The team began with a striking natural experiment built into Chinese pig genetics. Ningxiang pigs are an indigenous breed that is notably prone to accumulating fat, while commercial Duroc-Landrace-Yorkshire pigs remain comparatively lean under the same conditions. By comparing the gut microbiomes of these two breeds, the researchers found that the adiposity-prone Ningxiang animals carried an expanded population of Gram-negative bacteria, elevated levels of lipopolysaccharide, or LPS, in their circulation, and markedly reduced abundance of Clostridium butyricum, a beneficial gut bacterium, along with reduced levels of its signature metabolite, butyrate. LPS is a structural component of the outer membrane of Gram-negative bacteria, and when it leaks from a dysbiotic gut into the bloodstream it is recognized by the immune system as a danger signal, triggering chronic low-grade inflammation that is a hallmark of obesity.

To test whether these microbial differences were a cause rather than a consequence of fatness, the researchers performed fecal microbiota transplantation, transferring gut microbes from obese-prone Ningxiang donors into lean Duroc-Landrace-Yorkshire recipients. The lean pigs gained adiposity after receiving the microbiota of their fat-prone counterparts, and the transfer was accompanied by a significant drop in colonization by C. butyricum. This result suggested that the microbial community itself, depleted of butyrate-producing organisms and enriched in LPS-carrying Gram-negative species, could actively transmit a tendency toward weight gain.

The next step was intervention. In mice fed a high-fat diet, supplementation with C. butyricum and with butyrate itself effectively restored gut microbial homeostasis and ameliorated obesity. These findings established the bacterium and its metabolite as candidate therapeutic agents, but they left open the central question of mechanism: through what molecular circuitry does a gut microbe influence whole-body fat accumulation? To answer it, the team turned to large-scale transcriptomics, sequencing the RNA of multiple organs in both pigs and long-tailed macaques, a nonhuman primate, to search for gene regulatory programs conserved across species.

The search converged on a single transcription factor: early growth response 1, or EGR1. Across organs and across species, EGR1 emerged as a central regulator of obesity-associated inflammation, with consistent enrichment of the PI3K-Akt signaling pathway, a well-known intracellular cascade that controls cell growth, survival and metabolism. Single-cell RNA sequencing then sharpened the picture at the level of individual immune cells. Macrophages, the tissue-resident immune cells that infiltrate expanding fat tissue in obesity, showed a clear dichotomy: those with high EGR1 expression adopted a pro-inflammatory M1 phenotype, pumping out inflammatory cytokines, while those with low EGR1 expression displayed an anti-inflammatory M2 profile associated with tissue repair and metabolic calm. In obese adipose tissue, the balance tips toward the EGR1-high, M1-polarized state, and that shift is thought to be a major driver of insulin resistance and metabolic dysfunction.

To establish that EGR1 was not merely a bystander, the researchers used two complementary strategies. First, they performed an in silico knockout, computationally removing EGR1 from gene regulatory networks built from macrophage-specific expression data, and found that PI3K-Akt signaling depended functionally on EGR1 downstream. Second, they applied a pharmacological inhibitor of EGR1, designated EGR1i and known as IT25, and observed the same disruption of the pathway. Together, the computational and chemical perturbations supported a model in which EGR1 sits upstream of PI3K-Akt signaling within macrophages, orchestrating the inflammatory program that links gut-derived LPS to metabolic inflammation.

Integrating metagenomic data on microbial communities with single-cell data on immune cells, the team proposed what they call a conserved LPS-EGR1 axis governing macrophage polarization in obesity. According to this model, gut dysbiosis increases the translocation of LPS into the circulation, LPS activates EGR1 expression in macrophages, and EGR1 drives those macrophages toward the M1 state through PI3K-Akt-associated signaling, thereby sustaining the chronic inflammation that characterizes obesity. The loop is self-reinforcing: inflammation worsens gut barrier integrity, which permits more LPS to enter, which further activates the axis.

To validate the model experimentally rather than merely infer it from correlations, the researchers built two purpose-made systems. The first was a mouse model of obesity in which a high-fat diet was potentiated with LPS, mimicking the endotoxemia seen in dysbiotic guts. The second was a cell culture model in which LPS was used to drive M1 polarization of RAW264.7 macrophages, a widely used mouse macrophage cell line. Into these systems they introduced four candidate disruptors of the axis: live C. butyricum, butyrate, the amino acid arginine, and the EGR1 inhibitor IT25. All four treatments significantly attenuated weight gain in the animal model, downregulated EGR1 expression, and suppressed M1 macrophage polarization, restoring a healthier M1/M2 balance. The beneficial effects were accompanied by significant alterations in genes related to the PI3K-Akt pathway, suggesting that this pathway acts in concert with EGR1 within the regulatory network rather than as an independent route.

