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Singh SK, Prislovsky A, Ngwa DN, Munkhsaikhan U, Abidi AH, Brand DD, Agrawal A. C-reactive protein lowers the serum level of IL-17, but not TNF-α, and decreases the incidence of collagen-induced arthritis in mice. Front Immunol 2024; 15:1385085. [PMID: 38650931 PMCID: PMC11033386 DOI: 10.3389/fimmu.2024.1385085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 03/25/2024] [Indexed: 04/25/2024] Open
Abstract
The biosynthesis of C-reactive protein (CRP) in the liver is increased in inflammatory diseases including rheumatoid arthritis. Previously published data suggest a protective function of CRP in arthritis; however, the mechanism of action of CRP remains undefined. The aim of this study was to evaluate the effects of human CRP on the development of collagen-induced arthritis (CIA) in mice which is an animal model of autoimmune inflammatory arthritis. Two CRP species were employed: wild-type CRP which binds to aggregated IgG at acidic pH and a CRP mutant which binds to aggregated IgG at physiological pH. Ten CRP injections were given on alternate days during the development of CIA. Both wild-type and mutant CRP reduced the incidence of CIA, that is, reduced the number of mice developing CIA; however, CRP did not affect the severity of the disease in arthritic mice. The serum levels of IL-17, IL-6, TNF-α, IL-10, IL-2 and IL-1β were measured: both wild-type and mutant CRP decreased the level of IL-17 and IL-6 but not of TNF-α, IL-10, IL-2 and IL-1β. These data suggest that CRP recognizes and binds to immune complexes, although it was not clear whether CRP functioned in its native pentameric or in its structurally altered pentameric form in the CIA model. Consequently, ligand-complexed CRP, through an as-yet undefined mechanism, directly or indirectly, inhibits the production of IL-17 and eventually protects against the initiation of the development of arthritis. The data also suggest that IL-17, not TNF-α, is critical for the development of autoimmune inflammatory arthritis.
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Affiliation(s)
- Sanjay K. Singh
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Amanda Prislovsky
- The Lt. Col. Luke Weathers, Jr. VA Medical Center, Memphis, TN, United States
| | - Donald N. Ngwa
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Undral Munkhsaikhan
- College of Dental Medicine, Lincoln Memorial University, Knoxville, TN, United States
| | - Ammaar H. Abidi
- College of Dental Medicine, Lincoln Memorial University, Knoxville, TN, United States
| | - David D. Brand
- The Lt. Col. Luke Weathers, Jr. VA Medical Center, Memphis, TN, United States
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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Friend SF, Nachnani R, Powell SB, Risbrough VB. C-Reactive Protein: Marker of risk for post-traumatic stress disorder and its potential for a mechanistic role in trauma response and recovery. Eur J Neurosci 2022; 55:2297-2310. [PMID: 33131159 PMCID: PMC8087722 DOI: 10.1111/ejn.15031] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/17/2020] [Accepted: 10/06/2020] [Indexed: 01/08/2023]
Abstract
Increasing evidence indicates that inflammation plays a role in PTSD and stress disorder pathophysiology. PTSD is consistently associated with higher circulating inflammatory protein levels. Rodent models demonstrate that inflammation promotes enduring avoidance and arousal behaviors after severe stressors (e.g., predator exposure and social defeat), suggesting that inflammation may play a mechanistic role in trauma disorders. C-reactive protein (CRP) is an innate acute phase reactant produced by the liver after acute infection and chronic disease. A growing number of investigations report associations with PTSD diagnosis and elevated peripheral CRP, CRP gene mutations, and CRP gene expression changes in immune signaling pathways. CRP is reasonably established as a potential marker of PTSD and trauma exposure, but if and how it may play a mechanistic role is unclear. In this review, we discuss the current understanding of immune mechanisms in PTSD with a particular focus on the innate immune signaling factor, CRP. We found that although there is consistent evidence of an association of CRP with PTSD symptoms and risk, there is a paucity of data on how CRP might contribute to CNS inflammation in PTSD, and consequently, PTSD symptoms. We discuss potential mechanisms through which CRP could modulate enduring peripheral and CNS stress responses, along with future areas of investigation probing the role of CRP and other innate immune signaling factors in modulating trauma responses. Overall, we found that CRP likely contributes to central inflammation, but how it does so is an area for further study.
