Plasma YKL-40 during pregnancy and gestational diabetes mellitus

Increased levels of YKL-40 in patients with diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Diabetes mellitus (DM) could be classified as type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), gestational diabetes mellitus (GDM) and others according to etiology and pathology. Diabetic nephropathy (DN) is one of the most serious complications of DM. YKL-40 is a marker of inflammation and some studies have indicated that DM was related with inflammation. The objective of our study is to perform a systematic review and meta-analysis to confirm the relationship between YKL-40 and DM as well as DN.

METHODS

Pubmed, Embase, CNKI and Chinese wanfang databases were searched for eligible studies by two independent authors. Studies were included in this meta-analysis if they fulfilled the following inclusion criteria: (1) a study involving the role of YKL-40 in DM (or DN) designed as a case-control study or cohort study; (2) the data of serum YKL-40 levels were available; (3) studies were published in English or Chinese. Finally, twenty-five studies were included in this meta-analysis.

RESULTS

Compared with healthy controls, DM patients had significantly higher levels of YKL-40 (DM: SMD = 1.62, 95% CI 1.08 to 2.25, P = 0.000; GDM: SMD = 2.85, 95% CI 1.01 to 4.70, P = 0.002). Additionally, DM patients with different degree of albuminuria had significantly higher levels of YKL-40 compared with healthy controls (normoalbuminuria: SMD = 1.58, 95% CI 0.59 to 2.56, P = 0.002; microalbuminuria: SMD = 2.57, 95% CI 0.92 to 4.22, P = 0.002; macroalbuminuria: SMD = 2.69, 95% CI 1.40 to 3.98, P = 0.000) and serum YKL-40 levels increased with increasing severity of albuminuria among DM patients (microalbuminuria vs normoalbuminuria: SMD = 1.49, 95% CI 0.28 to 2.71, P = 0.016; macroalbuminuria vs microalbuminuria: SMD = 0.93, 95% CI 0.34 to 1.52, P = 0.002).

CONCLUSIONS

Our current meta-analysis demonstrates that serum level of YKL-40 is increased in DM and positively associated with the severe degree of albuminuria. Therefore, we suggest that YKL-40 could be considered to be detected, along with other inflammatory markers, if DM, especially DN, is suspected.

Alteration in Uterine Protease-Activated Receptor 2 Expression in Preterm Birth Induced Experimentally in Brp-39 Null Mutant Mice

Breast regression protein 39 (Brp-39) is a mouse homolog of human Chitinase 3-like 1, which belongs to the 18-glycosyl-hydrolase family and plays a role in inflammatory reaction and tissue remodeling. The aim of this study is to investigate the role of Brp-39 in a mouse model of preterm birth. Pregnant wild-type (WT) or Brp-39(-/-) mice were injected intraperitoneally with lipopolysaccharide (LPS) at embryonic day 15. Pregnancy outcomes were evaluated for 24 hours after LPS injection. Quantitative real-time polymerase chain reaction and immunoblotting were performed to analyze messenger RNA (mRNA) and protein expressions of cytokines and contraction-associated proteins in uterine and/or placental tissue after LPS injection. LPS injection led to preterm birth in both WT and Brp-39(-/-) mice, but the proportion of pubs delivered was reduced in Brp-39(-/-) mice, along with a longer interval from the LPS injection to delivery, compared to WT mice. Inflammatory cell infiltration and mRNA expression of cytokines and Ptgs2 in the uteri and the placentas were not significantly different between WT and Brp-39(-/-) mice. Par-2 mRNA expression in the WT uteri was increased before delivery after LPS injection and decreased after delivery, while there was no significant change in Par-2 expression in the Brp-39(-/-) uteri. Protein expressions of Par-2 and Ptgs2 were lower in the Brp-39(-/-) uteri than in the WT uteri before and after delivery. Attenuated preterm birth in Brp-39(-/-) mice indicates the significance of Brp-39 during murine preterm birth. Altered expression of Par-2 in Brp-39(-/-) uteri suggests its potential role in attenuated preterm birth of Brp-39(-/-) mice.

Serum YKL-40 and gestational diabetes - an observational cohort study

To examine serum YKL-40 in women developing gestational diabetes mellitus (GDM). In the present large observational cohort study of 1179 pregnant women, we determined serum YKL-40 four times during pregnancy (at gestational age 12, 20, 25, and 32 weeks). Pregnancy outcome was obtained from medical records. Sixty-eight women (5.8%) developed GDM. Serum YKL-40 increased from gestational age (GA) 12 weeks and the following weeks in the women who developed GDM and was independent of BMI, parity, and maternal age (OR = 2.69, 95% CI: 1.45-5.00, p = 0.002). No association was found between serum YKL-40 and the oral glucose tolerance test results. In conclusion, YKL-40 significantly increased in pregnant women with GDM compared with women without GDM, probably reflecting the low-grade inflammation of GDM. However, we did not find an association between serum concentrations of YKL-40 in early pregnancy and the development of GDM and thus we conclude that YKL-40 alone is not usable as a biomarker for early prediction of GDM.

Serum YKL-40 levels in gestational diabetes mellitus

OBJECTIVE

Serum YKL-40 levels are elevated in patients with type 1 and 2 diabetes. However, the correlation between YKL-40 and gestational diabetes mellitus (GDM) remains unknown. The present study compared serum YKL-40 levels in pregnant women with GDM and those with normal glucose tolerance and evaluated the relationship between YKL-40 and insulin-resistant syndrome.

METHODS

Thirty-five patients with GDM and 43 age-matched healthy pregnant women at 24-28 weeks of gestation were studied. In addition to anthropometric assessments, serum glucose, insulin, YKL-40, total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein and glycated hemoglobin were measured in all subjects. All subjects underwent a 2-h 75-g oral glucose tolerance test (OGTT). Body mass index (BMI) and the homeostasis model assessment of insulin resistance (HOMA-IR) were calculated.

RESULTS

Fasting and 2 h serum YKL-40 levels were significantly higher in pregnant women with GDM compared with controls (77.3 ± 29.3 versus 50.9 ± 16.7 ng/mL, p < 0.001, fasting concentrations; 63.5 ± 20.1 versus 40.6 ± 10.7 ng/mL, p = 0.009, 2 h concentrations). OGTT had no effect on YKL-40 levels in either group (p > 0.05). There were significant correlations between YKL-40 and glycated hemoglobin (β = 0.37, p = 0.006), fasting insulin (β = 0.49, p = 0.001) and HOMA-IR (β = 0.18, p = 0.015) in the GDM group.

CONCLUSIONS

Serum YKL-40 levels are elevated in patients with GDM but are unaffected by OGTT. YKL-40 levels are related to glycated hemoglobin, fasting insulin and HOMA-IR. These results suggest that YKL-40 may be a major contributor to GDM.