Plasma metabolomic profiling reveals a novel circulating biomarker signature in chronic pruritus of unknown origin.

Chronic pruritus of unknown origin (CPUO) is characterized by chronic itch for 6 weeks or greater without an identifiable primary cause. Studies are needed to investigate circulating blood biomarkers to elucidate disease pathogenesis. The objective of this study was to investigate changes in circulating blood metabolites in CPUO patients and to identify potential therapeutic targets. Our cross-sectional study collected plasma from 11 CPUO patients and 11 matched control patients for mass-spectrometry based metabolite data analysis. 15 metabolites differed significantly in the blood of CPUO patients compared to controls, including nine amino acids (isoleucine, L-tyrosine, threonine, DL-tryptophan, L-valine, methionine, glycine, lysine, and L-phenylalanine), four amino acid derivatives (creatinine, DL-carnitine, acetyl-L-carnitine, and indole-3-acrylic acid), and two aromatic and fatty acid derivatives (2-hydroxycinnamic acid and oleamide). These metabolites were also correlated with itch severity. Metabolic set enrichment analysis (MSEA) identified downregulation of several pathways in CPUO: phenylalanine, tyrosine, tryptophan biosynthesis; catecholamine biosynthesis; and glycine, serine, and threonine metabolism. Our study identified decreases in several circulating plasma metabolites in CPUO patients and downregulation of pathways related to catecholamine biosynthesis and tryptophan biosynthesis, providing insight into the pathogenesis of CPUO.

Serum Concentration of IL-5 Receptor (IL-5R) and Associations with Disease Severity in Patients with Chronic Spontaneous Urticaria (CSU) and Atopic Dermatitis (AD).

The immunological pathogenesis of atopic dermatitis (AD) and chronic spontaneous urticaria (CSU) has not been fully elucidated yet. The aim of our research was to assess the serum concentration of interleukin-5 receptor (IL-5R) in relation to the disease activity and pruritus intensity in adult patients with AD and CSU. This pilot study included 45 participants (15 patients with AD, 15 patients with CSU, and 15 healthy controls). Blood samples were taken to examine the serum levels of IL-5R using the enzyme-linked immunosorbent assay (ELISA) test. The Scoring Atopic Dermatitis (SCORAD) index, the Urticaria Activity Score (UAS7), and the Visual Analogue Scale (VAS) were used to assess the disease activity and the pruritus intensity, respectively. Obtained results revealed that the IL-5R concentration was significantly higher in patients with CSU than in patients with AD and in the controls (p = 0.038). There was a positive correlation between the IL-5R level and the SCORAD index in patients with AD (r = -0.9, p = 0.047), which was not found for the CSU activity by UAS7 and with the pruritus severity by VAS in both examined groups of patients. Our findings underscore higher serum levels of IL-5R among CSU and AD patients, which may highlight its functional role in the pathogenesis of these diseases. In contrast, IL-5R might not be fully useful in reflecting the severity of symptoms. Although our results are promising, this study should be conducted on a larger cohort of patients.

Abnormalities of serum magnesium levels in dialysis patients undergoing parathyroidectomy.

In primary hyperparathyroidism, postoperative hypocalcemia can be exacerbated by magnesium deficiency. However, the significance of magnesium homeostasis in surgery for secondary hyperparathyroidism is unknown. In this study, 268 consecutive adult patients on renal replacement therapy who underwent parathyroidectomy for secondary hyperparathyroidism were included for analysis. We found that about one fifth presented with hypomagnesemia (5.6%) or hypermagnesemia (14.6%). Hypomagnesemia was associated with lower calcium levels and longer postoperative hospital stays. Hypermagnesemia was associated with higher calcium-phosphorus products and lower parathyroid hormone levels. In multivariate analysis, patient age, alkaline phosphatase, and osteocalcin were independent predictors of prolonged stay after parathyroidectomy. There was a positive correlation between serum magnesium levels and severity of itching in these patients. Calcium-phosphorus products and serum magnesium levels were independently associated with pruritus. In conclusion, magnesium abnormalities play a minor role in hungry bone syndrome after parathyroidectomy for secondary hyperparathyroidism. Patients with higher serum magnesium levels had greater severity of pruritus.