The inclusion of arginine among the effective interventions adds an intriguing nutritional dimension to the work. Arginine is a semi-essential amino acid with known immunomodulatory and nitric-oxide-related functions, and its ability to blunt the LPS-EGR1 axis alongside a probiotic bacterium, a short-chain fatty acid and a targeted inhibitor suggests that the axis is a convergent point where diet, microbes and pharmacology all meet. For a field in which probiotic studies often report benefits without clear mechanisms, the strength of this study lies in its chain of evidence: a natural cross-breed comparison, a transplantation experiment, a dietary intervention, cross-species transcriptomics, single-cell resolution, computational and chemical perturbation, and finally purpose-built validation models. Each link in the causal chain from dysbiosis to inflammation to fat accumulation was tested separately.

The cross-species consistency is equally significant. Because the EGR1-centered program was observed in pigs, mice and macaques, the LPS-EGR1 axis appears to be a fundamental feature of mammalian metabolic inflammation rather than a quirk of any one model organism. That conservation raises the stakes for translation. If the same axis operates in humans, and the components are plausible given the well-documented role of endotoxemia and M1 macrophage infiltration in human obesity, then C. butyricum, butyrate, arginine supplementation or EGR1-targeted drugs could eventually complement existing strategies for metabolic disease. The authors note that the work was supported by the National Natural Science Foundation of China and several Hunan provincial programs, and the study was approved by the Biomedical Research Ethics Committee of Hunan Normal University. Much remains to be done, including direct demonstration of the axis in human tissues and safety testing of EGR1 inhibition, which is a transcription factor with roles in many cell types. But the study delivers something the obesity field has lacked: a single, targetable molecular hub, EGR1, that connects the gut microbiota to the immune cells that set the inflammatory tone of fat tissue. In doing so, it transforms a diffuse association between microbes and obesity into a defined circuit with identifiable points of intervention, and it suggests that reshaping the gut ecosystem with the right bacterium, or simply feeding it the right substrate, may be enough to quiet the inflammation that makes fat so metabolically dangerous.

Subject of Research: How Clostridium butyricum and butyrate modulate macrophage polarization via the LPS-EGR1 axis to alleviate obesity

Article Title: Clostridium butyricum and butyrate reprogram macrophages to alleviate obesity by disrupting the LPS-EGR1 axis and its associated PI3K-Akt signaling

Article References: Li, W., Chen, W., Wang, L., Zhu, Q., Zhang, Y., Zeng, X., Liu, J., Wang, Q., Ma, H., Yin, J., Li, J., Yin, Y., & Yang, H. (2026). Clostridium butyricum and butyrate reprogram macrophages to alleviate obesity by disrupting the LPS-EGR1 axis and its associated PI3K-Akt signaling. Microbiome. https://doi.org/10.1186/s40168-026-02554-y

Image Credits: AI Generated

DOI: 10.1186/s40168-026-02554-y

Keywords: Clostridium butyricum, butyrate, gut microbiota, obesity, LPS, EGR1, macrophage polarization, PI3K-Akt signaling, inflammation, fecal microbiota transplantation, metabolic disease, single-cell RNA sequencing

The cells at the center of the story are podocytes, highly specialized epithelial cells that wrap around the tiny capillary loops of the glomerulus, the kidney’s filtration unit. Podocytes extend intricate foot processes that interlock to form slits through which blood is filtered, and their integrity is essential for keeping protein from leaking into the urine. When podocytes are injured or lost, the filtration barrier breaks down, proteinuria develops, and progressive scarring follows. Podocyte injury is widely regarded as a decisive event in diabetic kidney disease, which is why understanding exactly how high blood sugar damages these cells has become one of the most pressing questions in nephrology.

The new research focuses on an unexpected player: FTO, the fat-mass and obesity-associated protein. FTO first rose to fame through genome-wide association studies linking variants in its gene to human obesity, but it was later shown to be an enzyme that removes a specific chemical modification from RNA molecules. That modification, N6-methyladenosine, or m6A, is the most abundant internal mark on messenger RNA in higher organisms. By adding or erasing m6A, cells can fine-tune how long a given mRNA survives, how efficiently it is translated into protein, and how it is processed. In earlier work, the team had manipulated FTO in podocytes and performed parallel methylated RNA immunoprecipitation sequencing and RNA sequencing, a combination that reveals both which transcripts carry m6A marks and how overall gene expression changes. That screen pointed them toward early growth response 1, or EGR1, a transcription factor whose precise role in diabetic kidney disease had remained unclear.

