Circadian variation of cytotoxicity and genotoxicity induced by an immunosuppressive agent “Mycophenolate Mofetil” in rats

Abstract

Immunosuppressive drugs such as Mycophenolate Mofetil (MMF) are used to suppress the immune system activity in transplant patients and reduce the risk of organ rejection. The present study investigates whether the potential cytotoxicity and genotoxicity varied according to MMF dosing-time in Wistar Rat. A potentially toxic MMF dose (300 mg/kg) was acutely administered by the i.p. route in rats at four different circadian stages (1, 7, 13 and 19 hours after light onset, HALO). Rats were sacrificed 3 days following injection, blood and bone marrow were removed for determination of cytotoxicity and genotoxicity analysis. The genotoxic effect of this pro-drug was investigated using the comet assay and the micronucleus test. Hematological changes were also evaluated according to circadian dosing time. MMF treatment induced a significant decrease at 7 HALO in red blood cells, in the hemoglobin rate and in white blood cells. These parameters followed a circadian rhythm in controls or in treated rats with an acrophase located at the end of the light-rest phase. A significant, thrombocytopenia was observed according to MMF circadian dosing time. Furthermore, abnormally shaped red cells, sometimes containing micronuclei, poikilocytotic in red cells and hypersegmented neutrophil nuclei were observed with MMF treatment. The micronucleus test revealed damage to chromosomes in rat bone marrow; the comet assay showed significant DNA damage. This damage varied according to circadian MMF dosing time. The injection of MMF in the middle of the dark-activity phase produced a very mild hematological toxicity and low genotoxicity. Conversely, it induced maximum hematological toxicity and genotoxicity when the administration occurred in the middle of the light-rest phase, which is physiologically analogous to the end of the activity of the diurnal phase in human patients.

A systematic overview of the spermatotoxic and genotoxic effects of methotrexate, ganciclovir and mycophenolate mofetil

“…The HED of MMF administered were 23.8 mg to 1.8 g/m 2 /day, thus not exceeding recommended doses of MMF in humans (1.2 to 5.0 g/m 2 /day). Both Dridi et al (2016) 54 and Ferjani et al (2016) 55 reported a significant increase in micronuclei formation and DNA damage of bone marrow cells, the latter further reporting genotoxic effects varying with circadian dosing time.…”

“…Two animal studies conducted in a rat model were identified 54,55 . The HED of MMF administered were 23.8 mg to 1.8 g/m 2 /day, thus not exceeding recommended doses of MMF in humans (1.2 to 5.0 g/m 2 /day).…”

“…Two animal studies conducted in a rat model were identified. 54,55 The HED of MMF administered were 23.…”

Fasting and Its Impact on Skin Anatomy, Physiology, and Physiopathology: A Comprehensive Review of the Literature

“…Similarly, since the proliferation of epidermal stem cells is higher during sleep hours, the ideal timing for immuno-modulators such as retinoids, azathioprine, methotrexate, and Apremilast is the evening to optimize their anti-inflammatory and anti-proliferative effects and minimize their side effects as seen in decreasing the gastrointestinal and hematological adverse reactions in a mouse model with a night dose of mycophenlate mofetil. Biological therapy is best administrated in the evening to counterbalance the night surge of pro-inflammatory cytokines [82,83].…”

Working Time Society consensus statements: Circadian time structure impacts vulnerability to xenobiotics—relevance to industrial toxicology and nonstandard work schedules

“…Laboratory animal research validates the critical importance of circadian time in determining the vulnerability of the skin, brain, and gastrointestinal tissues to tumor induction by the chemical carcinogens methylnitrosourea, beta-propiolactone, and 7,12-dimethylbenz[a]anthracene, and also Ehrlich ascites tumor cells17, 24, 78, 108,109,110,111 ) . Furthermore, prominent circadian-stage discrepancy is demonstrated in laboratory animals for the cytotoxicity and genotoxicity of the immunosuppressant mycophenolate mofetil and alkylating agent nitrosourea24, 112, 113 ) . Finally, circadian time disparity in risk for fetal teratogenesis during gestation is demonstrated through laboratory animal investigations entailing alcohol, dexamethasone, hydroxyurea, 5-fluorouracil, cyclophosphamide, and Th-R [N-mustard]24, 114 ) .…”