top of page
Investigación-Renal.jpg

Our research targets the reincorporation of metabolites in the CAC to ultimately reduce toxic solutes

The Origin

Everyday proteins we consume are synthesized and degraded into amino acids (AA) that contain nitrogen (N). Since amino acids can not be stored, they are catabolized in the liver, loosing their amino group (NH2) through deamination and forming ammonia (NH3). In the aqueous medium of the organism, at the physiological pH, ammonia occurs as ammonium ion (NH4+). Ammonium is converted to urea through the Urea Cycle in the liver.

In healthy people, urea is filtered in the renal glomeruli and mostly excreted in the urine. It corresponds to approximately 90-95% of the total nitrogen excretion. Alternately to renal excretion, expelling of urea and other low molecular weight nitrogen compounds is also carried out through sweat, feces, and as ammonium through the urine.

​

Patients with Chronic Kidney Disease (CKD) experience a decreased filtration rate given the loss of kidney function. Therefore, urea, ammonium and other nitrogenous compounds can not be excreted in full or as necessary in relation to the amount of proteins consumed, which degrade into nitrogen-containing amino acids. Thus, CKD patients are prescribed low-protein diets which typically range from 0.6 to 0.8 grams of protein per kilo of weight per day.

​

  • According to a diet restricted to 0.6 grams of protein per kilo of weight per day, a person of 70 kilos of weight would ingest 42 grams of protein, which would provide 6.72 grams of nitrogen (equivalent to 480 millimoles of nitrogen).

  • In the case of a diet of 0.8 grams of protein per kilo of weight per day, a person of 70 kilos of weight would ingest 56 grams of protein, which would provide 8.96 grams of nitrogen (equivalent to 640 millimoles of nitrogen).

Proteins

to AA

Urea Toxicity

Since patients with Chronic Kidney Disease suffer from a reduced glomerular filtration rate (GFR), their kidneys can not excrete sufficient urea, ammonium and other nitrogenous compounds. Thus, these toxic substances begin to accumulate in the blood up to a serious point causing uremia. Guidelines suggest that when the patient's GFR lowers to between 5 to 10 mL/min, the patient must begin with a renal replacement treatment (RRT), such as peritoneal dialysis (PD), hemodialysis (HD) or renal transplant (from living or deceased donor kidneys). At this point, classified as End-Stage Renal Disease (ESRD), quantity and quality of life become severely detrimental. Life-expectancy with dialysis (if the patient is lucky enough to have adequate affordable access to treatment) is well known and documented (read the Problem), as well as the side-effects and life-threatening complications of the established RRT. 

​

Very few options are available to treat excess of accumulated urea in early stages of CKD, making the progression to ESRD imminent. It is such, that guidelines and medical physicians are becoming more and more accurate as to calculating in how much time a patient will be needing RRT. 

Urea was long thought to be non-toxic and was monitored as a marker of dialysis adequacy. Recent studies shed light on the serious toxicity of urea at levels representative for chronic kidney disease, highlighting the importance of reducing urea concentration in early stages of CKD.

  • “Higher BUN [blood urea nitrogen] levels were identified as a risk factor for kidney disease progression in patients with moderate to severe CKD, independent of eGFR” [1].

​​

  • “Urea can exert direct toxicity to various tissues, such as the intestinal epithelium, vascular walls, pancreatic β cells, and adipocytes, and indirect toxicity through carbamylation” [2].

urea molecule

Urea

  • “Urea slowly dissociates into cyanate, which is rapidly converted to isocyanate. […] Carbamylation has been recognized as a spontaneous post-translational modification of amino acids and proteins mediated by cyanate, which leads to biochemical alterations” [1].

​​

  • “Hypercarbamylation is present in all stages of CKD before and after the start of hemodialysis” [3].

​​

  • “Urea induces the production of reactive oxygen species (ROS) in adipocytes, leading to insulin resistance” [4].

​​

  • “The insulin-secreting defects associated with CKD arise from elevated circulating levels of urea that increase the islet protein O-GlcNacylation and impair glycolysis” [5​].

​​

  • Carbamylated proteins have been reported to be associated with general mortality and cardiovascular mortality in patients with End-Stage Renal Disease (ESRD) [3,6,7​​].

​​

  • "Carbamoylation has important effects on the immune system, atherosclerosis, lipid metabolism, and the progression of chronic kidney disease" [8].

​​

  • "​​As carbamoylated amino acids cannot be used for protein synthesis, carbamoylation might contribute heavily to amino acid deficiencies and, thus, to protein malnutrition" [8].

Our Approach

Our approach to Chronic Kidney Disease lives on the understanding of the Citric Acid Cycle (CAC) and its intertwined relationship with the Urea Cycle. The Citric Acid Cycle is a universal metabolic process that takes place not only in the human being, but in the three domains of life on earth: 1) domain eukarya, where animalia, plantae, fungi, and protista kingdoms are included; 2) domain archaea, and 3) domain bacteria. The CAC constitutes the center of the general metabolism of any cell, be it eukaryote with true nucleus, as is the case with all the cells of the human being, or prokaryotic cell, as with bacteria that do not possess true nucleus.

