Anna Catania

Alpha-melanocyte-stimulating-hormone (α-MSH) has marked anti-inflammatory potential. Proinflammatory cytokines are critical mediators of the disturbed cartilage homeostasis in osteoarthritis, inhibiting anabolic activities and increasing catabolic activities in chondrocytes. Since human chondrocytes express α-MSH receptors, we evaluated the role of the peptide in modulating chondrocyte production of pro-inflammatory cytokines, matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in response to interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Human articular chondrocytes were obtained from osteoarthritic joint cartilage from subjects undergoing hip routine arthroplasty procedures. The cells were cultured with or without α-MSH in the presence of IL-1β or TNF-α. Cell-free supernatants were collected and cells immediately lysed for RNA purification. Expression of cytokines, MMPs, TIMPs, iNOS was determined by Reverse Transcription Real-time Polymerase Chain Reaction and enzyme-linked immunosorbent assay. Griess reaction was used for NO quantification. Gene expression and secretion of IL-6, IL-8, MMP-3, MMP-13 were significantly increased in IL-1β or TNF-α-stimulated chondrocytes; α-MSH did not modify the release of IL-6 or IL-8 while the peptide significantly reduced their gene expression on TNF-α-stimulated cells. A significant inhibition of MMP3 gene expression and secretion from IL-1β or TNFα-stimulated chondrocytes was induced by α-MSH. On the other hand, α-MSH did not modify the release of MMP-13 by cytokine-stimulated chondrocyte but significantly decreased gene expression of the molecule on TNF-α-stimulated cells. Detectable amount of TIMP-3 and TIMP-4 were present in the supernatants of resting chondrocytes and a significant increase of TIMP-3 gene expression and release was induced by α-MSH on unstimulated cells. TIMP-3 secretion and gene expression were significantly increased in IL-1β-stimulated chondrocytes and α-MSH down-regulated gene expression but not secretion of the molecule. TIMP-4 gene expression (but not secretion) was moderately induced in IL-1β-stimulated chondrocytes with a down-regulation exerted by α-MSH. IL-1β and TNF-α were potent stimuli for NO production and iNOS gene expression by chondrocytes; no inhibition was induced by α-MSH on cytokine-stimulated NO production, while the peptide significantly reduced gene expression of iNOS. Our results underscore a potential anti-inflammatory and chondroprotective activity exerted by α-MSH, increasing TIMP-3 gene expression and release on resting cells and down- modulating TNF-α-induced activation of human chondrocytes. However, the discrepancy between the influences exerted by α-MSH on gene expression and protein release as well as the difference in the inhibitory pattern exerted by α-MSH in TNF-α- or IL-1β-stimulated cells leave some uncertainty on the role of the peptide on chondrocyte modulation.

Previous investigations indicate that α-melanocyte-stimulating hormone (α-MSH) and certain synthetic analogues of it exert antimicrobial effects against bacteria and yeasts. However, these molecules have weak activity in standard microbiology conditions and this hampers a realistic clinical use. The aim in the present study was to identify novel peptides with broad-spectrum antimicrobial activity in growth medium. To this purpose, the Gly10 residue in the [ D Nal(2′)-7, Phe-12]-MSH(6–13) sequence was replaced with conventional and unconventional amino acids with different degrees of conformational rigidity. Two derivatives in which Gly10 was replaced by the residues Aic and Cha, respectively, had substantial activity against Candida strains, including C. albicans , C. glabrata , and C. krusei and against gram-positive and gram-negative bacteria. Conformational analysis indicated that the helical structure along residues 8–13 is a key factor in antimicrobial activity. Synthetic analogues of α-MSH can be valuable agents to treat infections in humans. The structural preferences associated with antimicrobial activity identified in this research can help further development of synthetic melanocortins with enhanced biological activity.

Activins control the growth of several tumour types including thoracic malignancies. In the present study, we investigated their expression and function in malignant pleural mesothelioma (MPM). The expression of activins and activin receptors was analysed by quantitative PCR in a panel of MPM cell lines. Activin A expression was further analysed by immunohistochemistry in MPM tissue specimens (N=53). Subsequently, MPM cells were treated with activin A, activin receptor inhibitors or activin-targeting siRNA and the impact on cell viability, proliferation, migration and signalling was assessed. Concomitant expression of activin subunits and receptors was found in all cell lines, and activin A was overexpressed in most cell lines compared with non-malignant mesothelial cells. Similarly, immunohistochemistry demonstrated intense staining of tumour cells for activin A in a subset of patients. Treatment with activin A induced SMAD2 phosphorylation and stimulated clonogenic growth of mesothelioma cells. In contrast, treatment with kinase inhibitors of activin receptors (SB-431542, A-8301) inhibited MPM cell viability, clonogenicity and migration. Silencing of activin A expression by siRNA oligonucleotides further confirmed these results and led to reduced cyclin D1/3 expression. Our study suggests that activin A contributes to the malignant phenotype of MPM cells via regulation of cyclin D and may represent a valuable candidate for therapeutic interference.

