The expression of mRNA for calcitonin receptor-like receptor/receptor-activity modifying proteins in rat peritoneal mast cells

Role of neuropeptides in skin inflammation and its involvement in diabetic wound healing

IMPORTANCE OF THE FIELD

In 2010, the world prevalence of diabetes is 6.4%, affecting 285 million adults. Diabetic patients are at risk of developing neuropathy and delayed wound healing that can culminate in incurable diabetic foot ulcerations (DFUs) or even foot amputation.

AREAS COVERED IN THIS REVIEW

The contrast between cellular and molecular events of wound healing and diabetic wound healing processes is characterized. Neuropeptides released from the autonomous nervous system and skin cells reveal a major role in the immunity of wound healing. Therefore, the signaling pathways that induce pro/anti-inflammatory cytokines expression and its involvement in diabetic wound healing are discussed. The involvement of neuropeptides in the activation, growth, migration and maturation of skin cells, like keratinocytes, Langerhans cells, macrophages and mast cells, are described.

WHAT THE READER WILL GAIN

This review attempts to address the role of neuropeptides in skin inflammation, focusing on signal transduction, inflammatory mediators and pro/anti-inflammatory function, occurring in each cell type, as well as, its connection with diabetic wound healing.

TAKE HOME MESSAGE

Understanding the role of neuropeptides in the skin, their application on skin wounds could be a potential therapy for skin pathologies, like the problematic and prevalent DFUs.

Ghrelin and obestatin promote the allergic action in rat peritoneal mast cells as basic secretagogues

Ghrelin is an endogenous ligand of the type 1a growth hormone secretagogue receptor (GHSR1a) that regulates energy balance. Ghrelin and obestatin, derived from the post-translational processing of preproghrelin, are involved in a diverse range of biological activities, yet their effect on the immune system is not fully understood. In the present study, we investigated the roles of ghrelin and obestatin on mast cell degranulation and found that both ghrelin and obestatin induce the release of histamine from rat peritoneal mast cells. This induced histamine release was inhibited by the pertussis toxin, an inhibitor of Gα(i) protein, and extracellular Ca(2+). Rat peritoneal mast cells and rat basophilic leukemia (RBL-2H3) cells did not express the ghrelin receptor GHSR1a, suggesting that histamine release induced by ghrelin occurs via a receptor-independent mechanism. We report here that ghrelin and obestatin, belonging to the family of basic secretagogues, stimulate mast cells independent of a receptor, and this may play a crucial role at the site of allergy or inflammation.

Colonic vascular conductance increased by Daikenchuto via calcitonin gene-related peptide and receptor-activity modifying protein 1

BACKGROUND

Daikencyuto (DKT) is a traditional Japanese medicine (Kampo) and is a mixture of extract powders from dried Japanese pepper, processed ginger, ginseng radix, and maltose powder and has been used as the treatment of paralytic ileus. DKT may increase gastrointestinal motility by an up-regulation of the calcitonin gene-related peptide (CGRP). CGRP is also the most powerful vasoactive substance. In the present study, we investigated whether DKT has any effect on the colonic blood flow in rats.

MATERIALS AND METHODS

Experiments were performed on fasted anesthetized and artificially ventilated Wistar rats. Systemic mean arterial blood pressure and heart rate were recorded. Red blood cell flux in colonic blood flow was measured using noncontact laser tissue blood flowmetry, and colonic vascular conductance (CVC) was calculated as the ratio of flux to mean arterial blood pressure. We examined four key physiological mechanisms underlying the response using blocker drugs: CGRP1 receptor blocker (CGRP(8-37)), nitric oxide synthase inhibitor, vasoactive intestinal polypeptide (VIP) receptor blocker ([4-Cl-DPhe6, Leu17]-VIP), and substance P receptor blocker (spantide). Reverse transcription-polymerase chain reaction was used for the detection of mRNA of calcitonin receptor-like receptor, receptor-activity modifying protein 1, the component of CGRP 1 receptor and CGRP. After laparotomy, a cannula was inserted into the proximal colon to administer the DKT and to measure CVC at the distal colon.

