Unraveling a new player in multiple sclerosis pathogenesis: The RNA-binding protein HuR.

BACKGROUND: ELAV-like proteins are a small family of RNA-binding proteins that are fundamental players in post-transcriptional mechanisms and are involved in the pathogenesis of neurologic and psychiatric disorders. HuR, the ubiquitously expressed member of the family, is also implicated in sustaining inflammation and inflammatory diseases, supporting the production of pro-inflammatory cytokines. Inflammation plays a central role in Multiple Sclerosis (MS), which represents the most common cause of permanent physical disability in young adults. MS is a chronic autoimmune disease affecting the Central Nervous System, with a complex aetiology involving genetic, environmental and epigenetic factors. No data are available on the potential entanglement of HuR in MS pathogenesis in patients. In the present work, we aimed at exploring HuR protein levels in peripheral blood mononuclear cells (PBMCs) from MS patients, compared to healthy controls. To further elucidate the possible involvement of HuR in MS, we also investigated the relationship between this specific RNA-binding protein and HSP70-2 protein, also considering the HSP70-2 rs1061581 polymorphism, given that HSP70-2 mRNA has been reported as a HuR target and this specific polymorphism to be associated with MS risk. METHODS: Alleles and genotypes for HSP70-2 rs1061581 polymorphism were assessed, by using a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism, followed by digestion with restriction enzyme, in MS patients and healthy controls. PBMCs from a subgroup of patients and controls were used to evaluate HuR and HSP70-2 protein content by Western blot. RESULTS: PBMCs from 52 MS patients had a lower HuR and higher HSP70-2 protein content compared to 43 healthy controls. An increase of 100 units of HuR significantly decreased the risk of developing MS by 9.8% (OR: 0.902, 95% CI: 0.83-0.98), controlling for HSP70-2 protein expression, HSP70-2 rs1061581 genotype, age and sex. Moreover, holding HuR levels, an increase of 100 units of HSP70-2 protein significantly increased the MS risk by 18.1% (OR: 1.181, 95% CI: 1.03-1.36) and the genetic susceptibility of developing MS for HSP70-2 rs1061581 GG carriers is confirmed. Of interest, MS patients with a moderate to severe form of MS (MSSS ≥ 3) showed a trend towards a reduction of HuR protein levels compared to patients with mild disease severity (MSSS < 3). CONCLUSIONS: HuR protein levels are reduced in MS patients compared to healthy subjects, and the protein amount may continue to decline with disease progression, suggesting a putative role of this RNA-binding protein. Moreover, our results suggest that MS pathology may have disrupted the link between HuR and its target transcript HSP70-2. It will be important to further explore the exact role of HuR in MS, considering the complex interplay with other RNA-binding factors and target mRNAs.

The Possible Involvement of HLA Class III Haplotype (RAGE, HSP70 and TNF Genes) in Alzheimer's Disease.

In the central nervous system Hsp70s seems to have a protective role in repair and removal of cellular proteins damaged by stress conditions. A protective role of Hsp70 was also shown in Alzheimer Disease. The HSP70-1 +190 G/C polymorphism is located in the gene 5'UTR region and it is implicated in alteration of the transcription binding factor; HSP70-2 +1267 A/G causes a silent mutation in the coding region and it seems to influence the mechanism of mRNA translation; HSP70-hom +2437 A/G causes a substitution Met → The (M493T) in the coding region and it seems to influence the bond with the substrate and therefore on the chaperone activity of hsp70. The aim of our study will be to investigate Alzheimer susceptibility to Hsp70 polymorphisms, taking into account our previous findings on HLA class III region, and to hypothesize a role of HLA class III haplotype configuration based on the variants of three genes: RAGE, HSP70 and TNF. We studied these polymorphisms with PCR-RFLP and PCR-TSP. We investigated 173 AD patients and 211 control subjects. Our results have shown a statistically significant decrease of the C allele frequency of the HSP70-1 +190 G/C polymorphism in AD patients vs controls (P value = 0,018), as well as the G allele of HSP70-2 +1267 G/A (p value = 0,02). We focalized our attention on haplotype reconstruction. We have observed a significant statistically decrease of GGT haplotype frequency (empirical p-value=0.0133 ); GAT haplotype was statistically significant increase in AD patients compared with control (empirical p-value=0.007). The total HLA class III haplotype are reconstructed. The causative haplotypes are the following ones: TTGATGGG ( p value =0,005; empirical p =0,0042); TTGATAGG (p value =0,45; empirical p =0,034). Patients with these haplotypes may show an earlier onset of the disease than patients with TTGGTGGG (p value=0,0138; empirical p =0,0102); TTCGTGGG (p value=0,021; empirical p =0,017); TTCGTGGA (p value =0,058; empirical p =0,043) haplotypes. The overall variation of the haplotypes formed by the RAGE and TNF and HSP70 variants influenced the presence of the AD phenotype (omnibus association LR test p-value 0.00185), HSP701 and HSP702 showed independent effect on AD risk after adjusting for the effect of the entire haplotype (conditional LR test p-value=0.0114 and p-value=0.0044 respectively). These data confirm the involvement of HLA class III in AD.

