Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting 1% of the population. The aetiology of rheumatoid arthritis is unknown, although there are multiple postulated theories. In 1950, Philip Hench won the Nobel prize for treating patients with rheumatoid arthritis with cortisone. He also treated 6 patients with adrenocorticotropic hormone (ACTH) with good results. ACTH is a melanocortin. The melanocortin system describes the five melanocortin receptors, their ligands, agonists and antagonists and the accessory proteins. The aim of this study was to explore the melanocortin receptors in rheumatoid arthritis synovium. Methods HA-tagged stable cell lines were created for MC1R, MC3R and MC5R. Multiple antibodies were tested for their utility using Western Blot, immunohistochemistry and flow cytometry. Samples of synovium from 28 patients with RA were tested using RTPCR for the presence of MC1R and MC3R. Gene expression was correlated with clinical characteristics, cytokine (RTPCR) expression and immunohistochemical score. Results The stable cell lines expressed MC1R, MC3R and MC5R respectively. Of the antibodies tested none were found to be of utility in detecting MC1R or MC3R .The MC1R RQ values in rheumatoid synovium appear to split into two groups, high and low. The medians of the two groups are significantly different (p=0.0005). There is almost a 5 cycle, or 64 fold, difference in gene expression between the medians of the two groups (1.59 v 6.23). Of note no MC3R positive samples were CD138 high (i.e. no MC3R positive samples had a significant plasma cell infiltrate) (p=0.006). Categorical analysis using Fishers Exact test revealed an association between MC1R high samples and CD68 lining high scores, (i.e. MC1R high samples also had a high macrophage score in the lining of the sample) (p=0.02). MC1R low samples were associated with not being on combination therapy, 15 this did not quite reach significance (p=0.07). Linear regression analysis confirmed these associations for MC1R. PCA analysis did not show any grouping of samples according to any of the variables tested, likely due to sample size. Conclusion MC1R and MC3R are found in human synovium. Current commercial antibodies are not of utility in detecting MC1R or MC3R. Synovial samples can be split into high and low MC1R gene expression groups. MC3R was either present or absent. High expression of MC1R was associated with a high macrophage score and MC3R expression was associated with a low plasma cell score. MC1R and MC3R expression in RA synovium could be used as biomarkers of disease state or severity as well as a target for therapy.

<p>A new approach to analysis of protein-ligand interactions, termed proteochemometrics, has been developed. Contrary to traditional quantitative structure-activity relationship (QSAR) methods that aim to correlate a description of ligands to their interactions with one particular target protein, proteochemometrics considers many targets simultaneously.</p><p>Proteochemometrics thus analyzes the experimentally determined protein-ligand interaction activity data by correlating the data to a complex description of all interaction partners and; in a more general case even to interaction environment and assaying conditions, as well. In this way, a proteochemometric model analyzes an “interaction space,” from which only one cross-section would be contemplated by any one QSAR model.</p><p>Proteochemometric models reveal the physicochemical and structural properties that are essential for protein-ligand complementarity and determine specificity of molecular interactions. From a drug design perspective, models may find use in the design of drugs with improved selectivity and in the design of drugs for multiple targets, such as mutated proteins (e.g., drug resistant mutations of pathogens).</p><p>In this thesis, a general concept for creating of proteochemometric models and approaches for validation and interpretation of models are presented. Different types of physicochemical and structural description of ligands and macromolecules are evaluated; mathematical algorithms for proteochemometric modeling, in particular for analysis of large-scale data sets, are developed. Artificial chimeric proteins constructed according to principles of statistical design are used to derive high-resolution models for small classes of proteins.</p><p>The studies of this thesis use data sets comprising ligand interactions with several families of G protein-coupled receptors. The presented approach is, however, general and can be applied to study molecular recognition mechanisms of any class of drug targets.</p>

