. Cancer cells may, through their secretory activity and extracellular transport mechanisms, enhance deterioration of the immune system which, in turn, may have prognostic implications.

Combined C-Reactive Protein and Novel Inflammatory Parameters as a Predictor in Cancer-What Can We Learn from the Hematological Experience?

The acute phase reaction is a systemic response to acute or chronic inflammation. The serum level of C-reactive protein (CRP) is the only acute phase biomarker widely used in routine clinical practice, including its uses for prognostics and therapy monitoring in cancer patients. Although Interleukin 6 (IL6) is a main trigger of the acute phase reactions, a series of acute phase reactants can contribute (e.g., other members in IL6 family or IL1 subfamily, and tumor necrosis factor α). However, the experience from patients receiving intensive chemotherapy for hematological malignancies has shown that, besides CRP, other biomarkers (e.g., cytokines, soluble cytokine receptors, soluble adhesion molecules) also have altered systemic levels as a part of the acute phase reaction in these immunocompromised patients. Furthermore, CRP and white blood cell counts can serve as a dual prognostic predictor in solid tumors and hematological malignancies. Recent studies also suggest that biomarker profiles as well as alternative inflammatory mediators should be further developed to optimize the predictive utility in cancer patients. Finally, the experience from allogeneic stem cell transplantation suggests that selected acute phase reactants together with specific markers of organ damages are useful for predicting or diagnosing graft versus host disease. Acute phase proteins may also be useful to identify patients (at risk of) developing severe immune-mediated toxicity after anticancer immunotherapy. To conclude, future studies of acute phase predictors in human malignancies should not only investigate the conventional inflammatory mediators (e.g., CRP, white blood cell counts) but also combinations of novel inflammatory parameters with specific markers of organ damages.

Serum interleukin-6 and C-reactive protein are associated with survival in melanoma patients receiving immune checkpoint inhibition

BACKGROUND

Inflammatory mediators, including acute phase reactants and cytokines, have been reported to be associated with clinical efficacy in patients with melanoma and other cancers receiving immune checkpoint inhibitors (ICI). Analyses of patient sera from three large phase II/III randomized ICI trials, one of which included a chemotherapy arm, were performed to assess whether baseline levels of C-reactive protein (CRP), interleukin-6 (IL-6) or neutrophil/lymphocyte (N/L) ratios were prognostic or predictive.

PATIENTS AND METHODS

Baseline and on-treatment sera were analyzed by multiplex protein assays from immunotherapy-naïve patients with metastatic melanoma randomized 1:1 on the Checkmate-064 phase II trial of sequential administration of nivolumab followed by ipilimumab or the reverse sequence. Baseline sera, and peripheral blood mononuclear cells using automated cell counting, were analyzed from treatment-naïve patients who were BRAF wild-type and randomly allocated 1:1 to receive nivolumab or dacarbazine on the phase III Checkmate-066 trial, and from treatment-naïve patients allocated 1:1:1 to receive nivolumab, ipilimumab or both ipilimumab and nivolumab on the phase III Checkmate-067 trial.

RESULTS

Higher baseline levels of IL-6 and the N/L ratio, and to a lesser degree, CRP were associated with shorter survival in patients receiving ICI or chemotherapy. Increased on-treatment levels of IL-6 in patients on the Checkmate-064 study were also associated with shorter survival. IL-6 levels from patients on Checkmate-064, Checkmate-066 and Checkmate-067 were highly correlated with levels of CRP and the N/L ratio.

CONCLUSION

IL-6, CRP and the N/L ratio are prognostic factors with higher levels associated with shorter overall survival in patients with metastatic melanoma receiving ICI or chemotherapy in large randomized trials. In a multi-variable analysis of the randomized phase III Checkmate-067 study, IL-6 was a significant prognostic factor for survival.

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-1β, 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.

Thrombogenic and Inflammatory Reactions to Biomaterials in Medical Devices

Blood-contacting medical devices of different biomaterials are often used to treat various cardiovascular diseases. Thrombus formation is a common cause of failure of cardiovascular devices. Currently, there are no clinically available biomaterials that can totally inhibit thrombosis under the more challenging environments (e.g., low flow in the venous system). Although some biomaterials reduce protein adsorption or cell adhesion, the issue of biomaterial associated with thrombosis and inflammation still exists. To better understand how to develop more thrombosis-resistant medical devices, it is essential to understand the biology and mechano-transduction of thrombus nucleation and progression. In this review, we will compare the mechanisms of thrombus development and progression in the arterial and venous systems. We will address various aspects of thrombosis, starting with biology of thrombosis, mathematical modeling to integrate the mechanism of thrombosis, and thrombus formation on medical devices. Prevention of these problems requires a multifaceted approach that involves more effective and safer thrombolytic agents but more importantly the development of novel thrombosis-resistant biomaterials mimicking the biological characteristics of the endothelium and extracellular matrix tissues that also ameliorate the development and the progression of chronic inflammation as part of the processes associated with the detrimental generation of late thrombosis and neo-atherosclerosis. Until such developments occur, engineers and clinicians must work together to develop devices that require minimal anticoagulants and thrombolytics to mitigate thrombosis and inflammation without causing serious bleeding side effects.

