Role of reactive oxygen species and Bcl-2 family proteins in TNF-α-induced apoptosis of lymphocytes.

We studied the in vitro apoptosis-inducing effect of recombinant TNF-α (rTNF-α) on blood lymphocytes from healthy donors. rTNF-α-induced apoptosis was accompanied by an increase in the number of cells with low mitochondrial transmembrane potential, increased intracellular content of reactive oxygen species, reduced content of Bcl-2, Bcl-xL, and Bax proteins, and elevated Bad content. The molecular mechanisms of these changes are discussed.

Regulatory role of nitric oxide in neutrophil apoptosis.

Apoptosis of blood neutrophils from healthy donors was studied under conditions of cell culturing with different concentrations of H(2)O(2), selective NO synthase inhibitor, and inductor of NO synthesis (L-arginine). In vitro incubation of neutrophilic leukocytes with 5 mM H(2)O(2) led to activation of the apoptotic program in neutrophils, which was seen from increased content of Bax protein in the cells and increased number of apoptotic cells in the culture. Increased content of annexin-positive cells after incubation of neutrophil culture with NO synthase inhibitor suggests involvement of NO in the regulation of neutrophil apoptosis under conditions of oxidative stress, while L-arginine prevented H(2)O(2)-induced programmed cell death.

Role of recombinant mitogen-activated protein kinases JNK and p38 in the regulation of apoptosis in blood mononuclear cells under conditions of oxidative stress in vitro.

Programmed death of peripheral blood mononuclear cells from healthy donors was studied during culturing with various concentrations of H(2)O(2) and selective inhibitors of JNK (SP600125) and p38 MAPK (ML3403). In vitro incubation of mononuclear leukocytes with 1 mM H(2)O(2) stimulated apoptotic cell death. Treatment with inhibitors (SP600125 and ML3403) during in vitro oxidative stress prevented the increase in the number of annexin-positive mononuclear cells.

Modulation of apoptosis of mononuclear cells under conditions of oxidative stress.

We studied mitochondrial and type 1 tumor necrosis factor-a receptor (TNFR1)-mediated pathways triggering the apoptotic program in mononuclear cells under conditions of oxidative stress. Intensification of intracellular production of reactive oxygen forms is accompanied by an increase in the number of annexin-positive TNFRI-presenting cells and mononuclear cells with reduced mitochondrial transmembrane potential in case of induction of oxidative stress with 1 mM H2O2 in vitro and in patients with pneumonia.