Selective loss of GABAB receptors in orexin/hypocretin-producing neurons results in disrupted sleep/wakefulness architecture

We generated mice with a selective loss of GABAB receptors in orexin neurons. Orexin neurons in these GABAB1<sup>-/-(orexin)</sup> mice showed reduced responsiveness to GABA<sub>A</sub> receptor agonists due to a compensatory increase in GABAA receptor-mediated inhibition. This increased GABA<sub>A</sub> receptor-mediated inhibition of orexin neurons is due to orexin-1 receptor-mediated activation of local GABAergic interneurons. Surprisingly, orexin neurons were also less responsive to glutamate, apparently because the augmented GABA<sub>A</sub> receptor-mediated inhibition increases the membrane conductance and shunts excitatory currents. These observations indicate that absence of GABA<sub>B</sub> receptors decreases the sensitivity of orexin neurons to both excitatory and inhibitory inputs. GABAB1<sup>-/-(orexin)</sup>mice exhibited severe fragmentation of sleep/wake states during both the light and dark periods without affecting total sleep time or inducing cataplexy, indicating that GABA<sub>B</sub> receptors are crucial regulators of orexin neurons and that "fine tuning" of orexin neurons by inhibitory and excitatory inputs is important for the stability of sleep/waking states

Reduced Inflammatory Threshold Indicates Skin Barrier Defect in Transglutaminase 3 Knockout Mice

Recently a transglutaminase 3 knockout (TGM3/KO) mouse was generated that showed impaired hair development, but no gross defects in the epidermal barrier, although increased fragility of isolated corneocytes was demonstrated. Here we investigated the functionality of skin barrier in vivo by percutaneous sensitization to fluorescein-isothiocyanate (FITC) in TGM3/KO (n=64) and C57BL/6 WT mice (n=36). Cutaneous inflammation was evaluated by mouse ear swelling test (MEST), histology, serum IgE levels, and by flow-cytometry from draining lymph nodes. Inflammation induced significant MEST difference (P<0.0001) was detected between KO and WT mice and was supported also by histopathology. A significant increase of CD4+ CD25+ activated T-cells (P<0.01) and elevated serum IgE levels (P<0.05) in KO mice indicated more the development of FITC sensibilization than an irritative reaction. P. acnes induced intracutaneous inflammation showed no difference (P=0.2254) between the reactivity of WT and KO immune system. As in vivo tracer, FITC penetration from skin surface followed by two-photon microscopy demonstrated a more invasive percutaneous penetration in KO mice. The clinically uninvolved skin in TGM3/KO mice showed impaired barrier function and higher susceptibility to FITC sensitization indicating that TGM3 has a significant contribution to the functionally intact cutaneous barrier.Journal of Investigative Dermatology accepted article preview online, 24 July 2013. doi:10.1038/jid.2013.307

Epidermal Transglutaminase (TGase 3) Is Required for Proper Hair Development, but Not the Formation of the Epidermal Barrier

Transglutaminases (TGase), a family of cross-linking enzymes present in most cell types, are important in events as diverse as cell-signaling and matrix stabilization. Transglutaminase 1 is crucial in developing the epidermal barrier, however the skin also contains other family members, in particular TGase 3. This isoform is highly expressed in the cornified layer, where it is believed to stabilize the epidermis and its reduction is implicated in psoriasis. To understand the importance of TGase 3 in vivo we have generated and analyzed mice lacking this protein. Surprisingly, these animals display no obvious defect in skin development, no overt changes in barrier function or ability to heal wounds. In contrast, hair lacking TGase 3 is thinner, has major alterations in the cuticle cells and hair protein cross-linking is markedly decreased. Apparently, while TGase 3 is of unique functional importance in hair, in the epidermis loss of TGase 3 can be compensated for by other family members

Pitfall in the Surgical Management of a Shrunken Skin Defect after Neoadjuvant Chemotherapy for Locally Advanced Breast Cancer

A 53-year-old woman with a large, easy-bleeding, and ulcerated breast tumor visited our hospital due to severe anemia. Transfusion and Mohs’ chemosurgery gave the patient marked improvement of her local and general condition. After confirming the human epidermal growth factor receptor type 2 (HER2)-positive breast cancer with no distant metastasis, anti-HER2 agents-containing chemotherapy brought about clinical complete response of the locally advanced breast cancer with a shrunken but still large skin defect. We, therefore, treated the patient with mastectomy and axillary node dissection but failed to directly close the skin even after full skin undermining. We then tried to cover the skin defect using a latissimus dorsi flap, that is, horizontal spindle skin 12 × 6 cm in size, but again failed to fully cover the skin defect. We finally and ostensibly covered the skin defect through an additional skin incision to the recipient skin, but could not get complete wound healing. Pathological study showed a marked collagen fiber around the skin defect and faint viable cancer cells beneath the nipple. The patient required 3 months of wound management for complete wound healing, leading to the application of anti-HER2 agents without anticancer agent to the patient during that time as an adjuvant therapy. Regrowth of her hair once lost by the neoadjuvant chemotherapy (NAC) made the patient refuse the adjuvant anthracycline-containing chemotherapy after wound healing. The patient, therefore, received trastuzumab-emtansine for a year and has been well for 17 months postoperatively. Breast surgeons should note that a skin defect after favorable response to NAC is often surrounded by less stretchable skin due to chemotherapy-induced massive collagen fiber and requires careful preoperative planning for skin closure