Gastrin-releasing peptide and pruritus: more than just scratching the surface

IL-31 and IL-8 in Cutaneous T-Cell Lymphoma: Looking for Their Role in Itch

The itch associated with cutaneous T-cell lymphoma (CTCL), including Mycosis Fungoides (MF) and Sézary syndrome (SS), is often severe and poorly responsive to treatment with antihistamines. Recent studies have highlighted the possible role of interleukins in nonhistaminergic itch. We investigated the role of IL-31 and IL-8 in CTCL, concerning disease severity and associated itch. Serum samples of 27 patients with CTCL (17 MF and 10 SS) and 29 controls (blood donors) were analyzed for interleukin- (IL-) 31 and IL-8; correlations with disease and itch severity were evaluated. IL-31 serum levels were higher in CTCL patients than in controls and higher in SS than in MF. Also, serum IL-31 levels were higher in patients with advanced disease compared to those with early disease, and they correlated positively with lactate dehydrogenase and beta 2-microglobulin levels, as well as with the Sézary cell count. Itch affected 67% of CTCL patients (MF: 47%; SS: 100%). Serum IL-31 levels were higher in itching patients than in controls and in patients without itching. There was no association between serum IL-8 and disease severity, nor with itching. Serum IL-8 levels correlated positively with peripheral blood leukocyte and neutrophil counts in CTCL patients. Our study suggests a role for IL-31 in CTCL-associated itch, especially in advanced disease and SS, offering a rational target for new therapeutic approaches. Increased serum IL-8 observed in some patients may be related to concomitant infections, and its role in exacerbating itch by recruiting neutrophils and promoting the release of neutrophil proteases deserves further investigation.

Prevalence and Severity of Dermatological Condition-Associated Skin Pain in the Chinese

BACKGROUND/AIM

Although the characteristics of cutaneous sensory symptoms in the general population have been documented, dermatological condition-associated skin pain has not been characterized yet. In the present study, we aimed to characterize dermatological condition-associated skin pain in the Chinese.

SUBJECTS AND METHODS

A questionnaire was given to outpatients to identify self-proclaimed skin pain at our dermatology clinic. The severity of skin pain was assessed using pain scale 0-10. Prevalence and pain severity were compared between males and females.

RESULTS

A total of 2144 patients, including 1254 females and 890 males aged 13-94 years, were included in this study. The overall prevalence of skin pain was 9.93% in this cohort. The prevalence of skin pain varied greatly with dermatological conditions (p<0.0001). Moreover, a higher prevalence of skin pain was observed in males than in females (p<0.05). Among the dermatological conditions reported, higher skin pain scales were found in subjects with either glucocorticoid-induced dermatitis (4.20 ± 0.73) or herpes zoster (4.00 ± 0.29). While the overall pain scales were comparable between males and females (2.38 ± 0.13 versus 2.68 ± 0.13), pain scales in patients with eczematous dermatitis were higher in females than in males (p<0.05). Furthermore, pain scales correlated positively with age. However, pain scales did not differ between subjects with versus without a family history of cutaneous sensory symptoms. These results demonstrate that the prevalence and severity of dermatological condition-associated skin pain vary with dermatological conditions and gender in the Chinese.

CONCLUSION

Patients with some dermatological conditions may experience skin pain. Although the pain is moderate, it can negatively impact the quality of patients' lives. Alleviation of skin pain should be considered when treating patients with certain dermatological conditions.

Anti-inflammatory Effects of a Small Molecule Gastrin-Releasing Peptide Receptor Antagonist on Adjuvant-Induced Rheumatoid Arthritis in Rats

