Microbial Metabolite Triggers Ageing Blood Disorders

In a groundbreaking advance illuminating the molecular landscape of pre-leukaemic progression, researchers have identified a pivotal role for the microbial metabolite ADP-heptose in driving clonal haematopoiesis through activation of the ALPK1 receptor. This discovery not only deepens our understanding of how age-associated genetic changes intersect with environmental and microbial factors but also reveals mechanistic insights that could revolutionize therapeutic strategies targeting early haematologic malignancies.

At the heart of this study lies ALPK1, a pattern recognition receptor uniquely tuned to sense ADP-heptose, a metabolite derived from bacterial lipopolysaccharide biosynthesis. ALPK1 expression was found to be markedly elevated in bone marrow-derived CD34⁺ haematopoietic stem and progenitor cells (HSPCs) sourced from individuals with myelodysplastic syndrome (MDS), a pre-leukaemic condition. The heightened ALPK1 mRNA levels correlated strongly with poor clinical prognosis, underscoring the receptor’s potential role as a biomarker and driver of disease severity.

Strikingly, the association between ALPK1 expression and leukaemic transformation extends beyond known genetic mutations such as those in DNMT3A, a commonly mutated epigenetic regulator in clonal haematopoiesis. While a higher incidence of DNMT3A mutations was observed in individuals exhibiting elevated ALPK1, increased ALPK1 expression also appeared in patients lacking these mutations. This suggests a broader, mutation-independent mechanism wherein ALPK1-mediated sensing may integrate diverse oncogenic signals to promote pre-leukaemic cell fitness.

At the protein level, immunoblotting confirmed that ALPK1 is significantly upregulated in CD34⁺ HSPCs from MDS patients when compared to healthy donors. Functionally, exposure of these cells to ADP-heptose induced a robust activation of NF-κB signaling, evident from increased phosphorylation of key pathway effectors IKKβ and RELA. This response was notably absent in comparable HSPCs derived from healthy controls, indicating a disease-specific gain of ALPK1-dependent sensing capacity within pre-leukaemic hematopoietic populations.

The epigenetic landscape further clarifies these molecular dynamics. Using publicly available datasets, the team demonstrated that hematopoietic stem cells deficient in Dnmt3a, or harboring heterozygous mutant alleles, exhibit hypomethylation of the Alpk1 promoter coupled with elevated Alpk1 transcript levels. This epigenetic rewiring extends to Tifa, a downstream adaptor protein of the ALPK1-ADP-heptose pathway, which also shows promoter hypomethylation with increased mRNA expression in Dnmt3a-null HSCs. Collectively, these data highlight an interplay wherein DNMT3A mutations precipitate epigenetic changes that prime pre-leukaemic stem cells for heightened responsiveness to microbial metabolites.

To investigate functional consequences, the research team generated HSPCs lacking Dnmt3a that expressed a fluorescently tagged TIFA reporter. Upon stimulation with ADP-heptose, these mutant cells formed large, durable TIFAsomes—multiprotein complexes that facilitate NF-κB activation—more robustly than their wild-type counterparts. Concomitantly, these expanded TIFAsomes correlated with intensified NF-κB signaling activity in mutant HSCs, as assessed by an eGFP reporter under NF-κB transcriptional control. Notably, wild-type HSCs required substantially higher concentrations of ADP-heptose to elicit comparable NF-κB activation.

Critically, this ADP-heptose-induced activation cascade was entirely dependent on ALPK1. HSPCs lacking both Dnmt3a and Alpk1 failed to form TIFAsomes or activate NF-κB in response to ADP-heptose, demonstrating the indispensability of ALPK1 in mediating this pro-leukaemic signaling axis. Moreover, ADP-heptose stimulation did not activate MAPK pathways in Dnmt3a-deficient HSPCs, pointing toward specificity in the molecular signaling routes engaged.

The relevance of these findings extends to in vivo contexts where intestinal epithelial integrity and microbiome composition are perturbed. In murine models, bone marrow transplantation of Dnmt3a-null HSCs followed by dextran sulfate sodium (DSS)–induced gut injury provoked expansion of mutant HSCs, an effect significantly dampened when ALPK1 was ablated. Similar observations were made upon systemic administration of ADP-heptose, which enhanced the competitive fitness and self-renewal of Dnmt3a-mutant HSCs but failed to do so in ALPK1-deficient backgrounds.

Interestingly, ALPK1-deficient mice exhibited no overt haematologic abnormalities under baseline conditions, suggesting that ALPK1’s functional importance may be contextually heightened in pre-leukaemic or mutant HSC compartments. This specificity could inform the development of targeted inhibitors aiming to disrupt the ADP-heptose–ALPK1 nexus selectively in diseased states without perturbing normal hematopoiesis.

Together, these findings reveal a compelling model in which age-associated clonal dominance in haematopoiesis is shaped not solely by intrinsic genetic mutations but also by extrinsic microbial metabolites arising from intestinal epithelial dysfunction and dysbiosis. The heightened ALPK1 expression and enhanced sensitivity to bacterial signals in mutant HSCs facilitate their expansion, thus linking microbial metabolites directly to leukaemogenesis.

This new paradigm elucidates how chronic inflammation and microbial metabolic cues converge on innate immune sensors within the haematopoietic system, steering cell fate decisions that may precede overt malignancy. Given the rising prevalence of clonal haematopoiesis with age and its association with cardiovascular and hematologic disorders, targeting ALPK1 or modulating ADP-heptose availability presents a tantalizing therapeutic avenue.

Future studies will need to dissect how environmental factors, diet, and microbiome composition influence systemic ADP-heptose levels and ALPK1 activity, potentially opening doors to microbiome-based interventions to mitigate pre-leukaemic expansion. Moreover, elucidating the downstream transcriptional networks engaged by ALPK1–NF-κB signaling may uncover additional druggable targets within this inflammatory axis.

In sum, this comprehensive work spearheaded by Agarwal et al. positions ALPK1 as a crucial molecular sentinel bridging microbial metabolism and the epigenetic landscape of pre-leukaemic cells. By unveiling a microbial metabolite-driven mechanism underlying aging-related clonal haematopoiesis, the study charts a transformative path toward understanding and ultimately intercepting early haematopoietic malignancies.

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Subject of Research: The role of the microbial metabolite ADP-heptose and ALPK1 receptor signaling in driving aging-related clonal haematopoiesis and pre-leukaemic stem cell expansion.

Article Title: Microbial metabolite drives ageing-related clonal haematopoiesis via ALPK1.

Article References:
Agarwal, P., Sampson, A., Hueneman, K. et al. Microbial metabolite drives ageing-related clonal haematopoiesis via ALPK1. Nature (2025). https://doi.org/10.1038/s41586-025-08938-8

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Tags: advancements in cancer diagnostics and treatmentsage-associated health conditionsALPK1 receptor in blood disordersbone marrow-derived stem cells researchclonal haematopoiesis and ageingenvironmental factors in haematologic malignanciesepigenetic regulation in leukaemialeukaemic transformation mechanismsmicrobial influences on genetic changesmicrobial metabolite ADP-heptosemyelodysplastic syndrome biomarkerstherapeutic strategies for pre-leukaemia