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Höpfinger A, Behrendt M, Schmid A, Karrasch T, Schäffler A, Berghoff M. A Cross-Sectional Study: Systematic Quantification of Chemerin in Human Cerebrospinal Fluid. Biomedicines 2024; 12:2508. [PMID: 39595074 PMCID: PMC11592017 DOI: 10.3390/biomedicines12112508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2024] [Revised: 10/16/2024] [Accepted: 10/25/2024] [Indexed: 11/28/2024] Open
Abstract
BACKGROUND Dysregulation of adipokines is considered a key mechanism of chronic inflammation in metabolic syndrome. Some adipokines affect food intake by crossing the blood/brain barrier. The adipokine chemerin is associated with metabolic syndrome, cardiovascular diseases and immune response. Little is known about chemerin's presence in cerebrospinal fluid (CSF) and its ability to cross the blood/CSF barrier. METHODS We quantified chemerin levels in paired serum and CSF samples of 390 patients with different neurological diagnoses via enzyme-linked immunosorbent assay (ELISA). Correlation analyses of serum and CSF chemerin levels with anthropometric, serum and CSF routine parameters were performed. RESULTS Overweight patients exhibited higher chemerin levels in serum and CSF. Chemerin CSF levels were higher in men. Chemerin levels in serum were associated with BMI (body mass index) and CRP (C-reactive protein). Chemerin levels in CSF were associated with age. Neurological diseases affected chemerin levels in CSF. The chemerin CSF/serum ratio was calculated as 96.3 ± 36.8 × 10-3 for the first time. CONCLUSIONS Our data present a basis for the development of standard values for chemerin quantities in CSF. CSF chemerin levels are differentially regulated in neurological diseases and affected by BMI and sex. Chemerin is able to cross the blood/CSF barrier under physiological and pathophysiological conditions.
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Schmid A, Liebisch G, Burkhardt R, Belikan H, Köhler S, Steger D, Schweitzer L, Pons-Kühnemann J, Karrasch T, Schäffler A. Dynamics of the human bile acid metabolome during weight loss. Sci Rep 2024; 14:25743. [PMID: 39468179 PMCID: PMC11519931 DOI: 10.1038/s41598-024-75831-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Accepted: 10/08/2024] [Indexed: 10/30/2024] Open
Abstract
Bile acids (BA) are supposed to cause metabolic alterations after bariatric surgery (BS). Here we report the longitudinal dynamics of the human BA metabolome by LC-MS/MS after BS versus low calory diet (LCD) in two obesity cohorts over 12 months. Rapid and persistent oscillations of 23 BA subspecies could be identified with highly specific patterns in BS vs. LCD. TCDCA, GLCA, and TLCA represent most promising candidates for drug development.
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Schmid A, Pankuweit S, Vlacil AK, Koch S, Berge B, Gajawada P, Richter M, Troidl K, Schieffer B, Schäffler A, Grote K. Decreased circulating CTRP3 levels in acute and chronic cardiovascular patients. J Mol Med (Berl) 2024; 102:667-677. [PMID: 38436713 PMCID: PMC11055757 DOI: 10.1007/s00109-024-02426-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 03/05/2024]
Abstract
C1q/TNF-related protein 3 (CTRP3) represents an adipokine with various metabolic and immune-regulatory functions. While circulating CTRP3 has been proposed as a potential biomarker for cardiovascular disease (CVD), current data on CTRP3 regarding coronary artery disease (CAD) remains partially contradictory. This study aimed to investigate CTRP3 levels in chronic and acute settings such as chronic coronary syndrome (CCS) and acute coronary syndrome (ACS). A total of 206 patients were classified into three groups: CCS (n = 64), ACS having a first acute event (ACS-1, n = 75), and ACS having a recurrent acute event (ACS-2, n = 67). The control group consisted of 49 healthy individuals. ELISA measurement in peripheral blood revealed decreased CTRP3 levels in all patient groups (p < 0.001) without significant differences between the groups. This effect was exclusively observed in male patients. Females generally exhibited significantly higher CTRP3 plasma levels than males. ROC curve analysis in male patients revealed a valuable predictive potency of plasma CTRP3 in order to identify CAD patients, with a proposed cut-off value of 51.25 ng/mL. The sensitivity and specificity of prediction by CTRP3 were congruent for the subgroups of CCS, ACS-1, and ACS-2 patients. Regulation of circulating CTRP3 levels in murine models of cardiovascular pathophysiology was found to be partly opposite to the clinical findings, with male mice exhibiting higher circulating CTRP3 levels than females. We conclude that circulating CTRP3 levels are decreased in both male CCS and ACS patients. Therefore, CTRP3 might be useful as a biomarker for CAD but not for distinguishing an acute from a chronic setting. KEY MESSAGES: CTRP3 levels were found to be decreased in both male CCS and ACS patients compared to healthy controls. Plasma CTRP3 has a valuable predictive potency in order to identify CAD patients among men and is therefore proposed as a biomarker for CAD but not for distinguishing between acute and chronic settings. Regulation of circulating CTRP3 levels in murine models of cardiovascular pathophysiology was found to be partly opposite to the clinical findings in men.
