Switching to the cyclic pentose phosphate pathway powers the oxidative burst in activated neutrophils

Abstract

Neutrophils are cells at the frontline of innate immunity that can quickly activate effector functions to eliminate pathogens upon stimulation. However, little is known about the metabolic adaptations that power these functions. Here we show rapid metabolic alterations in neutrophils upon activation, particularly drastic reconfiguration around the pentose phosphate pathway, which is specifically and quantitatively coupled to an oxidative burst. During this oxidative burst, neutrophils switch from glycolysis-dominant metabolism to a unique metabolic mode termed ‘pentose cycle’, where all glucose-6-phosphate is diverted into oxidative pentose phosphate pathway and net flux through upper glycolysis is reversed to allow substantial recycling of pentose phosphates. This reconfiguration maximizes NADPH yield to fuel superoxide production via NADPH oxidase. Disruptions of pentose cycle greatly suppress oxidative burst, the release of neutrophil extracellular traps and pathogen killing by neutrophils. Together, these results demonstrate the remarkable metabolic flexibility of neutrophils, which is essential for their functions as the first responders in innate immunity.

Quantitative modeling of pentose phosphate pathway response to oxidative stress reveals a cooperative regulatory strategy

“…Besides insights into the regulatory logic, the modeling approach could also identify the main rate-limiting processes for PPP flux increase and H 2 O 2 detoxification. In the models, the maximal PPP flux generates up to 3 mol of NADPH for 1 mol of glucose due to a cycling mode where each molecule of glucose can be oxidized multiple times ( Kuehne et al., 2015 ; Dick and Ralser, 2015 ; Britt et al., 2022 ), which is nevertheless far from the maximal yield of 12 mol of NADPH in case of complete inhibition of PRPP and GAPD enzymes. Besides the production of nucleotide precursors for DNA damage repair and of ATP for stress management, we also identify several rate-limiting reactions including GPx enzyme ( Ng et al., 2007 ), but also 6PGD enzyme.…”

Interplay of carbon dioxide and peroxide metabolism in mammalian cells

“…Indeed, the pH-independent rate constant for the reaction between ONOO − and CO2 has been determined as k20 = 3 x 10 4 M -1 s -1 (25 °C)(69) or 5.8 x 10 4 M -1 s -1 (37 °C) (64) ; the product of the reaction is a transient adduct (eq. [20]), nitrosoperoxocarboxylate (ONOOCO2 -) that readily undergoes homolysis to yield •NO2 and CO3• − in 35 % yields (eq. [21]), with the rest isomerizing to nitrate (NO3 -) (recently reviewed in (5,8)).…”

“…Because of the velocity of the reaction [20] which is a function of the product of k20 times [CO2], the biological chemistry of peroxynitrite is highly influenced by the existing levels of CO2 in cells and tissues; CO2 represents a key biological target of peroxynitrite (8). For J o u r n a l P r e -p r o o f a comparative analysis of the relative weight of the CO2 reaction on the fate of peroxynitrite vs that of other biotargets see (80,81).…”

“…CO2 is a relevant biological target of peroxynitrite (eq. [20]) and determines part of its fate and half-life in different biological compartments (8,80,81). The "CO2 pathway" of peroxynitrite decomposition is in competition with other relevant reactions including its catabolism by peroxiredoxins (8,24).…”

Regulation of Neutrophil NADPH Oxidase, NOX2: A Crucial Effector in Neutrophil Phenotype and Function

“…The main source of NADPH in neutrophils is the glucose-dependent pentose phosphate pathway (PPP). Activation of neutrophils with various stimuli leads to an increase in PPP metabolites ( Britt et al, 2022 ). In the PPP oxidative phase, the enzymes glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6 PGDH) catalyse the two steps leading to NADPH generation ( Curi et al, 2020 ).…”