Gualtiero Colombo

Targeting Melanocortin Receptors as a Novel Strategy to Control Inflammation

Adrenocorticotropic hormone and α-, β-, and γ-melanocyte-stimulating hormones, collectively called melanocortin peptides, exert multiple effects upon the host. These effects range from modulation of fever and inflammation to control of food intake, autonomic functions, and exocrine secretions. Recognition and cloning of five melanocortin receptors (MCRs) has greatly improved understanding of peptide-target cell interactions. Preclinical investigations indicate that activation of certain MCR subtypes, primarily MC1R and MC3R, could be a novel strategy to control inflammatory disorders. As a consequence of reduced translocation of the nuclear factor κB to the nucleus, MCR activation causes a collective reduction of the major molecules involved in the inflammatory process. Therefore, anti-inflammatory influences are broad and are not restricted to a specific mediator. Short half-life and lack of selectivity could be an obstacle to the use of the natural melanocortins. However, design and synthesis of new MCR ligands with selective chemical properties are already in progress. This review examines how marshaling MCR could control inflammation.

Deregulated FGFR3 mutants in multiple myeloma cell lines with t(4;14): comparative analysis of Y373C, K650E and the novel G384D mutations

The t(4;14)(p16.3;q32) chromosomal translocation occurs in approximately 20% of multiple myelomas (MM) and leads to the apparent deregulation of two genes located on 4p16.3: the fibroblast growth factor receptor 3 (FGFR3) and the putative transcription factor WHSC1/MMSET. Interestingly, FGFR3 mutations known to be associated with autosomal dominant human skeletal disorders have also been found in some MM cell lines with t(4;14) but their pathogenetic role in MM is still controversial. Since cell lines may represent useful models for investigating the effects of deregulated FGFR3 mutants in MM, we analysed the expression, activation, signaling pathways and oncogenic potential of three mutants identified so far: the Y373C and K650E in the KMS-11 and OPM-2 cell lines respectively, and the novel G384D mutation here identified in the KMS-18 cell line. All of the cell lines present a heterozygous FGFR3 gene mutation and transcribe the mutated allele; unlike KMS-11 and OPM-2 (which express the IIIc isoform), the KMS-18 cell line expresses prevalently the isoform IIIb. We demonstrated that, under serum-starved conditions, KMS-11 and OPM-2 cells express appreciable levels of phosphorylated FGFR3 mutants indicating a constitutive activation of the Y373C and K650E receptors; the addition of the aFGF ligand further increased the level of receptor phosphorylation. Conversely, the FGFR3 mutant in KMS-18 does not seem to be constitutively activated since it was phosphorylated only in the presence of the ligand. In all three MM cell lines, ligand-stimulated FGFR3 mutants activated the MAP kinase signaling pathway but did not apparently involve either the STAT1 or STAT3 cascades. However, when transfected in 293T cells, G384D, like Y373C and K650E, was capable of activating MAPK, STAT1 and STAT3 under serum-starved condition. Finally, a focus formation assay of NIH3T3 cells transfected with FGFR3-expressing plasmid vectors showed that Y373C and K650E (albeit at different levels) but not G384D or the wild-type receptor, can induce transformed foci. Overall, our results support the idea that FGFR3 mutations are graded in terms of their activation capability, thus suggesting that they may play a critical role in the tumor progression of MM patients with t(4;14).

Systemic lupus erythematosus candidate genes in the Italian population: evidence for a significant association with interleukin-10.

OBJECTIVE To determine whether 7 candidate genes, including tumor necrosis factor receptor II, bcl-2, CTLA-4, interleukin-10 (IL-10), CD19, Fcy receptor type IIA (CD32), and IL-1 receptor antagonist, may contribute to susceptibility to systemic lupus erythematosus (SLE) in the Italian population. METHODS The association with SLE of intragenic markers for each candidate gene, including either microsatellites or dimorphisms, was analyzed. Gene frequencies of these gene markers were compared for patients and ethnically matched controls. Significance was tested by chi-square test on 2 x 2 tables and by Monte Carlo simulation on 2 x N tables. RESULTS A significant increase was found in SLE patients (0.170 versus 0.095; chi2y = 4.11, P = 0.0425) in the frequency of the 140-basepair allele of the IL10.G microsatellite located in the promoter region of the IL-10 gene. This finding was confirmed in a second independent panel where, again, the frequency of the 140-bp allele was found to be significantly increased in SLE patients versus controls (0.176 versus 0.086; chi2y = 3.95, P = 0.0470). Considering the 2 panels together, the relative risk conferred by the presence of the 140-bp allele was 1.78 (95% confidence interval 1.19-2.66). Conversely, no significant association was detected for the remaining 6 candidate genes, even when the patients were stratified according to the presence of different clinical and immunologic features according to the presence of the associated HLA-DR or IL-10 alleles. CONCLUSION Of the 7 candidate genes tested, only IL-10 was significantly associated with SLE in Italian patients. This genetic marker represents, apart from HLA, the only genetic susceptibility factor for SLE found so far in the Italian population.