​

The CAC should not be viewed as a closed circle, since several compounds enter and exit the cycle and intermediates of the cycle connect to other metabolic pathways. The CAC, also known as Krebs Cycle, is both catabolic and anabolic in nature, thus regarded as amphibolic.

The Citric Acid Cyle

a) Catabolic pathway, in which nutrients such as proteins via amino acids, carbohydrates via glucose, triacylglycerols via glycerol and fatty acids, end up as pyruvate before entering the cycle. By losing a carbon and generating CO2, pyruvate is converted to acetyl coenzyme A and when it binds with oxaloacetate it regenerates citrate to enter the CAC, generating energy through the formation of ATP and various electron carriers like NAD and FAD.

​

b) Anabolic pathway, in which certain intermediates of the CAC are used for the biosynthesis of monomeric molecules. Thus, for glucose biosynthesis (gluconeogenesis), oxaloacetate is used, and for biosynthesis of fatty acids we use acetyl coenzyme A. For the biosynthesis of non-essential amino acids (glycine, L alanine, L asparagine, L aspartate, L cysteine, L glutamate, L glutamine, L proline, L serine and L tyrosine), oxaloacetate intermediate is used as the initiator of synthesis. Another cycle intermediate is alpha-ketoglutarate which serves as the initiator to form glutamate by reversible transamination. Then, by additional transamination forms glutamine, as well as other related amino acids.

These amino acid biosynthetic pathways, glucose and fatty acids, are pathways that extract intermediates from the cycle and are known as cataplerotic pathways or reactions, which hypothetically speaking, when extracting intermediates from the cycle would exhaust it. This is not the case because there are replacement pathways of these intermediates known as anaplerotic pathways, of which the most important is the catabolized by the enzyme pyruvate carboxylase that generates oxaloacetate from pyruvate (reaction 1). Another anaplerotic reaction for the replacement of cycle intermediates involves the direct conversion of phosphoenolpyruvate by the action of the enzyme phosphoenolpyruvate carboxylase to oxaloacetate (reaction 2). Another involves reversible transamination from aspartate to oxaloacetate (reaction 3). By the action of the malic enzyme or malate dehydrogenase on pyruvate, it catalyzes the reductive carboxylation thereof to generate malate (reaction 4). Finally, glutamate generates alpha ketoglutarate by reversible transamination (reaction 5). ​

New studies further prove the intertwined relationship between the Citric Acid Cycle and Chronic Kidney Disease, since metabolites from the CAC have been proven diminished in CKD patients, both diabetic and non-diabetic etiology.

  • Sharma et al performed a study that "used gas chromatography-mass spectrometry to quantify 94 urine metabolites in screening and validation cohorts of patients with diabetes mellitus (DM) and CKD(DM+CKD), in patients with DM without CKD (DM–CKD), and in healthy controls. Compared with levels in healthy controls, 13 metabolites were significantly reduced in the DM+CKD cohorts, and 12 of the 13 remained significant when compared with the DM–CKD cohort " [9].

​​

  • ​​Mitochondrial dysfunction is associated with kidney disease in non-diabetic and diabetic contexts [10].

​

  • Hallan et al "combined metabolomics (GCMS) with kidney gene expression studies to identify metabolic pathways that are altered in adults with non-diabetic stage 3–4 CKD versus healthy adults. Urinary excretion rate of 27 metabolites and plasma concentration of 33 metabolites differed significantly in CKD patients versus controls [...] Pathway analysis revealed that the citric acid cycle was the most significantly affected, [supporting] the emerging view of CKD as a state of mitochondrial dysfunction" [11].

Multifactorial Benefits

Our patented formulation comprises the reposition of Citric Acid Cycle intermediates, in combination with calcium phosphate chelators and sodium bicarbonate, resulting in the following benefits:

  1. increased eGFR​

  2. decreased serum creatinine

  3. decreased serum urea

  4. decreased serum phosphorus

  5. increased serum hemoglobin

  6. maintenance of albumin levels within normal ranges 

Download our 2024 published study  > >

Our studied population, contrary to other tested treatments, was conformed in its majority (53%) by Stage 5 End-stage chronic renal failure patients, 36% Stage 4 and only 11% in Stage 3b, averaging a basal eGFR of 16.73 mL/min and final of 19.18 mL/min after a mean study period of 11 months [13].

Until now, no other treatment has proven to increase eGFR in patients with chronic kidney disease, and even less, in late-stage chronic kidney disease.

​

A 2013 study in Taiwan compared the effects of a usual care versus a multidisciplinary care (MDC) in CKD patients. "Usual care of CKD consisted of care under a PCP [primary care physician], general internal medicine and specialists including endocrinologists, cardiologists, rheumatologists, orthopedics and nephrologists without referring to the MDC team for instruction", while the "MDC consisted of a nephrologist, nephrology nurse educator, renal dietitian, social worker, pharmacy specialist, and surgeon for vascular access placement, tenchoff catheter implantation and transplantation. For standardized intervention of CKD in the MDC group, the management and education was dependent upon the different stages of CKD and, according to the NKF K/DOQI guidelines, Taiwan pre-ESRD care program and reimbursement policy of NHI"; and resulted in "higher prescription rates of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB), phosphate binder, vitamin D3, uric acid lower agents and erythropoietin-stimulating therapy and better control in secondary hyperparathyroidism"  [14]. Despite of this holistic approach, eGFR decline per year was 5.8 for the MDC group and 6.7 for the usual-care group, having both groups a baseline eGFR of 32.7 and 32.9, respectively. 

