Giancarlo Conti

Production of monocyte chemoattractant protein-1 in amyotrophic lateral sclerosis.

The presence of activated microglia in the spinal cord of amyotrophic lateral sclerosis (ALS) patients is usually accompanied by inflammatory biochemical changes, but these are largely unexplored. Monocyte chemoattractant protein‐1 (MCP‐1) is critical for recruitment of inflammatory cells of monocytic lineage after inflammation or injury to the central nervous system. MCP‐1 concentrations were measured by an enzyme‐linked immunosorbent assay in the cerebrospinal fluid (CSF) and the serum of 27 patients with ALS and 30 patients with noninflammatory neurological diseases. In ALS, circulating MCP‐1 levels were significantly increased in the serum and particularly in the CSF. Immunoreactivity for MCP‐1 in ALS spinal cord was detected mostly in astrocytes but also in microglia, neurons, and within the vasculature of the cord. Our findings suggest a role for MCP‐1 as an important molecular mediator of the injury response in ALS. Muscle Nerve, 2005

IP-10 and MCP-1 levels in CSF and serum from multiple sclerosis patients with different clinical subtypes of the disease

Interferon-gamma-inducible Protein-10 (IP-10) and Monocyte Chemotactic Protein-1 (MCP-1) levels were measured by enzyme-linked immunosorbent assay (ELISA) in the CSF and in the serum from 74 patients affected by different clinical forms of Multiple Sclerosis (MS), including 39 patients with Relapsing Remitting (RR) MS in an active phase, 14 patients in a stable phase of the disease, 12 patients with Secondary Progressive (SP) MS and 9 patients with Primary Progressive (PP) MS. IP-10 and MCP-1 levels were also determined in 19 subjects with no neurological diseases or major systemic disorders, 18 patients with non-inflammatory neurological diseases, as well as in 15 patients with other inflammatory neurological diseases.IP-10 levels were significantly elevated in CSF and serum from RR and SP, but not PP-MS patients. On the contrary, MCP-1 levels were decreased in CSF and serum of all MS patients. CSF concentrations of IP-10 and MCP-1 did not significantly correlate neither with each other, nor with CSF mononuclear cell count, albumin quotient or CSF IgG index. No correlation between disease duration, clinical course or EDSS score and chemokine levels was found.IP-10 and MCP-1 undergo modifications in different subtypes of the disease: IP-10 levels in CSF and serum samples are markedly increased when inflammation is prominent, and not in PP--MS patients, where inflammation is less evident. MCP-1 decrease in CSF and serum from MS patients could be related to the regulation of T-cell polarization.

MCP-1 in Alzheimer’s disease patients: A-2518G polymorphism and serum levels

MCP-1 levels are increased in CSF of patients with Alzheimers disease (AD) compared with controls, suggesting a role in the development of dementia. Recently, a biallelic A/G polymorphism in the MCP-1 promoter at position -2518 has been found, influencing the level of MCP-1 expression in response to an inflammatory stimulus. The distribution of the A-2518G SNP was determined in 269 AD patients and in 203 healthy age matched controls, showing no differences between the two groups. On the contrary, a significant increase of MCP-1 serum levels in AD patients carrying at least one G mutated allele was observed. Moreover, the highest peaks of MCP-1 serum levels were present in patients carrying two G alleles. Stratifying by ApoE genotype, gender or age at onset, no differences in both allele frequency and MCP-1 serum concentration were observed. The A-2518G polymorphism in MCP-1 gene does not seem to be a risk factor for the development of AD, but its presence correlates with higher levels of serum MCP-1, which can contribute to increase the inflammatory process occurring in AD.