The therapeutic benefits of adrenocorticotropic hormone in multiple sclerosis are usually ascribed to its corticotropic actions. Evidence is presented that adrenocorticotropic hormone, approved for multiple sclerosis relapses, acts via corticosteroid-independent melanocortin pathways to engender down-modulating actions on immune-system cells and the cytokines they synthesize. Immune response-dampening effects are also brought about by agent-induced neurotransmitters that inhibit immunocytes. The likelihood that adrenocorticotropic hormone promotes microglial quiescence and counteracts glucocorticoid-mediated bone resorption is discussed.

Background: Melanocortin peptides improve hemodynamic parameters and prevent death during severe hemorrhagic shock. In the present research we determined influences of a synthetic melanocortin 1/4 receptor agonist on the molecular changes that occur in rat liver during hemorrhage. Methods: Controlled-volume hemorrhage was performed in adult rats under general anesthesia by a stepwise blood withdrawal until mean arterial pressure fell to 40 mmHg. Then rats received either saline or the synthetic melanocortin 1/4 receptor agonist Butir-His-D-Phe-Arg-Trp-Sar-NH2 (Ro27-3225; n = 6-8 per group). Hemogasanalysis was performed throughout a 60-min period. Gene expression in liver samples was determined at 1 or 3 h using quantitative real-time polymerase chain reaction. Results: At 1 h, in saline-treated shocked rats, there were significant increases in activating transcription factor 3 (Atf3), early growth response 1 (Egr1), heme oxygenase (decycling) 1 (Hmox1), FBJ murine osteosarcoma viral oncogene homolog (Fos), and jun oncogene (Jun). These changes were prevented by Ro27-3225 (mean ± SEM: Atf3 152.83 ± 58.62 vs. 579.00 ± 124.13, P = 0.002; Egr1 13.21 ± 1.28 vs. 26.63 ± 1.02, P = 0.001; Hmox1 3.28 ± 0.31 vs. 166.54 ± 35.03, P = 0.002; Fos 4.36 ± 1.03 vs. 14.90 ± 3.44, P < 0.001; Jun 6.62 ± 1.93 vs. 15.07 ± 2.09, P = 0.005; respectively). Increases in alpha-2-macroglobulin (A2m), heat shock 70kD protein 1A (Hspa1a), erythropoietin (Epo), and interleukin-6 (Il6) occurred at 3 h in shocked rats and were prevented by Ro27-3225 treatment (A2m 6.90 ± 0.82 vs. 36.73 ± 4.00, P < 0.001; Hspa1a 10.34 ± 3.28 vs. 25.72 ± 3.64, P = 0.001; Epo 0.49 ± 0.13 vs. 2.37 ± 0.73, P = 0.002; Il6 1.05 ± 0.15 vs. 1.88 ± 0.23, P < 0.001; respectively). Further, at 3 h in shocked rats treated with Ro27-3225 there were significant increases in tight junction protein 1 (Tjp1; 27.30 ± 2.43 vs. 5.03 ± 1.68, P < 0.001) and nuclear receptor subfamily 4, group A, member 1 (Nr4a1; 91.03 ± 16.20 vs. 30.43 ± 11.0, P = 0.01) relative to sham animals. Treatment with Ro27-3225 rapidly restored blood pressure, hemogasanalysis parameters, and lactate blood levels. Conclusions: Melanocortin treatment significantly prevents most of the systemic and hepatic detrimental changes induced by hemorrhage.

Infantile spasms is an epileptic encephalopathy of early infancy with specific clinical and electroencephalographic (EEG) features, limited treatment options, and a poor prognosis. Efforts to develop improved treatment options have been hindered by the lack of experimental models in which to test prospective therapies. The neuropeptide adrenocorticotropic hormone (ACTH) is effective in many cases of infantile spasms, although its mechanism(s) of action is unknown. This review describes the emerging candidate mechanisms that can underlie the therapeutic effects of ACTH in infantile spasms. These mechanisms can ultimately help to improve understanding and treatment of the disease. An overview of current treatments of infantile spasms, novel conceptual and experimental approaches to infantile spasms treatment, and a perspective on remaining clinical challenges and current research questions are presented here. This summary derives from a meeting of specialists in infantile spasms clinical care and research held in New York City on June 14, 2010.

Systemic inflammatory reactions are pivotal in many disorders and have important secondary influences in many more. Although inflammation is initially useful to limit infection, it can also be detrimental and cause organ failure. Modulation of systemic reactions is important to restrict mediator release and limit cell activation that could cause harmful consequences. Experiments in which different models and treatments were used show that melanocortins reduce host responses such as fever, shock, reperfusion injury and allograft rejection. Melanocortin-derived peptides could be an effective treatment to prevent organ failure caused by excessive production of pro-inflammatory mediators. The degree of the modulatory effect exerted by melanocortins should be sufficient to reduce severity of systemic inflammation without impairing the host defense mechanisms. Keywords Acute Lung Injury Reperfusion Injury Acute Phase Response Endogenous Pyrogen Melanocortin Peptide These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.