Dynamics of adipose tissue macrophage populations after gastric bypass surgery

FIGURE 1. Microphotographs illustrating crown‐like structures (CLS) and dispersed CD68‐positive cells in subcutaneous adipose tissue of participants with overweight. Identification of CLSs is facilitated with (A) CD68 staining (arrow) as compared with (B) H&E staining (arrow). Scale bar = 50 μm. (C) Sometimes CLSs were present at a high density as shown by CD68 staining. A 40‐year‐old woman with BMI 44.9 kg/m2 and no comorbidities had CLS density of 14.33 per 1000 adipocytes, the highest count found among the subjects. A particularly high‐density region is shown in the image. This patient's CLS density had decreased to 1.23 per 1000 adipocytes and BMI decreased to 37.7 kg/m2 at 12 months after the bariatric surgery. Arrows point to some CD68‐positive cells dispersed outside CLSs. Scale bar = 100 μm [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 2. Scatterplot showing correlation of total crown‐like structure (CLS) density (CLS/1000 fat cells [FC]) and dispersed CD68‐positive cells outside CLSs (area of CD68 expression/1000 FC) in subcutaneous adipose tissue samples of subjects with obesity taken before intervention. Correlation is significant (bivariate analysis; ρ = 0.53, p < 0.001, R 2 = 0.294)

FIGURE 3. Bariatric surgery (laparoscopic Roux‐en‐Y gastric bypass) decreases human SAT CLS density without affecting macrophage density elsewhere in SAT compared with conservative treatment of obesity at 1 year. (A) Before interventions, the mean CLS count/1000 adipocytes did not differ between the groups (p = 0.209, Welch t test), but after 12 months, the surgery group had a significantly lower CLS density (p < 0.000, Welch t test). In the conservative group, mean CLSs per 1000 adipocytes increased from 3.2 (SD 2.3) to 4.2 (SD 3.3) (p = 0.07, paired t test) after 12 months. In the surgery group, mean CLS density decreased from 4.1 (SD 3.6) to 1.1 (SD 0.8) (p < 0.000, Wilcoxon signed rank test). (B) CD68 positivity outside CLSs did not initially differ between the groups. However, after 12 months, the CD68 staining significantly increased in the conservative group (p = 0.021, paired t test) and was higher than in the surgery group (p = 0.008, Welch t test) in which no change was seen. (C) At baseline, the surgery group had a larger proportion of CD68 expression in CLSs as compared with the conservative group, but after 12 months, the proportion in this group had decreased and was now…

FIGURE 4. CLS density in SAT decreases independently of weight loss response after bariatric surgery (LRYGB). Total weight loss (TWL) of 20% or more at 12 months after bariatric (laparoscopic Roux‐en‐Y gastric bypass) surgery indicated a good response. (A) No significant difference was observed in the pretreatment CLS density between the subjects with good response (TWL > 20%; 3.88 (SD 3.1); N = 22) and those without such response (TWL < 20%; 5.3 (SD 4.3); N = 11; Student t test). However, along with treatment, CLS density declined in both groups (Wilcoxon signed rank test). In addition, the presence of good treatment response did not associate with (B) the pretreatment extent of CD68 positivity outside CLSs or (C) the distribution of CD68 positivity in and outside CLSs. However, the distribution of CD68 positivity significantly shifted from CLSs to cells outside CLSs, reflecting the decrease of CLS density and constancy of CD68 staining outside CLSs (paired t test). All bars are presented with 95% CI. CLS, crown‐like structure; SAT, subcutaneous adipose tissue

FIGURE 5. Density of CLSs found in subcutaneous adipose tissue 12 months after bariatric surgery (laparoscopic Roux‐en‐Y gastric bypass) declines in a similar fashion even in subjects with suboptimal weight loss response (TWL < 20%) to the surgery. CLS, crown‐like structure; TWL, total weight loss (kg)