Toomas Talme

Expression pattern of somatostatin receptor subtypes 1–5 in human skin: an immunohistochemical study of healthy subjects and patients with psoriasis or atopic dermatitis

Abstract:  In psoriasis and atopic dermatitis, the inflammatory events have neurogenic components and the neuropeptides modify the functions of immuno‐active cells in the skin. Somatostatin is a neuropeptide with several neuroendocrine and immunomodulating properties and mediates its actions by five distinct subtypes of G‐protein‐coupled receptors (SSTR1‐5). This study describes the distribution of SSTR1–5, analysed with immunohistochemistry, in psoriasis, atopic dermatitis and controls. Normal human skin and lesional skin from patients with psoriasis or atopic dermatitis showed many similarities, but also some differences, as regards SSTR expression. SSTR1–3 were strongly expressed in the epidermis of healthy skin, and in the skin of patients with psoriasis or atopic dermatitis. It is noteworthy that SSTR4 and 5 were strongly expressed in the epidermis of psoriasis patients, but weakly expressed in the epidermis of those with atopic dermatitis and normal skin. The intensity of the staining also varied considerably between the different layers of the epidermis, especially in psoriasis patients. In all cases, the dendritic cells, found mostly in the papillary and upper reticular dermis, showed a strong expression of SSTR1–4, but a weak expression of SSTR5. SSTR1–5 were strongly expressed in the sweat glands in all skin biopsies. Hair follicles and sebaceous glands expressed all five subtypes. Striated muscle fibres showed an intense positive expression of SSTR1–4, but a weak or negative expression of SSTR5. The wide distribution and expression pattern of all five SSTRs in human skin suggest that somatostatin is involved in the interactions between the nervous system and the skin.

Fear-avoidance beliefs and pain as predictors for low physical activity in patients with leg ulcer

BACKGROUND AND PURPOSE Previous studies have shown that patients with chronic venous insufficiency are deconditioned and physically inactive. The present study aimed to examine the occurrence of fear-avoidance beliefs in patients with chronic venous insufficiency, and to investigate the role of fear-avoidance beliefs and pain severity in predicting the low level of physical activity in these patients. METHOD Data were collected by a postal questionnaire sent to 146 patients with chronic venous insufficiency and current or previous venous leg ulcer. Complete data were collected from 98 patients aged 60-85 years - 63% women - giving a response rate of 67%. Fear-avoidance beliefs were assessed by the Fear-Avoidance Beliefs Questionnaire, physical activity subscale. Pain and physical activity were assessed by the Six-point Verbal Rating Scale of Pain Assessment and the Physical Activity Questionnaire, respectively. RESULTS Fear-avoidance beliefs were present in 81 (83%) of the patients with chronic venous insufficiency (range 0-24, median 12). Forty patients (41%) had strong fear-avoidance beliefs. One-third of the patients with healed ulcers had strong fear-avoidance beliefs. Patients with low physical activity had significantly stronger fear-avoidance beliefs and more severe pain than patients with high physical activity. Multiple logistic regression showed that the odds ratio (OR) for low physical activity were about three times higher for patients with strong fear-avoidance beliefs (OR 3.1, 95% confidence interval 1.1-8.3; p = 0.027) than for patients with weak fear-avoidance beliefs. CONCLUSIONS Fear-avoidance beliefs were present in most patients with chronic venous insufficiency and were associated with low physical activity. Clinical implications ought to include a better recognition of fear-avoidance beliefs, early information about the negative consequences of such beliefs, and the importance of physical activity to counteract poor mobility.

The neuropeptide calcitonin gene-related peptide (CGRP) stimulates T cell migration into collagen matrices

CGRP significantly stimulated migration of non-activated and anti-CD3 activated T lymphocytes into a collagen matrix when present inside the collagen, whereas somatostatin-14, NPY, substance P, VIP, beta-endorphin and metenkephalin had no or little effect. The CGRP antagonist CGRP 8-37 abrogated the CGRP-induced cell infiltration. Virtually all migrating cells were CD3+ (>96%) and CGRP did not stimulate B-cell migration. The migration capacity showed no selective relationship to the expression of CD4+, CD8+, CD45RO+ (memory), or CD45RA+ (naive) T cell markers indicating that the regulation of T cell migration is distinct from that of the major T cell phenotypes.

