Characterization of the long-term effects of lethal total body irradiation followed by bone marrow transplantation on the brain of C57BL/6 mice.

PURPOSE: Total body irradiation (TBI) followed by bone marrow transplantation (BMT) is used in pre-clinical research to generate mouse chimeras that allow to study the function of a protein specifically on immune cells. Adverse consequences of irradiation on the juvenile body and brain are well described and include general fatigue, neuroinflammation, neurodegeneration and cognitive impairment. Yet, the long-term consequences of TBI/BMT performed on healthy adult mice have been poorly investigated. MATERIAL AND METHODS: We developed a robust protocol to achieve near complete bone marrow replacement in mice using 2x550cGy TBI and evaluated the impact of the procedure on their general health, mood disturbances, memory, brain atrophy, neurogenesis, neuroinflammation and blood-brain barrier (BBB) permeability 2 and/or 16 months post-BMT. RESULTS: We found a persistent decrease in weight along with long-term impact on locomotion after TBI and BMT. Although the TBI/BMT procedure did not lead to anxiety- or depressive-like behavior 2- or 16-months post-BMT, long-term spatial memory of the irradiated mice was impaired. We also observed radiation-induced impaired neurogenesis and cortical microglia activation 2 months post-BMT. Moreover, higher levels of hippocampal IgG in aged BMT mice suggest an enhanced age-related increase in BBB permeability that could potentially contribute to the observed memory deficit. CONCLUSIONS: Overall health of the mice did not seem to be majorly impacted by TBI followed by BMT during adulthood. Yet, TBI-induced alterations in the brain and behavior could lead to erroneous conclusions on the function of a protein on immune cells when comparing mouse chimeras with different genetic backgrounds that might display altered susceptibility to radiation-induced damage. Ultimately, the BMT model we here present could also be used to study the related long-term consequences of TBI and BMT seen in patients.

Multimerin-2 is a ligand for group 14 family C-type lectins CLEC14A, CD93 and CD248 spanning the endothelial pericyte interface.

The C-type lectin domain containing group 14 family members CLEC14A and CD93 are proteins expressed by endothelium and are implicated in tumour angiogenesis. CD248 (alternatively known as endosialin or tumour endothelial marker-1) is also a member of this family and is expressed by tumour-associated fibroblasts and pericytes. Multimerin-2 (MMRN2) is a unique endothelial specific extracellular matrix protein that has been implicated in angiogenesis and tumour progression. We show that the group 14 C-type lectins CLEC14A, CD93 and CD248 directly bind to MMRN2 and only thrombomodulin of the family does not. Binding to MMRN2 is dependent on a predicted long-loop region in the C-type lectin domain and is abrogated by mutation within the domain. CLEC14A and CD93 bind to the same non-glycosylated coiled-coil region of MMRN2, but the binding of CD248 occurs on a distinct non-competing region. CLEC14A and CD248 can bind MMRN2 simultaneously and this occurs at the interface between endothelium and pericytes in human pancreatic cancer. A recombinant peptide of MMRN2 spanning the CLEC14A and CD93 binding region blocks CLEC14A extracellular domain binding to the endothelial cell surface as well as increasing adherence of human umbilical vein endothelial cells to the active peptide. This MMRN2 peptide is anti-angiogenic in vitro and reduces tumour growth in mouse models. These findings identify novel protein interactions involving CLEC14A, CD93 and CD248 with MMRN2 as targetable components of vessel formation.

Type IV hypersensitivity in the pathogenesis of FIPV-induced lesions.

In focal lesions of feline infectious peritonitis (FIP), the cells involved in the delayed-type hypersensitivity were identified in formalin-fixed paraffin-embedded and frozen samples taken from 35 affected cats. The clinical diagnosis of FIP was confirmed by necropsy, histology and direct immunofluorescence against the coronaviruses on cryostatic sections. The immune cells were detected immunohistochemically by the Avidin-Biotin-Complex (ABC) method using either polyclonal antibodies against lymphoid antigens (CD3) or monoclonal antibodies against lymphoid (PAN-T, CD4, CD8) and myeloid antigens (MAC387). Better identification of T cells and macrophages was found on formalin-fixed paraffin-embedded sections than on cryostatic ones, while T lymphocyte subpopulations could be differentiated only in cryostatic sections. Type IV hypersensitivity was detected in focal feline infectious peritonitis virus (FIPV)-induced lesions from progressive activation of T lymphocytes, mainly CD4+, and the presence of granulocytes and macrophages. The FIPV-induced lesions could be studied as examples of granulomas caused by unconventional antigens, such as viruses or immune complexes.

Clinical and immunological effects of immunotherapy with alum-absorbed grass allergoid in grass-pollen-induced hay fever.

A double-blind, placebo-controlled study of immunotherapy was conducted in 19 patients with grass-pollen hay fever to evaluate the efficacy and safety of a formalinized depot grass allergoid. The patients were assessed before and during IT by clinical (symptom-medication scores during the grass- pollen season, specific nasal and skin reactivity) and immunological (specific IgE, IgG, IgG1 and IgG4 antibodies) parameters. High doses of grass allergoid, corresponding to a cumulative pre-seasonal dosage of 46,050 PNU, were administered, with only one systemic reaction. The actively treated patients had significantly lower symptom-medication scores than placebo (p less than 0.01) during the month of May and showed a significant decrease in specific skin (p less than 0.01) and nasal (p less than 0.05) reactivity, and a significant early increase in specific IgE (p less than 0.01), IgG (p less than 0.0005), IgG1 (p less than 0.001) and IgG4 (p less than 0.05), with a subsequent decrease of IgE and IgG1. No differences were detected in any of these parameters in the placebo group. A correlation was found between high IgG4/IgG1 ratio and the specific skin reactivity decrease (r = 0.691, p less than 0.05), whereas a high IgG4/IgG1 ratio was associated with higher symptom-medication scores (r = 0.654, p less than 0.05). Possible explanations of these apparent discrepancies are proposed.