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Höpfinger A, Schmid A, Karrasch T, Pankuweit S, Schäffler A, Grote K. Cathelicidin Antimicrobial Peptide Levels in Atherosclerosis and Myocardial Infarction in Mice and Human. Int J Mol Sci 2024; 25:2909. [PMID: 38474156 PMCID: PMC10931542 DOI: 10.3390/ijms25052909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/28/2024] [Accepted: 02/28/2024] [Indexed: 03/14/2024] Open
Abstract
Obesity represents a worldwide health challenge, and the condition is accompanied by elevated risk of cardiovascular diseases caused by metabolic dysfunction and proinflammatory adipokines. Among those, the immune-modulatory cathelicidin antimicrobial peptide (human: CAMP; murine: CRAMP) might contribute to the interaction of the innate immune system and metabolism in these settings. We investigated systemic CAMP/CRAMP levels in experimental murine models of atherosclerosis, myocardial infarction and cardiovascular patients. Atherosclerosis was induced in low-density lipoprotein receptor-deficient (Ldlr-/-) mice by high-fat diet (HFD). C57BL/6J wild-type mice were subjected to myocardial infarction by permanent or transient left anterior descending (LAD)-ligation. Cramp gene expression in murine organs and tissues was investigated via real-time PCR. Blood samples of 234 adult individuals with or without coronary artery disease (CAD) were collected. Human and murine CAMP/CRAMP serum levels were quantified by ELISA. Atherosclerotic mice exhibited significantly increased CRAMP serum levels and induced Cramp gene expression in the spleen and liver, whereas experimental myocardial infarction substantially decreased CRAMP serum levels. Human CAMP serum quantities were not significantly affected by CAD while being correlated with leukocytes and pro-inflammatory cytokines. Our data show an influence of cathelicidin in experimental atherosclerosis, myocardial infarction, as well as in patients with CAD. Further studies are needed to elucidate the pathophysiological mechanism.
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Schmid A, Roderfeld M, Karrasch T, Roeb E, Schäffler A. Serum Chemerin Is Decreased by Roux-en-Y Gastric Bypass and Low Calorie-Formula Diet in Obese Individuals. Biomedicines 2023; 12:33. [PMID: 38255140 PMCID: PMC10813162 DOI: 10.3390/biomedicines12010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/13/2023] [Accepted: 12/16/2023] [Indexed: 01/24/2024] Open
Abstract
The pleiotropic chemokine chemerin is involved in multiple processes in metabolism and inflammation. The present study aimed to elucidate its regulation in morbid obesity and during therapy-induced rapid weight loss. A total of 128 severely obese patients were enrolled, and their basal anthropometric and clinical parameters were assessed. In total, 64 individuals attended a conservative 12-month weight loss program that included a low calorie-formula diet (LCD), and 64 patients underwent bariatric surgery (Roux-en-Y gastric bypass, RYGB). Blood serum was obtained at study baseline and at follow-up visits after 3, 6, and 12 months. Systemic chemerin concentrations, as well as metabolic and immunological parameters, were quantified. During the 12-month period studied, serum chemerin levels decreased significantly with weight loss after bariatric surgery, as well as with conservative low calorie therapy; however, the effects of RYGB were generally stronger. No substantial associations of systemic chemerin concentrations with therapy-induced improvement of type 2 diabetes and with indicators of liver function and fibrosis were observed. We conclude that systemic chemerin levels decrease in obese individuals during weight loss, regardless of the therapeutic strategy. A potential involvement in weight loss-associated improvement of metabolic disorders and liver fibrosis remains to be further investigated.
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Schmid A, Karrasch T, Schäffler A. The emerging role of bile acids in white adipose tissue. Trends Endocrinol Metab 2023; 34:718-734. [PMID: 37648561 DOI: 10.1016/j.tem.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/21/2023] [Accepted: 08/02/2023] [Indexed: 09/01/2023]
Abstract
The effects of bile acids (BAs) on liver, enteroendocrine function, small intestine, and brown adipose tissue have been described extensively. Outside the liver, BAs in the peripheral circulation system represent a specific but underappreciated physiological compartment. We discuss how systemic BAs can be regarded as specific steroidal hormones that act on white adipocytes, and suggest the name 'bilokines' ('bile hormones') for the specific FXR/TGR5 receptor interaction in adipocytes. Some BAs and their agonists regulate adipocyte differentiation, lipid accumulation, hypoxia, autophagy, adipokine and cytokine secretion, insulin signaling, and glucose uptake. BA signaling could provide a new therapeutic avenue for adipoflammation and metaflammation in visceral obesity, the causal mechanisms underlying insulin resistance and type 2 diabetes mellitus (T2D).
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Höpfinger A, Schmid A, Schweitzer L, Patz M, Weber A, Schäffler A, Karrasch T. Regulation of Cathelicidin Antimicrobial Peptide (CAMP) Gene Expression by TNFα and cfDNA in Adipocytes. Int J Mol Sci 2023; 24:15820. [PMID: 37958808 PMCID: PMC10649744 DOI: 10.3390/ijms242115820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 10/16/2023] [Accepted: 10/21/2023] [Indexed: 11/15/2023] Open
Abstract
Understanding the complex interactions between metabolism and the immune system ("metaflammation") is crucial for the identification of key immunomodulatory factors as potential therapeutic targets in obesity and in cardiovascular diseases. Cathelicidin antimicrobial peptide (CAMP) is an important factor of innate immunity and is expressed in adipocytes. CAMP, therefore, might play a role as an adipokine in metaflammation and adipose inflammation. TNFα, cell-free nucleic acids (cfDNA), and toll-like receptor (TLR) 9 are components of the innate immune system and are functionally active in adipose tissue. The aim of the present study was to investigate the impact of TNFα and cfDNA on CAMP expression in adipocytes. Since cfDNA acts as a physiological TLR9 agonist, we additionally investigated TLR9-mediated CAMP regulation in adipocytes and adipose tissue. CAMP gene expression in murine 3T3-L1 and human SGBS adipocytes and in murine and human adipose tissues was quantified by real-time PCR. Adipocyte inflammation was induced in vitro by TNFα and cfDNA stimulation. Serum CAMP concentrations in TLR9 knockout (KO) and in wildtype mice were quantified by ELISA. In primary adipocytes of wildtype and TLR9 KO mice, CAMP gene expression was quantified by real-time PCR. CAMP gene expression was considerably increased in 3T3-L1 and SGBS adipocytes during differentiation. TNFα significantly induced CAMP gene expression in mature adipocytes, which was effectively antagonized by inhibition of PI3K signaling. Cell-free nucleic acids (cfDNA) significantly impaired CAMP gene expression, whereas synthetic agonistic and antagonistic TLR9 ligands had no effect. CAMP and TLR9 gene expression were correlated positively in murine and human subcutaneous but not in intra-abdominal/visceral adipose tissues. Male TLR9 knockout mice exhibited lower systemic CAMP concentrations than wildtype mice. CAMP gene expression levels in primary adipocytes did not significantly differ between wildtype and TLR9 KO mice. These findings suggest a regulatory role of inflammatory mediators, such as TNFα and cfDNA, in adipocytic CAMP expression as a novel putative molecular mechanism in adipose tissue innate immunity.