The role of chemokines and extracellular matrix components in the migration of T lymphocytes into three-dimensional substrata

The role of chemokines and their interactions with extracellular matrix components (ECM) or the capacity of T cells to migrate into and accumulate within three‐dimensional (3D) collagen type 1 substrata was studied. We examined the influence of chemokines and fibronectin on the infiltration properties of non‐infiltrative (do not migrate into 3D substrata) and spontaneously infiltrative (migrate into 3D substrata) T‐cell lines. Infiltrative and non‐infiltrative T‐acute lymphocytic leukaemic cell lines exhibited no consistent differences with respect to the expression of various chemokine receptors or β1‐integrins. Chemokines presented inside the collagen increased the depth of migration of infiltrative T‐cell lines, but did not render non‐infiltrative T‐cell lines infiltrative, although they augmented the attachment of non‐infiltrative T‐cell lines to the upper surface of the collagen. The presence of fibronectin inside the collagen did not render non‐infiltrative T‐cell lines infiltrative, but markedly augmented the migration of ‘infiltrative’ T‐cell lines into collagen. Both infiltrative and non‐infiltrative T‐cell lines showed migratory responses to chemokines in Boyden assays (migration detected on 2D substrata). These results indicate that the process of T‐cell infiltration/migration into 3D substrata depends on a tissue penetration mechanism distinguishable from migration on 2D substrata and that the basic capacity of T cells to infiltrate is independent of chemokines and ECM components applied as attractants.

Somatostatin is a specific inhibitor of SDF-1α-induced T cell infiltration

The chemokine stromal cell‐derived factor 1α (SDF‐1α) is a potent stimulator of T cell infiltration into three‐dimensional type I collagen matrices as demonstrated using T cells freshly isolated from blood and an activated T cell clone. The neuropeptide somatostatin selectively inhibits SDF‐1α induced T cell infiltration by the same T cells including CD4 as well as CD8 positive cells, while somatostatin does not inhibit ‘spontaneous’ T cell infiltration. A number of other neuropeptides and opioids do not inhibit SDF‐1α‐induced T cell infiltration, indicating that the inhibitory effect is somatostatin‐specific. The neuropeptide antagonist cyclosomatostatin abrogated the inhibitory effect of somatostatin on T cell infiltration, indicating that the effect of somatostatin is mediated via specific somatostatin receptors. Somatostatin does not inhibit SDF‐1α‐induced T cell attachment to the collagen substrate, which indicates that this neuropeptide specifically inhibits the process of chemokine‐induced T cell penetration and migration through the collagen.

Regulation of T-lymphocyte motility, adhesion and de-adhesion by a cell surface mechanism directed by low density lipoprotein receptor-related protein 1 and endogenous thrombospondin-1.

T lymphocytes are highly motile and constantly reposition themselves between a free‐floating vascular state, transient adhesion and migration in tissues. The regulation behind this unique dynamic behaviour remains unclear. Here we show that T cells have a cell surface mechanism for integrated regulation of motility and adhesion and that integrin ligands and CXCL12/SDF‐1 influence motility and adhesion through this mechanism. Targeting cell surface‐expressed low‐density lipoprotein receptor‐related protein 1 (LRP1) with an antibody, or blocking transport of LRP1 to the cell surface, perturbed the cell surface distribution of endogenous thrombospondin‐1 (TSP‐1) while inhibiting motility and potentiating cytoplasmic spreading on intercellular adhesion molecule 1 (ICAM‐1) and fibronectin. Integrin ligands and CXCL12 stimulated motility and enhanced cell surface expression of LRP1, intact TSP‐1 and a 130 000 MW TSP‐1 fragment while preventing formation of a de‐adhesion‐coupled 110 000 MW TSP‐1 fragment. The appearance of the 130 000 MW TSP‐1 fragment was inhibited by the antibody that targeted LRP1 expression, inhibited motility and enhanced spreading. The TSP‐1 binding site in the LRP1‐associated protein, calreticulin, stimulated adhesion to ICAM‐1 through intact TSP‐1 and CD47. Shear flow enhanced cell surface expression of intact TSP‐1. Hence, chemokines and integrin ligands up‐regulate a dominant motogenic pathway through LRP1 and TSP‐1 cleavage and activate an associated adhesion pathway through the LRP1–calreticulin complex, intact TSP‐1 and CD47. This regulation of T‐cell motility and adhesion makes pro‐adhesive stimuli favour motile responses, which may explain why T cells prioritize movement before permanent adhesion.

Non-invasive preoperative assessment of basal cell carcinoma of nodular and superficial types.

Background/aims: Although various biophysical properties can be used to distinguish basal cell carcinoma (BCC) tissue from normal skin, none permits typing of the tumour. In this study, we assessed nodular (NBCC) and superficial (SBCC) types of BCC using three different non‐invasive instruments and placed special emphasis on their clinical value as diagnostic tools.

Evaluation of the effects of topical clobetasol propionate by visual score, electrical impedance and laser Doppler flowmetry.

Background/purpose: The intensity of steroid‐induced skin blanching is usually evaluated subjectively by a trained observer using a visual score although a few methods have been described for doing this objectively. In this study we wished to establish whether the effects of topical steroids can be detected by measuring the electrical impedance of the skin.

