Gut and liver are physiologically and anatomically connected; which known as the gut–liver axis. Gut microbiota component and their metabolites affect both hepatocytes and stromal cells (hepatic stellate cells and Kupffer cells). [24]
Intestinal dysbiosis is observed in different chronic hepatic diseases; which increased concern about its role in the development and progression of hepatic diseases with aggravation of liver disease-related complications. [25–26]
Few studies evaluated the role of gut dysbiosis in patients with viral hepatitis. So, in this study we try to compare changes that occur in gut microbiota in patients with chronic hepatitis C, HCC with normal healthy control.
The different species of Bifidobacterium has beneficial health effects, including the regulation of homeostasis of intestinal microbes, the suppression of pathogens and harmful bacteria that colonize the gut mucosa, the modification of local and systemic immune responses, the inhibition of procarcinogen enzymatic activities of the gut- microbiota and the mend of the gut mucosal barrier by lowering the level of lipopolysaccharides. [27–28]
In our study less than half of patients with HCC and chronic HCV infection have detected Bifidobacterium in their stool sample compared to 76% of healthy volunteers. This come in agreement with Yu et al. who found that decrease Bifidobacterium species, led to accumulation of lipopolysaccharides; which act as pathological mediator of inflammation-associated HCC. [29]
In our opinion also impairment of gut wall integrity due to absence of Bifidobacterium, may allow translocation of pathogenic bacteria and endotoxins which, may produce chronic hepatic inflammation with subsequent risk of development of HCC.
Although, its known that lactobacillus species is important for human health, by decreasing gastrointestinal PH, that protect the host against invasion by pathogens. [30] on the other hand, lactobacilli may be pathogenic in susceptible patients related to several mechanisms including, the ability of some strains to bind to intestinal wall with translocation to bloodstream leading to bacteremia, also they have ability to adhere to collagen in extracellular matrix with production of glycosidase enzyme leading to damage of affected tissues. [31–33]
In this study against usual, most patients with HCC and chronic HCV infection have lactobacillus in their stool compared with healthy controls, with more detected in HCC patients than chronic HCV infected patients.
This come with Sherid et al. Who found in their case study, an involvement of lactobacillus bacteria in the development of bacteremia and liver abscess. [34]
Against our results, Zhang et al. reported that disturbance of gut microbiota homeostasis with decrease lactobacilli, led to damage of mucosa with the development of endotoxemia, systemic inflammation and tumor formation. [35]
In healthy individuals, Faecalibacterium prausnitzii represent (> 5%) of the gut flora, it plays an important role in improvement of the immune system; it is an anti-inflammatory commensal activate IL-10 secretion and inhibiting IL-12 and interferon-γ expression. [36–37]
In this study, Faecalibacterium prausnitzii has been detected in about half of patients with HCC and (38%) of patients with chronic HCV infection, opposite to (70%) of healthy control.
This come in agreement with Munukka et al. who found that treatment of mice with Faecalibacterium prausnitzii improved hepatic ALT, AST, and decreases adipose tissue inflammation.[38]
Also, Liu et al. found in his study on patients with different causes of HCC, decreased level of Faecalibacterium resulting in reduction of the level of anti-inflammatory short-chain fatty acids.[39]
The family Enterobacteriaceae includes a medically important species such as Salmonella, Escherichia coli, Yersinia pestis, Klebsiella, Shigella, Proteus, Enterobacter, Serratia, and Citrobacter. Many members of this family are normally present in human as a gut microbiota. Some enterobacteria are pathogens, because they produce endotoxins; when released into the bloodstream, cause a systemic inflammatory and vasodilatory response. [40–41]
In this study, Enterobacteriaceae was found in stool samples of about 80% of patients with HCC and 70% of chronic HCV infected patients.
This come in agreement with, Sanduzzi, Chen, Lax and Bajaj et al. who found in their studies that, increased Enterobacteriaceae was linked to progression of liver cirrhosis and development of cirrhosis related complications. [42–45]
Bacteroides is the most predominant bacteria in the colon, with Bacteroides fragilis group is the most abundant one among Bacteroides species. [46] Bacteroides together with other gut commensal bacteria provide the human body with energy through Carbohydrate fermentation producing a pool of volatile fatty acids that are absorbed in the colon. [47] Akkermansia muciniphila is one of gut micro-biota known to have an anti-inflammatory effect in humans, improves hepatic inflammation and protect against liver cell damage through an immune-mediated mechanism. Also, it’s believed to have a role in cancer response to immunotherapy. [48–50]
In our study, we found no significant difference between HCC patients and chronic HCV infected patients, in comparison with control group, regarding the stool isolate of Bacteroides fragilis.
However, Chen et al. found in his study, a significant decreased in Bacteroid level in patients with liver cirrhosis related complications. [51] On the other hand, Guoxiang et al. found a marked increase in Bacteroid species level in mice model with HCC development post-NASH. [52]
Also, in this study, no significant difference has been detected between HCC patients and chronic HCV infected patients, compared with control group, as regard the stool isolate of Akkermansia muciniphila. Akkermansia muciniphila, was detected in the stool of less than half of patients with HCC and HCV groups.
To some extent different experimental studies on animal models; come in accordance with our results. They demonstrated that, the presence gut Akkermansia muciniphila can enhance the anticancer effect of T-cell-based immunotherapies. [53–56]
Though many staging systems for HCC were used worldwide, there is no system is considered the best in evaluating the suitable treatment and patient’s prognosis. [58] Child-Pugh and TNM had a better predictive ability for overall survival than BCLC. [59] However, TNM fails to evaluate patient’s prognosis accurately, because it only evaluates tumor extension and BCLC has a better prognostic ability than TNM staging system. [60] So, in this study we try to use different systems for evaluation of patients with HCC
In this study, no significant difference was detected between gut-microbiota and HCC progression with respect to Child or TNM systems. However, a significant difference was detected between number of positive stool isolate of Bacteroid Fragilis and BCLC staging system; where it was isolated from 66.7% of patients with BCLC stage IV opposite to 10.7% of patients with BCLC stage I.
This come in agreement with Guoxiang et al. who found in his experimental study, marked increased bacteroid species together with lipopolysaccharides levels; with the progression of liver disease from steatosis till HCC. [61]