Cigarette smoke (CS) is the most preventable cause of death and chronic disease in the United States. In addition to being a risk factor for atherosclerosis and cancer, recent epidemiologic studies suggest that cigarette smoke promotes the progression of kidney disease.
The mechanisms by which cigarette smoke may accelerate some types of chronic kidney disease are currently unknown. A new study, being published by the American Physiological Society, demonstrates for the first time that human mesangial cells (MC) ? cells in the blood vessels of the kidneys ? are endowed with nicotinic receptors (nAChRs) ?4, ?5, ?7, ?2, ?3, ?4 and ?5 (cells that interact with the nicotine in tobacco) and may play an active role in the development of certain kidney diseases.
The Study
The study, “Nicotine: The Link Between Cigarette Smoking and the Progression of Renal Injury?,” was conducted by Edgar A. Jaimes, MD, Run-Xia Tian, MD, and Leopoldo Raij, MD, all of the Miller School of Medicine, University of Miami, Miami, FL. It appears in the Articles in Press Section of the American Journal of Physiology ? Heart and Circulatory Physiology (http://ajpheart.physiology.org/), one of 11-peer reviewed journals published by the APS.
Overview of Methodology
Human mesangial cells were grown in CSC-Complete media, supplemented with 10 percent fetal calf serum. Cells were passed by trypsinization when confluent and used between the third and ninth passages. 3H-thymidine was used as an index of cell proliferation and cells were fasted for 72 hours in Maintenance Media and stimulated for 24 hours with nicotine (10-10 M to 10-7 M) or platelet derived growth factor.
Western blots were performed after the cells fasted and had been stimulated for 24 hours with nicotine (10-7). Cell homogenates were washed and thereafter centrifuged for 30 minutes. Blots were incubated overnight with one of nine antibodies, which included mouse anti-?2-nAChR mAb’s, anti-?3-nAChR mAb’s, or anti-?4-nAChR mAb’s. Fibronectin mRNA expression was determined by real time PCR and protein expression was measured by western blot. Flow cytometry measurement was generated for reactive oxygen species.
Data were expressed as mean ? SEM. For statistical comparisons involving two groups, an unpaired Student t test was used. For comparisons involving more than two groups, ANOVA was used. Significance was considered when P