Activation of the immune system by e.g. bacteria induces the acute-phase-response and sickness behaviour. The latter encompasses among other things fever, lethargy, anorexia and hyperalgesia. An often used model to study sickness behaviour is the intravenous injection of the gram negative bacterial endotoxin lipopolysaccharide (LPS). LPS induces the production of inflammatory mediators, such as cytokines and prostaglandins, which in turn can interact with the central nervous system (CNS) to affect behaviour. The CNS also memorises substances that have made us sick in the past to avoid future harm, a phenomenon called conditioned taste aversion (CTA). An often used model to study CTA is the intraperitoneal injection of LiCl. The pontine parabrachial nucleus (PB) is an autonomic relay nucleus situated in the rostral brain stem that integrates afferent somatosensory and interoceptive information and forwards this information to the hypothalamus and limbic structures. PB is crucial for the acquisition of CTA and PB neurons are activated by many anorexigenic substances. Further, PB neurons express neuropeptides, among those calcitonin gene related peptide (CGRP) and enkephalin, both of which have been implicated in immune signalling, nociception, food intake, and aversion. By using a dual-labelling immunohistochemical/in situ hybridization technique we investigated if enkephalinergic neurons in PB are activated by systemic immune challenge. While there were many neurons in the external lateral parabrachial subnucleus (PBel) that expressed the immediate early gene fos after intravenous injection of LPS and while a large proportion of the PBel neurons expressed preproenkephalin, there were very few double-labelled cells. The fos-expressing cells were predominantly located to the outer part of the PBel (PBelo), whereas the preproenkephalin-expressing PBel neurons were located closest to the peduncle. Thus we conclude that although enkephalin has been implicated in autonomic and immune signalling, enkephalinergic neurons in PB do not seem to be activated by immune stimulation (paper I). To further characterise the PBelo neurons activated by immune challenge we investigated if these neurons expressed CGRP. Dual-labelling in situ hybridisation showed that PBelo neurons that expressed fos after intravenous injection of LPS to a large extent co-expressed CGRP mRNA, indicating that CGRP may be involved in the regulation of the sickness response in immune challenge (paper II). Using dual-labelling immunohistochemistry we examined if PBel neurons activated by an immune stimulus projected to the amygdala, a limbic structure implicated in the affective response to homeostatic challenge. Animals were injected with the retrograde tracer substance cholera toxin b (CTb) into the amygdala and subsequently subjected to immune challenge. We found that approximately a third of the neurons that expressed fos after the intravenous injection of LPS also were labelled with CTb. Thus PBel neurons activated by immune challenge project to the amygdala. The PBel-amygdala pathway has earlier been suggested to be important in nociceptive signalling. To investigate if amygdala-projecting PBel neurons are activated by nociceptive stimuli we again injected animals with CTb into the amygdala. After recovery the animals were injected with formalin into a hindpaw. Dual-labelling immunohistochemistry against fos and CTb showed that very few noxiously activated PB neurons projected to the amygdala. Thus, the PBel-amygdala projection seems to be important in immune challenge but not in nociceptive signalling (paper III). Many PBel neurons express fos after intraperitoneal injection of LiCl. Melanocortins are neuropeptides that recently have been implicated in metabolism, food intake and aversive mechanisms. The PB is known to express melanocortin receptor-4 (MC4-R) mRNA. Using dual-labelling in situ hybridization we investigated if PB neurons activated by intravenous injection of LPS or intraperitoneal injection of LiCl expressed MC4-R mRNA. We found that many PBelo neurons were activated by either LPS or LiCl and that a large proportion of such activated neurons expressed MC4-R mRNA. Further, using dual-labelling in situ hybridization against MC4-R mRNA and CGRP mRNA, we found that a large proportion of the CGRP positive PBelo neurons also expressed MC4-R mRNA. In summary, this thesis shows that CGRP-expressing neurons in the PBel are activated by peripheral immune challenge, that lipopolysaccharide-activated PBel neurons project to the amygdala, that the amygdala-projecting neurons in the PBel are CGRP-positive, and that PBel neurons activated by immune or aversive challenge express MC4-R. Taken together, these data suggest the presence of a melanocortin-regulated CGRP-positive pathway from the PBel to the amygdala that relays information of importance to certain aspects of sickness behaviour. / On the day of the defence date the title of article II was: Feeding-related immune responsive brain stem neurons: association with CGRP. Article II: Erratum for in Neuroreport 2001;12(16):inside back cover. Neuroreport 2001;12(13):inside back cover. Article III: Erratum in: J Comp Neurol. 2005; 483:489-90.

