Mechanical Irritation in Vascularized Composite Tissue Allotransplantation Triggers Localized Skin Rejection

BACKGROUND

Mechanical and thermal stress has been observed to trigger skin rejection in hand-transplanted patients. This study aims to investigate this phenomenon.

METHODS

Syngeneic and allogeneic orthotopic hindlimb transplantations were performed using male rats (Brown Norway to Lewis). Using a specially designed device, standardized mechanical skin irritation at a force of 5 N was applied to the planta pedis of the transplanted limb for 10 days, 4 times daily for 10 minutes. Biopsies, taken on day 10 and after a 5-day observational period, were assessed for macroscopic alterations using a standardized scale, by histopathology and immunohistochemistry, and for inflammatory protein expression using Luminex technology.

RESULTS

Allogeneic animals displayed significant aggravated macroscopic skin alterations compared with naive (P < 0.0001) and syngeneic controls (P = 0.0023). Histopathology showed a trend toward higher rejection/inflammation grades in allogeneic animals compared with syngeneic controls. Minor skin alterations in syngeneic limbs recovered quickly; however, in allogeneic limbs, macroscopic skin alterations were significantly more pronounced (P < 0.0001) 5 days after irritation. Interleukin-1b and interferon-γ levels were upregulated in skin of allogeneic limbs.

CONCLUSIONS

Mechanical skin irritation in vascularized composite allotransplantation can trigger localized skin inflammation consistent with rejection.

Protein-retention expansion microscopy of cells and tissues labeled using standard fluorescent proteins and antibodies

Expansion microscopy (ExM) enables imaging of preserved specimens with nanoscale precision on diffraction-limited instead of specialized super-resolution microscopes. ExM works by physically separating fluorescent probes after anchoring them to a swellable gel. The first ExM method did not result in the retention of native proteins in the gel and relied on custom-made reagents that are not widely available. Here we describe protein retention ExM (proExM), a variant of ExM in which proteins are anchored to the swellable gel, allowing the use of conventional fluorescently labeled antibodies and streptavidin, and fluorescent proteins. We validated and demonstrated the utility of proExM for multicolor super-resolution (∼70 nm) imaging of cells and mammalian tissues on conventional microscopes.

Multispectral Imaging

The field of anatomic pathology has changed significantly over the last decades and, as a result of the technological developments in molecular pathology and genetics, has had increasing pressures put on it to become quantitative and to provide more information about protein expression on a cellular level in tissue sections. Multispectral imaging (MSI) has a long history as an advanced imaging modality and has been used for over a decade now in pathology to improve quantitative accuracy, enable the analysis of multicolor immunohistochemistry, and drastically reduce the impact of contrast-robbing tissue autofluorescence common in formalin-fixed, paraffin-embedded tissues. When combined with advanced software for the automated segmentation of different tissue morphologies (eg, tumor vs stroma) and cellular and subcellular segmentation, MSI can enable the per-cell quantitation of many markers simultaneously. This article covers the role that MSI has played in anatomic pathology in the analysis of formalin-fixed, paraffin-embedded tissue sections, discusses the technological aspects of why MSI has been adopted, and provides a review of the literature of the application of MSI in anatomic pathology.

Immunohistochemical localization of T-lymphocyte subsets in the developing lymphoid tissues of the tammar wallaby (Macropus eugenii)

Research into marsupial adaptive immunity during ontogeny has been hampered by the lack of antibodies that react to marsupial immunological cell populations. In this study, newly synthesised polyclonal antibodies to the T cell marker, CD8, have been developed and used to investigate the ontogeny and distribution of this T cell population in the tammar wallaby. Immunohistochemical analysis indicated that the distribution of the CD8 lymphocytes in the lymphoid tissues of tammar neonates during the first 144 days of pouch life was similar to that of the eutherian mammals. However, CD8α(+) lymphocytes were observed in the intestines of tammar neonates prior to their first appearance in the cervical thymus, an observation that has not been found in eutherians. A dual labelling immunohistochemical approach was used for the indirect demonstration of CD4 and enabled the simultaneous detection in the tammar wallaby tissues of the two major T-lymphocyte populations, CD4 and CD8 that are associated with adaptive immunity. As in eutherian mammals, CD4(+) cells were the predominant T cell lymphocyte subset observed in the spleen while in the nodal tissues, an age-related decrease in the CD4(+)/CD8(+) ratio was noted. These antibodies provide a new immunological tool to study the role of T cell subsets in marsupial immunity and disease pathogenesis studies.

Proliferative and nonproliferative lesions of the rat and mouse central and peripheral nervous systems

Harmonization of diagnostic nomenclature used in the pathology analysis of tissues from rodent toxicity studies will enhance the comparability and consistency of data sets from different laboratories worldwide. The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of four major societies of toxicologic pathology to develop a globally recognized nomenclature for proliferative and nonproliferative lesions in rodents. This article recommends standardized terms for classifying changes observed in tissues of the mouse and rat central (CNS) and peripheral (PNS) nervous systems. Sources of material include academic, government, and industrial histopathology databases from around the world. Covered lesions include frequent, spontaneous, and aging-related changes as well as principal toxicant-induced findings. Common artifacts that might be confused with genuine lesions are also illustrated. The neural nomenclature presented in this document is also available electronically on the Internet at the goRENI website (http://www.goreni.org/).