HLA class III genes involvement in Kawasaki disease: a case-control study in Caucasian population.

Kawasaki disease (KD) is an acute, multisystemic, febrile vasculitis of unknown aetiology, which affects young children mainly under 5 years of age. The clinical variability has until now prevented to decrypt KD aetiological factors. Recently, the importance of genetics and the pivotal role of the immune system have emerged. To investigate in this direction, genomic DNA from 74 Caucasian KD cases and 440 healthy controls has been analysed to characterize functional polymorphisms of relevant HLA class III genes: AGER -429 and -374, TNF -857, -308 and -238, HSPA1A +190, HSPA1B +1267 and HSPA1L +2437. Allele, genotype and haplotype frequencies were therefore compared with the chi-squared test and Fisher's exact test. Our data showed significant deviations between patients with Kawasaki disease and controls concerning the TNF -308 polymorphism genotype (GG: P = 0.0449) and allele (G,A: P = 0.0433) and -238 polymorphism genotype frequencies (AA: P = 0.0351). Moreover, we found differences concerning the HSPA1A +190 polymorphism (GC: P = 0.0317) and the HSPA1L +2437 polymorphism (TT: P = 0.0072; TC: P = 0.0250; T: P = 0.0037; C: P = 0.0037). The calculation of TNF -238 and HSPA1L haplotype frequencies also pointed out a statistically significant decrease in patients of CG haplotype (P = 0.0001), which could have a role in protecting from the inflammatory processes that characterize the disease progression. The results obtained point to a possible involvement of the entire HLA class III region in KD susceptibility.

The human leukocyte antigen class III haplotype approach: new insight in Alzheimer's disease inflammation hypothesis.

The Alzheimer's disease "inflammation hypothesis" has emerged only recently, suggesting the risk of developing AD might be influenced by variants of genes encoding for inflammatory mediators. In order to investigate in this direction, genomic DNA from 194 Italian AD cases and 454 healthy controls matched by gender and ethnicity was analyzed for the Receptor for Advanced Glycation End products (RAGE, HLA class III-centromere portion) -374 and - 429 SNPs and for the Tumor Necrosis Factor-alpha (TNF-α, HLA class III-telomere portion) -857, -308 and -238 SNPs by RFLP and Real Time PCR. Our data show statistically significant deviations between AD patients and healthy controls concerning RAGE -374 SNP genotype (TT: p=0.0084) and allele (T, A: p=0.0081) frequencies; TNF-α -308 SNP AA genotype (p=0.0433) and TNF-α -238 SNP genotype (GG: p=0.0138) and allele (G, A: p=0.0151) frequencies. Furthermore, significant differences between the study groups and regarding RAGE TC (p=0.05) and AC (p=0.009) haplotypes are present, while TNF-α haplotype reconstruction point out a statistically significant difference between patients and controls regarding AGG haplotype (p=0.002). Finally, from the combination of the individually significant SNPs of the two genes (RAGE -374, TNF-α -238 and -308) we performed an HLA class III haplotype reconstruction finding significant differences between AD subjects and controls regarding the TAG (p=0.019) and TGA (p=0.008) haplotypes. The implication of these haplotypes with the disease points to a possible involvement of entire HLA class III region in AD susceptibility.

Excess of activating killer cell immunoglobulin­like receptors and lack of HLA-Bw4 ligands: a two­edged weapon in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is an inflammatory disease of unknown aetiology. Researchers have proposed infectious, neurological and immunological causes of this syndrome. Recently, the xenotropic murine leukemia virus-related virus was detected in 67% of patients with CFS in a US study. This observation is in agreement with one ascertained aspect of the disease: a decreased efficiency in NK cell lytic activity in CFS patients. Here, we analyzed the genomic polymorphism of killer cell immunoglobulin-like receptors (KIRs) and their HLA class I cognate ligands in patients with certified CFS. An excess of KIR3DS1 was found in CFS patients with respect to controls, as well as an increased frequency of the genotype missing KIR2DS5. Forty-four CFS patients and 50 controls also underwent genomic typing for the HLA-ligands. In the patients, a great proportion of KIR3DL1 and KIR3DS1 receptors were found to be missing their HLA-Bw4Ile80 binding motif. We hypothesize that an excess of KIR3DS1, combined with an excess of ligand-free KIR3DL1 and KIR3DS1 receptors, may hamper the clearance of a pathogen via NK cells, thus favouring the chronicity of the infection.