C-Reactive Protein Causes Adult-Onset Obesity Through Chronic Inflammatory Mechanism

Obesity is characterized by low-grade chronic inflammation. As an acute-phase reactant to inflammation and infection, C-reactive protein (CRP) has been found to be the strongest factor associated with obesity. Here we show that chronic elevation of human CRP at baseline level causes the obesity. The obesity phenotype is confirmed by whole-body magnetic resonance imaging (MRI), in which the total fat mass is 6- to 9- fold higher in the CRP rats than the control rats. Univariate linear regression analysis showed different growth rates between the CRP rats and the control rats, and that the difference appears around 11 weeks old, indicating that they developed adult-onset obesity. We also found that chronic elevation of CRP can prime molecular changes broadly in the innate immune system, energy expenditure systems, thyroid hormones, apolipoproteins, and gut flora. Our data established a causal role of CRP elevation in the development of adult-onset obesity.

Mice expressing the variant rs1143679 allele of ITGAM (CD11b) show impaired DC-mediated T cell proliferation

Genome-wide association studies (GWAS) and functional genomic analyses have implicated several ITGAM (CD11b) single-nucleotide polymorphisms (SNPs) in the development of SLE and other disorders. ITGAM encodes the αM chain of the β2 integrin Mac-1, a receptor that plays important roles in myeloid cell functions. The ITGAM SNP rs1143679, which results in an arginine to histidine change at amino acid position 77 of the CD11b protein, has been shown to reduce binding to several ligands and to alter Mac-1-mediated cellular response in vitro. Importantly, however, the potential contribution of this SNP variant to the initiation and/or progression of immune and inflammatory processes in vivo remains unexplored. Herein, we describe for the first time the generation and characterization of a mouse line expressing the 77His variant of CD11b. Surprisingly, we found that 77His did not significantly affect Mac-1-mediated leukocyte migration and activation as assessed using thioglycollate-induced peritonitis and LPS/TNF-α-induced dermal inflammation models. In contrast, expression of this variant did alter T cell immunity, as evidenced by significantly reduced proliferation of ovalbumin (OVA)-specific transgenic T cells in 77His mice immunized with OVA. Reduced antigen-specific T cell proliferation was also observed when either 77His splenic dendritic cells (DCs) or bone marrow-derived DCs were used as antigen-presenting cells (APCs). Although more work is necessary to determine how this alteration might influence the development of SLE or other diseases, these in vivo findings suggest that the 77His variant of CD11b can compromise the ability of DCs to induce antigen-driven T cell proliferation.

C-Reactive Protein Promotes the Expansion of Myeloid Derived Cells With Suppressor Functions

Previously we established that human C-reactive protein (CRP) exacerbates mouse acute kidney injury and that the effect was associated with heightened renal accumulation of myeloid derived cells with suppressor functions (MDSC). Herein we provide direct evidence that CRP modulates the development and suppressive actions of MDSCs in vitro. We demonstrate that CRP dose-dependently increases the generation of MDSC from wild type mouse bone marrow progenitors and enhances MDSC production of intracellular reactive oxygen species (iROS). When added to co-cultures, CRP significantly enhanced the ability of MDSCs to suppress CD3/CD28-stimulated T cell proliferation. Experiments using MDSCs from FcγRIIB deficient mice (FcγRIIB^-/-) showed that CRP's ability to expand MDSCs and trigger their increased production of iROS was FcγRIIB-independent, whereas its ability to enhance the MDSC T cell suppressive action was FcγRIIB-dependent. Importantly, CRP also enabled freshly isolated primary human neutrophils to suppress proliferation of autologous T cells. These findings suggest that CRP might be an endogenous regulator of MDSC numbers and actions in vivo.

