PTK2B regulates immune responses of neutrophils and protects mucosal inflammation in ulcerative colitis

by Selleckchem | Oct 14 2023

Neutrophils participate in the pathogenesis of ulcerative colitis (UC) through regulating the intestinal homeostasis. Several inflammatory diseases are reported to be regulated by proline-rich tyrosine kinase 2B (PTK2B). However, the role of PTK2B in regulating the function of neutrophils and the pathogenesis of UC remains unknown. In this study, the mRNA and protein levels of PTK2B in the colonic tissues from UC patients were measured by using quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry. TAE226, a PTK2B inhibitor, was used to inhibit the activity of PTK2B in neutrophils, and then, the pro-inflammatory factors were analyzed by using qRT-PCR and ELISA. To determine the role of PTK2B in intestinal inflammation, a dextran sulfate sodium (DSS)-induced colitis model was established in PTK2B gene knockout (PTK2B KO) and wild-type (WT) mice. We found that compared with healthy donor controls, the expression level of PTK2B was significantly elevated in inflamed mucosa from UC patients. In addition, expression of PTK2B was positively correlated with the severity of disease. Pharmacological inhibition of PTK2B could markedly reduce the generation of reactive oxygen species (ROS), myeloperoxidase (MPO), and antimicrobial peptides (S100a8 and S100a9) in neutrophils. The vitro study showed that tumor necrosis factor (TNF)-α is involved in promoting the expression of PTK2B in neutrophils. As expected, UC patients treated with infliximab, an anti-TNF-α agent, showed significantly reduced level of PTK2B in neutrophils, as well as in the intestinal mucosa. Of note, compared with DSS-treated WT mice, DSS-treated PTK2B KO mice showed more severe colitis symptoms. Mechanistically, PTK2B could enhance neutrophil migration by regulating CXCR2 and GRK2 expression via the p38 MAPK pathway. Additionally, mice treated with TAE226 exhibited the same effects. In conclusion, PTK2B is involved in the pathogenesis of UC by promoting the migration of neutrophils and inhibiting mucosal inflammation, highlighting PTK2B as a new potential therapeutic target to treat UC.

Comments:

The study you described investigated the role of proline-rich tyrosine kinase 2B (PTK2B) in the pathogenesis of ulcerative colitis (UC) and its effect on neutrophil function and intestinal homeostasis. The researchers measured the mRNA and protein levels of PTK2B in colonic tissues from UC patients using various techniques such as quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry.

They found that the expression level of PTK2B was significantly elevated in the inflamed mucosa of UC patients compared to healthy controls. Moreover, the expression of PTK2B correlated positively with the severity of the disease. To investigate the function of PTK2B in neutrophils, they used TAE226, a PTK2B inhibitor, to inhibit its activity. They observed that inhibiting PTK2B reduced the generation of reactive oxygen species (ROS), myeloperoxidase (MPO), and antimicrobial peptides (S100a8 and S100a9) in neutrophils. This suggests that PTK2B plays a role in regulating the inflammatory response of neutrophils in UC.

In vitro studies revealed that tumor necrosis factor (TNF)-α promotes the expression of PTK2B in neutrophils. Treatment of UC patients with infliximab, an anti-TNF-α agent, resulted in a significant reduction in the level of PTK2B in neutrophils and intestinal mucosa.

To further investigate the role of PTK2B in intestinal inflammation, the researchers established a dextran sulfate sodium (DSS)-induced colitis model in PTK2B gene knockout (PTK2B KO) mice and wild-type (WT) mice. Surprisingly, the PTK2B KO mice exhibited more severe colitis symptoms compared to the WT mice when exposed to DSS. This suggests that PTK2B may have a protective role in UC by inhibiting mucosal inflammation.

Mechanistically, the researchers found that PTK2B enhances neutrophil migration by regulating the expression of CXCR2 and GRK2 via the p38 MAPK pathway. Treating mice with TAE226, the PTK2B inhibitor, yielded similar effects.

In conclusion, the study demonstrates that PTK2B is involved in the pathogenesis of UC by promoting the migration of neutrophils and inhibiting mucosal inflammation. The findings highlight PTK2B as a potential therapeutic target for the treatment of UC.