Fig 2: Quantified levels of CHI3L1 from rat serum samples (n = 8/group) assessed by ELISA. Abbreviations: S, sham control group; MI, myocardial infarction group; ME, post-MI exercise trained group. Symbol * indicates p < 0.05 when comparing groups MI and ME.

Fig 3: Post-myocardial infarction (MI) aerobic exercise training activates CHI3L1/PAR2-PI3K-AKT/ERK signaling pathway in the rat heart. (A) Representative pictures of western blotting indicating the protein levels of the relevant signaling molecules. (B) Quantitative analysis for CHI3L1 and PAR2 protein levels, and phosphorylation levels of PI3K, Akt and ERK in heart tissues (n = 3/group). (C) Relative mRNA level of CHI3L1 in myocardium assessed by RT-qPCR (n = 3/group). Abbreviations: S, sham control group; MI, myocardial infarction group; ME, post-MI exercise trained group. Symbol * indicates p < 0.05 and ** indicates p < 0.01 between the relevant groups that are compared.

Fig 4: Plasma YKL-40 changes following surgery in humans and mice. A) Human plasma concentrations of YKL-40 revealed increased levels following surgery when compared to preoperative levels within the same patients. B) Individual patient preoperative and postoperative levels are represented in grey (normal) or colored (patients with delirium). C) A trend toward increase was observed in plasma YKL-40 change levels (24 h vs preoperative) between normal and patients with delirium. D) Mouse plasma samples were collected from aged mice 24 h following tibial fracture or from naïve control mice. A similar increase in mouse plasma YKL-40 was observed 24 h following surgery. E) Plasma IL-6, a marker of inflammation, revealed that aged mice had increased inflammation 24 h after surgery. Human data are expressed as mean ± SD, and mouse data as mean ± SEM. Analyses were performed as follows: Paired and Unpaired Student's t-test when appropriate, ***p < 0.001. Note: Individual dot colors represent the same patient with delirium across panels B and C. . (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig 5: CNS YKL-40 changes following surgery in mice and humans. Mouse brains were collected from aged mice 24 h following tibial fracture or from naïve unoperated control mice. A) Representative immunohistochemical images of YKL-40 protein expression in the dentate gyrus of the hippocampus. B) The percent area of YKL-40 immunostaining was lower in the tibial surgery mice vs naïve controls. C) RT-PCR of Ykl-40 mRNA expression expressed as log2 of fold changes in the hippocampus found that Ykl-40 levels were reduced following tibial fracture. Interestingly, RT-PCR Il1-B log 2 of fold change in the hippocampus analysis showed increased Il1-B levels following tibial fracture. D) YKL-40 levels in CSF samples from human surgery patients examined before and 24 h after surgery revealed a significant decrease in YKL-40 in the CSF following surgery. E) Individual patient's preoperative and postoperative levels are represented in grey (normal) or colored (patients with delirium). F) Patients were divided into 2 groups: normal and patients with delirium. CSF YKL-40 change levels (24 h vs preoperative) between normal and patients with delirium. Mouse data are expressed as mean ± SEM, and human data as mean ± SD except for CSF YKL-40 data, which are expressed as Median ± (interquartile range). Analyses were performed as follows: Unpaired Student's t-test, Wilcoxon Rank Sum Test when appropriate, *p < 0.05. Representative scale for A) is 50 µm. Note: Individual dot colors represent the same patient with delirium across panels E and F. . (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)