The findings that followed connect the dots in a strikingly mechanistic way. The researchers demonstrated that FTO is critical to podocyte injury because it enhances the stability of EGR1 mRNA in a manner dependent on m6A and on YTHDF2, a reader protein that binds methylated RNA and directs its fate. In other words, by removing methyl marks from the EGR1 transcript, FTO protects that message from YTHDF2-mediated degradation, allowing more EGR1 protein to be produced. The team also found that EGR1 is elevated in podocytes taken from people with diabetic kidney disease, and that its levels correlate with estimated glomerular filtration rate and with 24-hour urinary protein, two clinical measures of how well the kidney is functioning and how badly the filter is leaking.

Experiments in cultured human podocytes reinforced the picture. When the cells were exposed to high glucose, mimicking the diabetic environment, EGR1 expression climbed. Silencing EGR1 eased both the injury and the inflammation that high glucose provokes in podocytes, while forcing the cells to overproduce EGR1 made the damage worse. This dose-and-direction relationship, in which turning the gene down protects and turning it up harms, is exactly what one would expect from a genuine driver of the disease process rather than a passive bystander.

The mechanistic core of the study lies in what EGR1 does once it is produced. Using chromatin immunoprecipitation, the researchers showed that EGR1 binds directly to the promoter of STING1, the gene encoding stimulator of interferon genes 1, a protein better known as a central hub of innate immune signaling. By occupying its promoter, EGR1 boosts STING1 transcription, which in turn activates the STING1/TBK1/NF-κB signaling cascade. This cascade is a classic inflammatory pathway: STING1 activates TBK1, a kinase that then activates NF-κB, a transcription factor that switches on a battery of inflammatory genes. The result is a self-reinforcing inflammatory attack on the podocyte from within, driven ultimately by an RNA modification laid down by FTO.

To test whether the pathway matters in a living organism, the team turned to mouse models of diabetes induced by streptozotocin and a high-fat diet, which together reproduce key features of the human disease. Using adeno-associated virus vectors to deliver genetic constructs specifically to podocytes, they deleted or upregulated EGR1 in these cells. The outcome was unambiguous. Podocyte-specific deletion of EGR1 significantly reduced podocyte and glomerular damage in the diabetic mice, preserving the structure of the filtration barrier. Conversely, when EGR1 was deliberately elevated in podocytes, the mice suffered worse podocyte injury and heavier proteinuria. The same gene that protected cells when removed caused harm when amplified, confirming EGR1 as a pivotal node in the disease cascade in vivo.

The study is notable for the way it stitches together three layers of biology that are usually studied separately: epitranscriptomics, the chemistry of RNA modifications; transcriptional regulation, the control of gene expression by DNA-binding factors; and innate immunity, the inflammatory machinery that cells deploy against perceived threats. In the podocytes of a diabetic kidney, these layers converge into a single pathway. High glucose and FTO activity conspire to stabilize EGR1 mRNA, EGR1 protein then switches on STING1, and the STING1/TBK1/NF-κB axis ignites inflammation that erodes the kidney’s filter. Each link in that chain is a potential point of intervention, and the authors suggest that EGR1 itself could be a prospective new treatment strategy for diabetic kidney disease.

The clinical stakes are considerable. Current therapy for diabetic kidney disease rests on controlling blood glucose and blood pressure and on blocking the renin-angiotensin system with drugs such as angiotensin-converting enzyme inhibitors, alongside newer agents including SGLT2 inhibitors. Yet a large fraction of patients still progress toward dialysis or transplant, so molecular targets that address the injury process itself, rather than its systemic drivers, are eagerly sought. Because EGR1 sits downstream of FTO and upstream of the inflammatory cascade, drugging it or its partners might blunt podocyte inflammation even when metabolic control is imperfect. Any such approach would need to reckon with the fact that EGR1 is an immediate-early transcription factor with many roles in other tissues, so specificity will be a central challenge for future drug development.

There are also caveats that temper the excitement. The human evidence consists of correlations between EGR1 levels in podocytes and clinical markers, which, while consistent with the mechanistic data, cannot by themselves prove causation in patients. The mouse model, though well established, does not capture every feature of human diabetic nephropathy, and the viral vectors used to manipulate EGR1 in podocytes are research tools rather than therapeutic vehicles. The published version of the study is open access, allowing clinicians and researchers worldwide to scrutinize the data, and the work was approved by the relevant ethics committees at Shandong Provincial Hospital with informed consent from all participants. Even so, the study offers something the field has lacked: a complete, testable narrative linking an RNA demethylase, a methylated mRNA, an immune signaling hub, and the slow-motion catastrophe of the diabetic glomerulus. If that narrative holds up in further studies, the humble chemical tag on a strand of RNA may turn out to be one of diabetes’ most consequential accomplices, and shutting down its effects could help millions of people keep their kidneys working longer.