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Affiliation(s)
- Samantha F. Friend
- Veterans Affairs Center of Excellence for Stress and Mental HealthSan DiegoCAUSA,Department of PsychiatryUniversity of California San DiegoSan DiegoCAUSA
| | - Rahul Nachnani
- Department of PharmacologyPenn State College of MedicineHersheyPAUSA
| | - Susan B. Powell
- Department of PsychiatryUniversity of California San DiegoSan DiegoCAUSA,Research ServiceVA San Diego Healthcare SystemSan DiegoCAUSA
| | - Victoria B. Risbrough
- Veterans Affairs Center of Excellence for Stress and Mental HealthSan DiegoCAUSA,Department of PsychiatryUniversity of California San DiegoSan DiegoCAUSA
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Yang M, Qiu S, He Y, Li L, Wu T, Ding N, Li F, Zhao AZ, Yang G. Genetic ablation of C-reactive protein gene confers resistance to obesity and insulin resistance in rats. Diabetologia 2021; 64:1169-1183. [PMID: 33544171 DOI: 10.1007/s00125-021-05384-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 11/06/2020] [Indexed: 12/30/2022]
Abstract
AIMS/HYPOTHESIS Besides serving as a traditional inflammatory marker, C-reactive protein (CRP) is closely associated with the development of obesity, diabetes and cardiovascular diseases as a metabolic and inflammatory marker. We hypothesise that CRP protein directly participates in the regulation of energy and glucose metabolism rather than just being a surrogate marker, and that genetic deficiency of CRP will lead to resistance to obesity and insulin resistance. METHODS Crp gene deletion was achieved by transcription activator-like effector nuclease (TALEN) technology in rats. The Crp knockout animals were placed on either a standard chow diet or a high-fat diet. Phenotypic changes in body weight, glucose metabolism, insulin sensitivity, energy expenditure and inflammation condition were examined. The central impact of CRP deficiency on leptin and insulin hypothalamic signalling, as well as glucose homeostasis, were examined via intracerebral ventricular delivery of leptin and CRP plus glucose clamp studies in the wild-type and Crp knockout rats. RESULTS CRP deficiency led to a significant reduction in weight gain and food intake, elevated energy expenditure and improved insulin sensitivity after exposure to high-fat diet. Glucose clamp studies revealed enhanced hepatic insulin signalling and actions. Deficiency of CRP enhanced and prolonged the weight-reducing effect of central injected leptin and promoted the central and peripheral roles of leptin. By contrast, reinstatement of CRP into the hypothalamus of the knockout rats attenuated the effects of central leptin signalling on insulin sensitivity and peripheral glucose metabolism. CONCLUSIONS/INTERPRETATION This study represents the first line of genetic evidence that CRP is not merely a surrogate blood marker for inflammation and metabolic syndromes but directly regulates energy balance, body weight, insulin sensitivity and glucose homeostasis through direct regulation of leptin's central effect and hypothalamic signalling.
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Affiliation(s)
- Mengliu Yang
- Department of Endocrinology, the 2nd Affiliated Hospital, Chongqing Medical University, Chongqing, China
- The Center of Clinical Research of Endocrinology and Metabolic Diseases in Chongqing and Department of Endocrinology, Chongqing Three Gorges Central Hospital, Chongqing, China
| | - Sheng Qiu
- Department of Endocrinology, the 2nd Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Yirui He
- Department of Endocrinology, the 2nd Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Ling Li
- Key Laboratory of Diagnostic Medicine (Ministry of Education) and Department of Clinical Biochemistry, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China
| | - Tong Wu
- Department of Endocrinology, the 2nd Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Ning Ding
- The School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Fanghong Li
- The School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Allan Z Zhao
- The School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China.
| | - Gangyi Yang
- Department of Endocrinology, the 2nd Affiliated Hospital, Chongqing Medical University, Chongqing, China.
