Optical histology based on label-free multiphoton imaging allows quantification of distinct inflammatory patterns in murine colitis

Clinical diagnosis as well as fundamental research of inflammatory bowel diseases (IBD) require reliable quantification of mucosal inflammation. Label-free multiphoton microscopy (MPM) is an advanced optical technology for 3D imaging of native tissues. In contrast to the rather time-consuming workflow of conventional histopathology, MPM does not require additional preparation or staining and therefore can provide information without delay. Compared to confocal laser imaging that is based on contrast agents, multiphoton imaging enables label-free imaging at cellular resolution with increased penetration depth.

We have applied this emerging technology to various murine experimental colitis models.Therefore, five different murine colitis models were tested against healthy control samples. These colitis models included acute and chronic DSS colitis, acute trinitrobenzene sulfonic acid (TNBS) colitis, oxazolone colitis and transfer colitis. Fresh tissue samples were imaged by label-free MPM and a novel multiphoton colitis score (MCS) was used to grade crypt morphology, collagen remodeling, immune infiltration and epithelial deformations. The data were validated by conventional H&E histology of the same samples.

We could show that label-free MPM and its quantification via the MCS can accurately discriminate between healthy and inflamed tissue. Moreover, it was possible to find specific characteristics of each inflammatory phenotype. While the MCS score of in stroma cellularity is increased in TNBS, oxazolone and transfer colitis, chronic DSS, transfer and acute DSS colitis show higher values in epithelial damage. Acute DSS colitis further shows deformation of the crypt shape and size. Upon validation, the total MCS of all categories showed agreement of above 90 % with conventional H&E scoring

In conclusion, we could show that MPM is able to find morphological differences between different colitis models. Label-free images can accurately be quantified by the MCS. Advances in this field are highly relevant for fundamental research on inflammatory pathways. Furthermore, endoscopic implementations of MPM have already been reported and the translation towards label-free in vivo histology in clinical IBD patients seems feasible in the future.

Publication History

Article published online:
07 September 2021