Subject of Research: FTO-mediated m6A modification of EGR1 mRNA and its role in podocyte injury and inflammation in diabetic kidney disease

Article Title: FTO-mediated m6A modification of EGR1 mRNA promotes podocyte injury and inflammation via STING1 in diabetic kidney disease

Article References: Hu, J., Liu, Y., Lang, Y., Liu, B., Fan, X., Yang, M., Shen, N., Zhang, D., Zhang, X., Chai, S., Zeng, Z., Shang, J., Wang, R., & Lv, Z. (2026). FTO-mediated m6A modification of EGR1 mRNA promotes podocyte injury and inflammation via STING1 in diabetic kidney disease. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06474-w

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06474-w

Keywords: diabetic kidney disease, podocytes, FTO, EGR1, STING1, m6A modification, RNA demethylase, YTHDF2, NF-kappaB, inflammation, proteinuria, nephrology

Canine malignant insulinoma is a functional neuroendocrine tumour of pancreatic beta cells: a cancer that not only grows and spreads but keeps manufacturing insulin as though it were still serving the body. Middle-aged and older dogs are typically affected, with Boxers, German shepherds, Labrador retrievers and West Highland white terriers among the predisposed breeds. Affected animals may show increased appetite and weight gain, weakness between meals or after exercise, and, as the disease advances, collapse and hypoglycaemic seizures. Diagnosis rests on documenting clinical signs alongside inappropriately high serum insulin concentrations in the face of low blood glucose, often supported by imaging of a pancreatic nodule. Surgical excision is the mainstay of treatment but is rarely curative, because functional metastases frequently seed new insulin-producing lesions and bring the clinical signs roaring back.

The prognosis is sobering. The largest study of canine insulinoma to date, covering 93 dogs, reported a median survival of eight months with medical management and twenty months with surgery. Adjunctive drugs such as prednisolone, octreotide and diazoxide aim to blunt insulin’s effects rather than attack the tumour itself, while small studies of beta-cell-toxic streptozotocin and the tyrosine kinase inhibitor toceranib have hinted at benefit without establishing clear efficacy. This therapeutic vacuum is precisely what makes a high-resolution map of the tumour’s cellular landscape so valuable: it offers both candidate drug targets and potential biomarkers to identify which patients are at risk of metastasis before it happens.

Single-cell RNA sequencing overcomes the fundamental limitation of bulk RNA-sequencing, which averages gene expression across thousands of heterogeneous cells and thereby blurs the very distinctions that matter most. By profiling individual cells, researchers can identify malignant sub-populations, reconstruct the tumour microenvironment, and infer the communication channels between cancer and immune cells. Until now, only human and mouse pancreatic neuroendocrine tumours had been examined this way, and the mouse work relied on an experimentally induced model rather than spontaneous disease. The new study is the first to apply the technique to naturally occurring insulinoma in any species, using tissue surplus to diagnostic requirements after planned therapeutic surgery, with owner consent and no influence on clinical management.

The technical execution was meticulous. Fresh tumour tissue was transported in cold buffer within two hours of excision, minced, enzymatically digested with Liberase TL, and processed into single-cell suspensions before library preparation on the 10X Chromium system and sequencing on an Illumina HiSeq4000. Reads were aligned to the canine reference genome CanFam3.1, and clustering and differential expression analyses were performed in Seurat, with cell types assigned through canonical marker genes and automatic classifiers. Quality control demanded more than fifty detected genes per cell and less than ten percent mitochondrial read content, yielding an average of 123,536 reads per cell and transcripts from a median of 1,010 genes per cell.

The headline discovery is that all three tumour samples contained two transcriptionally distinct populations of insulin-expressing cancer cells, separated by roughly 8,000 differentially expressed genes. One population, dubbed INS+ FOS+ EGR1+ TP53+ and abbreviated INS+, maintains expression of the tumour suppressor TP53, the transcription factor EGR1, and the AP-1 component FOS. The second, INS+ FOSlow, shows strong downregulation of these genes and of around sixty other tumour suppressors, including NF1, ARID1A and CDKN1A, together with a 23.5-fold reduction in DUSP1, a regulator of MAPK signalling. Pathway analysis of the genes separating the two populations flagged the MAPK, mTOR, PI3K-AKT, Notch, Wnt and p53 signalling pathways, along with cellular senescence and apoptosis, all of them famous for their deregulation in cancer.

