Pretransplant Free Fatty Acids (FFA) and Allograft Survival in Renal Transplantation1

The C18:3n6/C22:4n6 ratio is a good lipid marker of chronic kidney disease (CKD) progression

Background

Chronic kidney disease (CKD) is a major challenge for public health due to increased risk of cardiovascular diseases (CVD) and premature death. The aim of this study was to determine the clinical picture of FA and the course of the pathophysiological mechanisms of CKD.

Methods

The study involved 149 patients with CKD and a control group including 43 people. Fatty acid profiles were investigated using gas chromatography. A total of 30 fatty acids and their derivatives were identified and quantified. The omega3, omega6, SFA, MUFA, and PUFA fatty acid contents were calculated. The correlation matrix was obtained for parameters relating to patients with CKD vs. FA, taking patients’ sex into consideration. The index C18:3n6/C22:4n6 was calculated according to the length of the treatment. Statistica 12.0 software (Tulsa, Oklahoma, USA) was used for the statistical analyses.

Results

The results showed decreased levels of total PUFA and increased concentrations of MUFA, including the activation of the palmitic and oleic acid pathway. An increase in the levels of n-6 9C22: 4n6 family fatty acids in all the patients and a reduction in the n-3 family (EPA, DHA) were observed. C18:3n6 was negatively correlated and C22:4n6 was positively correlated with the duration of the treatment. The index C18:3n6/C22:4n6 was defined as a new marker in the progression of the disease. Moreover, the index C18:3n6/ C22:4n6 was drastically decreased in later period. Nervonic acid was higher in the CKD group. In the group of men with CKD, there was a negative correlation between the excretion of K+, anthropometric measurements, and the levels of EPA and DHA.

Conclusions

The course of inflammation in CKD occurs through the decrease in PUFA and the synthesis of MUFA. The dominating cascade of changes is the elongation of GLA-C18:3n6 into DGLA-C20:3n6 and AA-C20:4n6. As CKD progresses, along with worsening anthropometrical parameters and increased secretion of potassium, the activity of Ʌ6-desaturase decreases, reducing the synthesis of EPA and DHA. The synthesis of AdA-C22:4n6 increases and the ratio C18:3n6/C22:4n6 drastically decreases after 5 years. This parameter can be used to diagnose disease progression.

Comparison of Fatty Acid Profiles in a Group of Female Patients with Chronic Kidney Diseases (CKD) and Metabolic Syndrome (MetS)⁻Similar Trends of Changes, Different Pathophysiology

Fatty acid (FA) profiles in the plasma of patients with metabolic syndrome and chronic kidney disease (CKD) seem to be identical despite their different etiology (dietary mistakes vs. cachexia). The aim of this study was to compare both profiles and to highlight the differences that could influence the improvement of the treatment of patients in both groups. The study involved 73 women, including 24 patients with chronic kidney disease treated with haemodialysis, 19 patients with metabolic syndrome (MetS), and 30 healthy women in the control group. A total of 35 fatty acids and derivatives were identified and quantified by gas chromatography. Intensified elongation processes from acid C10:0 to C16:0 were noted in both groups (more intense in MetS), as well as an increased synthesis of arachidonic acid (C20:4n6), which was more intense in CKD. Significant correlations of oleic acid (C18:1n9), gamma linoleic acid (C18:3n6), and docosatetraenoate acid (C22:4n6) with parameters of CKD patients were observed. In the MetS group, auxiliary metabolic pathways of oleic acid were activated, which simultaneously inhibited the synthesis of eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) from alpha lipoic acid (ALA). On the other hand, in the group of female patients with CKD, the synthesis of EPA and DHA was intensified. Activation of the synthesis of oleic acid (C18: 1n9 ct) and trans-vaccinic acid (C18:1) is a protective mechanism in kidney diseases and especially in MetS due to the increased concentration of saturated fatty acid (SFA) in plasma. The cause of the increased amount of all FAs in plasma in the CKD group, especially in the case of palmitic (C16:0) and derivatives stearic (C18:0) acids, may be the decomposition of adipose tissue and the progressing devastation of the organism, whereas, in the MetS group, dietary intake seems to be the main reason for the increase in SFA. Moreover, in MetS, auxiliary metabolic pathways are activated for oleic acid, which cause the simultaneous inhibition of EPA and DHA synthesis from ALA, whereas, in the CKD group, we observe an increased synthesis of EPA and DHA. The higher increase of nervonic acid (C24:1) in CKD suggests a higher degree of demyelination and loss of axons.