Fc receptor for IgG (FcR) on rat microglia

Receptor for IgG (FcR) was demonstrated on rat microglia in vivo and in vitro by immunohistochemical staining with immune complexes of horseradish peroxidase (HRP) and rabbit IgG anti-HRP. Astrocytes, oligodendrocytes and neurons did not express FcR. Microglia in culture also showed FcR-mediated agglutination and phagocytosis of IgG-sensitized erythrocytes. A radiolabelled cDNA probe for rat FcRIII hybridized with a 1.4-kb RNA band in Northern blots prepared from total RNA from rat brain. FcRIII mRNA-positive cells in rat brain, presumably microglia, were demonstrated by in situ hybridization. FcR participates in the initiation of cytotoxic responses and of phagocytosis by microglia and is therefore likely to be important in mediating immune reactions in the brain.

Macrophage infiltration and death in the nerve during the early phases of experimental diabetic neuropathy: a process concomitant with endoneurial induction of IL-1β and p75NTR

This study describes the infiltration and death of monocyte/macrophages and concomitant endoneurial expression of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) and neurotrophin receptor p75 (p75NTR) in the sciatic nerve at the early phases of experimental diabetic neuropathy induced in Lewis rats by streptozotocin (STZ) intraperitoneal injection. Immunocytochemistry and single nerve fiber immunostaining showed the presence of macrophages in diabetic nerves by weeks 2 and 3 after STZ administration, and the 15% of these cells were TUNEL positive. IL-1beta was evident in scattered macrophages, and along few isolated nerve fibers until week 5, when it became undetectable, in concomitance with complete endoneurial clearance of macrophages. p75NTR showed an up-regulation in the sciatic nerve of diabetic rats that began by week 3 after STZ administration, reached its peak by week 5, and returned then to a barely detectable level by week 6. These findings seem to indicate that macrophages and IL-1beta may be involved in the pathogenesis of diabetic neuropathy, participating not only to nerve damage but also to the promotion of an attempt of regeneration via p75NTR induction.

Inducible nitric oxide synthase (iNOS) in immune-mediated demyelination and Wallerian degeneration of the rat peripheral nervous system

The inducible isoform of nitric oxide synthase (iNOS), produces nitric oxide (NO) from l-arginine in response to inflammatory stimuli. NO sub-serves different functions from cytotoxicity to neuroprotection and triggers either necrosis or apoptosis. This study shows by Northern blot analysis that during experimental allergic neuritis (EAN), at the beginning of clinical signs, there is a transient extensive iNOS mRNA induction in nerve roots, in which morphology is mainly characterized by severe demyelination, but not in sciatic nerve, where scattered axonal degeneration is evident. Immunocytochemistry performed on teased nerve fibers and ultrastructural analysis showed that iNOS was localized in both inflammatory and Schwann cells, and the study of cell membrane permeability detected with fluorescent dyes showed a diffuse necrotic phenotype in the whole peripheral nervous system (PNS). With EAN clinical progression toward spontaneous recovery, endoneurial iNOS was rapidly down-regulated and in nerve roots almost all cells shifted their membrane permeability to an apoptotic phenotype, while necrosis persisted in sciatic nerve, until complete clinical recovery, when both root and nerve returned to normal. During wallerian degeneration following sciatic nerve transection, iNOS was undetectable in PNS, while endoneurial cell membrane had a diffuse necrotic phenotype. These data support the hypothesis that, during cell-mediated demyelination, iNOS may influence Schwann cell-axon relationship causing axonal damage and regulating endoneurial cell life and death.

p75 neurotrophin receptor induction and macrophage infiltration in peripheral nerve during experimental diabetic neuropathy: possible relevance on regeneration

In this study we examined the expression of the neurotrophin receptor p75 (p75NTR) and the activation of macrophages in the sciatic nerve of rats at different time points after the induction of diabetes with streptozotocin (STZ). Northern blot and immunocytochemical analysis showed that p75NTR was not detectable in the sciatic nerve by Week 2 after STZ treatment. At this time, single nerve fiber immunostaining using ED1 monoclonal antibody revealed that active macrophages were infiltrating the endoneurium, which had a normal morphological aspect. By Weeks 5 and 15 p75NTR mRNA and protein were induced in the endoneurium of diabetic animals. Immunocytochemical analysis of teased single nerve fibers showed that p75NTR protein was distributed uniformly along isolated fibers with no pathological evidence of axonal degeneration or myelin disruption. At this time, cells of the phagocyte lineage had already disappeared from the nerve. These data show that during experimental diabetic neuropathy, the endoneurial induction of p75NTR is localized along isolated nerve fibers showing no morphological alterations, and in time, follows the recruitment of active macrophages in the nerve, suggesting that these cells, directly or through their products, can influence p75NTR induction. This process might play an important role in STZ diabetic neuropathy, as a response to decreased levels of neurotrophins such as NGF and promoting nerve regeneration in the early phases of the disease.

