Intestinal epithelial barrier integrity investigated by label-free techniques in ulcerative colitis patients

The intestinal epithelial barrier, among other compartments such as the mucosal immune system, contributes to the maintenance of intestinal homeostasis. Therefore, any disturbance within the epithelial layer could lead to intestinal permeability and promote mucosal inflammation. Considering that disintegration of the intestinal epithelial barrier is a key element in the etiology of ulcerative colitis, further assessment of barrier integrity could contribute to a better understanding of the role of epithelial barrier defects in ulcerative colitis (UC), one major form of chronic inflammatory bowel disease. Herein, we employ fast, non-destructive, and label-free non-linear methods, namely coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG), two-photon excited fluorescence (TPEF), and two-photon fluorescence lifetime imaging (2P-FLIM), to assess the morpho-chemical contributions leading to the dysfunction of the epithelial barrier. For the first time, the formation of epithelial barrier gaps was directly visualized, without sophisticated data analysis procedures, by the 3D analysis of the colonic mucosa from severely inflamed UC patients. The results were compared with histopathological and immunofluorescence images and validated using transmission electron microscopy (TEM) to indicate structural alterations of the apical junction complex as the underlying cause for the formation of the epithelial barrier gaps. Our findings suggest the potential advantage of non-linear multimodal imaging is to give precise, detailed, and direct visualization of the epithelial barrier in the gastrointestinal tract, which can be combined with a fiber probe for future endomicroscopy measurements during real-time in vivo imaging

Liposomal prednisolone inhibits tumor growth in a spontaneous mouse mammary carcinoma model

Cancers are abundantly infiltrated by inflammatory cells that are modulated by tumor cells to secrete mediators fostering tumor cell survival and proliferation. Therefore, agents that interfere with inflammatory signaling molecules or specific immune cell populations have been investigated as anticancer drugs. Corticosteroids are highly potent anti-inflammatory drugs, whose activity is intensified when targeted by nanocarrier systems. Liposome-targeted corticosteroids have been shown to inhibit tumor growth in different syngeneic murine tumor models as well as human xenograft mouse models, which is attributed to a switch in the tumor microenvironment from a pro-inflammatory to an anti-inflammatory state. Despite the recognized value of implantation tumor models in preclinical research, the “acute” inflammation induced by inoculation of tumor cells together with the exponential tumor growth in a relatively short period of time does not resemble slow progressive human disease that develops in situ. Therefore, in this study, the antitumor effect of liposomal corticosteroids was investigated in a clinically more relevant setting of transgenic mice developing spontaneous breast carcinomas. Here we show that liposomal prednisolone phosphate inhibits the growth of spontaneous breast carcinoma. Interestingly, the liposomal prednisolone was significantly more active than free drug. At 72 h after injection of the liposomal formulation, 3 μg prednisolone per gram of tumor tissue was recovered whereas no drug could be recovered after injection of the free agent. This indicates that, despite etiological and morphological differences between implanted and spontaneous tumor models, EPR-mediated accumulation of drug occurs to similar extent in this spontaneous mammary carcinoma model as in the syngeneic tumor models. Finally, we analyzed miRNA profiles in the MMTV/neu model and showed that the top 10 of miRNAs in the MMTV/neu tumor consisted of miRNAs with a known involvement in breast carcinoma proliferation and metastasis. The only exception was the appearance of miR-146b, a known inflammation-regulating miRNA species, after liposomal prednisolone treatment