Metabolites Associated With Uremic Symptoms in Patients With CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: The toxins that contribute to uremic symptoms in patients with chronic kidney disease (CKD) are unknown. We sought to apply complementary statistical modeling approaches to data from untargeted plasma metabolomic profiling to identify solutes associated with uremic symptoms in patients with CKD. STUDY DESIGN: Cross-sectional. SETTING & PARTICIPANTS: 1,761 Chronic Renal Insufficiency Cohort (CRIC) participants with CKD not treated with dialysis. PREDICTORS: Measurement of 448 known plasma metabolites. OUTCOMES: The uremic symptoms of fatigue, anorexia, pruritus, nausea, paresthesia, and pain were assessed by single items on the Kidney Disease Quality of Life-36 instrument. ANALYTICAL APPROACH: Multivariable adjusted linear regression, least absolute shrinkage and selection operator linear regression, and random forest models were used to identify metabolites associated with symptom severity. After adjustment for multiple comparisons, metabolites selected in at least 2 of the 3 modeling approaches were deemed "overall significant." RESULTS: Participant mean estimated glomerular filtration rate was 43mL/min/1.73m2, with 44% self-identifying as female and 41% as non-Hispanic Black. The prevalence of uremic symptoms ranged from 22% to 55%. We identified 17 metabolites for which a higher level was associated with greater severity of at least one uremic symptom and 9 metabolites inversely associated with uremic symptom severity. Many of these metabolites exhibited at least a moderate correlation with estimated glomerular filtration rate (Pearson's r≥0.5), and some were also associated with the risk of developing kidney failure or death in multivariable adjusted Cox regression models. LIMITATIONS: Lack of a second independent cohort for external validation of our findings. CONCLUSIONS: Metabolomic profiling was used to identify multiple solutes associated with uremic symptoms in adults with CKD, but future validation and mechanistic studies are needed. PLAIN-LANGUAGE SUMMARY: Individuals living with chronic kidney disease (CKD) often experience symptoms related to CKD, traditionally called uremic symptoms. It is likely that CKD results in alterations in the levels of numerous circulating substances that, in turn, cause uremic symptoms; however, the identity of these solutes is not known. In this study, we used metabolomic profiling in patients with CKD to gain insights into the pathophysiology of uremic symptoms. We identified 26 metabolites whose levels were significantly associated with at least one of the symptoms of fatigue, anorexia, itchiness, nausea, paresthesia, and pain. The results of this study lay the groundwork for future research into the biological causes of symptoms in patients with CKD.

Seladelpar treatment reduces IL-31 and pruritus in patients with primary biliary cholangitis.

BACKGROUND AND AIMS: Pruritus is a debilitating symptom for many people living with primary biliary cholangitis (PBC). In studies with seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, patients with PBC experienced significant improvement in pruritus and reduction of serum bile acids. Interleukin-31 (IL-31) is a cytokine known to mediate pruritus, and blocking IL-31 signaling provides relief in pruritic skin diseases. This study examined the connection between seladelpar's antipruritic effects and IL-31 and bile acid levels in patients with PBC. APPROACH AND RESULTS: IL-31 levels were quantified in serum samples from the ENHANCE study of patients with PBC receiving daily oral doses of placebo (n = 55), seladelpar 5 mg (n = 53) or 10 mg (n = 53) for 3 months, and for healthy volunteers (n = 55). IL-31 levels were compared with pruritus using a numerical rating scale (NRS, 0-10) and with bile acid levels. Baseline IL-31 levels closely correlated with pruritus NRS ( r = 0.54, p < 0.0001), and total ( r = 0.54, p < 0.0001) and conjugated bile acids (up to 0.64, p < 0.0001). Decreases in IL-31 were observed with seladelpar 5 mg (-30%, p = 0.0003) and 10 mg (-52%, p < 0.0001) versus placebo (+31%). Patients with clinically meaningful improvement in pruritus (NRS ≥ 2 decrease) demonstrated greater dose-dependent reductions in IL-31 compared to those without pruritus improvement (NRS < 2 decrease). Strong correlations were observed for the changes between levels of IL-31 and total bile acids ( r = 0.63, p < 0.0001) in the seladelpar 10 mg group. CONCLUSIONS: Seladelpar decreased serum IL-31 and bile acids in patients with PBC. The reductions of IL-31 and bile acids correlated closely with each other and pruritus improvement, suggesting a mechanism to explain seladelpar's antipruritic effects.

