Eosin solution

The fixed synovial tissue of ankle joint was embedded in paraffin, followed by deparaffinized and rehydrated. Subsequently, the de-waxed sections were immersed in hematoxylin solution
(Solarbio, Beijing, China) for 5 min, soaked in double distilled water for 5 min. Then dissimilation caused by 1% hydrochloric acid ethanol for 3 s, and rinsed with running water for 20 min.
After soaked in double distilled water for 2 min, the sections were stained by eosin solution (Sangon, Shanghai, China) for 3 min. At last, the slices were dehydrated, transparent and
sealed. The pathomorphological changes of synovial tissues were observed under microscope.

The intestinal tissues were fixed in 10% neutral formalin, followed by dehydration in ascending series of ethanol, transparention using xylene and paraffin embedding. Subsequently the paraffin-embedded tissues were cut into 5 μm-thick sections, dewaxed in xylene, and rehydrated through decreasing concentrations of ethanol. The slides were successively incubated with hematoxylin solution (Sangon Biotech, Shanghai, China) for 10 min and eosin solution (Sangon Biotech, Shanghai, China) for 3 min, followed by dehydration with graded ethanol. After the addition of xylene, the sections were observed using a light microscope (Nikon, Tokyo, Japan).
Pathologic scoring was performed using hematoxylin and eosin (H & E) staining data in a blinded manner. Three independent parameters of each sample were examined, including severity of inflammation (0–3: none, slight, moderate and severe), depth of injury (0–3: none, mucosal, mucosal and submucosal, and transmural) and extent of crypt damage (0–4: none, basal 1/3 damaged, basal 2/3 damaged, only surface epithelium intact, and entire crypt and epithelium lost).^{23 (link)} The sum of these parameter scores was multiplied by a factor which reflected the percentage of tissue involvement (1–4: 0%-25%, 26%-50%, 51%-75%, and 76%-100%).