Saori Ogasawara

Pancreatic stellate cells (PSCs) are the origin of cancer-associated fibroblasts. Type 2 diabetes mellitus (T2D) may promote pancreatic ductal adenocarcinoma (PDAC), eliciting changes in the quiescent PSC (qPSC) population from the precancerous stage. However, the details are unknown. We evaluated the subpopulations of qPSCs and the impact of T2D. PSCs isolated from 8-week-old C57BL/6J mice and diabetic db/db mice were analyzed by single-cell RNA-seq. Sorted qPSCs and PDAC cells were transplanted into allogenic mice. The isolated qPSCs were broadly classified into mesothelial cell and pancreatic fibroblast (Paf) populations by single-cell RNA-seq. Pafs were subclassified into inflammatory Pafs, myofibroblastic Pafs (myPafs) and a small population named tumor immunity- and angiogenesis-promoting Pafs (tapPafs), expressing Cxcl13 . In the subcutaneous transplantation model, the tumors transplanted with myPafs were significantly larger than the tumors transplanted with tapPafs. An increase in myPafs and a decrease in tapPafs were observed from the precancerous stage in human T2D, indicating the effects of tumor progression. This study revealed the subpopulation changes in qPSCs in T2D. A therapy that increases the number of tapPafs could be a therapeutic option for patients with PDAC and T2D and even those in a precancerous stage of T2D.

It is suggested that activation of receptor for advanced glycation end products (RAGE) induces proinflammatory response in diabetic nerve tissues. Macrophage infiltration is invoked in the pathogenesis of diabetic polyneuropathy (DPN), while the association between macrophage and RAGE activation and the downstream effects of macrophages remain to be fully clarified in DPN. This study explored the role of RAGE in the pathogenesis of DPN through the modified macrophages. Infiltrating proinflammatory macrophages impaired insulin sensitivity, atrophied the neurons in dorsal root ganglion, and slowed retrograde axonal transport (RAT) in the sciatic nerve of type 1 diabetic mice. RAGE-null mice showed an increase in the population of antiinflammatory macrophages, accompanied by intact insulin sensitivity, normalized ganglion cells, and RAT. BM transplantation from RAGE-null mice to diabetic mice protected the peripheral nerve deficits, suggesting that RAGE is a major determinant for the polarity of macrophages in DPN. In vitro coculture analyses revealed proinflammatory macrophage–elicited insulin resistance in the primary neuronal cells isolated from dorsal root ganglia. Applying time-lapse recording disclosed a direct impact of proinflammatory macrophage and insulin resistance on the RAT deficits in primary neuronal cultures. These results provide a potentially novel insight into the development of RAGE-related DPN.

Normal-high HbA1c levels are a risk factor for attenuated pain sensation in normoglycemic subjects. It is unclear, however, what mechanisms underlie the pathogenesis of attenuated pain sensation in such a population. We, therefore, explored the relationship between oxidative stress (OS) and pain sensation in a rural Japanese population. A population-based study of 894 individuals (average age 53.8 ± 0.5 years) and 55 subjects with impaired fasting glucose (IFG) were enrolled in this study. Individuals with diabetes were excluded. Relationships between pain threshold induced by intraepidermal electrical stimulation (PINT) and clinico-hematological parameters associated with OS were evaluated. Univariate linear regression analyses revealed age, BMI, HbA1c, the OS biomarker urine 8-hydroxy-2′-deoxyguanosine (8-OHdG), systolic blood pressure, and decreased Achilles tendon reflex on the PINT scores. Adjustments for age, gender, and multiple clinical measures confirmed a positive correlation between PINT scores and urine 8-OHdG (β = 0.09, p < 0.01). Urine 8-OHdG correlated positively with higher HbA1c levels and age in the normoglycemic population. Unlike in the normoglycemic population, both inflammation and OS were correlated with elevated PINT scores in IFG subjects. OS may be a major contributing factor to elevated PINT scores in a healthy Japanese population.