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Höpfinger A, Karrasch T, Schäffler A, Schmid A. Circulating Concentrations of Cathelicidin Anti-Microbial Peptide (CAMP) Are Increased during Oral Glucose Tolerance Test. Int J Mol Sci 2023; 24:12901. [PMID: 37629082 PMCID: PMC10454907 DOI: 10.3390/ijms241612901] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Recent investigation has revealed the significant role of Cathelicidin antimicrobial peptide (CAMP) in infection defense and innate immunity processes in adipose tissue. Meanwhile, knowledge of its regulation and functions in metabolic contexts as an adipokine remains sparce. The present study investigated the postprandial regulation of circulating CAMP levels during oral glucose tolerance tests (OGTTs). Eighty-six metabolically healthy volunteers participated in a standardized 75 g-2 h-OGTT setting. The effects of exogenous glucose, insulin, and incretins on CAMP expression in human adipocyte culture (cell-line SGBS) were studied in vitro. CAMP concentrations in blood serum samples were measured by ELISA techniques and adipocyte gene expression levels were quantified by real-time PCR. Of note, base-line CAMP serum quantities were negatively correlated with HDL cholesterol levels as well as with the anti-inflammatory adipokine adiponectin. During the 2 h following glucose ingestion, a significant rise in circulating CAMP concentrations was observed in considerable contrast to reduced quantities of fatty acid binding proteins (FABP) 2 and 4 and dipeptidyl peptidase 4 (DPP4). In SGBS adipocytes, neither differing glucose levels nor insulin or incretin treatment significantly induced CAMP mRNA levels. According to our data, glucose represents a positive postprandial regulator of systemic CAMP. This effect apparently is not mediated by the regulatory impact of glucose metabolism on adipocyte CAMP expression.
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Höpfinger A, Karrasch T, Schäffler A, Schmid A. Circulating Levels of Cathelicidin Antimicrobial Peptide (CAMP) Are Affected by Oral Lipid Ingestion. Nutrients 2023; 15:3021. [PMID: 37447348 DOI: 10.3390/nu15133021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023] Open
Abstract
INTRODUCTION Obesity and related diseases are among the main public health issues in the western world. They are thought to be caused by a state of chronic, low-grade inflammation. Cathelicidin antimicrobial peptide (CAMP) was recently discovered to be expressed and secreted by adipocytes. Representing a novel immunomodulatory adipokine, CAMP might play an important role in the complex interaction between metabolism and inflammation. METHODS In a cohort of 80 volunteers, serum samples were collected prior to, and 2 h, 4 h, and 6 h after, oral lipid ingestion. CAMP, fatty acid binding proteins 2 and 4 (FABP-2/-4), and dipeptidylpeptidase-4 (DPP-4) serum concentrations were measured via ELISA. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were treated with free fatty acids, and gene expression levels of CAMP, FABP-4, and DPP-4 were quantified by RT-PCR. RESULTS The mean base-line CAMP serum concentration was 55.78 ± 29.26 ng/mL, with a range of 10.77-146.24 ng/mL. Interestingly, CAMP serum levels were positively correlated with LDL cholesterol, but negatively correlated with HDL cholesterol and adiponectin. Men exhibited higher CAMP serum concentrations than women, an effect apparently linked to oral contraception in the majority of female participants. In both genders, CAMP serum concentrations significantly decreased in a stepwise manner 4 h and 6 h after oral lipid ingestion. This decline was paralleled by a rise of serum bile acid and triglyceride levels upon lipid ingestion. In human SGBS adipocytes, treatment with free fatty acids did not affect CAMP gene expression, but increased FABP-4 gene expression. CONCLUSIONS In conclusion, systemic levels of the antimicrobial peptide and novel adipokine CAMP are significantly decreased upon oral lipid ingestion. While this decline might be linked to the simultaneous increase in bile acids, the underlying mechanisms remain to be elucidated. Furthermore, CAMP might indicate a putative novel cardiovascular biomarker of both inflammatory and metabolic relevance in metaflammation and adipose inflammation.
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Altmannova V, Firlej M, Müller F, Janning P, Rauleder R, Rousova D, Schäffler A, Bange T, Weir JR. Biochemical characterisation of Mer3 helicase interactions and the protection of meiotic recombination intermediates. Nucleic Acids Res 2023; 51:4363-4384. [PMID: 36942481 PMCID: PMC10201424 DOI: 10.1093/nar/gkad175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/23/2023] Open
Abstract
Crossing over between homologs is critical for the stable segregation of chromosomes during the first meiotic division. Saccharomyces cerevisiae Mer3 (HFM1 in mammals) is a SF2 helicase and member of the ZMM group of proteins, that facilitates the formation of the majority of crossovers during meiosis. Here, we describe the structural organisation of Mer3 and using AlphaFold modelling and XL-MS we further characterise the previously described interaction with Mlh1-Mlh2. We find that Mer3 also forms a previously undescribed complex with the recombination regulating factors Top3 and Rmi1 and that this interaction is competitive with Sgs1BLM helicase. Using in vitro reconstituted D-loop assays we show that Mer3 inhibits the anti-recombination activity of Sgs1 helicase, but only in the presence of Dmc1. Thus we provide a mechanism whereby Mer3 interacts with a network of proteins to protect Dmc1 derived D-loops from dissolution.
