Environmental NO2 and CO Exposure: Ignored Factors Associated with Uremic Pruritus in Patients Undergoing Hemodialysis

Abstract

Uremic pruritus (UP), also known as chronic kidney disease–associated pruritus, is a common and disabling symptom in patients undergoing maintenance hemodialysis (MHD). The pathogenesis of UP is multifactorial and poorly understood. Outdoor air pollution has well-known effects on the health of patients with allergic diseases through an inflammatory process. Air pollution–induced inflammation could occur in the skin and aggravate skin symptoms such as pruritus or impair epidermal barrier function. To assess the role of air pollutants, and other clinical variables on uremic pruritus (UP) in HD patients, we recruited 866 patients on maintenance HD. We analyzed the following variables for association with UP: average previous 12-month and 24-month background concentrations for nitrogen dioxide (NO2) and carbon monoxide (CO), and suspended particulate matter of <2.5 μm (PM2.5). In a multivariate logistic regression, hemodialysis duration, serum ferritin levels, low-density lipoprotein levels, and environmental NO2/CO levels were positively associated with UP, and serum albumin levels were negatively associated with UP. This cross-sectional study showed that air pollutants such as NO2 and CO might be associated with UP in patients with MHD.

Association Between Serum Aluminum Level and Uremic Pruritus in Hemodialysis Patients

“…In addition, abnormalities interactions between dermal mast cells and the distal ends of nonmyelinated C fibers may play a role in UP through the release of various triggering substances from mast cells, including histamine, proteases, interleukin-2, and tumor necrosis factor-α 12 . Several other factors have also been implicated in the pathogenesis of UP, including xerosis 2 , environmental air pollution 13 , inadequate dialysis 14 , serum phosphate 15 and magnesium 16 , iron deficiency anemia 17 , neuropathy and neurological changes 18 , hepatitis virus infection and others 2 .…”

Associations between air pollution, climate factors and outpatient visits for eczema in West China Hospital, Chengdu, south‐western China: a time series analysis

“…30 Particulate matter is a complex mixture of liquid and solid droplets suspended in gas which comprises sulphates, nitrates, carbon compounds, various types of dust, biological contaminants and gaseous contaminants. [37][38][39] Consequently, PM 10 , SO 2 and NO 2 have acute influence on eczema outpatients. 31,32 Oxidative stress via excessive ROS production by particulate matter exposure increases pro-inflammatory cytokines, such as TNF-a and IL-8, and MMPs.…”

“…Besides, exposure to NO 2 has been shown to damage the skin barrier function, thus increasing transepidermal water loss, and these factors worsen the skin symptoms and immunological function. [37][38][39] Consequently, PM 10 , SO 2 and NO 2 have acute influence on eczema outpatients. In addition, air pollution might increase the levels of aeroallergens and strengthen the effects of aeroallergens which are the trigger of exacerbations in eczema.…”

Association between exposure to ambient air pollution and renal function in Korean adults

“…A recent cross-sectional study also investigated the association between environmental exposure and uremic pruritus (UP), also known as chronic renal disease-related pruritus, among 866 patients undergoing hemodialysis. The researchers found that outdoor air pollution, including that from NO 2 and CO, was closely related to UP [ 12 ]. In addition, short- and long-term exposure to NO 2 has been shown to be significantly associated with respiratory and cardiovascular mortality [ 3 , 5 ].…”

“…Previous reports have focused primarily on exposure to PM air pollution, represented by PM with an aerodynamic diameter of ≤ 10 μm (PM 10 ) or ≤ 2.5 μm (PM 2.5 ); no evidence has been reported regarding the association of renal function with other pollutants. Considering that exposure to other pollutants, such as nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and black carbons significantly associated with various diseases including CVD [ 3 , 5 , 11 , 12 ], an integrated analysis of air pollutants for renal function is important.…”