Fig 2: Flii regulates immune responses in a DSS-induced model of UC. (A,B) Representative images and graphical analysis of TNF-a levels in distal colon of colitis-induced Flii+/-, wild-type and FliiTg/Tg mice. TNF-a levels were predominantly present in apical enterocytes and significantly lower levels were observed in Flii+/- colitis-induced mice. Magnification ×10. Scale Bar = 100 µm. (C) Overexpression of Flii increases distal colon inflammation with significant upregulation of both Th1 and Th2 pro-inflammatory cytokine profiles while Flii reduction decreases inflammatory responses in a DSS-induced mouse model of UC. n = 6. Mean +/- SEM. *p < 0.05.

Fig 3: Increased disease histological severity is observed in Flii over-expressing mice. (A) Flii overexpressing mice showed significantly higher histological disease severity compared with Flii deficient mice, with significantly damaged mucosal tissue and high level of pro-inflammatory cell infiltrate. (B) Flii overexpression resulted in significantly delayed healing of blistered mucosal tissue with significantly reduced distal colon crypt depth compared to both wild-type controls and Flii deficient mice counterparts. Magnification ×4 and ×20. Scale Bar = 200 µm. n = 8/genotype. Mean +/- SEM. *p < 0.05.

Fig 4: Significantly increased number of Flii positive cells were observed in colonic tissue sourced from UC patients. (A) Representative H&E and Flii stained sections of colonic tissue from UC patients and healthy control patients. UC patients have a clear increase in inflammatory cell infiltrate and increased numbers of Flii positive inflammatory cells (red) in lamina propria compared to healthy control tissue. DAPI nuclear marker is stained blue. Magnification × 20. Scale bar = 50 µms. (B) Graphical representation of numbers of Flii positive cells in lamina propria of UC patients compared to healthy control patients. Mean +/- SEM. *p < 0.05.

Fig 5: (a) Immunohistochemical detection and quantification of vascular endothelial growth factor (VEGF) in 4 µm sections of paraffin-embedded diabetic Flii+/-, WT and FliiTg/Tg wounds. Images taken at 20× objective, scale bar = 50 µm. Data displayed as mean ± SEM, n = 7. (b) Immunohistochemical detection and quantification of CD31 in 4 µm sections of paraffin-embedded diabetic Flii+/-, WT and FliiTg/Tg wounds. Images taken at 20× objective, scale bar = 50 µm. Data displayed as mean ± SEM, n = 7. (c) Representative images of tube formation in HDMECs alone and HDMECs co-cultured with hPC-PLs, siControl hPC-PLs, siFlii hPC-PLs and hPC-PL CM at 6, 24, 48 and 72 h. Images taken at 4× objective, scale bar = 200 µm. (d) Effect of untreated, siControl-treated or siFlii-treated hPC-PLs on human dermal microvascular endothelial cells (HDMECs) and (e) Effect of hPC-PL CM or hPC-PL co-culture on HDMEC sprouting in a matrigel tube formation assay. All data displayed as mean ± SEM, n = 5. Results representative of three independently conducted experiments. Statistical significance calculated by two-way ANOVA, where * = p < 0.05, ** = p < 0.01, *** = p < 0.001, **** = p < 0.0001.