Knocking out matrix metalloproteinase 12 causes the accumulation of M2 macrophages in intestinal tumor microenvironment of mice.

MMP12 is mainly secreted by macrophages, is involved in macrophage development, and decomposes the extracellular matrix. Herein, we investigated whether macrophages would change in the intestinal tumor microenvironment after MMP12 knockout. ApcMin/+;MMP12-/-mice were obtained by crossbreeding ApcMin/+ mice with MMP12 knockout mice (MMP12-/- mice). The data showed that the number and volume of intestinal tumors were significantly increased in ApcMin/+;MMP12-/- mice compared with ApcMin/+ mice. Additionally, the tumor biomarkers CA19-9, CEA, and ß-catenin appeared relatively early in intestinal tumors in ApcMin/+;MMP12-/- mice. The results demonstrated that knocking out MMP12 accelerated the tumor growth and pathological process. On further investigation of its mechanism, the proportions of M2 macrophages in the spleen and among peritoneal macrophages were significantly up-regulated in ApcMin/+;MMP12-/- mice. Expression of M2 macrophage-related genes was up-regulated in tumor and peritoneal macrophages. The M2-related cytokine levels of IL-4 and IL-13 were increased in the serum of ApcMin/+;MMP12-/-mice. In vitro, bone marrow-derived M2 macrophages were obtained by treating bone marrow cells with IL-4 and IL-13, and these M2 macrophages secreted cytokines being changed. This finding reveals the crucial role of MMP12 in macrophage development and provides a new target for the control of macrophage polarization. Knocking out MMP12 causes intestinal M2 macrophage accumulation in tumor microenvironment, promoting the growth of intestinal tumors in ApcMin/+ mice.

A Novel Rabbit Dry Eye Model Induced by a Controlled Drying System.

Purpose: To establish an environment-induced dry eye model in rabbits using a controlled drying system (CDS). Methods: Rabbits were randomly divided into two groups. The rabbits in the dry group were housed in the CDS, in which the relative humidity, airflow, and temperature were controlled at 22% ± 4%, 3 to 4 m/s, and 23°C to 25°C for 14 days. The rabbits in the control group were housed in a normal environment at the same time. A Schirmer test, fluorescein staining, and lissamine green staining were performed. On day 14, the eyeballs and lacrimal glands were processed for evaluating the corneal epithelial thickness, inflammatory cell infiltration index, goblet cell density, and expression of the MUC5AC protein and caspase-3 protein. The mRNA expression of the involved inflammatory genes was analyzed. Results: The CDS was able to maintain a dry environment, in which the tear production decreased, and the ocular surface staining increased over time in the rabbits. In the dry group, the corneal epithelium became thinner, inflammatory cells were noted, goblet cells and MUC5AC proteins decreased, and the increased levels of caspase-3 proteins and inflammatory cytokines were observed in the ocular surface tissues and lacrimal glands. Conclusions: This CDS could create a dry environment, in which the rabbits exhibited a pathological change in dry eye similar to that in humans. Translational Relevance: This model would be helpful in offering a platform to identify and test candidate therapies for environment-induced dry eye and to explore its underlying mechanisms.

Gastric precancerous lesions present in ApcMin/+ mice.

The ApcMin/+ mouse is an animal model for familial adenomatous polyposis, and aged ApcMin/+ mice also spontaneously develop multiple tumors in their stomachs. However, gastric premalignant lesions in ApcMin/+ mice have not been well characterized. The stomachs of ApcMin/+ mice were compared with those of their wild type littermates at 24 weeks with hematoxylin and eosin (H&E) staining and alcian blue staining. Ki67, CD68 and CA199 expression was analyzed by immunohistochemistry. The results revealed the presence of epithelial proliferation and inflammatory infiltration in the forestomachs, glandular atrophy and intestinal metaplasia in the gastric bodies, and dysplasia in the gastric antra. The effect of mutations in the Apc gene on chronic gastritis and gastric precancerous lesions was characterized in ApcMin/+ mice. These results suggest that ApcMin/+ mice represent a genetic model for mechanistic studies and drug discovery in gastric precancerous lesions.

Trp53 regulates platelets in bone marrow via the PI3K pathway.

The p53 gene is well known as a key tumor suppressor gene; it is vital for hematopoietic stem cell differentiation and growth. In the present study, the change of platelets (PLTs) in p53 knockout mice (p53-/- mice) was investigated. The peripheral blood cell subsets and PLT parameters in p53-/-mice were compared with those in age-matched p53+/+ mice. Bleeding time as well as the alteration of PLT levels, were analyzed with the PLT marker CD41 antibody using flow cytometry. The results revealed that the number of PLTs in p53-/- mice was significantly lower than that in p53+/+ mice. Bleeding time was prolonged in the peripheral blood of p53-/- mice compared with that of p53+/+ mice. Furthermore, the related gene expression of the PI3K signaling pathway in the bone marrow of p53-/- mice was shown to be associated with plateletogenesis. PI3K inhibitor (LY294002) was also used to treat p53-/- mice, and the results demonstrated that LY294002 revert the change of PLTs in these mice. In summary, PLTs were altered in p53-/- mice, and the PI3K signaling pathway was involved in that process, suggesting that the p53-dependent PI3K signaling pathway is involved in thrombocytopenia or PLT diseases. PLT number is reduced in p53 deficiency; however, this reduction could be reverted by inhibiting the PI3K pathway.