Changes in the hemopoietic system of mice deficient for tumor necrosis factor or lymphotoxin-alpha

Current Perspectives on the Role of TNF in Hematopoiesis Using Mice With Humanization of TNF/LT System

TNF is a multifunctional cytokine with its key functions attributed to inflammation, secondary lymphoid tissue organogenesis and immune regulation. However, it is also a physiological regulator of hematopoiesis and is involved in development and homeostatic maintenance of various organs and tissues. Somewhat unexpectedly, the most important practical application of TNF biology in medicine is anti-TNF therapy in several autoimmune diseases. With increased number of patients undergoing treatment with TNF inhibitors and concerns regarding possible adverse effects of systemic cytokine blockade, the interest in using humanized mouse models to study the efficacy and safety of TNF-targeting biologics in vivo is justified. This Perspective discusses the main functions of TNF and its two receptors, TNFR1 and TNFR2, in steady state, as well as in emergency hematopoiesis. It also provides a comparative overview of existing mouse lines with humanization of TNF/TNFR system. These genetically engineered mice allow us to study TNF signaling cascades in the hematopoietic compartment in the context of various experimental disease models and for evaluating the effects of various human TNF inhibitors on hematopoiesis and other physiological processes.

Reactive oxygen species produced in mitochondria are involved in age-dependent changes of hematopoietic and mesenchymal progenitor cells in mice. A study with the novel mitochondria-targeted antioxidant SkQ1

Lifelong treatment of mice with the effective mitochondria-targeted antioxidant SkQ1 [10-(6'-plastoquinonyl) decyltriphenylphosphonium] does not affect hematopoietic stem cells (HSC) and more differentiated hematopoietic progenitors but significantly decelerates age-dependent changes in peripheral blood. During the first 13 months, SkQ1 (0.9 or 28.8 nmol/kg day) prevents age-dependent myeloid shift (increase in the proportion of granulocytes and decrease in the proportion of lymphocytes). During the next year of treatment the effect disappears, and the hemogram of 2-year-old treated mice does not differ from the control. The number of mesenchymal stem cells (MSC) in the bone marrow does not change during 2 years of treatment with SkQ1, but the concentration of MSC progeny fibroblast colony-forming units (CFU-F) increases with dose of SkQ1. The concentration of CFU-F after 1 and 2 years treatment with SkQ1 is twice higher than in young mice. Our data indicate that the stromal environment of hematopoietic cells could be the primary target of age-dependent changes mediated by reactive oxygen species produced in mitochondria. The anti-aging effects of SkQ1 described here are in perfect agreement with the inhibitory effects of this antioxidant on aging observed in the other models.