Science Innovation
Clinical Trials Research Article

Relationship Between Chronic Kidney Disease and Intestinal Flora


With the understanding and study of the intestinal tract, it is found that the intestinal flora is exactly the invisible commander of the human body, it affects people's health, and many diseases are related to it. Even chronic kidney disease (CKD) has been linked to intestinal flora in various ways.

CKD is Destructive to Intestinal Flora

Growing numbers of scholars have found in their studies that CKD patients have obvious intestinal flora disorders [1-4]. The clinical studies show that the abundance ratio and composition of intestinal flora of CKD patients have changed significantly. CKD patients have an increased number of pathogenic bacteria (including opportunistic pathogens) in their gastrointestinal tracts. If patients do not receive treatment, these pathogens will continue to increase, and when they reach a certain level, they will induce or aggravate the accumulation of uremia toxins and related bacterial toxins, thus accelerating the CKD process and the occurrence of complications.

In addition, CKD patients will also have a significant decrease in beneficial intestinal bacteria, which also has adverse effects on CKD patients. The reduction of beneficial intestinal bacteria will cause a range of health problems, such as metabolic problems, blood pressure problems, or other health hazards [2, 5, 6, 7]. And when the intestinal flora is damaged by the kidney, it will damage the kidney in return.

Interdependent and Mutually Antagonistic Kidney and Intestine

The existing evidence shows that CKD can not only induce the change of intestinal flora, but also transform from a more uniform and complex community to a more single and dominant community. Over time, this transformation will in return make intestinal flora affect the kidney, as shown in the following aspects:

1. Synthesis of uremic toxin

The worst scenario for CKD is uremia, and the imbalance of intestinal flora in CKD patients will lead to an increase in the production of intestinal uremia toxin IS, PCS and trimethylamine oxide. Furthermore, the imbalance of intestinal flora can destroy the tight junction of intestinal epithelium, increase intestinal permeability and lead to bacterial and toxin translocation. The accumulation of enterogenic uremic toxin will further aggravate the disorder of intestinal flora, promoting the growth of pathogenic bacteria, thus forming a vicious circle and making CKD patients rapidly enter into the end-stage of renal failure [8].

2. Causing multisystem inflammation in CKD patients

CKD patients are most afraid of the invasion of inflammation and infection, which will increase the burden on the kidneys and accelerate the deterioration of CKD. If the intestinal flora is disordered, it can promote the generation of intestinal immune inflammation, and then participate in the systemic immune inflammatory regulation of CKD, and the inflammatory response will run through the whole process of the occurrence and development of CKD. Recent experiments on human and animals shows that the disorder of intestinal flora in patients with CKD is accompanied by systemic inflammatory response, which is closely related to bacterial translocation and toxin influx caused by the imbalance of intestinal mucosal barrier function due to disorder of intestinal flora [9].

3. Resulting in disorder of nutrition metabolism

There are obvious disorder of nutrition metabolism in CKD patients, especially in children with CKD, whose nutritional status will seriously affect their growth, and the main culprit is the change of intestinal flora. According to the metagenomic sequencing of intestinal flora, the number of sclerotinia in the intestinal flora of CKD patients increases while that of bacteroides decreases, which is very similar to that of obese patients. Therefore, scientists believe that the disorder of intestinal flora will induce the disorder of insulin resistance and nutrition metabolism, and then aggravate the CKD [10-12].

Probiotics Destroy The Kidney-Intestine Deteriorating Link One By One

The main function of probiotics in the treatment of CKD is to destroy the interaction between intestinal flora and CKD, so as to slow down the rate of renal failure, delay the CKD patients' entering into the end-stage of renal failure, and postpone the time of kidney replacement therapy. The mechanism is as follows:

1. Probiotics can reconstruct the balance of intestinal flora, stabilize the intestinal mucosal barrier, reduce the production and accumulation of creatinine, urea nitrogen and enterogenic uremic toxin, and improve the immune defense ability of the host.

2. Probiotics can reduce the levels of uremic toxins such as IS and PCS in the serum of CKD patients, reduce the release of inflammatory mediators, and relieve the damage of tight junction of intestinal epithelium, thus improving endotoxemia and improving the quality of life in patients with CKD [13-16].

3. In addition, the clinical trials shows that the probiotics can effectively reduce the levels of serum TNF-α and IL-6 in CKD PD patients, reduce the level of C-reactive protein in maintenance hemodialysis patients, and inhibit inflammatory response [17.18].

4. Probiotics can increase the activity of bile salt hydrolase, regulate the synthesis of cholesterol in the liver, and reduce the hepatic steatosis. By down-regulating the expression of lipid metabolism open genes, lactobacillus rhamnosus can inhibit the synthesis of cholesterol and triglycerides and increase the level of fatty acids [19]. Thus, the nutrition metabolism of CKD patients can be changed.

Although CKD patients experience a lot of pain, probiotics can help them fend off disease together. Due to individual differences, not all CKD patients have the same intestinal flora imbalance, so the specific probiotics should be taken under the guidance of the professional doctor.


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