RESULTS

Intracolonal administration of DKT (10, 100, and 300 mg/kg) increased CVC (basal CVC, 0.10 mL/mmHg) from the first 15-min observation period (0.14, 0.17, and 0.17 mL/mmHg, respectively) and with peak response at either 45 min (0.17 mL/mmHg by 10 mg/kg), or 75 and 60 min (0.23 and 0.21 mL/mmHg by 100 and 300 mg/kg, respectively). CGRP(8-37) completely abolished the DKT-induced hyperemia, whereas nitric oxide synthase inhibitor partially attenuated the DKT-induced hyperemia. [4-Cl-DPhe6, Leu17]-VIP and spantide did not affect the hyperemia. Japanese pepper significantly increased CVC at 45 min or later, whereas ginseng radix only showed a significant increase at 15 min. Reverse transcription-polymerase chain reaction showed that mRNA for calcitonin receptor-like receptor, receptor-activity modifying protein 1, and CGRP were expressed in rat colon and up-regulated by DKT.

CONCLUSIONS

The present study demonstrated that DKT increased CVC, which was mainly mediated by CGRP and its receptor components.

Adrenomedullin is a cross-talk molecule that regulates tumor and mast cell function during human carcinogenesis

We have previously demonstrated that adrenomedullin (AM) plays a critical role as an autocrine/paracrine tumor cell survival factor. We now present evidence that AM is an important regulator of mast cell (MC) function and that this modulation is potentially involved in tumor promotion. AM induced histamine or beta-hexosaminidase release from rat and human MCs through a receptor-independent pathway. AM was chemotactic for human MCs and stimulated mRNA expression of vascular endothelial growth factor, monocyte chemoattractant protein-1, and basic fibroblast growth factor in this cell type. Differentiated but not undifferentiated human MCs responded to hypoxic insult with elevated AM mRNA/protein expression. Using confocal microscopy, we identified AM-producing MCs in tumor infiltrates of human breast and lung cancer patients. In mixed culture assays the AM-producing human MC line HMC-1 augmented both anchorage-dependent and -independent growth of human lung cancer A549 cells, an effect that was suppressed by MC-targeted siRNA AM knockdown. Finally, HMC-1 cells induced in vivo angiogenesis as assessed by directed in vivo angiogenesis assay analysis; neutralizing anti-AM monoclonal antibody blocked this ability. Our collective data suggest a new role for AM as a cross-talk molecule that integrates tumor and MC communication, underlying a unique promotion mechanism of human cancers.

The expression of mRNA for calcitonin gene-related peptide receptors in a mucosal type mast cell line, RBL-2H3

Calcitonin gene-related peptide (CGRP) and adrenomedullin (ADM) belong to a calcitonin-family of regulatory peptides. Receptors for CGRP and ADM have been suggested to be present on both mucosal (MMC) and connective tissue (CTMC) type of mast cells, based on histamine release by these peptides. Recently, it was reported that mRNA for ADM receptors, but not for CGRP receptors, was expressed in rat peritoneal mast cells, a representative of type CTMC. However, mRNA expression for the receptors in MMC has not been studied yet. Therefore, we examined whether mRNAs encoding CGRP or ADM receptor subunit, RDC-1, calcitonin receptor-like receptor (CRLR), and receptor activity-modifying proteins (RAMPs) are present, and if so, whether their expression is modified by IgE receptor triggering, in a mucosal type mast cell line, rat basophilic leukemia (RBL-2H3) cells using RT-PCR. RBL-2H3 cells constitutively express mRNA for RDC-1, CRLR, RAMP3 but not that for RAMP1 and RAMP2, and IgE receptor triggering was shown neither to induce the gene expression of RAMP1 and RAMP2, nor to enhance that of RDC-1, CRLR or RAMP3. These results indicate that RBL-2H3 cells posses receptors for both CGRP and ADM, suggesting various functions of these peptides in physiological and pathophysiological conditions where mast cells of the mucosal type are involved.