In the same way, studies of the inhibitors of sodium–glucose cotransporter 2 (SLGT2) have resulted in a declined eGFR, although, a slower decline versus the placebo groups [15-17]. Likewise, the study of finerenone, a nonsteroidal, selective mineralocorticoid receptor antagonist, concluded with a eGFR baseline of 44.4 and a yearly decrease of 2.66 [18].

CONTACT US and join us in improving renal function!

Cited References

  1. Seki M. et al. (2019). Blood urea nitrogen is independently associated with renal outcomes in Japanese patients with stage 3–5 chronic kidney disease: a prospective observational study. BMC Nephrology. 20:115.

  2. Vanholder R, Gryp T, Glorieux G. (2018). Urea and chronic kidney disease: the comeback of the century?. Nephrol Dial Transplant. 33:4–12.

  3. Berg AH, Drechsler C, Wenger J, Buccafusca R, Hod T, Kalim S, et al. (2013). Carbamylation of serum albumin as a risk factor for mortality in patients with kidney failure. Sci Transl Med. 5:175ra29.

  4. D’Apolito M, Du X, Zong H, Catucci A, Maiuri L, Trivisano T, et al. (2010). Urea-induced ROS generation causes insulin resistance in mice with chronic renal failure. J Clin Invest. 120:203–13. 

  5. Koppe L, et al. (2016). Urea impairs β cell glycolysis and insulin secretion in chronic kidney disease. The Journal of Clinical Investigation. 126(9), 3598-3612.

  6. Drechsler C, Kalim S, Wenger JB, et al. (2015). Protein carbamylation is associated with heart failure and mortality in diabetic patients with ESRD. Kidney Int. 87:1201–8.

  7. Koeth RA, Kalantar-Zadeh K, Wang Z, Fu X, Tang WH, Hazen SL. Protein carbamylation predicts mortality in ESRD. (2013). J Am Soc Nephrol. 24:853–61.

  8. Delanghe S, et al. (2017). Mechanisms and consequences of carbamoylation. Nature Reviews Nephrology. 1-14.

  9. Sharma K., Karl B., Matthew A.V., et al. (2013). Metabolomics Reveals Signature of Mitochondrial Dysfunction in Diabetic Kidney Disease. J Am Soc Nephrol. 24: 1901–1912.

  10. Forbes MJ, Thorburn DR. (2018). Mitochondrial dysfunction in diabetic kidney disease. Nature Reviews Nephrology. (14) 291-312.

  11. Hallan S, Afkarian M, Zelnick LR, Kestenbaum B, Sharma S, et al. (2017). Metabolomics and gene expression analysis reveal down-regulation of the Citric Acid Cycle in non-diabetic CKD patients. EBioMedicine. (26) 68-77.

  12. Czibik G, Steeples V, Yavari A, et al. (2014). Metabolomics, Citric Acid Cycle intermediates in cardioprotection. Circ Cardiovasc Genet. (7) 711-719.

  13. Hernández-Miramontes JA, Méndez-Durán A, Hernández-Villanueva JA. (2024). Tricarboxylic cycle intermediates in combination with calcium phosphate chelators and sodium bicarbonate increase eGFR in patients with stages 3b, 4 and 5 CKD: a retrospective observational study. Rev Colomb Nefrol. 11(2):1-18. https://revistanefrologia.org/index.php/rcn/article/view/778/1115

  14. Chen YR, Yang Y, Wang SC, et al. (2013). Effectiveness of multidisciplinary care for chronic kidney disease in Taiwan: a 3-year prospective cohort study. Nephrol Dial Transplant. 28:671–682.

  15. Perkovic V, Jardine MJ, Neal B, et al. (2019). Canaglifozin and renal outcomes in type 2 diabetes and nephropathy. N Engl J Med. 380(24): 2295-2306. https://www.nejm.org/doi/full/10.1056/NEJMoa1811744

  16. Heerspink HJL, Stefánsson BV, Correa-Rotter R, et al. (2020). Dapaglifozin in patients with chronic kidney disease. N Engl J Med. 383(15):1436-1445. https://www.nejm.org/doi/full/10.1056/NEJMoa2024816

  17. Herrington WG, Staplin N, Wanner C, et al. (2023). Empaglifozin in patients with chronic kidney disease. N Engl J Med. 388(2):117-126. https://www.nejm.org/doi/full/10.1056/NEJMoa2204233

  18. Bakris GL, Agarwal R, Anker SD, et al. (2020). Effect of finerenone on chronic kidney disease outcomes in type 2 diabetes. N Engl J Med. 383(23):2219-2229. https://www.nejm.org/doi/full/10.1056/NEJMoa2025845

References
bottom of page