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Karrasch T, Eul B, Gattenlöhner S, Steiner D, Roller F, Padberg W, Schäffler A. [Whipple's triad with high and low insulin levels]. INNERE MEDIZIN (HEIDELBERG, GERMANY) 2023; 64:393-400. [PMID: 36703082 PMCID: PMC10036438 DOI: 10.1007/s00108-023-01473-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 01/02/2023] [Indexed: 06/18/2023]
Abstract
A 69-year-old female patient and a 70-year-old male patient were admitted to hospital with recurrent, severe hypoglycemic episodes and a typical manifestation of Whipple's triad. In the female, elevated levels of insulin, C‑peptide and pro-insulin together with pathological findings during a fasting test proved the presence of an insulinoma, which could be detected by Ga-68-DOTATOC-PET-CT in the pancreas. There was a very rare co-existence of a neuroendocrine Merkel cell carcinoma. In the male, levels of insulin and C‑peptide were suppressed and a diagnosis of paraneoplastic hypoglycemia by IGF‑2 secretion was made with increased glucose disposal in skeletal muscle proven by 18F‑FDG-PET-CT.
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Schäffler A. [Role of metaflammation as a systemic manifestation of metabolic diseases]. INNERE MEDIZIN (HEIDELBERG, GERMANY) 2023; 64:313-322. [PMID: 36346457 DOI: 10.1007/s00108-022-01416-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/22/2022] [Indexed: 11/09/2022]
Abstract
Visceral obesity as a component of the metabolic syndrome is characterized by systemic and local inflammation, which can be quantified in organs (metaflammation). This process can be regarded as a chronic, sterile, and low-grade state of inflammation without infection, trauma, tumor or autoimmunity. It is caused by an inflammation of the visceral adipose tissue (adipose inflammation or adipoflammation) due to adipocyte hypertrophy and hyperplasia with increased infiltration by monocytes and macrophages. Important is the presence of proinflammatory, so-called polarized M1 macrophages that are induced by interferon gamma (IFN-γ) and lipopolysaccharides (LPS) with secretion of interleukin (IL)-6, tumor necrosis factor (TNF) and IL‑1. In contrast, the anti-inflammatory, so-called polarized M2 macrophages induced by IL‑4 and IL-13 with secretion of IL‑8 and IL-10 decrease. In addition, the secreted adipokine pattern changes from anti-inflammatory to proinflammatory. Adipocyte necrosis, local hypoxia, dysregulated autophagy, activation of inflammasomes, modulation of toll-like receptors, and epigenetic factors play a complex role. This mechanism results in local insulin resistance and subsequently a systemic insulin resistance of peripheral organs as well as a spillover of local mediators of inflammation into the systemic circulation (measured as obesity C‑reactive protein, CRP). The activation of inflammatory signal transduction cascades leads to inhibitory phosphorylation of the insulin signaling pathway and a weakening of the effect of insulin. In parallel, ectopic lipid accumulation occurs in the liver, musculature, pancreas, pericardium and lungs. Diacylglycerol (DAG) activates specific isoforms of protein kinase C (ε in the liver and τ in the musculature), which in turn lead to inhibition of the insulin signaling pathway. Insulin resistance in obesity and type 2 diabetes mellitus is an inflammatory disease. The aim of future translational approaches is an anti-inflammatory, molecularly individualized (precision medicine) treatment in adipose tissue (targeted therapy) and in organs of insulin resistance.
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Thomalla M, Schmid A, Hehner J, Koehler S, Neumann E, Müller-Ladner U, Schäffler A, Karrasch T. Toll-like Receptor 7 (TLR7) Is Expressed in Adipocytes and the Pharmacological TLR7 Agonist Imiquimod and Adipocyte-Derived Cell-Free Nucleic Acids (cfDNA) Regulate Adipocyte Function. Int J Mol Sci 2022; 23:ijms23158475. [PMID: 35955609 PMCID: PMC9369246 DOI: 10.3390/ijms23158475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 02/05/2023] Open
Abstract
Endosome-localized Toll-like receptors (TLRs) 3 and 9 are expressed and functionally active in adipocytes. The functionality and role of TLR7 in adipocyte biology and innate immunity of adipose tissue (AT) is poorly characterized. We analyzed TLR7 mRNA and protein expression in murine 3T3-L1 and primary adipocytes, in co-cultures of 3T3-L1 adipocytes with murine J774A.1 monocytes and in human AT. The effects of TLR7 agonists imiquimod (IMQ) and cell-free nucleic acids (cfDNA) on adipokine concentration in cell-culture supernatants and gene expression profile were investigated. We found that TLR7 expression is strongly induced during adipocyte differentiation. TLR7 gene expression in adipocytes and AT stroma-vascular cells (SVC) seems to be independent of TLR9. IMQ downregulates resistin concentration in adipocyte cell-culture supernatants and modulates gene expression of glucose transporter Glut4. Adipocyte-derived cfDNA reduces adiponectin and resistin in cell-culture supernatants and potentially inhibits Glut4 gene expression. The responsiveness of 3T3-L1 adipocytes to imiquimod is preserved in co-culture with J774A.1 monocytes. Obesity-related, adipocyte-derived cfDNA engages adipocytic pattern recognition receptors (PRRs), modulating AT immune and metabolic homeostasis during adipose inflammation.
