Clinical trial NCT02302287: Renal Effects of Meditarranean Diet and Low-protein Diet With Ketoacids on Physiological Intestinal Mibrobiota in CKD
Official title: Gut-kidney Axis: Renal Effects of Meditarranean Diet and Low-protein Diet With Ketoacids to Restore Physiological Intestinal Mibrobiota in Chronic Kidney Disease
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: PHASE4
Conditions: Chronic Renal Insufficiency
Keywords: Chronic kidney disease
mediterranean diet
low-protein diet
ketoacids
intestinal microbiota
Lead sponsor: Azienda Sanitaria ASL Avellino 2
Sponsor class: OTHER
First posted: 2014-11-27
Enrollment: 60
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: Food intake has a deep influence on gut microbiota composition and function, both in health and in disease status. In chronic kidney disease (CKD), a microbiota dysbiosis status is observed. Moreover, many toxic uremic molecules are microbial-derived and their accumulation promotes, in turn, disease progression.

Investigators' hypothesis foresees a beneficial effect of nutritional treatments, able to restore gut microbiota balance, to lower microbial-derived uremic toxins and to improve clinical conditions in CKD patients.

Mediterranean Diet (MD) is supposed to have beneficial effect on microbiota composition, while low-protein diet supplemented with ketoacids (KD) is used in CKD patients for the improvement of clinical conditions, but its effects on gut microbiota are currently unknown. Investigators' project aim is to verify the effects of MD and KD on: microbiota and metabolome composition, microbial-derived uremic toxins level and clinical conditions in a cohort of CKD patients.

Detailed description: Background: In CKD the biochemical milieu of gastrointestinal tract (GI) is altered by several mechanisms, affecting gut microbiota composition and function. Beyond exerting metabolic functions, microbiota influences the general healthy status. It digests food mainly through saccharolytic or proteolytic catabolism, with a prevalence of the former in healthy status. On the contrary, in CKD, dysbiosis with the prevalence of the latter is observed.

In this setting, reduction in glomerular filtration rate and increase in urea levels result in its heavy influx into the GI. Here urea is hydrolyzed spontaneously and/or by microbial urease, releasing ammonia, readily converted into ammonium hydroxide. The latter raises GI pH, causing mucosa irritation, enterocolitis and changes in microbiota composition. This contributes to worsening of inflammation and disease progression: indeed, microbiota has been identified as the primary source of several well known and yet unidentified volatile organic compounds (VOC), including some of the main uremic toxins.

Some beneficial effects observed from studies with low-protein diet supplemented with ketoacids in CKD cannot be solely explained by the reduced protein intake. Investigators' hypothesis is that ketoacids may have direct protective effects on renal damage progression, through induced modifications in gut biochemical milieu and in microbiota composition.

Similarly, the Mediterranean Diet with its fibers supply can contribute to restore gut microbiota balance.

Hypothesis:

The first hypothesis foresees a beneficial effect of KD on microbiota balancing and microbial-derived uremic toxins decrease in CKD patients, through KD-induced urea reduction. The second envisages MD direct effects on gut microbiota composition with an increase in protective species and a decrease in uremic toxins production.

The study will evaluate the effects of three different dietary regimens, composed as follows:

FD contains 1 g/bw/day of protein, plant protein 15-20 g/day;

* MD contains 0.7-0.8 g/bw/day of protein, plant protein 40-50 g/day;
* KD contains 0.3-0.5 g/bw/day of protein, animal protein zero g/day, plant protein 30-40 g/day, plus ketoacids of 0.05 g/bw/day.

Specific aim:

1. To evaluate the effects of Mediterranean diet (MD) and low-protein diet supplemented with ketoacids (KD) on microbiota composition
2. To evaluate the effects of KD and MD on microbial-derived VOC (already identified and yet unidentified uremic toxins) levels by metabolomics
3. To evaluate the effects of KD or MD on renal function parameters, uremia, inflammatory and nutritional status

Experimental Design Aim 1:

The designed study will be experimental, randomized, cross-over. It will be carried out according to the Declaration of Helsinki (IV Adaptation) and will be submitted to the approval of the local Ethics Committee; written consent will be obtained from all subjects. 60 patients with CKD stages 3b-4 (MDRD formula) will be enrolled, according to the inclusion and exclusion criteria (see below).