Despite their deep differences, both malignant populations retained the molecular identity of their beta-cell origin, expressing insulin-related genes such as IAPP, PCSK2, NKX2-2 and SLC30A8, and the chromogranin and secretogranin family markers CHGA, CHGB, SCG2, SCG3, SCG5 and SCGN that define neuroendocrine tumours. Strikingly, one of the very few genes ubiquitously expressed and significantly upregulated in both insulin-expressing populations was COX7A2L, elevated more than twenty-fold, with a mean of twenty-seven-fold, over other captured cells. The gene encodes a subunit of cytochrome c oxidase involved in mitochondrial respiration, has been linked to poor prognosis in pancreatic, ovarian and breast cancers, and its knockdown reduces tumour growth in mice, making it an obvious candidate for further investigation in insulinoma.

Copy number analysis added an evolutionary dimension. The INS+ FOSlow population carried more chromosomal alterations than the INS+ population, and in the patient with more advanced disease, these cells showed frequent deletion of chromosomes 13, 20 and 29 and amplification of 11, 14 and 15, alterations that were rare in the other population and largely absent in the less-affected patient. This pattern suggests that whole-chromosome copy number changes are not the initiating event in these tumours but accumulate as the disease progresses, potentially serving as a marker of advanced disease state. Meanwhile, comparisons between the two primary tumours revealed far fewer differences, roughly 600 differentially expressed genes, than existed between the two cancer cell populations within each patient, including genes such as TMSB4X, proposed as a cancer prognostic marker and reportedly overexpressed in toceranib-resistant liver cancer cells, and CLTRN, a stimulator of beta cell replication that was upregulated in the patient with more advanced disease.

Two findings from the metastatic lesion were genuinely unexpected. First, the metastasis contained all the cell types represented in the primary tumour, including immune populations, rather than presenting as a pure mass of neoplastic endocrine cells, a pattern consistent with locally invasive spread rather than lymph node metastasis. Second, and more startling, both insulin-expressing populations in the metastasis showed more than twenty- to seventy-fold upregulation of exocrine pancreatic genes, including CLPS, PRSS2, PRSS and CTRC, markers normally associated with digestive enzyme production and pancreatitis. For a tumour of endocrine origin, this is deeply atypical, and the authors suggest these genes may mark metastatic transformation, invasion or de-differentiation, though their significance remains to be determined.

The immune analysis completed the picture. The tumours harboured effector and memory T cells, naive CD4-positive T cells, B lymphocytes, and two macrophage populations distinguished by MS4A7 and S100A12 expression, with the greatest inter-patient differences appearing in the macrophage cluster. Cell communication analysis using CellChat identified significant interactions between cancer and immune cells, most notably CD40LG expressed by both insulin-expressing tumour populations engaging CD40 on infiltrating B cells, an axis implicated in angiogenesis and described as a prognostic indicator in breast cancer, and an APP interaction with the TREM2-TYROBP complex on macrophages. Insulin-expressing cells also showed upregulation of inflammatory response genes including C15orf48 and TRAF3IP2, while insulin-expressing tumour cells had the highest proportion of cells in S phase of any cell type examined, with the peak in the metastasis, underscoring why DNA replication remains a therapeutic target. The authors are candid about the study’s limits: two dogs, one breed, and no matched blood or healthy beta-cell reference data. Yet the demonstration that single-cell data can be recovered from veterinary surgical material surplus to diagnostic needs opens a translational window, since canine insulinoma shares histopathological features with human pancreatic neuroendocrine tumours, and any future therapy would need to hit both malignant sub-populations simultaneously, in dogs and potentially in people.

Subject of Research: Single-cell transcriptomic profiling of canine insulinoma and its tumour microenvironment

Article Title: Single-cell transcriptomic analysis of canine insulinoma reveals distinct sub-populations of insulin-expressing cancer cells

Article References: Wallace, M. D., Herrtage, M. E., Gostelow, R., Owen, L., Rutherford, L., Hughes, K., Denyer, A., Catchpole, B., O’Callaghan, C. A., & Davison, L. J. (2025). Single-cell transcriptomic analysis of canine insulinoma reveals distinct sub-populations of insulin-expressing cancer cells. Veterinary Oncology, 2(1), Article 13. https://doi.org/10.1186/s44356-025-00026-3

Image Credits: AI Generated

DOI: 10.1186/s44356-025-00026-3

Keywords: single-cell RNA sequencing, canine insulinoma, pancreatic neuroendocrine tumour, beta cells, tumour microenvironment, TP53, EGR1, COX7A2L, metastasis, copy number alteration, tumour immunology, veterinary oncology