A new approach to analysis of protein-ligand interactions, termed proteochemometrics, has been developed. Contrary to traditional quantitative structure-activity relationship (QSAR) methods that aim to correlate a description of ligands to their interactions with one particular target protein, proteochemometrics considers many targets simultaneously. Proteochemometrics thus analyzes the experimentally determined protein-ligand interaction activity data by correlating the data to a complex description of all interaction partners and; in a more general case even to interaction environment and assaying conditions, as well. In this way, a proteochemometric model analyzes an “interaction space,” from which only one cross-section would be contemplated by any one QSAR model. Proteochemometric models reveal the physicochemical and structural properties that are essential for protein-ligand complementarity and determine specificity of molecular interactions. From a drug design perspective, models may find use in the design of drugs with improved selectivity and in the design of drugs for multiple targets, such as mutated proteins (e.g., drug resistant mutations of pathogens). In this thesis, a general concept for creating of proteochemometric models and approaches for validation and interpretation of models are presented. Different types of physicochemical and structural description of ligands and macromolecules are evaluated; mathematical algorithms for proteochemometric modeling, in particular for analysis of large-scale data sets, are developed. Artificial chimeric proteins constructed according to principles of statistical design are used to derive high-resolution models for small classes of proteins. The studies of this thesis use data sets comprising ligand interactions with several families of G protein-coupled receptors. The presented approach is, however, general and can be applied to study molecular recognition mechanisms of any class of drug targets.

Melanocortins (MCs) play an important role in feeding, metabolism, and energy expenditure. While melanocortin receptor (MCR) mRNA has been found in the mesolimbic dopamine (DA) pathway, the ability of melanocortins to regulate feeding and other behaviors through actions on the mesolimbic DA system have not been examined. Short-hairpin RNAs (shRNAs) were created targeting MC3R and MC4R and were tested via in vitro studies for their ability to knockdown their target receptor. A total of three shRNAs were created targeting each receptor, and each shRNA caused successful knockdown. These shRNAs are tools that can be used for future in vivo studies to examine the various behavioral effects of melanocortins on the mesolimbic DA pathway.

Ph.D.

The inability to tan properly after sun exposure strongly correlates with increased incidence of skin cancer. The melanocortin 1 receptor (MC1R) is a transmembrane Gs-coupled cell surface receptor found on epidermal melanocytes that transmits pro-survival and pro-differentiation signals mediated by the second messenger cAMP. Humans carrying loss-of-function polymorphisms in MC1R signaling exhibit higher incidences of skin cancers including melanoma. This study focused on the physiologic effects of topical application of forskolin, an adenylate cyclase activator, in extension (Mc1re/e) K14-SCF animals, which model the fair-skinned UV-sensitive human. Twice daily application of the drug promoted accelerated pigmentation, increased skin darkening due to epidermal deposition of melanin pigment, and induced epidermal melanin, which protected the skin against UV injury as judged by “minimal erythematous dose” (MED). Moreover, MC1R signaling regulated the expression of antioxidant enzymes at the transcriptional level. The human melanoma cell line A375, known to harbor a loss-of-function signaling mutation in MC1R, was used to determine effects of cAMP stimulation on the expression of antioxidant enzymes. We observed increases in expression of genes that control the biosynthesis and regulation of glutathione including the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2), glutathione peroxidase, GPX, and glutathione reductase GSR. In addition, there is an increase in manganese superoxide dismutase (MnSOD) at the protein level. There was accumulation of MnSOD in the mitochondria after pharmacologic induction of cAMP with forskolin. Addition of the oxidative agent H2O2 enhanced the expression of MnSOD at the protein level as early as one hour after MC1R stimulation. Oxygen consumption rate on mitochondria was measured using Seahorse analysis; pharmacologic activation of MC1R/cAMP signaling did not affect mitochondrial metabolism. In addition, topical application of a crude extract of Solidago inhibited UV-induced inflammation in K14-SCF mice. Several UV-induced cytokines, including TNF-α, were down-regulated at the transcriptional level after topical application of Solidago extract. Together, these results indicate that MC1R signaling protects melanocytes from UV damage by regulating antioxidant enzyme expression and suggest that pharmacologic cAMP induction may be a useful preventive mechanism against UV-mediated skin sunburn and oxidative injury.

付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24185号 / 理博第4876号 / 新制||理||1698(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 今井 啓雄, 教授 古賀 章彦, 准教授 Huffman Michael Alan / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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