Effect of inositol hexaphosphate (IP 6 ) on human normal and leukaemic haematopoietic cells

Summary. Inositol hexaphosphate (IP6), a naturally polyphosphorylated carbohydrate, has been reported to have significant in vivo and in vitro anticancer activity against numerous tumours, such as colon, prostate, breast, liver and rhabdomyosarcomas. To confirm this activity in haematological malignancies and to characterize some of the mechanisms of IP6 action, we analysed its effects on human leukaemic cell lines and fresh chronic myelogenous leukaemia (CML) progenitor cells using a combined cellular and molecular approach. IP6 had a dose‐dependent cytotoxic effect on all of the evaluated cell lines, with accumulation in the G2M phase in two out of five cell lines tested. At the molecular level, cDNA microarray analysis after IP6 exposure showed an extensive downmodulation of genes involved in transcription and cell cycle regulation and a coherent upregulation of cell cycle inhibitors. Furthermore, IP6 treatment of fresh leukaemic samples of bone marrow CD34+ CML progenitor cells significantly inhibited granulocyte–macrophage colony‐forming unit (CFU‐GM) formation (P = 0·0062) in comparison to normal bone marrow specimens, which were not affected. No differentiating effect on HL60 cells was observed. Taken together, our results confirm the antiproliferative activity of IP6 and suggest that it may have a specific antitumour effect also in chronic myeloid leukaemias, via active gene modulation.

DNA typing of maternal HLA in congenital complete heart block: comparison with systemic lupus erythematosus and primary Sjögren's syndrome.

OBJECTIVE To investigate which maternal HLA allele or haplotype is primarily associated with isolated congenital complete heart block (CCHB) in offspring. METHODS HLA class II typings were assessed by line probe assay and polymerase chain reaction-sequence-specific oligonucleotide probe methods, and HLA class I by the microlymphocytotoxicity test, in 13 Italian anti-Ro-positive mothers of children with CCHB and 41 anti-Ro-positive mothers with healthy children (20 mothers with systemic lupus erythematosus [SLE] and 21 with Sjögrens syndrome [SS]). Anti-Ro antibodies were studied by immunoblot. RESULTS HLA-DRB1*03011 and DRB1*03011; DQA1*0501;DQB1*0201 were more frequent in mothers of infants with CCHB than in mothers who had SLE, but not in mothers who had SS and whose children were healthy. Mothers of infants with CCHB were either HLA-B5/35, B17, or B44 positive and had a higher prevalence of B44;DRB11;DQA1*0501;DQB1*0301 and isolated anti-52-kd antibodies, which were absent in SS and SLE controls. CONCLUSION Mothers of infants with CCHB presented a strong genetic similarity to mothers who had SS, except for HLA class I phenotype. HLA-DRB1*03011;DQA1*0501;DQB1*0201 seemed not to be primary CCHB-associated genes, but were involved in an SS-like anti-Ro/La response. The combined presence of HLA-DRB1*03011 and anti-52-kd SSA/Ro antibodies conveyed the highest risk of giving birth to an affected child.

α-Melanocyte-Stimulating Hormone Is Decreased in Plasma of Patients with Acute Brain Injury

The neuropeptide α-melanocyte-stimulating hormone (α-MSH) is a proopiomelanocortin derivative that has potent anti-inflammatory influences within the brain. The aim of the present research was to d...

Gene Expression Profiling Reveals Multiple Protective Influences of the Peptide α-Melanocyte-Stimulating Hormone in Experimental Heart Transplantation

Novel therapies are sought to increase efficiency and survival of transplanted organs. Previous research on experimental heart transplantation showed that treatment with the anti-inflammatory peptide α-melanocyte-stimulating hormone (α-MSH) prolongs allograft survival. The aim of the present research was to determine the molecular mechanism of this protective activity. Gene expression profile was examined in heart grafts removed on postoperative days 1 and 4 from rats treated with saline or the synthetic α-MSH analog Nle4DPhe7 (NDP)-α-MSH. On postoperative day 1, the peptide induced expression of cytoskeleton proteins, intracellular kinases, transcription regulators, metallopeptidases, and protease inhibitors. Conversely, NDP-α-MSH repressed immune, inflammatory, cell cycle, and protein turnover mediators. Later effects of α-MSH treatment included down-regulation of oxidative stress response and up-regulation of ion channels, calcium regulation proteins, phosphatidylinositol signaling system, and glycolipidic metabolism. NDP-α-MSH exerted its effects on both Ag-dependent and -independent injury. The results indicate that NDP-α-MSH preserves heart function through a broad effect on multiple pathways and suggest that the peptide could improve the outcome of organ transplantation in combination with immunosuppressive treatments.

