Table 1.

A comparison of tight junction expression in patients with CD and UC and experimental models of colitis

Junction complex protein	Function	Human IBD		Mouse models of colitis
		CD	UC	TNBS	DSS
Claudin-1	Decreases paracellular permeability [39]	↑ [45]	↑ [43]	↓ [46] [47]	↑ [48]
Claudin-2	Increases paracellular permeability. Important pore forming protein [39]	↑ [42, 43]	↑ [42, 43]	↓ [49]	↑ [50]
Claudin -3	Decreases paracellular permeability [40]	↓ [42]	↓ [42]	↓ [47]	↓ [48]
Claudin-4	Decreases paracellular permeability [39]	↓ [42]	↓ [42]	–	↓ [51]
Claudin-5	Decreases paracellular permeability [39]	↓ [44]	–	No change [47]	↓ [48]
Claudin-7	Acts as an anion barrier and pore [40]	No change [44]	↓	–	↓ [48]
Claudin-8	Decreases permeability [39]	↓ [44]	–	↓ [47]	↓ [48]
Occludin	Regulates paracellular permeability and cellular adhesion [39]	↓ [52]	↓ [52]	↓ [47]	↓ [53]
ZO-1	Facilitates connection between TJ and intracellular actin cytoskeleton [39]	↓ [54]	↓ [55]	↓ [47]	↓ [46]
MLCK	Phosphorylates MLC causing contraction of peri junctional actomyosin [56]	↑ [57]	↑ [57]	↑ [58]	↑ [59]
Phosphorated (active) MLC	MLC facilitates internalisation of TJ [56]	↑ [57]	↑ [57]	↑ [60]	↑ (59)

↑ upregulated; ↓ downregulated; – no explicit data; JAM junctional adhesion molecule; MLC myosin II regulatory light chain; MLCK myosin light chain kinase