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Obesity is a state of chronic, sterile, and systemic inflammation that alters the body’s metabolic and endocrine functions. One hallmark of obesity-associated inflammation is an increase in the frequency of myeloid cells in the circulation. These myeloid cells accumulate in tissues such as the adipose tissue, where they disrupt the tissue’s normal function, leading to metabolic changes such as insulin resistance. Weight loss is the main treatment for obesity, but there is evidence that metabolic inflammation persists after weight loss. The bone marrow (BM) is the site of immune cell production and is altered in obesity to promote myeloid cell generation, and these changes are refractory to weight loss, though the mechanisms driving these persistent changes remain unclear. Here, we show that obesity promotes myelopoiesis by altering the density of neutrophils in the BM. Endotoxemia is developed during obesity and promotes adipose tissue macrophages to recruit neutrophils from the BM in mice. Recruitment of BM neutrophils activates hematopoietic stem cells, which overproduce myeloid cells that accumulate in the circulation and drive inflammation. This recruitment is not resolved by weight loss, leading to sustained myelopoiesis in previously obese mice. Inhibiting neutrophil recruitment out of the BM in obese mice or during weight loss reduces BM myelopoiesis, adipose tissue inflammation, and improves glucose tolerance. In humans with obesity, plasma neutrophil chemokines are increased, correlate with increased insulin resistance, but do not decrease with weight loss. These results demonstrate that neutrophil recruitment is a key mediator of myelopoiesis during obesity, and targeting this pathway is a potential strategy to improve inflammation during obesity and weight loss.

Tu et al. show that Tff2 corpus isthmus cells are TA progenitors, and they, not chief cells, are the primary source of SPEM following injury. Upon Kras mutation, these progenitors directly progress to dysplasia, bypassing metaplasia, highlighting them as a potential origin of gastric cancer. Tff2 corpus cells are TA progenitors that give rise to secretory cells. Tff2 progenitors, not chief cells, are the primary source of SPEM after injury. Kras-mutant Tff2 progenitors progress directly to dysplasia, bypassing metaplasia. Multi-omics analysis reveals distinct trajectories for SPEM and gastric cancer. Pyloric metaplasia, also known as spasmolytic polypeptide-expressing metaplasia (SPEM), arises in the corpus in response to oxyntic atrophy, but its origin and role in gastric cancer remain poorly understood. Using knockin mice, we identified highly proliferative Tff2 progenitors in the corpus isthmus that give rise to multiple secretory lineages, including chief cells. While lacking long-term self-renewal ability, Tff2 corpus progenitors rapidly expand to form short-term SPEM following acute injury or loss of chief cells. Genetic ablation of Tff2 progenitors abrogated SPEM formation, while genetic ablation of GIF chief cells enhanced SPEM formation from Tff2 progenitors. In response to infection, Tff2 progenitors progressed first to metaplasia and then later to dysplasia. Interestingly, induction of Kras mutations in Tff2 progenitors facilitated direct progression to dysplasia in part through the acquisition of stem cell-like properties. In contrast, Kras-mutated SPEM and chief cells were not able to progress to dysplasia. Tff2 mRNA was downregulated in isthmus cells during progression to dysplasia. Single-cell RNA sequencing and spatial transcriptomics of human tissues revealed distinct differentiation trajectories for SPEM and gastric cancer. These findings challenge the conventional interpretation of the stepwise progression through metaplasia and instead identify Tff2 progenitor cells as potential cells of origin for SPEM and possibly for gastric cancer.

Nerves have been shown to regulate cancer progression. However, a clear demonstration of a role for axon guidance molecules in pancreatic tumorigenesis, innervation, and metastasis has been lacking. Using murine -mutant pancreatic organoids, we screened axon guidance molecules by qRT-PCR, identified upregulation, and then verified its upregulation during pancreatic tumorigenesis in humans and mice. NTN1 and its receptor NEO1 were upregulated in epithelial cells by the mutation and β-adrenergic signaling, in part, through the MAPK pathway. culture of celiac ganglia showed that NTN1 promoted the axonogenesis of sympathetic neurons through the nerve NEO1 receptor. In the model, knockout decreased sympathetic innervation and the development of pancreatic intraepithelial neoplasia. Treatment of pancreatic tumor organoids with recombinant NTN1 enhanced cell growth, epithelial-mesenchymal transition (EMT), and cancer stemness with the upregulation of ZEB1 and SOX9 through NEO1-mediated activation of focal adhesion kinase (FAK). In mice, knockout reduced innervation, FAK phosphorylation, and the features of EMT and stemness to extend mouse survival. In a liver metastasis model of PDAC (pancreatic ductal adenocarcinoma), treatment with a NTN1-neutralizing antibody or tumoral knockdown of reduced ZEB1 and SOX9 and decreased tumor progression. In contrast, overexpression promoted innervation and the progression of PDAC liver metastasis. These data suggest that the NTN1/NEO1 axis is a key regulator of PDAC progression, directly influencing cancer cell stemness and EMT, while indirectly promoting tumor growth through nerves. Inhibiting the NTN1/NEO1 axis could represent a potential therapeutic approach for PDAC.

Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are pathologically activated neutrophils that potently impair immunotherapy responses. The chemokine receptor CXCR4, a central regulator of hematopoiesis, represents an attractive PMN-MDSC target1. Here, we fused a secreted CXCR4 partial agonist TFF2 to mouse serum albumin (MSA) and demonstrated that TFF2-MSA peptide synergized with anti-PD-1 to induce tumor regression or eradication, inhibited distant metastases, and prolonged survival in multiple gastric cancer (GC) models. Using histidine decarboxylase (Hdc)-GFP transgenic mice to track PMN-MDSC , we found TFF2-MSA selectively reduced the immunosuppressive Hdc-GFP CXCR4 tumor PMN-MDSCs while preserving proinflammatory neutrophils, thereby boosting CD8 T cell-mediated anti-tumor response together with anti-PD-1. Furthermore, TFF2-MSA systemically reduced PMN-MDSCs and bone marrow granulopoiesis. In contrast, CXCR4 antagonism plus anti-PD-1 failed to provide a similar therapeutic benefit. In GC patients, expanded PMN-MDSCs containing a prominent CXCR4 LOX-1 subset are inversely correlated with the TFF2 level and CD8 T cells in circulation. Collectively, our studies introduce a strategy of using CXCR4 partial agonism to restore anti-PD-1 sensitivity in GC by targeting PMN-MDSCs and granulopoiesis.

The intestinal epithelium functions both in nutrient absorption and as a barrier, separating the luminal contents from a network of vascular, fibroblastic, and immune cells underneath. Following injury to the intestine, multiple different cell populations cooperate to drive regeneration of the mucosa. Immature myeloid cells (IMCs), marked by histidine decarboxylase (Hdc), participate in regeneration of multiple organs such as the colon and central nervous system. Here, we found that IMCs infiltrate the injured intestine and promote epithelial regeneration and modulate LEC activity. IMCs produce prostaglandin E2 (PGE2), which promotes LEC lymphangiogenesis and upregulation of pro-regenerative factors including RSPO3. Moreover, we found that IMC recruitment into the intestine is driven by invading microbial signals. Accordingly, antibiotic eradication of the intestinal microbiome prior to WB-IR inhibits IMC recruitment, and consequently, intestinal recovery. We propose that IMCs play a critical role in intestinal repair and implicate gut microbes as mediators of intestinal regeneration.Competing Interest StatementThe authors have declared no competing interest.