Pentraxins and Fc Receptor-Mediated Immune Responses

C-reactive protein (CRP) is a member of the pentraxin family of proteins. These proteins are highly conserved over the course of evolution being present as far back as 250 million years ago. Mammalian pentraxins are characterized by the presence of five identical non-covalently linked subunits. Each subunit has a structurally conserved site for calcium-dependent ligand binding. The biological activities of the pentraxins established over many years include the ability to mediate opsonization for phagocytosis and complement activation. Pentraxins have an important role in protection from infection from pathogenic bacteria, and regulation of the inflammatory response. It was recognized early on that some of these functions are mediated by activation of the classical complement pathway through C1q. However, experimental evidence suggested that cellular receptors for pentraxins also play a role in phagocytosis. More recent experimental evidence indicates a direct link between pentraxins and Fc receptors. The Fc receptors were first identified as the major receptors for immunoglobulins. The avidity of the interaction between IgG complexes and Fc receptors is greatly enhanced when multivalent ligands interact with the IgG binding sites and activation of signaling pathways requires Fc receptor crosslinking. Human pentraxins bind and activate human and mouse IgG receptors, FcγRI and FcγRII, and the human IgA receptor, FcαRI. The affinities of the interactions between Fc receptors and pentraxins in solution and on cell surfaces are similar to antibody binding to low affinity Fc receptors. Crystallographic and mutagenesis studies have defined the structural features of these interactions and determined the stoichiometry of binding as one-to-one. Pentraxin aggregation or binding to multivalent ligands increases the avidity of binding and results in activation of these receptors for phagocytosis and cytokine synthesis. This review will discuss the structural and functional characteristics of pentraxin Fc receptor interactions and their implications for host defense and inflammation.

C-Reactive Protein Stimulates Nicotinic Acetylcholine Receptors to Control ATP-Mediated Monocytic Inflammasome Activation

Blood levels of the acute phase reactant C-reactive protein (CRP) are frequently measured as a clinical marker for inflammation, but the biological functions of CRP are still controversial. CRP is a phosphocholine (PC)-binding pentraxin, mainly produced in the liver in response to elevated levels of interleukin-1β (IL-1β) and of the IL-1β-dependent cytokine IL-6. While both cytokines play important roles in host defense, excessive systemic IL-1β levels can cause life-threatening diseases such as trauma-associated systemic inflammation. We hypothesized that CRP acts as a negative feedback regulator of monocytic IL-1β maturation and secretion. Here, we demonstrate that CRP, in association with PC, efficiently reduces ATP-induced inflammasome activation and IL-1β release from human peripheral blood mononuclear leukocytes and monocytic U937 cells. Effective concentrations are in the range of marginally pathologic CRP levels (IC50 = 4.9 µg/ml). CRP elicits metabotropic functions at nicotinic acetylcholine (ACh) receptors (nAChRs) containing subunits α7, α9, and α10 and suppresses the function of ATP-sensitive P2X7 receptors in monocytic cells. Of note, CRP does not induce ion currents at conventional nAChRs, suggesting that CRP is a potent nicotinic agonist controlling innate immunity without entailing the risk of adverse effects in the nervous system. In a prospective study on multiple trauma patients, IL-1β plasma concentrations negatively correlated with preceding CRP levels, whereas inflammasome-independent cytokines IL-6, IL-18, and TNF-α positively correlated. In conclusion, PC-laden CRP is an unconventional nicotinic agonist that potently inhibits ATP-induced inflammasome activation and might protect against trauma-associated sterile inflammation.

Exploring the Immunomodulatory Moonlighting Activities of Acute Phase Proteins for Tolerogenic Dendritic Cell Generation

The acute phase response is generated by an overwhelming immune-inflammatory process against infection or tissue damage, and represents the initial response of the organism in an attempt to return to homeostasis. It is mediated by acute phase proteins (APPs), an assortment of highly conserved plasma reactants of seemingly different functions that, however, share a common protective role from injury. Recent studies have suggested a crosstalk between several APPs and the mononuclear phagocyte system (MPS) in the resolution of inflammation, to restore tissue integrity and function. In fact, monocyte-derived dendritic cells (Mo-DCs), an integral component of the MPS, play a fundamental role both in the regulation of antigen-specific adaptive responses and in the development of immunologic memory and tolerance, particularly in inflammatory settings. Due to their high plasticity, Mo-DCs can be modeled in vitro toward a tolerogenic phenotype for the treatment of aberrant immune-inflammatory conditions such as autoimmune diseases and allotransplantation, with the phenotypic outcome of these cells depending on the immunomodulatory agent employed. Yet, recent immunotherapy trials have emphasized the drawbacks and challenges facing tolerogenic Mo-DC generation for clinical use, such as reduced therapeutic efficacy and limited in vivo stability of the tolerogenic activity. In this review, we will underline the potential relevance and advantages of APPs for tolerogenic DC production with respect to currently employed immunomodulatory/immunosuppressant compounds. A further understanding of the mechanisms of action underlying the moonlighting immunomodulatory activities exhibited by several APPs over DCs could lead to more efficacious, safe, and stable protocols for precision tolerogenic immunotherapy.