Hyperplastic polyp-like adenoma: a subtype of colonic adenoma with a proliferative zone confined to the lower two-thirds of the crypt

BACKGROUND

The proliferative zone of colonic adenomas is confined to the upper third of the crypt or is scattered along its entire axis. In contrast, there are unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. We investigated the frequency and endoscopic features of adenomas with lower proliferative zones.

METHODS

We retrospectively reviewed consecutive patients who underwent colonoscopies between September 2022 and March 2023 at the Toyoshima Endoscopy Clinic. Colorectal polyps were endoscopically assessed using the Japan Narrow-Band Imaging Expert Team (JNET) classification. All resected polyps were histologically examined, and the proliferative zone locations were assessed in the adenomas.

RESULTS

The frequency of adenomas with a lower proliferative zone was 1.8% (44/2420) in adenomas. Among these adenomas, JNET type 1 incidence was 43.2% (19/44), which was significantly higher than that in adenomas with a normal proliferative zone. Adenomas with a lower proliferative zone were diminutive (mean size: 2.5 mm) and prone to develop in the proximal colon.

CONCLUSION

Colonic adenomas with proliferative zones confined to the lower two-thirds of the crypt often appear as diminutive, hyperplastic polyps.

Mechanobiological analysis of porcine spines instrumented with intra-vertebral staples

OBJECTIVE

To characterize growth plate histology of porcine spines instrumented with a new intra-vertebral staple.

METHODS

Spinal segments (T7-T9) previously instrumented with an intra-vertebral staple (experimental group, n=7) or non-instrumented (control group, n=4) underwent average growth rate (AGR), and histomorphometric measurements: heights of proliferative (PZH) and hypertrophic (HZH) growth plate zones, hypertrophic cells height (CH), and the number of proliferative chondrocytes per column (CC). These measurements were done over three regions: (1) left side; (2) middle; (3) right side (instrumented side). The two groups were analyzed by comparing the difference between results for regions 1 and 3 (Dif-R1R3).

RESULTS

A significantly higher Dif-R1R3 was found for AGR and HZH for the experimental group as compared with controls. This Dif-R1R3 was also significantly higher for CC at T8 level, CH at T7 level and PZH at both levels. No significant changes for the Dif-R1R3 were observed in the adjacent vertebrae (T11-T12).

CONCLUSIONS

This study confirmed the local growth modulation capacity of the intra-vertebral staple, translated at the histomorphometric level by a significant reduction in all parameters, but not in all spinal levels. Further analyses are needed to confirm the regional effect, especially for the intervertebral disc and other connective tissues.

Critical role of microbiota within cecal crypts on the regenerative capacity of the intestinal epithelium following surgical stress

Cecal crypts represent a unique niche that are normally occupied by the commensal microbiota. Due to their density and close proximity to stem cells, microbiota within cecal crypts may modulate epithelial regeneration. Here we demonstrate that surgical stress, a process that invariably involves a short period of starvation, antibiotic exposure, and tissue injury, results in cecal crypt evacuation of their microbiota. Crypts devoid of their microbiota display pathophysiological features characterized by abnormal stem cell activation as judged by leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) staining, expansion of the proliferative zone toward the tips of the crypts, and an increase in apoptosis. In addition, crypts devoid of their microbiota display loss of their regenerative capacity as assessed by their ability to form organoids ex vivo. When a four-member human pathogen community isolated from the stool of a critically ill patient is introduced into the cecum of mice with empty crypts, crypts become occupied by the pathogens and further disruption of crypt homeostasis is observed. Fecal microbiota transplantation restores the cecal crypts' microbiota, normalizes homeostasis within crypts, and reestablishes crypt regenerative capacity. Taken together, these findings define an emerging role for the microbiota within cecal crypts to maintain epithelial cell homeostasis in a manner that may enhance recovery in response to the physiological stress imposed by the process of surgery.

NEW & NOTEWORTHY

This study provides novel insight into the process by which surgical injury places the intestinal epithelium at risk for colonization by pathogenic microbes and impairment of its regenerative capacity via loss of its microbiota. We show that fecal transplant restores crypt homeostasis in association with repopulation of the microbiota within cecal crypts.