Alteration in the transcriptional profile of livers from brain-dead organ donors

Background. There is evidence that brain death causes changes in peripheral organs. Marked inflammation is found in organs collected during experimental brain death and clinical studies indicate that, despite genetic mismatch, organs obtained from living donors show improved survival over those from brain-dead donors. The aim of the present clinical research was to explore changes in the transcriptional profile of livers from brain-dead organ donors. Methods. Using the cDNA macroarray technique, we compared gene expression in liver biopsies from 21 brain-dead organ donors and in normal liver tissue obtained during resection of benign focal lesions. Results. Analysis of gene expression showed significant differences in the mRNA levels of 117 genes. There was reduced expression of 93 genes whereas expression of 24 genes was enhanced. Downregulated pathways included transcripts related to morphogenesis, blood coagulation, complement cascade, amine metabolism, lipid metabolism, nucleic acid metabolism, biodegradation of xenobiotics, signal transduction, and transcription. Conversely, there was induction of genes related to acute phase response, damage-related response, electron transport, and energy metabolism. Conclusions. The present research demonstrates major changes in the transcriptional profile of livers from brain-dead organ donors. The presence of both down- and upregulated gene families suggests that the alteration in transcriptional profile is not a consequence of death-associated organ failure, but rather, an active change in regulatory mechanisms.

Autocrine inhibitory influences of α-melanocyte-stimulating hormone in malignant pleural mesothelioma

Malignant pleural mesothelioma is a highly aggressive tumor arising from the mesothelial cells that line the pleural cavities. This tumor is resistant to most conventional anticancer treatments and appears to be very sensitive to growth‐promoting influences of cytokines and growth factors. Identification of natural inhibitory pathways that control growth should aid discovery of novel therapeutic approaches. We hypothesized that α‐melanocyte‐stimulating hormone (α‐MSH), which is produced by many cell types and antagonizes cytokines and growth factors, could be an endogenous inhibitory molecule in mesothelioma. Twelve mesothelioma cell lines were established from pleural effusions of patients with malignant mesothelioma. Mesothelioma cells were found to express mRNA for proopiomelanocortin and its processing enzymes; release α‐MSH peptide into supernatants; and express melanocortin 1 receptor (MC1R), the high‐affinity receptor for α‐MSH. Immunoneutralization of MC1R in the cell lines enhanced expression of interleukin‐8 (IL‐8), IL‐6, and transforming growth factor‐β. These molecules promote mesothelioma proliferation and are considered therapeutic targets in this tumor. Coincubation of mesothelioma cells with synthetic α‐MSH significantly reduced cell proliferation. The present research shows an autocrine‐inhibitory circuit based on α‐MSH and its receptor MC1R. Activation of MC1R by selective peptides or peptidomimetics might provide a novel strategy to reduce mesothelioma cell proliferation by taking advantage of this endogenous inhibitory circuit.

Reduced expression of the melanocortin-1 receptor in human liver during brain death.

Objective: There is evidence that brain death has detrimental effects on peripheral organs. Clinical and experimental studies on organ donors showed marked inflammation in tissue samples of livers and kidneys collected during brain death. The inflammatory reaction is characterized by release of cytokines and inflammatory cell infiltration. Because melanocortins and their receptors are significant modulators of inflammation, we hypothesized that downregulation of melanocortin receptors during brain death could contribute to enhance inflammation. Methods: Using real-time polymerase chain reaction (PCR) analysis, we determined expression of melanocortin receptors in liver biopsies obtained from brain-dead organ donors before cold ischemia and in normal liver tissue during resection of benign focal lesions of the liver. Tissue biopsies were also analyzed for expression of intercellular adhesion molecule-1 (ICAM-1), which has a central function in inflammatory cell migration. Results: Expression of melanocortin-1 receptor (MC1R) mRNA was markedly reduced in liver samples obtained from brain-dead organ donors compared to hepatic tissue collected during resection of benign focal lesions of the liver. Conversely, expression of the adhesion molecule ICAM-1 was significantly increased in livers of brain-dead organ donors. Conclusions: Disruption of the endogenous anti-inflammatory circuit based on MC1R could contribute to tissue damage during brain death.