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Tsai MH, Lin CH, Tsai KW, Lin MH, Ho CJ, Lu YT, Weng KP, Lin Y, Lin PH, Li SC. S100A6 Promotes B Lymphocyte Penetration Through the Blood-Brain Barrier in Autoimmune Encephalitis. Front Genet 2019; 10:1188. [PMID: 31850060 PMCID: PMC6901080 DOI: 10.3389/fgene.2019.01188] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/28/2019] [Indexed: 12/12/2022] Open
Abstract
Autoimmune encephalitis (AE) is a severe neurological disease. The brain of the AE patient is attacked by a dysregulated immune system, which is caused by the excessive production of autoantibodies against neuronal receptors and synaptic proteins. AE is also characterized by the uncontrolled B lymphocyte infiltration through the blood–brain barrier (BBB) layer, and the investigation of the underlying mechanism involved in this infiltration may facilitate the discovery of novel therapies for AE. However, few AE-related studies have focused on this issue. In this study, we aimed to identify the factors involved in B lymphocyte infiltration in AE. For this purpose, we first enrolled four healthy control and five AE subjects, collecting their serum and/or total white blood cell samples. The white blood cell samples were further used for collecting RNA and DNA. Then, we simulated the in vivo B lymphocyte infiltration with an in vitro leukocyte transendothelial migration model. It turned out that AE serum treatment significantly and specifically promoted B cells to penetrate the BBB endothelial layer without affecting neutrophils. Next, through genome-wide DNA methylation assays on bisulfite-conversion DNA samples, we identified S100A6 and S100A11 as potential hypo-methylated disease genes in the AE samples. Further qPCR assays demonstrated their upregulation in AE samples, reflecting the negative correlations between gene expression and DNA methylation. Finally, recombinant S100A6 protein treatment significantly increased B lymphocyte infiltration through the BBB endothelial layer, which partially recapitulated the effect of AE serum. In summary, by using an in vitro leukocyte transendothelial migration model, we confirmed that S100A6 promoted B lymphocyte to penetrate the BBB endothelial layer, which is similar to the in vivo clinical manifestations of AE. Therefore, further studies on how the S100A6 protein facilitates B lymphocyte infiltration and on whether other factors in serum also contribute to this phenomenon are likely to improve our understanding of AE and hopefully to reveal novel therapeutic targets for this emerging treatable neurological disorder.
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Affiliation(s)
- Meng-Han Tsai
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Chih-Hsiang Lin
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Kuo-Wang Tsai
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Ming-Hong Lin
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chen-Jui Ho
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Yan-Ting Lu
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Ken-Pen Weng
- Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.,Department of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Nursing, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan
| | - Yuyu Lin
- Genomics and Proteomics Core Laboratory, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Pei-Hsien Lin
- Genomics and Proteomics Core Laboratory, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Sung-Chou Li
- Genomics and Proteomics Core Laboratory, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
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Jimenez RV, Wright TT, Jones NR, Wu J, Gibson AW, Szalai AJ. C-Reactive Protein Impairs Dendritic Cell Development, Maturation, and Function: Implications for Peripheral Tolerance. Front Immunol 2018; 9:372. [PMID: 29556231 PMCID: PMC5845098 DOI: 10.3389/fimmu.2018.00372] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/09/2018] [Indexed: 12/23/2022] Open
Abstract
C-reactive protein (CRP) is the prototypical acute phase reactant, increasing in blood concentration rapidly and several-fold in response to inflammation. Recent evidence indicates that CRP has an important physiological role even at low, baseline levels, or in the absence of overt inflammation. For example, we have shown that human CRP inhibits the progression of experimental autoimmune encephalomyelitis (EAE) in CRP transgenic mice by shifting CD4+ T cells away from the TH1 and toward the TH2 subset. Notably, this action required the inhibitory Fcγ receptor IIB (FcγRIIB), but did not require high levels of human CRP. Herein, we sought to determine if CRP’s influence in EAE might be explained by CRP acting on dendritic cells (DC; antigen presenting cells known to express FcγRIIB). We found that CRP (50 µg/ml) reduced the yield of CD11c+ bone marrow-derived DCs (BMDCs) and CRP (≥5 μg/ml) prevented their full expression of major histocompatibility complex class II and the co-stimulatory molecules CD86 and CD40. CRP also decreased the ability of BMDCs to stimulate antigen-driven proliferation of T cells in vitro. Importantly, if the BMDCs were genetically deficient in mouse FcγRIIB then (i) the ability of CRP to alter BMDC surface phenotype and impair T cell proliferation was ablated and (ii) CD11c-driven expression of a human FCGR2B transgene rescued the CRP effect. Lastly, the protective influence of CRP in EAE was fully restored in mice with CD11c-driven human FcγRIIB expression. These findings add to the growing evidence that CRP has important biological effects even in the absence of an acute phase response, i.e., CRP acts as a tonic suppressor of the adaptive immune system. The ability of CRP to suppress development, maturation, and function of DCs implicates CRP in the maintenance of peripheral T cell tolerance.
