Isabelle Rottiers

Human mast cells express leptin and leptin receptors

Mast cells are immune cells that produce and secrete a variety of mediators and cytokines that influence various inflammatory and immune processes. Leptin is a cytokine regulating metabolic, endocrine as well as immune functions via the leptin receptor which is expressed by many immune cells. However, there are no data about leptin receptor expression in mast cells. Immunohistochemical and immunofluorescent double stainings showed the expression of leptin and leptin receptors in mast cells in human skin and several parts of the respiratory, gastrointestinal and urogenital tract. Leptin was expressed in mast cells expressing the classification marker chymase, whereas a variable expression was observed in tryptase positive mast cells. For leptin receptors, the expression pattern was tissue dependent and not related to tryptase or chymase expression. Our results demonstrate the expression of leptin and leptin receptors on mast cells, suggesting paracrine and/or autocrine immunomodulatory effects of leptin on mast cells.

Xenotransplantation of cryopreserved human ovarian tissue into murine back muscle

BACKGROUND Ovarian tissue (OT) cryopreservation and transplantation are options for fertility preservation in young female cancer patients. METHODS We investigated xenotransplantation of human OT into back muscle (B) of severe combined immunodeficiency mice. OT follicle content was evaluated by stereomicroscopy and pre-transplantation. Xenograft survival, follicular development (with/without FSH administration), apoptosis and vascularization were compared in B- versus K-site (under the kidney capsule) several times after grafting using histology, immunohistochemistry and magnetic resonance imaging. In vitro maturation (IVM) was also performed. RESULTS Anastomoses which developed from existing human and invading murine vessels were seen in OT at both sites, but angiogenesis was more prominent at the B- than K-site (P < 0.001). Vascularization and follicle size were correlated in the B-group (Spearmans coefficient 0.73; P < 0.001). FSH increased early (8 days) micro-vessel formation in B but not in K grafts (P < 0.0001, versus no FSH). B-site grafts showed a better histological morphology and survival (P = 0.0084), formation of larger antral follicles (P = 0.005), more metaphase-II (MII) oocytes, growing follicles (P = 0.028) and slightly fewer apoptotic follicles than K grafts. One MI oocyte from B underwent IVM and reached MII stage next day. CONCLUSIONS To our knowledge, this is the first report of MII and IVM-MII oocytes obtained from B xenografts. We report the largest oval-shaped antral follicles containing an MII oocyte obtained after OT xenotransplantation to date. Xenografting in the mouse B should be further explored as a method for human OT transplantation.

Inflamed intestinal mucosa features a specific epithelial expression pattern of indoleamine 2,3-dioxygenase.

Indoleamine 2,3-dioxygenase (IDO) catalyzes the first step in the degradation of tryptophan, an essential amino acid. During inflammation IDO can be induced in different cell types resulting in local tryptophan depletion. This inhibits T cell proliferation and may induce apoptosis. High expression of IDO was previously found in inflammatory bowel disease and is thought to represent a mechanism for downregulation of the local immune response. Our aim is to investigate the expression pattern of IDO in normal and inflamed murine and human intestinal mucosa. Immunohistochemical staining for IDO was performed on paraffin sections of colon of two mouse models for colitis and their controls and on paraffin sections of human ileum and colon in normal and two different inflammatory conditions, namely inflammatory bowel disease and diverticulitis. IDO immunohistochemistry showed similar results in murine and human tissue. In normal, as well as in inflamed mucosa, some mononuclear cells, fibroblasts and endothelial cells were positive for IDO. In inflamed mucosa a specific expression pattern of epithelial IDO was found where epithelial cells flanking ulcers or bordering crypt abscesses showed high IDO expression. Moreover, in human intestinal inflammation, IDO was expressed in ulcer associated cell lineage. Since bacterial invasion is more pronounced in erosions and in crypt abscesses and since IDO activity and the resulting local tryptophan depletion can cause growth arrest of several tryptophan-dependent microorganisms, IDO expression in the vicinity of interruptions of the epithelial barrier may point to a role for IDO as a local anti-infectious agent. Furthermore, expression of IDO at the margin of ulcerations and in the reparative ulcer-associated cell lineage suggests involvement of IDO in repair processes.

Distinguishing score 0 from score 1+ in HER2 immunohistochemistry-negative breast cancer: clinical and pathobiological relevance

OBJECTIVES To investigate the clinical and pathobiological significance of distinguishing score 0 and score 1+ within the group of immunohistochemistry (IHC)-negative invasive breast cancers. METHODS We studied HER2 status using both IHC and fluorescence in situ hybridization (FISH) in 150 consecutive breast tumors submitted to our laboratory after a negative IHC result in local testing centers. RESULTS We were able to discern a group of score 0 tumors that had a lower HER2 copy number than the group consisting of score 1+ tumors. In contrast with the group of score 1+ tumors, HER2 FISH was consistently negative for both copy number-based and ratio-based tumors without equivocal results. CONCLUSIONS In a setting with stringent quality assurance, score 0 and score 1+ tumors emerge as distinct and clinically important subgroups within the HER2 IHC-negative population.

Identification of the nasal mucosa as a new target for leptin action

Taildeman J, Demetter P, Rottiers I, Holtappels G, Bachert C, Cuvelier C A & Pérez‐Novo C A
(2010) Histopathology 56, 789–798
Identification of the nasal mucosa as a new target for leptin action