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Kjaergaard AD, Helby J, Johansen JS, Nordestgaard BG, Bojesen SE. Elevated plasma YKL-40 and risk of infectious disease: a prospective study of 94665 individuals from the general population. Clin Microbiol Infect 2020; 26:1411.e1-1411.e9. [PMID: 31972315 DOI: 10.1016/j.cmi.2020.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/06/2020] [Accepted: 01/11/2020] [Indexed: 01/08/2023]
Abstract
OBJECTIVES YKL-40 is an acute phase protein elevated in patients with infectious and inflammatory diseases. We tested the hypothesis that baseline elevated YKL-40 is associated with increased risk of future infectious disease in healthy individuals in the general population. METHODS We prospectively followed 94 665 individuals from the Danish general population for up to 23 years and analysed for plasma YKL-40 levels (n = 21 584) and CHI3L1 rs4950928 genotype (n = 94 184). Endpoints were any infection, bacterial pneumonia, urinary tract infection, skin infection, sepsis, diarrhoeal disease, and other infections. RESULTS For YKL-40 percentile category 91-100% versus 0-33%, the multifactorially and C-reactive protein (CRP) adjusted hazard ratios were 1.71 (95% confidence interval 1.50-1.96; p 4 × 10-14) for any infection, 1.97 (1.64-2.37; p 4 × 10-13) for bacterial pneumonia, 1.62 (1.24-2.11; p 0.002) for urinary tract infection, 1.74 (1.31-2.32; p 2 × 10-4) for skin infection, 1.76 (1.25-2.46; p 0.004) for sepsis, 1.90 (1.29-2.78; p 0.002) for diarrhoeal disease and 2.71 (1.38-5.35; p 0.01) for other infections. In multifactorially and CRP-adjusted models, a twofold increase in YKL-40 was associated with increased risk of all infectious disease endpoints. Mendelian randomization did not support causality, as CHI3L1 rs4950928 was associated with 94% and 190% higher YKL-40 levels (for CG and CC versus GG genotype), but not with increased risk of any infectious disease endpoint. DISCUSSION Baseline elevated plasma YKL-40 was not a cause but a strong marker of increased risk of future infectious diseases in individuals in the general population.
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Affiliation(s)
- A D Kjaergaard
- Department of Clinical Epidemiology and Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark.
| | - J Helby
- Department of Clinical Biochemistry, Department of Internal Medicine, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark
| | - J S Johansen
- Department of Oncology and Medicine, Herlev and Gentofte Hospital, Copenhagen University Hospital, Denmark and Faculty of Health and Medical Sciences, University of Copenhagen, Herlev, Denmark
| | - B G Nordestgaard
- Department of Clinical Biochemistry, Herlev and Gentofte Hospital, Copenhagen University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Herlev, Denmark
| | - S E Bojesen
- Department of Clinical Biochemistry, Herlev and Gentofte Hospital, Copenhagen University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Herlev, Denmark
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Kjaergaard AD, Johansen JS, Bojesen SE, Nordestgaard BG. Role of inflammatory marker YKL-40 in the diagnosis, prognosis and cause of cardiovascular and liver diseases. Crit Rev Clin Lab Sci 2016; 53:396-408. [PMID: 27187575 DOI: 10.1080/10408363.2016.1190683] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review summarizes present evidence for the role of YKL-40 in the diagnosis, prognosis and cause of cardiovascular and alcoholic liver disease. The question of whether YKL-40 is merely a marker or a causal factor in the development of cardiovascular and liver disease is addressed, with emphasis on the Mendelian randomization design. The Mendelian randomization approach uses genetic variants associated with lifelong high plasma YKL-40 levels that are largely unconfounded and not prone to reverse causation. Thus, the approach mimics a controlled double-blind randomized trial, but it uses genetic variants rather than a drug and placebo, and like a blinded trial, it allows inference about causality. Moreover, the review also covers background on the molecular biology and functions of YKL-40, YKL-40 levels in healthy individuals and reference range, and the role of YKL-40 as a biomarker of cardiovascular and alcoholic liver disease. YKL-40 is a plasma protein named after its three N-terminal amino acids, Y (tyrosine), K (lysine) and L (leucine), and its molecular weight of 40 kDa. It is produced by local inflammatory cells in inflamed tissues, such as lipid-laden macrophages inside the vessel wall and perhaps also hepatic stellate cells. Observational studies show that plasma YKL-40 levels are elevated in patients with cardiovascular and liver disease and are associated with disease severity and prognosis. Furthermore, elevated plasma YKL-40 levels in apparently healthy individuals are associated with a 2-fold increased risk of future ischemic stroke and venous thromboembolism, but not with myocardial infarction, suggesting that YKL-40 could play a role in the formation of embolisms rather than atherosclerosis per se. Further, elevated YKL-40 levels combined with excessive alcohol consumption are associated with 10-years risk of alcoholic liver cirrhosis of up to 7%, suggesting that YKL-40 can be used as a strong noninvasive marker of predicting alcoholic liver cirrhosis. Importantly, in Mendelian randomization studies, genetically elevated plasma YKL-40 levels were not associated with risk of cardiovascular and alcoholic liver disease, thus suggesting that plasma YKL-40 does not play a causal role in the development of these diseases. Despite this, plasma YKL-40 levels may play a role in disease progression after diagnosis, and inhibition of YKL-40 activity might be a novel therapy in some cardiovascular and liver diseases.
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Affiliation(s)
- A D Kjaergaard
- a Department of Clinical Biochemistry , Aarhus University Hospital , Aarhus , Denmark
| | - J S Johansen
- b Department of Medicine and Oncology , Herlev and Gentofte Hospital, Copenhagen University Hospital, University of Copenhagen , Copenhagen , Denmark .,c Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - S E Bojesen
- c Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark .,d Department of Clinical Biochemistry , Herlev and Gentofte Hospital, Copenhagen University Hospital , Herlev , Copenhagen , Denmark .,e The Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, University of Copenhagen , Denmark , and.,f The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospital, University of Copenhagen, Copenhagen , Denmark
| | - B G Nordestgaard
- c Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark .,d Department of Clinical Biochemistry , Herlev and Gentofte Hospital, Copenhagen University Hospital , Herlev , Copenhagen , Denmark .,e The Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, University of Copenhagen , Denmark , and.,f The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospital, University of Copenhagen, Copenhagen , Denmark
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