Intestinal permeability — how easily substances pass through the intestinal barrier rather than being kept out — plays a central role in celiac disease and gluten sensitivity.
Remission Can Mean a Return to Normal Barrier Function
Hollon et al. (2015) exposed intestinal biopsy specimens to gliadin and measured the resulting change in permeability across several groups. Even specimens from the control group showed increased permeability on gliadin exposure — a reminder that gliadin’s effect on the gut barrier isn’t unique to celiac disease. But the differences between groups were striking: those with non-celiac gluten sensitivity showed greater intestinal permeability than celiac patients in remission — in fact, as great as celiac patients with active disease. Meanwhile, the permeability seen in celiac patients in remission was comparable to the healthy control group.
That’s an encouraging result to share with celiac patients: it suggests that achieving remission can mean the intestinal barrier returns to something close to normal function, rather than remaining permanently compromised. It would be worth watching for research using other measures of intestinal permeability to see whether this finding is replicated.
The Cellular Machinery Behind the Barrier
Two more recent studies help explain what’s actually happening at the tight junctions that make this barrier function possible.
Niu et al. (2024) investigated how killer T cells help regulate intestinal permeability through a molecule called granzyme A. They found that granzyme A contributed to an increase in the activity of glutathione peroxidase 4 (GPX4), which in turn influenced intestinal epithelial cells to differentiate toward an increased expression of occludin and zonula occludens-1 (ZO-1) — two proteins essential to forming the tight junctions that give the intestinal epithelium its barrier function.
Hasegawa et al. (2021) looked at whether adequate cysteine — a limiting factor in the body’s production of glutathione — could help protect against increased intestinal permeability driven by oxidative stress and the resulting inflammatory cytokines like IL-6. They found that with sufficient cystine, tight junctions were less susceptible to oxidative-stress-induced permeability, alongside a corresponding increase in glutathione. This study also points to occludin and ZO-1 as central to tight junction barrier function, and describes a self-perpetuating scenario: once intestinal permeability increases, more lipopolysaccharides can enter the bloodstream, triggering more inflammatory cytokines (TNF-α, IL-1β, IL-6), which further reduce occludin and ZO-1 expression via the NF-κB pathway — deepening the very permeability that started the cycle.
The Takeaway
Between these studies, a coherent picture emerges: intestinal permeability isn’t a fixed state, and the tight junction proteins occludin and ZO-1 sit at the center of both the problem and its potential resolution. The Hollon findings suggest the barrier can genuinely normalize with disease remission, while the mechanistic work from Niu et al. and Hasegawa et al. point to specific pathways — granzyme A/GPX4 signaling and adequate cysteine/glutathione status — that support that same tight junction machinery, along with a feedback loop once permeability and inflammation start reinforcing each other.
The content of this blog is for educational purposes and is not intended as medical advice. Please work with a qualified healthcare provider for personalized guidance.
References
Hasegawa, T., Mizugaki, A., Inoue, Y., Kato, H., & Murakami, H. (2021). Cystine reduces tight junction permeability and intestinal inflammation induced by oxidative stress in Caco-2 cells. Amino Acids, 53(7), 1021–1032.
Hollon, J., Puppa, E. L., Greenwald, B., Goldberg, E., Guerrerio, A., & Fasano, A. (2015). Effect of gliadin on permeability of intestinal biopsy explants from celiac disease patients and patients with non-celiac gluten sensitivity. Nutrients, 7(3), 1565–1576.
Niu, R., Lan, J., Liang, D., Xiang, L., Wu, J., Zhang, X., Li, Z., Chen, H., Geng, L., Xu, W., Gong, S., & Yang, M. (2024). GZMA suppressed GPX4-mediated ferroptosis to improve intestinal mucosal barrier function in inflammatory bowel disease. Cell Communication & Signaling, 22(1), 1–13.
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