Prurido no paciente em hemodiálise: associação com ingestão de fósforo e nível sérico de cálcio / Prurido en el paciente en hemodiálisis: asociación con ingestión de fósforo y nivel sérico de cálcio / Pruritus in hemodialysis patients: association with phosphorus intake and serum calcium level

Resumo OBJETIVO Analisar a associação entre a ocorrência do prurido e a adesão à dieta prescrita, indicadores bioquímicos da função renal e a qualidade da hemodiálise, em pacientes renais crônicos. MÉTODO Estudo transversal, realizado em uma clínica de diálise no Nordeste do Brasil, com 200 pacientes submetidos à hemodiálise, no primeiro semestre de 2015. Para análise dos dados fez-se uso da estatística inferencial, através dos testes de Qui-Quadrado e Exato de Fisher; e teste de U de Mann Whitney. RESULTADOS O prurido esteve presente em 51% da amostra, associando-se estatisticamente com o consumo de fósforo (P=0,024) e a elevação do cálcio sérico (P=0,009). CONCLUSÃO O prurido em pacientes renais crônicos submetidos à hemodiálise sofre influência da não adesão adequada à dieta prescrita, além da elevação de indicadores bioquímicos da função renal.

Resumen OBJETIVO Analizar la asociación entre la ocurrencia del prurito y la adhesión a la dieta prescrita, indicadores bioquímicos de la función renal y la calidad de la hemodiálisis, en pacientes renales crónicos. MÉTODO Estudio transversal, realizado en una clínica de diálisis en el Nordeste de Brasil, con 200 pacientes sometidos a la hemodiálisis, en el primer semestre de 2015. Para el análisis de los datos se utilizó la estadística inferencial, a través de las pruebas de Qui-Cuadrado y Exacto de Fisher; y prueba de U de Mann Whitney. RESULTADOS El prurito estuvo presente en el 51% de la muestra, asociándose estadísticamente con el consumo de fósforo (P = 0,024) y la elevación del calcio sérico (P = 0,009). CONCLUSIÓN El prurito en pacientes renales crónicos sometidos a la hemodiálisis sufre influencia de la no adhesión adecuada a la dieta prescrita, además de la elevación de indicadores bioquímicos de la función renal.

Abstract OBJECTIVE To analyze the association between the occurrence of pruritus and adherence to the prescribed diet, biochemical indicators of renal function and the quality of hemodialysis in chronic renal patients. METHOD A cross-sectional study performed at a dialysis clinic in the Northeast of Brazil, with 200 patients undergoing hemodialysis in the first half of 2015.To analyze the data, inferential statistics were used, using Chi-Square and Fisher's Exact tests; and Mann Whitney U test. RESULTS The pruritus was present in 51% of the sample, being associated statistically with phosphorus consumption (P = 0.024) and elevation of serum calcium (P = 0.009). CONCLUSION Pruritus in chronic renal patients undergoing hemodialysis is influenced by adequate nonadherence to the prescribed diet, in addition to the elevation of biochemical indicators of renal function.