Neurokinin B is a potential target for treating disruption of intestinal mucosal barrier in acute mechanical intestinal obstruction

Abstract

Background

The neurokinin-B (NKB)/neurokinin-3-receptor (NK3R) pathway is involved in the inflammatory response. However, its role in the disruption of intestine mucosal barrier during mechanical intestinal obstruction (IO) remains unknown.

Methods

We collected serum samples from 30 mechanical IO patients and 30 healthy volunteers and measured the serum levels of NKB, lipopolysaccharide (LPS), diamine oxidase (DAO), and D‑lactate (D‑LA) by using ELISA. We subsequently used a mechanical IO mice model and intraperitoneally injected the mice with NKB (Senktide) and NK3R antagonist (NK3Ra). We used the ELISA to measure the tumor necrosis factor (TNF)-α, interleukin (IL)-6, LPS, DAO, and D-LA serum concentrations in the mice. Hematoxylin-eosin (H&E) staining and transmission electron microscopy (TEM) were used to observe structural changes in the intestinal mucosa. Immunohistochemistry was used to detect the expression of claudin-1, occludin and ZO-1 in intestinal tissues.

Results

Serum NKB (75.36 ± 28.67 pg/mL vs. 44.95 ± 16.92 pg/mL) and LPS (7.38 ± 3.63 μg/mL vs. 4.50 ± 2.94 μg/mL) levels were higher in mechanical IO patients than in control people (P < 0.05). We found a positive correlation between serum NKB and LPS levels in mechanical IO patients. The serum LPS concentration in the IO+NKB mice was greater than that in the IO mice (P = 0.001). After the use of NK3Ra, the serum LPS, DAO and D-LA levels decreased (P < 0.05). H&E staining indicated that the intestinal mucosal epithelial structure was severely damaged, including lamina propria hemorrhage, atrophied villi, and inflammatory cell infiltration in IO+NKB mice. TEM revealed that the junctional complexes between epithelial cells were disrupted and absent in the IO+NKB mice. Compared with those in the IO mice, the expression levels of claudin-1 and occludin in intestinal tissues were lower in the IO+NKB mice. However, the intraperitoneal injection of NK3Ra attenuated the damage to tight junction proteins and the intestinal mucosal structure caused by NKB. Additionally, we observed that the serum IL-6 and TNF-α levels in the IO+NK3Ra mice were lower than those in the IO mice (P < 0.05).

Conclusions

NKB might increase the levels of serum IL-6 and TNF-α by acting on the NK3 receptor, promoting intestinal inflammation, and subsequently destroying the intestinal mucosal barrier during mechanical IO.