Backgrounds:

Tuberculosis (TB) is the biggest global infectious killer in the last decade and young children are especially vulnerable. Mycobacterium tuberculosis (Mtb), the bacteria that causes TB, is phagocytosed by macrophages. To mount an appropriate immune response, the macrophage needs to alter metabolism, increasing glycolysis and decreasing oxidative phosphorylation (Warburg effect). It was hypothesized that umbilical cord derived macrophages have an altered immunometabolic response compared with adult macrophages, which may explain infant susceptibility to TB.

Methods

Monocyte derived macrophages (MDM) were derived from buffy coats or from umbilical cord blood prior to analysis in the XFe Seahorse analyzer. TNF in supernatant was measured by Mesoscale Discovery assay.

Results:

The Warburg effect was demonstrated in adult MDM after Mtb stimulation. Cord blood MDM however, did not decrease OXPHOS (Figure, A). Cord blood MDM secreted less TNF than adult MDM following Mtb stimulation (Figure, B).

The effects of IFN-γ or IL-4 on macrophage immunometabolism was investigated. IFN-γ increased glycolysis and OXPHOS and IL-4 markedly reduced glycolysis. IFN-γ increased cord TNF production in response to Mtb, equating to adult levels (Figure, C). IL-4 caused a decrease in IL-1β production in Mtb stimulated MDM.

A consequence of raised glycolysis is increased extracellular lactate. The addition of exogenous lactate has an immediate effect on metabolism, decreasing glycolysis and increasing OXPHOS. Lactate significantly reduced the concentrations of TNF produced in response to Mtb (Figure, D). In addition, lactate significantly improved bacillary clearance in adult macrophages infected with Mtb.

Conclusions/Learning Points:

These data indicate that adult and cord blood macrophages exhibit distinct immunometabolic function upon stimulation which may underlie their differential ability to respond to infection and inform therapeutic strategies for host-directed therapies for TB.

Backgrounds:

Tuberculosis (TB) is the biggest global infectious killer in the last decade and young children are especially vulnerable. Mycobacterium tuberculosis (Mtb), the bacteria that causes TB, is phagocytosed by macrophages. To mount an appropriate immune response, the macrophage needs to alter metabolism, increasing glycolysis and decreasing oxidative phosphorylation (Warburg effect). It was hypothesized that umbilical cord derived macrophages have an altered immunometabolic response compared with adult macrophages, which may explain infant susceptibility to TB.

Methods

Monocyte derived macrophages (MDM) were derived from buffy coats or from umbilical cord blood prior to analysis in the XFe Seahorse analyzer. TNF in supernatant was measured by Mesoscale Discovery assay.

Results:

The Warburg effect was demonstrated in adult MDM after Mtb stimulation. Cord blood MDM however, did not decrease OXPHOS (Figure, A). Cord blood MDM secreted less TNF than adult MDM following Mtb stimulation (Figure, B).

The effects of IFN-γ or IL-4 on macrophage immunometabolism was investigated. IFN-γ increased glycolysis and OXPHOS and IL-4 markedly reduced glycolysis. IFN-γ increased cord TNF production in response to Mtb, equating to adult levels (Figure, C). IL-4 caused a decrease in IL-1β production in Mtb stimulated MDM.

A consequence of raised glycolysis is increased extracellular lactate. The addition of exogenous lactate has an immediate effect on metabolism, decreasing glycolysis and increasing OXPHOS. Lactate significantly reduced the concentrations of TNF produced in response to Mtb (Figure, D). In addition, lactate significantly improved bacillary clearance in adult macrophages infected with Mtb.

Conclusions/Learning Points:

These data indicate that adult and cord blood macrophages exhibit distinct immunometabolic function upon stimulation which may underlie their differential ability to respond to infection and inform therapeutic strategies for host-directed therapies for TB.