Autoantibodies, polymorphisms in the serotonin pathway, and human leukocyte antigen class II alleles in chronic fatigue syndrome: are they associated with age at onset and specific symptoms?

This study aimed to determine the influence of autoantibodies, polymorphisms in the serotonin pathway, and human leukocyte antigen (HLA) class II genes on age at chronic fatigue syndrome (CFS) onset and symptoms. Eighty-one CFS patients were enrolled, and clinical data were recorded. Autoantibodies to different components of the central nervous system were tested. Polymorphisms in the promoter of the serotonin transporter gene (l/s) and a single nucleotide polymorphism in the serotonin receptor-2A gene (A/G) as well as HLA class II alleles were determined. Multivariate logistic-regression analyses were carried out. The mean age at CFS onset +/- SD was 33.5 +/- 12.5 years. An age at CFS onset (ACFSO) during the third decade of life was associated with the serotonin receptor AA genotype and the HLA-DRB1*03 allele. An ACFSO during the fourth decade of life was associated with the HLA-DRB1*07 allele, whereas an ACFSO > or = 43 years was associated with having at least one copy of the serotonin G allele. Concerning CFS symptoms, the serotonin AG genotype was protective against depressive symptoms. Although having at least one copy of the serotonin A allele and being female were associated with risk for arthralgia, the presence of antineuronal cell antibodies was protective against this. Episodes of unexplained fever were associated with the HLA-DRB1*11 allele. None of the genetic or serological features was associated with myalgia. None of the antibodies determined correlated with any ACFSO or other symptoms. Our results reveal that in CFS, like other autoimmune diseases, different genetic features are related to age at CFS onset and symptoms.

Expression of receptor for advanced glycation end products in sarcoid granulomas.

RATIONALE: The receptor for advanced glycation end products (RAGE) engages a number of ligands implicated in inflammatory processes. The RAGE coding gene maps to the 6p21.32 region, close to the genes DRB1 and BTNL2, which are associated with sarcoidosis. OBJECTIVES: We investigated a possible implication of RAGE in sarcoid granulomas. METHODS: RAGE and major ligands (N-epsilon-carboxy-methyl-lysine [CML], S100A12, and S100B) expression was investigated by immunostaining of 99 paraffin-embedded biopsies of sarcoid tissues, and expression patterns were determined. Among the three RAGE gene single-nucleotide polymorphisms investigated, -374 T/A was selected, characterized in terms of transcriptional effect (immunocytochemistry and real-time polymerase chain reaction), and its frequency was determined in DNA extracted from biopsies. MEASUREMENTS AND RESULTS: RAGE, CML, S100A12, and S100B immunoreactivity was observed in all sarcoid granulomas, although at different intensities. The degree of RAGE expression significantly correlated with the degree of S100A12 expression. The -374 TT/AT genotypes, associated with higher RAGE transcriptional activity, were more frequent in the sarcoidosis biopsy group than in control subjects, and the association was confirmed in a second, independent series of 101 patients with sarcoidosis. CONCLUSIONS: We showed the association of RAGE and its ligands with sarcoidosis and suggest that an intrinsic genetic factor could be in part involved in its expression. In Italian patients, the -374 T/A polymorphism seems to be significantly associated with this disease.

Specific polymorphisms of cytokine genes are associated with different risks to develop single-system or multi-system childhood Langerhans cell histiocytosis.

Cytokines and chemokines determine mobilisation of Langerhans cells and their dysregulation is implicated in the pathogenesis of Langerhans cell histiocytosis (LCH). Twenty point mutations of 12 different cytokine genes were studied in 41 Italian children, 15 with single-system (SS) and 26 with multi-system disease. The allele and genotype distributions of interleukin-4 (IL-4) and interferon-gamma (IFNgamma) were significantly different in patients vs. 140 controls (P = 0.007, and P = 0.018). Older children with single-system disease shared the 'anti-inflammatory profile' determined by the intermediate producer genotype IFNgamma +874A/T (P = 0.029) and the high-producer genotypes IL-4 -590C/T and T/T (P = 0.029). Our findings suggest that specific cytokine gene variants affect susceptibility to LCH and its clinical heterogeneity.