The anti-inflammatory effects of (R)-2-(1H-Imidazol-1-yl) ethyl-3-(1H-indol-3-yl)-2-(2-p-tolylacetamido)propanamide (RH-1402), a previous designed small molecule Gastrin releasing peptide (GRP) antagonist were evaluated in adjuvant-induced arthritic model of rats, and the inhibitory effect on neutrophil migration induced by GRP was determined by a transwell system experiment in vitro. The arthritis was induced by injection of Complete Freund's Adjuvant (CFA) containing 10 mg/mL of heat killed mycobacterium into the left hind footpad. Experimental rats were randomly divided into 6 groups, including control, placebo, positive control group, RH-1402 of low/middle/high dose group. Disease incidence and severity was evaluated through scoring of the paw edema and histologic features of joint synovial. Blood of all experimental rats was collected for interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) cytokine levels. A transwell system was used to investigate whether RH-1402 would inhibit neutrophils migrating up a gradient of GRP in vitro. RH-1402 (5 and 10 mg/kg) significantly decreased adjuvant induced increased arthritis index during the administration period (days 14-20). Significant inhibition of joint synovial histological features can be found in the RH-1402 treated group, including alleviated Hyperplasia, Inflammatory of infiltration and activation of pannus formation. It also suppressed TNF-α and IL-1β level. Five and 10 mg/kg of RH-1402 significantly inhibited the effect of GRP on neutrophil migration with a dose dependent relationship. These findings indicate that RH-1402 have potential protective anti-inflammatory effects on experimental models of arthritis.

Rise of the sensors: nociception and pruritus

Once there was a day when all type C nonmyelinated neurons were indistinguishable. That time of histologic analysis has passed, and we have entered an era of unparalleled technological insight into the mechanisms of pain and pruritus. Since the description of the capsaicin receptor, transient receptor protein vanilloid 1 (TRPV1), in 1997, we have seen the number of related sensor ion channels, G protein-coupled receptors, and signaling proteins explode. Specific nociceptive pathways have been identified based on their sensitivity to mechanical, heat, chemical, and cold stimuli. Pruritus is now recognized to have both histamine-sensitive and histamine-independent afferent arcs. Cross-talk between C-fibre systems and myelinated neural pathways has become more complex, but through complexity, a new reality of sensory coding is emerging. A multitude of novel therapeutics have been and are in planning and production stages. These will almost certainly revolutionize our understanding and treatment of pain and itch by the end of this decade.

Neuroregulation of human nasal mucosa

Multiple subsets of nociceptive, parasympathetic, and sympathetic nerves innervate human nasal mucosa. These play carefully coordinated roles in regulating glandular, vascular, and other processes. These functions are vital for cleaning and humidifying ambient air before it is inhaled into the lungs. The recent identification of distinct classes of nociceptive nerves with unique patterns of transient receptor potential sensory receptor ion channel proteins may account for the polymodal, chemo- and mechanicosensitivity of many trigeminal neurons. Modulation of these families of proteins, excitatory and inhibitory autoreceptors, and combinations of neurotransmitters introduces a new level of complexity and subtlety to nasal innervation. These findings may provide a rational basis for responses to air-temperature changes, culinary and botanical odorants ("aromatherapy"), and inhaled irritants in conditions as diverse as allergic and nonallergic rhinitis, occupational rhinitis, hyposmia, and multiple chemical sensitivity.

Gastrin-releasing peptide: different forms, different functions

All forms of the neuropeptide gastrin-releasing peptide (GRP) are derived from the precursor proGRP1-125. Amidated GRP18-27, which together with amidated GRP1-27 was long thought to be the only biologically relevant product of the GRP gene, is involved in a multitude of physiological functions and acts as a mitogen, morphogen, and proangiogenic factor in certain cancers. Recently, GRP has been implicated in several psychiatric conditions, in the maintenance of circadian rhythm, in spinal transmission of the itch sensation, and in inflammation and wound repair. The actions of GRP are mediated by the GRP receptor. Over the last decade, nonamidated peptides derived from proGRP, such as the glycine-extended form GRP18-28 and recombinant and synthetic fragments from proGRP31-125, have been shown to be biologically active in a range of tissues and in cancer cell lines. While GRP18-28 acts via the GRP receptor, the identity of the receptor for proGRP31-125 and its fragments has not yet been established. Nonamidated fragments are also present in normal tissues and in various cancers. In fact, proGRP31-98 is the most sensitive serum biomarker in patients with small cell lung cancer and is a significant predictor of poor survival in patients with advanced prostate cancer.