Experimental Design Aim 2:

Untarget metabolomic analysis will be carried out on fecal and urine samples collected at the same time points described in Experimental design aim 1 for VOC (GC-MS/MS) and non-VOC profiling (LC-MS/MS). Sera collected at the same time points will be also analyzed by untarget metabolomic for non-VOC profiling and by target metabolomic to quantify the already known uremic toxins, namely indoxyl sulfate and p-cresyl sulfate, and potential metabolite biomarkers found by the untarget experiment.

Experimental Design Aim 3:

Additionally, each patient will undergo medical examination every three months, with evaluation of: blood pressure and nutritional status. Moreover, at the same time points of aim 1 (T0, T3, T9, T12 and T18 months from the beginning of the study) each patient will provide blood and urine samples, both for routine and experimental analysis.

Eligibility criteria: Inclusion Criteria:

* prevalent patients in tertiary nephrology clinic;
* patients over 18 years;
* CKD stage 3b-4 (eGFR between 15 and 45 ml/min/1.73m2, estimated by MDRD formula);
* clinically proven adherence to prescribed therapies;
* informed consent signed.

Exclusion Criteria:

* change of GFR \>30% within the last 3 months;
* acute, intercurrent disease during the previous 3 months;
* severe undernutrition as indicated by: BMI \< 20 kg/m2 and serum albumin \< 3.2 g/dl, or BMI \< 17.5 kg/m2 whatever albumin value, or body weight reduction \> 5% within the last month or \> 10% within the last six months;
* pregnancy or feeding;
* chronic treatment with steroid or cytotoxic drugs; fast progressing glomerulonephritis; active SLE and vasculitis;
* gastrointestinal diseases (Crohn disease, Ulcerative colitis, Celiac Sprue, Stypsis); 7) infectious diseases; 8) cardiac failure stage III-IV NYHA; advanced liver cirrhosis; active cancer diseases; severe encephalopathy associated with lack of spontaneous feeding; chronic obstructive respiratory diseases needing oxygen treatment; 9) use of antibiotics or probiotics until 15 days before the enrolment; 10) psychiatric disease or inability to assess follow-up.

Primary outcomes:
measure: Change from baseline in fecal microbiota by MD and KD at 18 months
timeFrame: 0-18 months from the beginning of the study
Secondary outcomes:
measure: Change from baseline in microbial-derived uremic toxins level at 18 months
timeFrame: 0-18 months from the beginning of the study
measure: Change from baseline in renal function at 18 months
timeFrame: 0-18 months from the beginning of the study
measure: Change from baseline in nutritional status at 18 months
timeFrame: 0-18 months from the beginning of the study
measure: Change from baseline in inflammatory status at 18 months
timeFrame: 0-18 months from the beginning of the study
measure: Change from baseline in microbial-derived uremic toxins level at 18 months
timeFrame: 0-18 months from the beginning of the study
Other outcomes:
Locations:
city: Solofra
country: Italy
facility: UOC Nefrologia
state: Avellino
Study officials:
affiliation: Azienda Sanitaria ASL Avellino 2
name: Biagio Raffaele Di Iorio, PI
role: PRINCIPAL_INVESTIGATOR
References:
citation: Bellizzi V, Chiodini P, Cupisti A, Viola BF, Pezzotta M, De Nicola L, Minutolo R, Barsotti G, Piccoli GB, Di Iorio B. Very low-protein diet plus ketoacids in chronic kidney disease and risk of death during end-stage renal disease: a historical cohort controlled study. Nephrol Dial Transplant. 2015 Jan;30(1):71-7. doi: 10.1093/ndt/gfu251. Epub 2014 Jul 30.
citation: Bellizzi V, Di Iorio BR, De Nicola L, Minutolo R, Zamboli P, Trucillo P, Catapano F, Cristofano C, Scalfi L, Conte G; ERIKA Study-group. Very low protein diet supplemented with ketoanalogs improves blood pressure control in chronic kidney disease. Kidney Int. 2007 Feb;71(3):245-51. doi: 10.1038/sj.ki.5001955. Epub 2006 Oct 11.
citation: Marzocco S, Dal Piaz F, Di Micco L, Torraca S, Sirico ML, Tartaglia D, Autore G, Di Iorio B. Very low protein diet reduces indoxyl sulfate levels in chronic kidney disease. Blood Purif. 2013;35(1-3):196-201. doi: 10.1159/000346628. Epub 2013 Mar 13.
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