CCR2-64I polymorphism and CCR5Δ32 deletion in patients with Alzheimer's disease

Monocyte chemoattractant protein-1 (MCP-1) and RANTES, as well as their related receptors, have been shown to be involved in Alzheimers disease (AD) pathogenesis. Genes for their related receptors, CCR2 and CCR5, respectively, are characterized by the presence of two polymorphisms: a conservative change of a valine with an isoleucine at codon 64 of CCR2 (CCR2-64I) and a 32-bp deletion in the coding region of CCR5 (CCR5Δ32), which leads to the expression of a nonfunctional receptor. The distribution of the CCR2-64I and CCR5Δ32 polymorphisms was determined in 290 AD patients and in 222 controls. A decreased frequency and an absence of homozygous for the polymorphism CCR2-64I were found, thus suggesting a protective effect of the mutated allele on the occurrence of AD. However, these findings must be cautiously interpreted as the overall significance was found without adjustment for multiple comparisons and is coming from the complete absence of the genotype 64I/64I in AD patients. Conversely, no different distribution of the CCR5Δ32 deletion in the two populations was shown. Stratifying by the presence of ApoE ɛ4 allele, gender or age at onset, no differences in either allele frequencies were observed.

Interleukin-1beta and interferon-gamma induce proliferation and apoptosis in cultured Schwann cells

This study reports that in Schwann cell tissue culture the administration of the two pro-inflammatory cytokines, interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma), at different dosages, singly or in combination, can induce apoptosis and/or mitosis. Schwann cell apoptosis was maximal within 24 h of stimulation with 50 U/ml of IFN-gamma, while proliferation was at its peak within 24 h with 10 U/ml IL-1 beta, and both processes decreased progressively by 48 and 72 h. Moreover, the combination of the two cytokines did not show any synergistic effect. These data can be interpreted as a possible involvement of pro-inflammatory cytokines not only in myelin disruption but also in promoting remyelination.

Production of IL-6 by human myoblasts stimulated with Aβ Relevance in the pathogenesis of IBM

Objective: To determine whether amyloid-β protein (Aβ) can induce the production of proinflammatory cytokines by cultured normal muscle cells. Background: Sporadic inclusion body myositis (IBM) is characterized by the presence of rimmed vacuoles and fibrillary inclusions of Aβ in muscle fibers, and often inflammatory cells. Endomysial expression of proinflammatory molecules has suggested an ongoing immune process, but the site of sensitization and the mechanisms that trigger an inflammatory reaction is unknown. Method: The authors used Northern blot analysis and specific immunoassays to study the expression and secretion in cell-free supernatants of tumor necrosis factor-α (TNFα), interleukin-1β (IL-1β), and interleukin-6 (IL-6) by purified human myoblasts and C2C12 mouse skeletal muscle cells incubated with Aβ[1-42] or Aβ[25-35] peptides. Results: Nonstimulated muscle cells produced detectable IL-6, whereas secretion of IL-1β and TNFα was absent. Incubation with Aβ peptides increased IL-6 production, whereas TNFα and IL-1β levels remained undetectable. Northern blot analysis of Aβ-stimulated human myoblasts revealed an increase in IL-6 mRNA expression. Conclusions: Cultured muscle cells increase the constitutive production of IL-6 in response to local deposition of Aβ in sporadic IBM. IL-6 could be a CD8+ proliferation and differentiation agent, an autocrine proteolysis-inducing factor of damaged myotubes, and a proliferation-stimulating agent for satellite cells to replace the destroyed myofibers in IBM.