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Karakus E, Schmid A, Leiting S, Fühler B, Schäffler A, Jakob T, Geyer J. Role of the Steroid Sulfate Uptake Transporter Soat (Slc10a6) in Adipose Tissue and 3T3-L1 Adipocytes. Front Mol Biosci 2022; 9:863912. [PMID: 35573729 PMCID: PMC9095825 DOI: 10.3389/fmolb.2022.863912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/24/2022] [Indexed: 11/22/2022] Open
Abstract
In addition to the endocrine and paracrine systems, peripheral tissues such as gonads, skin, and adipose tissue are involved in the intracrine mechanisms responsible for the formation of sex steroids via the transformation of dehydroepiandrosterone and dehydroepiandrosterone sulfate (DHEA/DHEAS) into potent androgenic and estrogenic hormones. Numerous studies have examined the relationship between overweight, central obesity, and plasma levels of DHEA and DHEAS. The sodium-dependent organic anion transporter Soat (Slc10a6) is a plasma membrane uptake transporter for sulfated steroids. Significantly increased expression of Slc10a6 mRNA has been previously described in organs and tissues of lipopolysaccharide (LPS)-treated mice, including white adipose tissue. These findings suggest that Soat plays a role in the supply of steroids in peripheral target tissues. The present study aimed to investigate the expression of Soat in adipocytes and its role in adipogenesis. Soat expression was analyzed in mouse white intra-abdominal (WAT), subcutaneous (SAT), and brown (BAT) adipose tissue samples and in murine 3T3-L1 adipocytes. In addition, adipose tissue mass and size of the adipocytes were analyzed in wild-type and Slc10a6−/− knockout mice. Soat expression was detected in mouse WAT, SAT, and BAT using immunofluorescence. The expression of Slc10a6 mRNA was significantly higher in 3T3-L1 adipocytes than that of preadipocytes and was significantly upregulated by exposure to lipopolysaccharide (LPS). Slc10a6 mRNA levels were also upregulated in the adipose tissue of LPS-treated mice. In Slc10a6−/− knockout mice, adipocytes increased in size in the WAT and SAT of female mice and in the BAT of male mice, suggesting adipocyte hypertrophy. The serum levels of adiponectin, resistin, and leptin were comparable in wild-type and Slc10a6−/− knockout mice. The treatment of 3T3-L1 adipocytes with DHEA significantly reduced lipid accumulation, while DHEAS did not have a significant effect. However, following LPS-induced Soat upregulation, DHEAS also significantly inhibited lipid accumulation in adipocytes. In conclusion, Soat-mediated import of DHEAS and other sulfated steroids could contribute to the complex pathways of sex steroid intracrinology in adipose tissues. Although in cell cultures the Soat-mediated uptake of DHEAS appears to reduce lipid accumulation, in Slc10a6−/− knockout mice, the Soat deletion induced adipocyte hyperplasia through hitherto unknown mechanisms.
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Schmid A, Arians M, Karrasch T, Pons-Kühnemann J, Schäffler A, Roderfeld M, Roeb E. Improvement of Type 2 Diabetes Mellitus and Attenuation of NAFLD Are Associated with the Success of Obesity Therapy. J Clin Med 2022; 11:jcm11071756. [PMID: 35407364 PMCID: PMC8999703 DOI: 10.3390/jcm11071756] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 03/16/2022] [Indexed: 12/13/2022] Open
Abstract
Obesity and type 2 diabetes mellitus (T2D) represent important comorbidities of the metabolic syndrome, which are associated with non-alcoholic fatty liver disease (NAFLD)-related hepatic fibrosis. In total, 160 morbidly obese patients-81 following a low-calorie formula diet (LCD) program and 79 undergoing bariatric surgery (Roux-en-Y gastric bypass, RYGB)-were examined for anthropometric and metabolic parameters at base-line and during 12 months of weight loss, focusing on a putative co-regulation of T2D parameters and liver fibrosis risk. High NAFLD fibrosis scores (NFS) before intervention were associated with elevated HbA1c levels and T2D. Loss of weight and body fat percentage (BFL) were associated with improved glucose and lipid metabolism and reduced risk of NAFLD-related fibrosis, with particularly beneficial effects by RYGB. Both T2D improvement and NFS decrease were positively associated with high BFL. A highly significant correlation of NFS reduction with BFL was restricted to male patients while being absent in females, accompanied by generally higher BFL in men. Overall, the data display the relation of BFL, T2D improvement, and reduced NAFLD-related fibrosis risk during weight loss in morbidly obese individuals induced by diet or RYGB. Furthermore, our data suggest a considerable sexual dimorphism concerning the correlation of fat loss and improved risk of liver fibrosis.
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Schmid A, Vlacil AK, Schuett J, Karrasch T, Schieffer B, Schäffler A, Grote K. Anti-Inflammatory Effects of C1q/Tumor Necrosis Factor-Related Protein 3 (CTRP3) in Endothelial Cells. Cells 2021; 10:2146. [PMID: 34440913 PMCID: PMC8391708 DOI: 10.3390/cells10082146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/13/2021] [Accepted: 08/18/2021] [Indexed: 01/18/2023] Open
Abstract
The C1q/TNF-related protein 3 (CTRP3) represents a pleiotropic adipokine reciprocally associated with obesity and type 2 diabetes mellitus and exhibits anti-inflammatory properties in relation to lipopolysaccharides (LPS)-mediated effects in adipocytes, as well as monocytes/macrophages. Here, we focused on the influence of CTRP3 on LPS-mediated effects in endothelial cells in order to expand the understanding of a possible anti-inflammatory function of CTRP3 in a setting of endotoxemia. An organ- and tissue-specific expression analysis by real-time PCR revealed a considerable Ctrp3 expression in various adipose tissue compartments; however, higher levels were detected in the aorta and in abundantly perfused tissues (bone marrow and the thyroid gland). We observed a robust Ctrp3 expression in primary endothelial cells and a transient upregulation in murine endothelial (MyEND) cells by LPS (50 ng/mL). In MyEND cells, CTRP3 inhibited the LPS-induced expression of interleukin (Il)-6 and the tumor necrosis factor (Tnf)-α, and suppressed the LPS-dependent expression of the major endothelial adhesion molecules Vcam-1 and Icam-1. The LPS-induced adhesion of monocytic cells to an endothelial monolayer was antagonized by CTRP3. In C57BL/6J mice with an LPS-induced systemic inflammation, exogenous CTRP3 did not affect circulating levels of TNF-α, ICAM-1, and VCAM-1. In conclusion, we characterized CTRP3 beyond its function as an adipokine in a setting of vascular inflammation. CTRP3 inhibited LPS-induced endothelial expression of adhesion molecules and monocyte cell adhesion, indicating an important vascular anti-inflammatory role for CTRP3 in endotoxemia.
