SGK1 rises as a plausible myeloid senescence signal in ME/CFS
Myalgic encephalomyelitis/chronic fatigue syndrome ME/CFS still lacks a usable biomarker, and that absence continues to hinder both diagnosis and mechanistic clarity. In this integrative transcriptomic and experimental study, investigators converged on SGK1 as a candidate regulator linked to myeloid cell senescence, bringing an aging-associated immune signal into a disease space long defined by physiologic uncertainty.
The work matters because ME/CFS is not framed here as a vague fatigue state. It is treated as a biologically active syndrome with immune dysregulation and chronic inflammation that resembles aging phenotypes, especially in the myeloid compartment. If senescent immune cells accumulate or function abnormally, they can sustain inflammatory tone, distort innate immune responses, and interfere with normal tissue repair. The study builds that argument from several angles rather than relying on a single dataset.
Transcriptomic filtering narrowed the field to two hub genes
The analysis began with bulk transcriptomic data from GSE14577, where differentially expressed genes were identified and then organized through weighted gene co-expression network analysis to find modules associated with the ME/CFS phenotype. Those modules were intersected with aging-related genes from the GenAge database, a strategy designed to search specifically for overlap between disease biology and senescence biology. From there, LASSO regression and random forest approaches were used to refine the list further.
This layered filtering produced two core hub genes: HMGCR and SGK1. The transcriptomic signal was not random noise scattered across the genome. It pointed toward pathways tied to cellular senescence and inflammation, suggesting that the disease signature may be shaped in part by altered aging programs within immune cells. HMGCR displayed a broader expression pattern, while SGK1 emerged with a more cell-type-focused profile that drew attention to the myeloid lineage.
Myeloid enrichment placed SGK1 in the center of the signal
Single-cell RNA sequencing data from GSE214283 helped localize where the candidate genes were expressed. SGK1 was enriched in myeloid cell populations, including monocytes and neutrophils, among individuals with ME/CFS. That cellular localization is clinically meaningful because monocytes and neutrophils sit at the front line of innate immunity and are major contributors to inflammatory signaling. A candidate gene enriched in those compartments is more plausible as a driver of systemic immune dysfunction than one with only diffuse expression.
The functional interpretation deepened when single-gene GSEA linked SGK1 to autophagy and lysosomal function. Those pathways are central to cellular housekeeping. When autophagy and lysosomal activity falter, cells can accumulate damaged proteins and organelles, amplify stress responses, and drift toward senescence-like behavior. In myeloid cells, that kind of dysfunction can alter cytokine handling, pathogen responses, and inflammatory persistence. The pattern offers a mechanistic bridge between transcriptomic association and immune-cell aging.
SGK1 tracked with senescence markers in a THP-1 model
Experimental validation came through a THP-1 cell senescence model induced with D-galactose. In that system, SGK1 expression was significantly upregulated in senescent cells. The direction of change fits the transcriptomic findings and strengthens the case that SGK1 is not just a passive marker but part of the senescence-associated program itself.
The intervention was straightforward and biologically direct: siRNA knockdown of SGK1. Once SGK1 was reduced, the mRNA expression levels of the canonical senescence markers p16, p21, and p53 fell markedly. That is a compact but important result. It suggests SGK1 sits upstream of, or at least alongside, pathways that help sustain the senescent phenotype in myeloid-like cells. In practical terms, the experiment ties a computational candidate to a functional readout rather than leaving the gene at the level of association alone.
Why a myeloid senescence pathway could matter in ME/CFS
The immune system in ME/CFS has long been suspected of behaving abnormally, but suspicion is not mechanism. Myeloid senescence offers one possible explanation for chronic inflammatory features that do not resolve cleanly over time. Senescent immune cells can become metabolically inefficient yet pro-inflammatory, creating a state in which signaling remains active while function becomes less effective. In a disorder marked by persistent symptoms and no objective diagnostic marker, that kind of dysregulated state is attractive as a hypothesis because it can account for both immune activation and immune exhaustion within the same framework.
SGK1 is especially interesting in this context because the pathway analysis linked it to autophagy and lysosomal biology. Those processes are often treated as cellular maintenance systems, but in immune cells they also govern the clearance of intracellular stress and the fine-tuning of inflammatory output. If SGK1 contributes to defective cleanup or abnormal stress responses, it could help lock myeloid cells into a senescence-associated state. The study does not prove that SGK1 causes ME/CFS, and it does not establish that the gene functions identically in patients and in THP-1 cells. It does, however, place SGK1 in a biologically credible position.
One result stands out sharply. SGK1 knockdown reduced p16, p21, and p53 in senescent cells.
The remaining gap is patient-level validation
The work still stops short of clinical translation. Primary immune cells from people with ME/CFS were not used for the functional experiments, and the analysis does not yet establish whether SGK1 can discriminate patients from controls in a diagnostic setting. The study also relies on transcriptomic inference across datasets, which is powerful for hypothesis generation but still vulnerable to cohort-specific effects and indirect biological interpretation.
Even so, the design has a clear strength: it triangulates bulk transcriptomics, single-cell localization, pathway enrichment, and an experimental knockdown model around the same candidate gene. That convergence makes SGK1 more than a speculative marker. It now stands as a testable node in a senescence-centered model of ME/CFS, one that should next be examined in primary patient-derived monocytes and neutrophils, ideally alongside clinical phenotypes and immune functional readouts. Until those data arrive, SGK1 remains a candidate with mechanistic promise rather than a validated biomarker.