Alteration in Lactate Production and Decrease in MTT Dye Reduction in Serum-starved Human Peripheral Blood Mononuclear Cells (PBMCs)

Immunometabolism targeting therapy of auto-inflammatory diseases is an emerging strategy compared to immune system global suppression. However, our knowledge in this field needs promotion.

We examined the effects of serum starvation stress on metabolic activity in human peripheral blood mononuclear cells (PBMCs).

Fresh immune cells were isolated from four healthy adult volunteers and cultivated with or without fetal bovine serum (FBS) at various time points under standard conditions. Glucose and intra- and extracellular lactate levels were assessed using routine techniques, and 3-(4, 5 -dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) reduction assay was used to determine mitochondrial function.

Spindle shape macrophage-like cells, which appeared early, were replaced at 96 h by large round monocytes/macrophagelike cells, with more frequency in the non-starved group. Interestingly, serum starvation dictated a status, especially in monocyte/macrophage-like cells, that led to prolong decrement in mitochondrial dehydrogenase-mediated reduction of MTT. This difference was confirmed with the MTT assay quantitatively (P < 0.05). Moreover, the intra- and extracellular lactate concentrations were lower in starved cells than in non-starved controls (P < 0.05), and glucose levels were higher in 72 h starved cell culture supernatants than in non-starved control cells (P < 0.05).

This study showed that under serum starvation-induced metabolic stress, lactate production is altered in immune cells, and total oxidative mitochondrial activity is reduced in macrophage-like cells. These findings open a new window to target immune cell metabolism for the treatment of autoinflammatory and autoimmune diseases.