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Karrasch T, Höpfinger A, Schäffler A, Schmid A. The adipokine C1q/TNF-related protein-3 (CTRP-3) inhibits Toll-like receptor (TLR)-induced expression of Cathelicidin antimicrobial peptide (CAMP) in adipocytes. Cytokine 2021; 148:155663. [PMID: 34388476 DOI: 10.1016/j.cyto.2021.155663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND AIM CAMP (Cathelicidin antimicrobial peptide) expression in adipocytes is regulated by Toll-like receptor (TLR) agonists. Secreted adipokines such as CTRP-3 have been suggested to participate in innate immune signaling in adipose tissue (AT). This study investigates whether TLR-induced CAMP expression in adipocytes is antagonized by CTRP-3. METHODS 3T3-L1 adipocytes were co-stimulated with TLR agonists (LPS, MALP-2, Pam3CSK4, pI:C) and recombinant CTRP-3. In a SIRS model, C57BL/6 wild-type mice were intraperitoneally (ip) injected with recombinant CTRP-3 prior to LPS. CAMP expression was analyzed by real-time PCR in AT of wild-type mice and in AT and primary adipocytes from transgenic mice lacking adipocyte CTRP-3 expression. Comparative transcriptome analysis by RNA seq. was applied in CTRP-3 KO adipocytes. RESULTS In vitro, CTRP-3 antagonized TLR4- and TLR1/2-induced CAMP expression in adipocytes whereas TLR3- and TLR2/6-mediated induction of CAMP was not affected. in vivo, application of exogenous CTRP-3 dose-dependently antagonized LPS-induced CAMP expression in intra-abdominal AT. CAMP expression in total AT and in primary adipocytes of subcutaneous and intra-abdominal AT did not differ between wild-type mice and transgenic mice lacking adipocyte CTRP-3 expression. CONCLUSIONS The study suggests a hypothetical role of CAMP in host defense not only against Gram-positive bacteria sensed by TLR1/2 and TLR2/6 but also against Gram-negative bacteria sensed by TLR4 and potentially against viruses sensed by TLR3. The machinery of TLR-mediated pro-inflammatory activation of the CAMP gene in adipocytes seems to be partly modulated by secreted adipokines belonging to the growing family of C1q/TNF-related proteins such as CTRP-3.
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Schmid A, Schäffler A, Karrasch T. CTRP-3 Regulates NOD1-mediated Inflammation and NOD1 Expression in Adipocytes and Adipose Tissue. Inflammation 2021; 44:2260-2269. [PMID: 34165676 PMCID: PMC8616866 DOI: 10.1007/s10753-021-01497-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 11/29/2022]
Abstract
The anti-inflammatory adipokine CTRP-3 might affect innate immune reactions such as NOD1. The impact of CTRP-3 on NOD1-mediated inflammation in adipocytes and monocytic cells as well as on NOD1 expression was investigated. Murine 3T3-L1 pre-adipocytes and adipocytes as well as human THP-1 monocyte-like cells were co-stimulated with the synthetic NOD1 agonist Tri-DAP and recombinant CTRP-3. Gonadal adipose tissue and primary adipocytes were obtained from a murine model carrying a knockout (KO) of CTRP-3 in adipocytes but not in stroma-vascular cells. Wildtype mice with lipopolysaccharide (LPS)-induced elevated NOD1 expression were treated with CTRP-3. Secreted inflammatory cytokines in cell supernatants were measured by ELISA and mRNA levels were quantified by RT-PCR. Pro-inflammatory chemokine and cytokine secretion (MCP-1, RANTES, TNFα) was induced by NOD1 activation in adipocytes and monocyte-like cells, and MCP-1 and RANTES release was effectively inhibited by pre-incubation of cells with CTRP-3. CTRP-3 also antagonized LPS-triggered induction of NOD1 gene expression in murine adipose tissue, whereas adipocyte CTRP-3 deficiency upregulated NOD1 expression in adipose tissue. CTRP-3 is an effective antagonist of peptidoglycan-induced, NOD1-mediated inflammation and of LPS-induced NOD1 expression. Since basal NOD1 expression is increased by adipocyte CTRP-3 deficiency, there have to be also inflammation-independent mechanisms of NOD1 expression regulation by CTRP-3.
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Höpfinger A, Berghoff M, Karrasch T, Schmid A, Schäffler A. Systematic Quantification of Neurotrophic Adipokines RBP4, PEDF, and Clusterin in Human Cerebrospinal Fluid and Serum. J Clin Endocrinol Metab 2021; 106:e2239-e2250. [PMID: 33484131 DOI: 10.1210/clinem/dgaa983] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Indexed: 02/08/2023]
Abstract
CONTEXT Data on the presence/quantification of the neurotrophic adipokines retinol-binding protein-4 (RBP4), clusterin, and pigment epithelium-derived factor (PEDF) in human cerebrospinal fluid (CSF) are scarce and migration of these adipokines across of the blood-brain barrier (BBB) is uncertain. OBJECTIVE This work aimed to quantify RBP4, PEDF, and clusterin in paired serum and CSF samples of patients undergoing neurological evaluation. METHODS A total of 268 patients (109 male, 159 female) were included. Adipokine serum and CSF concentrations were measured by enzyme-linked immunosorbent assay in duplicate. RESULTS RBP4 was abundant in serum (mean, 31.9 ± 24.2 μg/mL). The serum concentrations were approximately 145 times higher than in CSF (CSF to serum RBP4 ratio, 8.2 ± 4.3 × 10-3). PEDF was detectable in serum (mean, 30.2 ± 11.7 μg/mL) and concentrations were approximately 25 times higher than in CSF (CSF to serum PEDF ratio, 42.3 ± 15.6 × 10-3). Clusterin serum concentrations were abundant with mean levels of 346.0 ± 114.6 μg/mL, which were approximately 40 times higher than CSF levels (CSF to serum clusterin ratio, 29.6 ± 23.4 × 10-3). RBP4 and PEDF serum levels correlated positively with CSF levels, which were increased in overweight/obese patients and in type 2 diabetic patients. The CSF concentrations of all 3 adipokines increased with BBB dysfunction. RBP4 in CSF correlated positively with inflammatory parameters. In detail, only RBP4 showed the kinetics and associations that are mandatory for a putative mediator of the fat-brain axis. CONCLUSION RBP4, PEDF, and clusterin are permeable to the BBB and increase with the measure of BBB dysfunction. RBP4 represents an inflammatory neurotrophic adipokine and is a promising mediator of the fat-brain axis.