CD24 can be used to isolate Lgr5+ putative colonic epithelial stem cells in mice

A growing body of evidence has implicated CD24, a cell-surface protein, as a marker of colorectal cancer stem cells and target for antitumor therapy, although its presence in normal colonic epithelium has not been fully characterized. Previously, our group showed that CD24-based cell sorting can be used to isolate a fraction of murine small intestinal epithelial cells enriched in actively cycling stem cells. Similarly, we hypothesized that CD24-based isolation of colonic epithelial cells would generate a fraction enriched in actively cycling colonic epithelial stem cells (CESCs). Immunohistochemistry performed on mouse colonic tissue showed CD24 expression in the bottom half of proximal colon crypts and the crypt base in the distal colon. This pattern of distribution was similar to enhanced green fluorescent protein (EGFP) expression in Lgr5-EGFP mice. Areas expressing CD24 contained actively proliferating cells as determined by ethynyl deoxyuridine (EdU) incorporation, with a distinct difference between the proximal colon, where EdU-labeled cells were most frequent in the midcrypt, and the distal colon, where they were primarily at the crypt base. Flow cytometric analyses of single epithelial cells, identified by epithelial cell adhesion molecule (EpCAM) positivity, from mouse colon revealed an actively cycling CD24(+) fraction that contained the majority of Lgr5-EGFP(+) putative CESCs. Transcript analysis by quantitative RT-PCR confirmed enrichment of active CESC markers [leucine-rich-repeat-containing G protein-coupled receptor 5 (Lgr5), ephrin type B receptor 2 (EphB2), and CD166] in the CD24(+)EpCAM(+) fraction but also showed enrichment of quiescent CESC markers [leucine-rich repeats and immunoglobin domains (Lrig), doublecortin and calmodulin kinase-like 1 (DCAMKL-1), and murine telomerase reverse transcriptase (mTert)]. We conclude that CD24-based sorting in wild-type mice isolates a colonic epithelial fraction highly enriched in actively cycling and quiescent putative CESCs. Furthermore, the presence of CD24 expression in normal colonic epithelium may have important implications for the use of anti-CD24-based colorectal cancer therapies.

Alterations in the growth plate associated with growth modulation by sustained compression or distraction

Sustained mechanical load is known to modulate endochondral growth in the immature skeleton, but it is not known what causes this mechanical sensitivity. This study aimed to quantify alterations in parameters of growth plate performance associated with mechanically altered growth rate. Vertebral and proximal tibial growth plates of immature rats and cattle, and rabbit (proximal tibia only) were subjected to different magnitudes of sustained loading, which altered growth rates by up to 53%. The numbers of proliferative chondrocytes, their rate of proliferation, and the amount of chondrocytic enlargement occurring in the hypertrophic zone were quantified. It was found that reduced growth rate with compression and increased growth rate with distraction were associated with corresponding changes in the number of proliferative chondrocytes per unit width of growth plate, and in the final (maximum) chondrocytic height in the hypertrophic zone (overall correlation coefficients 0.38 and 0.56 respectively). According to multiple linear regression coefficients for these two variables (0.72 and 1.39 respectively), chondrocytic enlargement made a greater contribution to altered growth rates.

Autoradiographic and immunohistochemical study on the proliferative kinetics of intestinal metaplasia

In order to elucidate the proliferative behavior of the intestinal metaplasia around gastric cancer, the authors used both in vitro tritiated thymidine (3H-thymidine) autoradiography and in vivo bromodeoxyuridine (BrdUrd) immunohistochemistry for labeling the proliferative cells of the normal pyloric glands and metaplastic gastric glands. The results of the methods were comparable: The labeling pattern and the rate of labeling were very similar. In the normal pyloric mucosa, the labeled cells were confined to the isthmus region, indicating that pyloric glandular cells are normally renewed from the isthmus region. On the other hand, a zone of the labeled cells was found in the lower half of the intestinalized mucosa, indicating that cell proliferation took place deep in the mucosa, just like the case of normal intestinal glands. The labeling indices of the pyloric mucosa were 19.4% by autoradiography and 18.0% by immunohistochemistry, and that of the intestinalized gastric glands were 25.2% by autoradiography and 24.2% by immunohistochemistry. In conclusion, both 3H-thymidine autoradiography and BrdUrd immunohistochemistry showed that the proliferative kinetics of the intestinalized gastric glands was similar to that of the normal intestinal glands rather than the pyloric glands, i.e. a lower level of proliferative zone and higher labeling index were present.