## Results
### Effect of Probiotics Administration on TJP Expression  
The effect size on TJP expression is indicated in Figure 2. All analyzed items, including claudin, occludin, and ZO-1, showed a positive effect size in the random effects model by the administration of probiotics, and there was a significance (claudin, SMD: 4.45; 95% confidence interval (CI): 3.12-5.78; \(p<0.01\); \(l^{2}=92\%\); occludin, SMD: 5.64; 95% CI: 4.44-6.83; \(p<0.01\); \(l^{2}=90\%\); ZO-1, SMD: 4.20; 95% CI: 3.17-5.23; \(p<0.01\); \(l^{2}=88\%\)). This suggests that the administration of probiotics to animals positively affects TJP expression in damaged intestinal environments. In the case of claudin (Figure 2A), most studies indicated positive effect sizes. However, some studies, including those by [PERSON] et al. (2019), and [PERSON] et al. (2019), represented a negative effect size. Among the studies with positive effect sizes, [PERSON] et al. (2019), [PERSON] et al. (2019), [PERSON] et al. (2019), and [PERSON] et al. (2019) showed the most significant weight in the random effects model (4.9%). Figure 2B indicates occludin expression. Except for the studies by [PERSON] et al. (2019), and [PERSON] et al. (2019), most studies indicated positive effect sizes. Among them, [PERSON] et al. (2019) indicated the most significant effect size (SMD: 79.26; 95% CI: 49.95-108.57) in the random effect model. However, it showed the smallest weight in the random effect model (0.2%), and its influence was more minor than others. In ZO-1 expression (Figure 2C), only one study ([PERSON] et al. (2019)) showed negative effect size. The studies of [PERSON] et al. (2019), [PERSON] et al. (2019), [PERSON] et al. (2019) showed the highest weight (3.8%) among the studies that had positive effect size in the random effect model. In this study, the Q statistics of claudin was highest (340.94) and significant (\(p<0.0001\)) (data not shown). Furthermore, all items, for instance, claudin, occludin, and ZO-1, showed a high level of \(l^{2}\), especially claudin, which was highest at 92.4%. In other words, all items had significantly high heterogeneity.  
Figure 2: _Cont_.  
Figure 3 denotes the effect size on mRNA expression of TJP. All analyzed items, including claudin, occludin, and ZO-1, showed a positive effect model. There were significance in  
Figure 2: Forest plot for effect size of probiotics administration on tight junction protein expression by random effect model. (**A**) claudin; (**B**) occludin; (**C**) ZO\(-\)1, [24; 25; 26; 27; 28; 30; 32; 37; 38; 40; 41; 42; 43; 45; 46; 50; 51; 57; 59; 61; 62; 63; 64; 65; 66; 67; 68; 69].  
all analyzed items (claudin, SMD: 2.08; 95% CI: 0.61-3.55; \(p<0.01\); \(l^{2}=94\%\); occludin, SMD: 3.37; 95% CI: 2.35-4.38; \(p<0.01\); \(l^{2}=94\%\); ZO-1, SMD: 3.94; 95% CI: 3.20-4.68; \(p<0.01\); \(l^{2}=90\%\)). It means that probiotics administration is effective for mRNA expression of TJP in an animal model. In the case of claudin (Figure 3A), some studies, such as [PERSON] et al. [35] and [PERSON] et al. [55], showed a negative effect size. However, except for two studies, all other studies showed a positive effect size. Figure 3B shows the mRNA expression of occludin. Most studies indicated a positive effect size except for [PERSON] et al. [48] and [PERSON] et al. [49]. In particular, [PERSON] et al. [33] denoted the largest effect size (SMD: 29.45; 95% CI: 15.03-43.86). Similarly, most studies showed a positive effect size in Figure 3C except for [PERSON] et al. [55]. [PERSON] et al. [54] showed the largest SMD (SMD: 20.43; 95% CI: 11.44-29.41). However, its weight in the random effect model was 0.6%. On the other hand, the study of [PERSON] et al. [29] showed the highest weight (3.5%) in the random effect model. Among the analyzed items, occludin showed the highest Q statistics (499.12) with significance (\(p<0.0001\)) in the random effect model of TJP mRNA expression.  
Figure 3: \(Cont.\)