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Chronic pruritus is one of the most common symptoms of dermatological diseases. It may occur in the course of other disorders, such as kidney disease. Chronic kidney disease-associated pruritus (CKD-aP) most often affects people with end-stage renal disease. The etiology of this condition is still not fully understood, but researchers are currently focusing on a thorough analysis of the association between disturbed opioid balance and increased neuronal signaling leading to pruritus. The aim of this study is to assess the concentration of endogenous opioids in dialysis patients with and without pruritus and in the control group, and to determine the correlation between the concentration of these substances and the occurrence and severity of itching. The study involved 126 dialysis patients and 50 healthy controls. Patients were divided into groups with pruritus (n = 62) and without pruritus (n = 64). The severity of pruritus was assessed using the NRS scale. The concentration of endogenous opioids was determined using the ELISA. The concentration of met-enkephalin was higher in the group of patients with pruritus compared to the control group. Moreover, significantly lower levels of β-endorphin and dynorphin A were observed in the group of dialysis patients compared to the control group. In addition, a statistically significant difference was seen between the β-endorphin concentration in the group of dialysis patients with pruritus compared to the group without pruritus. The ratio of β-endorphin/dynorphin A concentrations was significantly lower in the group of patients with pruritus compared to patients without pruritus and the control group. No correlations were found between serum level of studied opioids and the severity of pruritus. The concentrations of the studied opioids did not correlate with the severity of pruritus. Observed opioid imbalance may affect the occurrence of CKD-aP in dialysis patients, but a thorough understanding of the mechanism of action of these substances in the sensation of pruritus is necessary to assess the possibility of finding a new therapeutic target.

Recent studies place great importance on Protein-Bound Uraemic Toxins (PBUT) in the context of etiopathogenesis of chronic kidney disease-associated pruritus (CKD-aP). This study aimed to investigate the possible contribution of free and total Indoxyl Sulfate (IS) and p-Cresol Sulfate (PCS) to the cause of CKD-aP. Group A included 64 patients on maintenance haemodialysis (HD) with CKD-aP. Group B included 62 patients on maintenance HD that did not report CKD-aP, and group C included 50 healthy controls. Pruritus severity was assessed using a Numerical Rating Scale (NRS). Moreover, other tools like UP-Dial, ItchyQoL, and the 4-Item Itch Questionnaire evaluating CKD-aP were completed by the patients. The serum levels of free and total IS and PCS concentrations were measured using the Ultra Performance Liquid Chromatography System. No significant difference in the serum level of free and total IS, or PCS, was observed between the patients who reported CKD-aP and those without pruritus. Moreover, there was no correlation between serum IS or PCS levels and the severity of the itch. Our study does not support earlier findings about higher levels of IS and PCS in patients reporting CKD-aP. Further studies will be needed to investigate these discrepancies as well as to understand the cause of CKD-aP.

Chronic kidney disease-associated pruritus (CKD-aP) is a bothersome condition that occurs in patients with advanced chronic kidney disease (CKD) and severely reduces their quality of life. Recently, much research has focused on the search for markers that are involved in the pathogenesis of CKD-aP and may become a therapeutic target. One of the suggested hypotheses is the increased activation of sensory neurons by molecules such as neurotrophins (NTs). An increased serum concentration of NTs has been demonstrated in pruritic patients, which may suggest their involvement in the pathogenesis of itch. The purpose of this study is to assess the serum concentration of neurotrophin-4 (NT-4) and brain-derived neurotrophic factor (BDNF) in hemodialysis patients. The study enrolled 126 patients undergoing dialysis. Participants were divided into 2 groups: with and without CKD-aP. NRS scale was used to evaluate itch severity. Serum levels of NT-4 and BDNF have been assessed using ELISA. The results showed a significantly higher level of NT-4 in the group with pruritus. No significant difference was reported in the serum level of BDNF between the two groups of patients. There was also no correlation between serum NT-4 nor BDNF levels and the severity of pruritus. In summary, NT-4 may play an important role in the pathophysiology of pruritus in dialysis patients. More research is needed to understand the exact mechanism by which NTs influence the pathogenesis of CKD-aP.

Chronic itch (CI) is a common symptom caused by both dermatological and systemic disorders. CI is also a frequent, burdensome symptom among renal transplant recipients (RTR); however, its pathophysiology is not fully understood. The aim of this study was to assess the differences in concentration of IL-31 among itchy RTR. The study was performed on a group of selected 129 RTRs (54 itchy and 75 non-itchy patients). Itch severity was assessed with the use of the numeral rating scale (NRS) and the 4-item itch questionnaire (4IIQ). Every subject had his blood drawn to measure the concentration of IL-31. The results were subsequently compared and correlated. The mean concentration differed significantly between RTR suffering from itch (602.44 ± 534.5 pg/mL), non-itchy RTR (161.49 ± 106.61 pg/mL), and HC (110.33 ± 51.81 pg/mL) (p < 0.001). Post-hoc analysis revealed a statistically significantly increased IL-31 serum concentration in itchy RTR in comparison to the non-itchy RTR group (p < 0.001) and HC (p < 0.001). No significant difference was observed in IL-31 serum levels between non-itchy RTRs and HC. No correlation between IL-31 and itch intensity was found. The results of our study clearly demonstrate the association between IL-31 levels and CI in patients after renal transplantation.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease. Recently, some S100 proteins have been suggested to play an important role in the pathogenesis of chronic immune-mediated inflammatory diseases and they may constitute valuable biomarkers for these diseases' diagnosis and monitoring. The objective of the current study was to investigate, for the first time, serum levels of S100A4 and S100A15 in individuals suffering from HS. Furthermore, we assessed the associations between S100A4 and S100A15 serum levels and the severity of disease, CRP serum concentration and some demographic and clinical data. Serum levels of S100A4 and S100A15 were evaluated with the commercially available ELISA kit according to the manufacturer's instructions. The serum level of S100A4 in individuals with HS was significantly elevated as compared to controls, with the highest level found in the individuals in Hurley stage II. The S100A15 serum level was positively correlated with the CRP concentration and was associated with the severity of the disease. The serum level of S100A15 in the individuals in Hurley stage III was significantly elevated compared to that of the controls and the individuals with HS in Hurley stages I and II. S100A4 and S100A15 may be considered as new serum biomarkers for the monitoring of HS progression, and they may play a role in the pathogenesis of HS by promoting inflammatory process and fibrosis.