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Müller-Ladner U, Frommer K, Karrasch T, Neumann E, Schäffler A. [The effect of obesity on disease activity of inflammatory rheumatic diseases]. Z Rheumatol 2021; 80:353-361. [PMID: 33774725 DOI: 10.1007/s00393-021-00987-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2021] [Indexed: 11/26/2022]
Abstract
One of the most recent scientific fields is the interaction between the immune system and metabolic processes. These interactions increasingly involve intracellular and extracellular signaling molecules and their receptors as well as molecular mechanisms that are used by both systems. The result of these intensive interactions is characterized by the term "metaflammation" and involves in particular, the ubiquitous adipose tissue present throughout the body. The links identified to date between the immune system and metabolism play a greater role in inflammatory rheumatic joint diseases than previously thought. In general, a markedly high body mass index (BMI) in particular, is associated with increased inflammatory activity and this is independent of the underlying disease entity. A higher BMI at the beginning of an immunomodulatory therapy also causes a more difficult response to the medication. Thus, the current scientific objective is to identify the individual "immuno-metabolic" pathways in order to apply the medications specifically to the site of action. Furthermore, all newer therapeutic agents, especially those specifically acting against individual immunological molecules, should be systematically analyzed with respect to their metabolic concomitant effects and their influence on metabolic comorbidities.
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Hempel F, Roderfeld M, Müntnich LJ, Albrecht J, Oruc Z, Arneth B, Karrasch T, Pons-Kühnemann J, Padberg W, Renz H, Schäffler A, Roeb E. Caspase-Cleaved Keratin 18 Measurements Identified Ongoing Liver Injury after Bariatric Surgery. J Clin Med 2021; 10:jcm10061233. [PMID: 33809676 PMCID: PMC8002276 DOI: 10.3390/jcm10061233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 12/30/2022] Open
Abstract
Bariatric surgery has emerged as an effective treatment option in morbidly obese patients with non-alcoholic fatty liver disease (NAFLD). However, worsening or new onset of non-alcoholic steatohepatitis (NASH) and fibrosis have been observed. Caspase-cleaved keratin 18 (ccK18) has been established as a marker of hepatocyte apoptosis, a key event in NASH development. Thus, ccK18 measurements might be feasible to monitor bariatric surgery patients. Clinical data and laboratory parameters were collected from 39 patients undergoing laparoscopic Roux-en-Y gastric bypass at six timepoints, prior to surgery until one year after the procedure. ccK18 levels were measured and a high-throughput analysis of serum adipokines and cytokines was carried out. Half of the cohort’s patients (20/39) presented with ccK18 levels indicative of progressed liver disease. 21% had a NAFLD-fibrosis score greater than 0.676, suggesting significant fibrosis. One year after surgery, a mean weight loss of 36.87% was achieved. Six and twelve months after surgery, ccK18 fragments were significantly reduced compared to preoperative levels (p < 0.001). Yet nine patients did not show a decline in ccK18 levels ≥ 10% within one year postoperatively, which was considered a response to treatment. While no significant differences in laboratory parameters or ccK18 could be observed, they presented with a greater expression of leptin and fibrinogen before surgery. Consecutive ccK18 measurements monitored the resolution of NAFLD and identified non-responders to bariatric surgery with ongoing liver injury. Further studies are needed to elicit the pathological mechanisms in non-responders and study the potential of adipokines as prognostic markers.
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Hochberg A, Patz M, Karrasch T, Schäffler A, Schmid A. Serum Levels and Adipose Tissue Gene Expression of Cathelicidin Antimicrobial Peptide (CAMP) in Obesity and During Weight Loss. Horm Metab Res 2021; 53:169-177. [PMID: 33434932 PMCID: PMC7924992 DOI: 10.1055/a-1323-3050] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
CAMP (Cathelicidin antimicrobial peptide) is synthesized and secreted by adipocytes and involved in adipose tissue (AT) innate immune response and host defense of subcutaneous AT against Gram positive bacteria. Data on the regulation of CAMP in obesity and during weight loss are scarce and reference values do not exist. Serum CAMP levels (ELISA) and AT gene expression levels (quantitative real time PCR) were investigated in two large and longitudinal (12 months) cohorts of severely obese patients undergoing either a low calorie diet (LCD; n=79) or bariatric surgery (BS; n=156). The impact of metabolic factors on CAMP expression in vitro was investigated in differentiated 3T3-L1 adipocytes. CAMP serum levels significantly increased after BS but not during LCD. Females had lower CAMP serum levels and lower gene expression levels in subcutaneous AT. CAMP was positively correlated to unfavorable metabolic factors/adipokines and negatively to favorable factors/adipokines. CAMP gene expression was higher in subcutaneous than in visceral AT but serum CAMP levels were not correlated to levels of AT gene expression. While certain bile acids upregulated CAMP expression in vitro, high glucose/insulin as well as GLP-1 had an inhibitory effect. There exist gender-specific and AT compartment-specific effects on the regulation of CAMP gene expression. Weight loss induced by BS (but not by LCD) upregulated CAMP serum levels suggesting the involvement of weight loss-independent mechanisms in CAMP regulation such as bile acids, incretins and metabolic factors. CAMP might represent an adipokine at the interface between metabolism and innate immune response.
