Acute lung injury (ALI) is a severe inflammatory syndrome with limited therapeutic options. The interplay between cellular metabolism and inflammation—particularly macrophage glycolytic reprogramming—has emerged as a key driver of pathological inflammation in ALI and acute respiratory distress syndrome (ARDS). The published study investigates whether a natural product, seco-tanapartholide B (SB), can target metabolic nodes to blunt inflammatory responses and ameliorate LPS-induced ALI.
The authors focus on pyruvate kinase M2 (PKM2), a regulator of glycolysis that also modulates inflammatory signaling. They hypothesize that activating PKM2 to favor its enzymatically active tetrameric form could suppress glycolysis-dependent inflammatory pathways and reduce lung injury.
To determine SB’s molecular target, the investigators applied multiple target-engagement and proteome-wide approaches. These included thermal proteome profiling (TPP), cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS), and bio-layer interferometry (BLI). Across these complementary techniques, PKM2 emerged as a direct binder of SB, indicating a primary molecular interaction between the compound and this glycolytic enzyme.
These orthogonal assays provide biochemical and biophysical evidence that SB engages PKM2 in cells and in vitro. The abstract identifies PKM2 as the direct molecular target but does not provide detailed assay conditions, binding affinities, or full proteome lists in the summary; the full text is required for those specifics.
Mass spectrometry (LC-MS/MS) analysis identified a covalent adduct between SB and PKM2 at Cys424, formed via SB’s α-methylene-γ-lactone moiety. This covalent modification correlated with functional changes in PKM2: SB increased pyruvate kinase enzymatic activity and promoted PKM2 tetramerization.
Promotion of the tetrameric PKM2 state is significant because tetrameric PKM2 has higher catalytic activity and is less associated with non-metabolic nuclear signaling functions. By favoring the tetramer, SB shifts PKM2 toward glycolytic flux control and away from proinflammatory transcriptional coactivator roles.
Functionally, SB suppressed glycolysis in vitro and in vivo in LPS-challenged models and reduced inflammatory readouts. The metabolic shift coincided with downregulation of several inflammation-linked pathways reported in the abstract: NF-κB and STAT3 signaling were suppressed, and HIF-1α expression was reduced.
These pathway-level changes align with the proposed mechanism that PKM2 activation and tetramerization lower glycolysis-dependent inflammatory programming in immune cells, particularly macrophages, thereby attenuating tissue inflammation in the lung. Specific quantitative measures of glycolytic flux, cytokine levels, or lung injury scores are not described in the abstract and require the full article for numeric results.
The authors performed genetic knockdown of PKM2 in macrophages to test whether SB’s effects depend on PKM2. Knockdown of PKM2 attenuated SB’s anti-inflammatory and glycolysis-inhibitory effects, supporting that PKM2 is the functional on-target mediator for SB in these cells.
This genetic evidence complements the biochemical target-identification data and strengthens the causal link between covalent PKM2 activation by SB and downstream suppression of inflammatory metabolism and signaling. Details about the knockdown method, efficiency, and specific macrophage models were not reported in the abstract.
The study positions SB as a natural PKM2 activator that therapeutically targets metabolic-inflammatory crosstalk in ALI. By demonstrating covalent modification of PKM2 at Cys424, increased pyruvate kinase activity, and promotion of PKM2 tetramers, the work provides a biochemical rationale for promoting PKM2 tetramerization as a therapeutic strategy for ALI/ARDS.
The authors note that PKM2 activators have mostly been explored in oncology; these findings extend potential applications to inflammatory lung diseases. The abstract indicates SB reduced LPS-induced ALI in vitro and in vivo, but specific experimental details, dosing regimens, safety assessments, and quantitative efficacy endpoints are not provided in the abstract and must be consulted in the full text.
Overall, the reported data support a model in which covalent activation of PKM2 by a plant-derived sesquiterpene lactone reprograms glycolysis and suppresses key inflammatory signaling pathways, resulting in amelioration of LPS-induced acute lung injury. Further evaluation in detailed preclinical and clinical studies would be required to define therapeutic potential, dosing, and safety profiles; those data are not included in the abstract.