Renal Fanconi syndrome: taking a proximal look at the nephron

Renal Fanconi syndrome (RFS) refers to the generalized dysfunction of the proximal tubule (PT) (Kleta R. Fanconi or not Fanconi? Lowe syndrome revisited. Clin J Am Soc Nephrol 2008; 3: 1244-1245). In its isolated form, RFS only affects the PT, but not the other nephron segments. The study of isolated RFS can thus provide specific insights into the function of the PT. In a recent paper, Klootwijk et al. investigated one such form of isolated RFS and revealed the underlying molecular basis (Klootwijk ED, Reichold M, Helip-Wooley A et al. Mistargeting of peroxisomal EHHADH and inherited renal Fanconi's syndrome. N Engl J Med 2014; 370: 129-138). The affected family had been described previously, demonstrating the typical features of RFS, such as low-molecular weight proteinuria, aminoaciduria, glycosuria and phosphaturia with consequent rickets; yet, importantly, patients had no evidence of impaired glomerular filtration (Tolaymat A, Sakarcan A, Neiberger R. Idiopathic Fanconi syndrome in a family. Part I. Clinical aspects. J Am Soc Nephrol 1992; 2: 1310-1317). Inheritance was consistent with an autosomal dominant mode. Klootwijk et al. discovered a surprising explanation: a heterozygous missense mutation causing partial mistargeting of the peroxisomal enzyme EHHADH to the mitochondria. Notably, disease causing was not the absence of the enzyme in the peroxisome, but its interference with mitochondrial function. The discovery of this novel disease mechanism not only confirmed the importance of mitochondrial function for PT transport, but also demonstrated the critical dependence of PT on fatty acid metabolism for energy generation.

Effect of immunosuppressive therapy on the serum fatty acids of phospholipids fraction in patients after heart transplantation

BACKGROUND

The effects of tacrolimus (Tac) and cyclosporine (CsA) on lipid profile is well known; however, little is known about the changes in fatty acids (FA) of phosholipids fraction (PL) in heart transplant patients after treatment with these immunosuppressants. This study aimed to investigate the effect of Tac and CsA on serum FA of PL in heart transplant patients.

METHODS

The study included 23 patients after heart transplantation on Tac (n = 14; group II) or CsA (n = 9; group I). Eleven healthy persons served as a control group. Serum FA of PL were extracted, separated on Sep-Pak NH2, methylated, and measured with the use of gas chromatography. Chemstation software was used to analyze the data.

RESULTS

No differences between the studied groups and control were noted for saturated FA, monounsaturated FA, polyunsaturated FA (PUFA), total FA, and PUFA n-6. The mean value of PUFA n-3 was significantly higher in the CsA group compared with the Tac group (P < .015) and control (P < .002) as well as in the Tac group compared with control (P < .001). For individual FA, higher mean concentration, compared with control, was found for C24, C20:2, C20:4, and C22:6 (P < .001 in all cases) and lower for C18:2cis (P < .001 in both groups) and for C18:3 in the Tac group. The mean values of PUFA n-6 to PUFA n-3 ratios were lower than in control (both P < .001).

CONCLUSIONS

Different pattern of FA of PL may indicate the different FA metabolism in heart transplant patients treated by different immunosuppressants. This should be taken into account when FA supplementation in these patients is considered.