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Schmid A, Roderfeld M, Gehl J, Roeb E, Nist A, Chung HR, Stiewe T, Karrasch T, Schäffler A. C1q/TNF-Related Protein 3 (CTRP-3) Deficiency of Adipocytes Affects White Adipose Tissue Mass but Not Systemic CTRP-3 Concentrations. Int J Mol Sci 2021; 22:ijms22041670. [PMID: 33562308 PMCID: PMC7915696 DOI: 10.3390/ijms22041670] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 12/20/2022] Open
Abstract
CTRP-3 (C1q/TNF-related protein-3) is an adipokine with endocrine and immunological function. The impact of adipocyte CTRP-3 production on systemic CTRP-3 concentrations and on adipocyte biology is unknown. A murine model of adipocyte CTRP-3 knockout (KO) was established (via the Cre/loxP system). Serum adipokine levels were quantified by ELISA and adipose tissue (AT) gene expression by real-time PCR. Preadipocytes were isolated from AT and differentiated into adipocytes. Comparative transcriptome analysis was applied in adipocytes and liver tissue. Body weight and AT mass were reduced in CTRP-3 KO mice together with decreased serum leptin. In primary cells from visceral AT of KO mice, expression of adiponectin, progranulin, and resistin was induced, while peroxisome proliferator activated receptor γ (PPARγ) was decreased. M1/M2 macrophage polarization markers were shifted to a more anti-inflammatory phenotype. CTRP-3 expression in AT did not contribute to serum concentrations. AT and liver morphology remained unaffected by CTRP-3 KO. Myelin transcription factor 1-like (Myt1l) was identified as a highly upregulated gene. In conclusion, adipocyte CTRP-3 has a role in adipogenesis and AT weight gain whereas adipocyte differentiation is not impaired by CTRP-3 deficiency. Since no effects on circulating CTRP-3 levels were observed, the impact of adipocyte CTRP-3 KO is limited to adipose tissue. Modified AT gene expression indicates a rather anti-inflammatory phenotype.
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Höpfinger A, Karrasch T, Schäffler A, Schmid A. Regulation of CAMP (cathelicidin antimicrobial peptide) expression in adipocytes by TLR 2 and 4. Innate Immun 2021; 27:184-191. [PMID: 33509002 PMCID: PMC7882808 DOI: 10.1177/1753425920988167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Recent data argue for a pro-inflammatory role of CAMP (cathelicidin antimicrobial peptide) in adipocytes and adipose tissue (AT) and for regulatory circuits involving TLRs. In order to investigate regulatory effects of TLR2 and TLR4, 3T3-L1 adipocytes were stimulated with TLR2 agonistic lipopeptide MALP-2 and with TLR4 agonist LPS in presence or absence of signal transduction inhibitors. CAMP gene expression was analysed by quantitative real-time PCR in adipocytes and in murine AT compartments and cellular subfractions. CAMP expression was higher in gonadal than in subcutaneous AT and there was a gender-specific effect with higher levels in males. Adipocytes had higher CAMP expression than the stroma-vascular cell (SVC) fraction. MALP-2 up-regulated CAMP expression significantly, mediated by STAT3 and PI3K and potentially (non-significant trend) by NF-κB and MAPK, but not by raf-activated MEK-1/-2. Moreover, LPS proved to act as a potent inducer of CAMP via NF-κB, PI3K and STAT3, whereas specific inhibition of MAPK and MEK-1/-2 had no effect. In conclusion, activation of TLR2 and TLR4 by classical ligands up-regulates adipocyte CAMP expression involving classical signal transduction elements. These might represent future drug targets for pharmacological modulation of CAMP expression in adipocytes, especially in the context of metabolic and infectious diseases.
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von Stebut E, Boehncke WH, Ghoreschi K, Gori T, Kaya Z, Thaci D, Schäffler A. IL-17A in Psoriasis and Beyond: Cardiovascular and Metabolic Implications. Front Immunol 2020; 10:3096. [PMID: 32010143 PMCID: PMC6974482 DOI: 10.3389/fimmu.2019.03096] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 12/18/2019] [Indexed: 12/14/2022] Open
Abstract
Interleukin 17A (IL-17A) is one of the currently known six members of the IL-17 cytokine family and is implicated in immune responses to infectious pathogens and in the pathogenesis of inflammatory autoimmune diseases like psoriasis. Psoriatic skin is characterized by high expression of IL-17A and IL-17F, which act on immune and non-immune cell types and strongly contribute to tissue inflammation. In psoriatic lesions, IL-17A, IL-17E, and IL-17F are involved in neutrophil accumulation, followed by the formation of epidermal micro abscesses. IL-17A together with other Th17 cytokines also upregulates the production of several chemokines that are implicated in psoriasis pathogenesis. IL17A-targeting antibodies show an impressive clinical efficacy in patients with psoriasis. Studies have reported an improvement of at least 75% as measured by the psoriasis area and severity index (PASI) in >80% of patients treated with anti-IL-17A therapy. Psoriasis skin manifestations, cardiovascular as well as metabolic disease in psoriasis appear to share pathogenic mechanisms evolving around IL-17A and its proinflammatory role. Thus, anti-IL-17A therapy not only improves skin manifestations of psoriasis, but also cardiovascular inflammation as well as metabolic factors and different domains of psoriatic arthritis (PsA) including peripheral arthritis, enthesitis, dactylitis, and axial involvement. This review summarizes the biological role of IL-17A, before reviewing currently available data on its role in the physiology and pathophysiology of the skin, as well as the cardiovascular and the metabolic system. In conclusion, clinical recommendations for patients with moderate to severe psoriasis based on the current available data are given.
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