Treatment strategy in patients with acute viral hepatitis, including HAV infection, is based on supportive interventions, as well as anti-viral treatments in symptomatic cases. Potential beneficiary effects of UDCA are unclear in the clinical course of childhood acute HAV. In the present study, we demonstrated that UDCA had some beneficial effects on children with acute HAV infection. Although there was no significant difference in the rate of AST or ALT reductions at the end of six months of therapy, a higher ratio of patients in the UDCA group (61, 80.3%) than in the control group (51, 68%) had normal ALT levels at the end of two months (P = 0.06). Accordingly, the ratio of patients with normal AST level was significantly higher in the UDCA group than in the control group at the end of the first month (44.7% vs. 26.7%, respectively; P = 0.02), two months (67.1% vs. 41.3%, respectively; P = 0.001), and three months (86.8% vs. 74.7%, respectively; P = 0.04) after therapy initiation.
UDCA has been described as an effective agent in improving some disease markers in adult patients with acute or chronic viral hepatitis. In a study by Fabris et al. on 79 adult patients with acute viral hepatitis including 15 patients with acute HAV infection, hepatic aminotransferases levels showed no significant differences between patients who received UDCA for three weeks and non-treated patients (
15). In a meta-analysis by Chen et al. it was shown that UDCA was effective to alleviate the levels of HBsAg, HBV DNA, and hepatic aminotransferases in patients with HBV infection (
16). In addition, patients with HCV infection treated with UDCA had significantly lower hepatic enzymes levels than those receiving placebo (
16). Moreover, treatment with UDCA for one year reduced hepatic enzymes levels and accelerated viral clearance in patients affected with acute viral hepatitis (
17). In patients with HCV infection, incorporating UDCA into the therapeutic protocol significantly improved ALT levels in patients who either could not tolerate (
18) or did not respond to (
19,
20) interferon-based therapies. Other studies also showed that UDCA dose-dependently reduced AST, ALT, and GGT levels in patients with chronic HCV infection (
19,
21,
22). In the comparison between the two groups of HCV-infected patients who were treated with either alpha-IFN or alpha-IFN+UDCA, the latter group had significantly higher reductions in ALT levels at the end of six months following therapy (
20). According to another study by Attily et al. UDCA administration reduced transaminases and GGT peptidases in patients with chronic active hepatitis (
23). In another study conducted by Leuschner et al. UDCA reduced serum levels of ALT and AST in patients with biliary cirrhosis and chronic hepatitis (
24). Similar results were also observed in studies carried out by Bellentani et al. (
25) and Rolandi et al. (
26) who showed that UDCA significantly affected hepatic liver enzymes in patients with chronic active hepatitis.
Contrary to previous studies, Galsky et al. reported no significant differences in liver enzymes comparing HBV-infected patients treated with UDCA and with placebo after 12 months of therapy (
17). Nevertheless, we here observed that UDCA accelerated the reduction in hepatic enzymes in children with acute HAV infection. In this regard, the ratio of patients with normal AST levels was significantly higher in the UDCA group than in the control group one month (n = 34, 44.7% vs. n = 20, 26.7%, respectively; P = 0.02), two months (n = 51, 67.1% vs. n = 31, 41.3%, respectively; P = 0.001), and three months (n = 66, 86.8% and n = 56, 74.7%, respectively; P = 0.04) post-therapy. Likewise, the ratio of patients with normal ALT levels was higher in the UDCA group (61, 80.3%) than in the control group (51, 68%) two months post-therapy (P = 0.06). Six months post-therapy, however, all the patients reached normal AST and ALT levels in both groups.
Therapeutic response to UDCA can be influenced by the clinical characteristics of patients with acute or chronic hepatitis. In this regard, superior responses to UDCA treatment may be achieved in patients with lower initial levels of hepatic aminotransferases and higher initial levels of GGT and those with liver cirrhosis (
27). In additions, genetic factors and other inter-individual variables may also influence the therapeutic outcomes, which need to be assessed in future population-based studies.
Detailed downstream mechanisms involved in therapeutic actions of UDCA are yet to be elucidated. As noted, UDCA is a secondary dihydrofolicdihydroxyl bile acid with hydrophilic properties (
7). It is assumed that one of the main mechanisms of UDCA protective actions in cholestatic liver disease is to replace hepatotoxic bile acids within hepatocytes (
28). In experimental models of liver cholestatic diseases, the accumulation of hydrophobic bile acids such as chenodeoxycholic and deoxycholic acids in hepatocytes caused multiple cellular damages including increased fluidity and permeability of hepatocytes membranes, cell death (apoptosis), and necrosis (
15). The extent and the duration of liver exposure to these hepatotoxic bile acids determine the extent of damage to hepatocytes, and transient accumulation of these toxicants can reversibly increase transaminases (
29). The substitution of these bile acids with more hydrophilic components (i.e. UDCA) can stabilize hepatocytes membranes and protect these cells from apoptosis. UDCA also has immunomodulatory effects by inhibiting IFN-γ production by intrahepatic lymphocytes (
30). Furthermore, UDCA can also induce the release of cytochrome c from mitochondria and suppress apoptosis in hepatocytes (
15). In addition, anti-apoptosis, anti-inflammatory, and antioxidant properties of UDCA have been shown in neural cells exposed to high levels of bilirubin (
28,
31). Other potential molecular events involved in UDCA protective actions against hepatic damage are yet to be elucidated.
5.1. Limitations
Although AST and ALT can reliably reflect the liver health, histological examination is the gold standard for assessing liver functional status. In uncomplicated HAV infection, however, histological examinations are rarely indicated. The histological effects of UDCA may help more reliably conclude on the applicability of UDCA in clinical settings.
5.2. Conclusions
Our findings showed that UDCA administration in children with acute HAV infection accelerated the normalization of liver enzymes. However, there were no significant differences in the ratios of AST and ALT normalization between children receiving UDCA and non-treated children after six months of therapy.