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Affiliation(s)
- Rachel V Jimenez
- Department of Medicine, Division of Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Tyler T Wright
- Division of Drug Development, Southern Research, Birmingham, AL, United States
| | - Nicholas R Jones
- Department of Medicine, Division of Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jianming Wu
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Minneapolis, MN, United States
| | - Andrew W Gibson
- Department of Medicine, Division of Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Alexander J Szalai
- Department of Medicine, Division of Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, United States
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Chen W, Pilling D, Gomer RH. C-reactive protein (CRP) but not the related pentraxins serum amyloid P and PTX3 inhibits the proliferation and induces apoptosis of the leukemia cell line Mono Mac 6. BMC Immunol 2017; 18:47. [PMID: 29202702 PMCID: PMC5716379 DOI: 10.1186/s12865-017-0230-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/19/2017] [Indexed: 12/23/2022] Open
Abstract
Background Pentraxins are a family of highly conserved secreted proteins that regulate the innate immune system, including monocytes and macrophages. C-reactive protein (CRP) is a plasma protein whose levels can rise to 1000 μg/ml from the normal <3 μg/ ml during inflammation. Results We find that CRP inhibits proliferation of the human myeloid leukemia cell line Mono Mac 6 with an IC50 of 75 μg/ ml by inducing apoptosis of these cells. The related proteins serum amyloid P (SAP) and pentraxin 3 (PTX3) do not inhibit Mono Mac 6 proliferation. CRP has no significant effect on the proliferation of other leukemia cell lines such as HL-60, Mono Mac 1, K562, U937, or THP-1, or the survival of normal peripheral blood cells. The effect of CRP appears to be dependent on the CRP receptor FcγRI, and is negatively regulated by a phosphatidylinositol −3-kinase pathway. Conclusion These data reveal differential signaling by pentraxins on immune cells, and suggest that CRP can regulate the proliferation of some myeloid leukemia cells.
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Affiliation(s)
- Wensheng Chen
- Department of Biology, Texas A&M University, College Station, TX, 77843-3474, USA.,Institute of Clinical Pharmacology, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Hefei, 230032, China
| | - Darrell Pilling
- Department of Biology, Texas A&M University, College Station, TX, 77843-3474, USA
| | - Richard H Gomer
- Department of Biology, Texas A&M University, College Station, TX, 77843-3474, USA.
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Monocyte differentiation and macrophage priming are regulated differentially by pentraxins and their ligands. BMC Immunol 2017; 18:30. [PMID: 28619036 PMCID: PMC5472910 DOI: 10.1186/s12865-017-0214-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/08/2017] [Indexed: 01/01/2023] Open
Abstract
Background Circulating bone marrow-derived monocytes can leave the blood, enter a tissue, and differentiate into M1 inflammatory, M2a remodeling/fibrotic, or M2c/Mreg resolving/immune-regulatory macrophages. Macrophages can also convert from one of the above types to another. Pentraxins are secreted proteins that bind to, and promote efficient clearance of, microbial pathogens and cellular debris during infection, inflammation, and tissue damage. The pentraxins C-reactive protein (CRP), serum amyloid P (SAP), and pentraxin-3 (PTX3) can also bind a variety of endogenous ligands. As monocytes and macrophages are exposed to differing concentrations of pentraxins and their ligands during infection, inflammation, and tissue damage, we assessed what effect pentraxins and their ligands have on these cells. Results We found that many polarization markers do not discriminate between the effects of pentraxins and their ligands on macrophages. However, pentraxins, their ligands, and cytokines differentially regulate the expression of the hemoglobin-haptoglobin complex receptor CD163, the sialic acid-binding lectin CD169, and the macrophage mannose receptor CD206. CRP, a pentraxin generally thought of as being pro-inflammatory, increases the extracellular accumulation of the anti-inflammatory cytokine IL-10, and this effect is attenuated by GM-CSF, mannose-binding lectin, and factor H. Conclusions These results suggest that the presence of pentraxins and their ligands regulate macrophage differentiation in the blood and tissues, and that CRP may be a potent inducer of the anti-inflammatory cytokine IL-10. Electronic supplementary material The online version of this article (doi:10.1186/s12865-017-0214-z) contains supplementary material, which is available to authorized users.
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