Methotrexate and its therapeutic antagonists caffeine and theophylline, target a motogenic T‐cell mechanism driven by thrombospondin‐1 (TSP‐1)

Methotrexate (MTX) is a widely used treatment for inflammatory diseases such as rheumatoid arthritis and psoriasis, based on the concept that it is immunosuppressive. Its mechanism of action, however, remains unclear, although it is thought to depend on adenosine. Caffeine and theophylline, which have several targets including adenosine receptors, have been shown to suppress the beneficial clinical effects of MTX. Here we show that MTX and caffeine and theophylline differentially affect a motogenic T‐cell mechanism driven by endogenous thrombospondin‐1 (TSP‐1) and its receptor, low density lipoprotein receptor‐related protein 1 (LRP1). MTX stimulated TSP‐1 expression and the motogenic TSP‐1/TSP‐1 receptor mechanism in primary human T cells, hence mimicking IL‐2 and CXCL12, which similar to MTX, dampen inflammatory disease. SiRNA‐mediated gene silencing of TSP‐1 and LRP1 inhibited this stimulatory effect. Caffeine and theophylline inhibited the TSP‐1/TSP‐1 receptor mechanism by inhibiting LRP1 expression. These results indicate that the effect of MTX on T cells is immunoregulatory rather than immunosuppressive, and suggest a pathway dependent on TSP‐1/TSP‐1 receptor interactions for the regulation of immune responses.

The Effects of Somatostatin on Immune Cells, Functions and Diseases

Somatostatin (SST) is a ubiquitous neuropeptide hormone that was first extracted from bovine hypothalamus as an inhibitor of growth hormone secretion (Brazeau et al. 1973). The SST gene is a very ancient gene present in all vertebrate classes (Tostivint et al. 2004). Since its discovery in 1973, SST has stimulated a plethora of studies investigating its multiple physiological actions in a great variety of tissues. The continued scientific interest has been evident over the years including the cloning of a family of five somatostatin receptors (SSTRs) in 1992 (Yamada et al. 1992; O’Carroll et al. 1992; Panetta et al. 1994), the characterization of the related neuropeptide corticostatin in 1996 (de Lecea et al. 1996; Tostivint et al. 1996), and the development of hundreds of synthetic SST analogues, some of them with clinical applications. SST exists in two bioactive forms, as a 14 amino acid peptide (Brazeau et al. 1973) and as a cogener of somatostatin-14 extended at the N-terminus called somatostatin-28 (Pradayrol et al. 1980) (Fig. 7.1). SST is widely distributed in the central and peripheral nervous system but also present in endocrine pancreas, gut thyroid, prostate, placenta, adrenals, kidneys and skin (Luft et al. 1974; Arimura et al. 1975; Dubois 1975; Hokfelt et al. 1975; Orci et al. 1975; Pelletier et al. 1975; Polak et al. 1975; Patel and Reichlin 1978; Johansson and Nordlind 1984). SST is present in the peripheral nervous system in sympathetic and sensory neurons innervating lymphoid organs and may thus influence functional responses of lymphocytes and antigen-presenting cells (Aguila et al. 1991; Felten et al. 1985). SST is expressed in both cortical and medullary thymic epithelial cells (Solomou et al. 2002). SST suppresses the synthesis and secretion of growth factors such as growth hormone and insulin-like growth factor 1. SST inhibits gastrointestinal hormones that include gastrin, cholecystokinin, serotonin, glucagon, vasoactive intestinal peptide, and others (Alberti et al. 1973; Koerker et al. 1974; Zhang et al. 1991; Philippe 1993; Nelson-Piercy et al. 1994; Kleinman et al. 1995; Ballian et al. 2006; Corleto 2010). There is evidence from several test systems that SST can modulate the responses of lymphocytes to mitogens and T cell antigen receptor (TCR)/CD3 stimulation and even that SST influences adhesion and motility of lymphocytes. SST stimulates adhesion of lymphocytes to extracellular matrix components (ECM) (Levite et al. 1998). SST inhibits proliferation directly by regulating tyrosine kinase, tyrosine phosphatase, nitric oxide synthase, cyclic guanosine 3′, 5′-cyclic monophosphate–dependent protein kinase, and RAS/extracellular signal–regulated kinase signalling pathways (Pyronnet et al. 2008). SST also has antiangiogenic properties and can induce apoptosis (Sharma and Srikant 1998; Woltering 2003; Pyronnet et al. 2008). Glucagons, growth-releasing hormone, neurotensin, corticotrophin-releasing hormone, calcitonin gene-related peptide and bombesin are potent stimulators of SST secretion, while opiate and GABA are inhibitors (Patel et al. 1991; Epelbaum et al. 1994). Inflammatory cytokines have also shown regulatotory effects on SST secretion: IL-1, IL-6, IL-10; INF-γ, and TNF-α thus stimulate whereas TGF-β inhibits SST release (Scarborough et al. 1989; Quintela et al. 1997; Elliott 2004).