Dysregulated inflammatory response to urogynecologic meshes in women with diabetes and its implications

Abstract

Background: Diabetes is an independent risk factor for mesh complications in women undergoing mesh-augmented surgical repairs of stress urinary incontinence and/or pelvic organ prolapse. The underlying mechanism remains unclear.

Objective: This study aimed to define the diabetes-associated alterations in the host inflammatory response to mesh and correlate them with perioperative glucose management.

Study design: Deidentified demographics and medical records of patients who underwent mesh removal and participated in a mesh biorepository study were reviewed (n=200). In patients with diagnosed diabetes (n=25), blood glucose management before initial mesh implantation and before and after mesh removal was assessed by blood glucose and hemoglobin A1c levels. Age- and body mass index-matched tissue samples excised from patients with and without diabetes were examined. Transcriptomic profiles of immune cell markers, immune mediators, key inflammatory regulators, cell senescence, and epigenetic enzymes were determined by multiplex transcriptomic assays (NanoString). Ratios of apoptotic cells to CD68+ macrophages were examined with immunofluorescence. Protein profiles of 12 molecules involved in apoptotic cell clearance were examined with a multiplex protein assay (Luminex).

Results: Demographic and clinical characteristics, including duration between mesh implantation and removal, reason for removal, and type of mesh, etc., were comparable between patients with and without diabetes, except for 11.6% higher body mass index in the former (P=.005). In patients with diabetes, suboptimal management of blood glucose following mesh implantation was observed, with 59% of the patients having loosely or poorly controlled glucose before and after the mesh removal. Ongoing chronic inflammatory response was observed in the excised mesh-tissue complexes in both groups, whereas markers for M2 macrophages (Mrc1 [mannose receptor C-type 1]) and helper T cells (Cd4 [CD4 molecule]) were increasingly expressed in the diabetic vs nondiabetic group (P=.023 and .047, respectively). Furthermore, the gene expressions of proinflammatory Ccl24 (C-C motif chemokine ligand 24) and Ccl13 (C-C motif chemokine ligand 13) were upregulated by 1.5- and 1.8-fold (P=.035 and .027, respectively), whereas that of Il1a (interleukin 1 alpha) was paradoxically downregulated by 2.2-fold (P=.037) in the diabetic vs nondiabetic group. Interestingly, strong positive correlations were found between the expression of Ccl13, Setdb2 (SET domain bifurcated histone lysine methyltransferase 2), and M2 macrophage markers, and between the expression of Il1a, Fosl1 (activator protein-1 transcription factor subunit), and dendritic cell markers, suggesting the involvement of macrophages and dendritic cells in the diabetes-dysregulated proinflammatory response. Supportively, apoptotic cell clearance, which is an important function of macrophages, appeared to be impaired in the diabetic group, with a significantly increased protein level of CALR (calreticulin), an "eat-me" signal on the surface of apoptotic cells (P=.031), along with an increase of AXL (AXL receptor tyrosine kinase) (P=.030), which mediates apoptotic cell clearance.

Conclusion: Diabetes was associated with altered long-term inflammatory response in complicated mesh implantation, particularly involving innate immune cell dysfunction. Suboptimal blood glycemic control following mesh implantation may contribute to this immune dysregulation, necessitating further mechanistic studies.

Keywords: apoptotic cell clearance; blood glucose management; cell senescence; dendritic cell; epigenetics; macrophage; proinflammatory cytokines/chemokines.

Figure 1.

Differential mRNA expression of cytokines, chemokines and growth factors in mesh-grafted vaginal tissues excised from women with vs. without diabetes due to mesh complications. Heatmaps show the relative levels and pattern of the gene expression of various factors. Arrows indicate genes that were differentially expressed in diabetic vs. nondiabetic specimens (p<0.05). Scale bars below heatmaps represent normalized copies of mRNA. ND: Nondiabetic; D: Diabetic.

Figure 2.

Differential mRNA expression of epigenetic enzymes and regulatory molecules in mesh-grafted vaginal tissues excised from women with vs. without diabetes due to mesh complications. (A) Differential expression of 29 epigenetic enzymes comparing diabetic vs. nondiabetic samples excised from women with mesh complications. (B) Heatmaps show that diabetic specimens had an upregulated level of a histone lysine methyltransferase – Setdb2 and a downregulated transcription factor – Fosl1 (arrows, p<0.05). (C) Box-whisker plots shows the distribution of values representing medians (minimum, maximum). Scale bars below heatmaps represent normalized copies of mRNA. ND: Nondiabetic; D: Diabetic.

Figure 3.

Correlations between differential gene expression and immune cell markers in mesh-tissue explants obtained from patients with vs. without diabetes. (A) Heatmap of immune cell markers, comparing diabetic and nondiabetic samples. Mrc1 and Cd4 were increasingly expressed in the diabetic vs. nondiabetic groups. Arrows indicate p<0.05. (B) A correlation plot showing the close links of Il1a – Fosl1 – dendritic cells and Ccl13 – Setdb2 – M2 macrophages in the diabetic samples, with larger bubble size representing stronger correlations. Scale bars below heatmaps represent normalized copies of mRNA. Mφ: Macrophages; DC: Dendritic cells; Ma: Mast cells; N: Neutrophils; T: T cells; B: B cells; ND: Nondiabetic; D: Diabetic.

Figure 4.

Levels of apoptotic cell clearance protein panel in the mesh-tissue explants derived from women with vs. without diabetes. AXL and CALR levels were significantly increased in the former. The box-whisker plot shows the distribution of values with medians (minimum, maximum). ND: Nondiabetic; D: Diabetic.