-374T/A polymorphism of the RAGE gene promoter in relation to severity of coronary atherosclerosis.

BACKGROUND: We have recently reported that homozygosity for the minor A-allele of RAGE (receptor for advanced glycation end products) -374T/A polymorphism may exert a protective effect toward the development of angiographic coronary artery disease (CAD). Here we focused on the putative involvement of this functional RAGE polymorphism on the severity of coronary atherosclerosis as assessed by angiography. METHODS: In a total of 234 consecutive Caucasian patients with angiographically proven CAD, the severity of coronary atherosclerosis was assessed by the number of diseased vessels (greater than 50% stenosis). Genotyping for the -374T/A variant was performed by means of PCR-RFLPs. RESULTS: The mean number of diseased vessels was significantly lower in patients with the AA genotype (1.47+/-0.68) than in those with the AT or TT genotype (1.88+/-0.82, p=0.029). After confounding variables were controlled for, the number of diseased vessels remained significantly different in the AA genotype carriers from that in the AT or TT carriers (p=0.041, ANCOVA). CONCLUSIONS: Our data suggest that the RAGE -374T/A polymorphism is one of the likely candidate determinants for the genetic variance of disease phenotype in coronary atherosclerosis.

[Chronic fatigue syndrome: a review]. / La sindrome da stanchezza cronica.

Chronic fatigue sindrome is a relatively unknown and underdiagnosed entity in Italy where its epidemiology remains uncertain, as well as its etiology, although it causes important disability in those affected. Classification criteria by Fukuda are available to diagnose the syndrome. Its epidemiology indicates that it is probably more frequent in Northern countries and it is described in Gulf War veterans. Etiological hypotheses include infectious diseases, immunology and neurology. Among these hypotheses sickness behavior mimes certain aspects of this syndrome and is characterized by a cytokine imbalance in the central nervous system and in the periphery. There are no valid therapies available at the moment. In the laboratory of Immunogenetics, we are constituting a biological bank of the syndrome to study the immunogenetic aspects of the disease in the hope of delucidating some of the obscure areas of its etiopathogenesis.

Relationship between the -374T/A RAGE gene polymorphism and angiographic coronary artery disease.

The receptor for advanced glycation end products (RAGE) is thought to play a critical role in diabetic atherosclerosis. Accordingly, a functional -374T/A polymorphism in RAGE gene promoter has been associated with macrovascular complications in type 1 diabetic patients. However, the extent to which this common variant influences the risk of coronary artery disease (CAD) in the general population remains to be determined. We genotyped the -374T/A RAGE polymorphism in 259 non-diabetic individuals, of whom 175 had angiographically documented coronary artery disease (CAD patients) and 84 had normal coronary angiography (CAD-free control subjects). Homozygosity for the -374A allele was found in 9.7% of the CAD patients versus 22.6% of the CAD-free subjects (p=0.005). By means of a multiple logistic regression analysis, the AA genotype of the -374T/A polymorphism was shown to be independently associated with a reduced risk of CAD (adjusted odds ratio 0.33, 95% CI 0.15 to 0.73; p=0.006). Our observations suggest that the -374T/A polymorphism of the RAGE gene may reduce susceptibility to CAD, thus exerting a protective effect on coronary risk. Future pathophysiological studies may be worthwhile to clarify the mechanisms behind this association.

Evaluation of gene expression in human lymphocytes activated in the presence of melatonin.

The effect of melatonin on the expression of genes previously correlated to T lymphocyte activation (HLA-DRB, thymosin beta 10 (beta-Tim)) and to Lymphokine Activated Killer (LAK) activity (beta-Tim, Tumour Rejection Antigen (TRA 1), nRap 2) was investigated in phytohemagglutinin (PHA)-stimulated human lymphocyte cultures. The aim was to find an enhancing effect of this substance on anti-tumoral immune defences as suggested by studies on tumour progression in mice and clinical immunotherapy trials in humans. mRNA obtained from melatonin-treated and -untreated PHA-stimulated lymphocytes was retrotranscribed and amplified by RT-PCR using primers based on the sequences of the selected genes. The results suggest that melatonin does not increase T and LAK cell responses: in fact, a reduction in the transcription of all the considered genes was observed. These data are correlated with the antiproliferative effect of melatonin observed in in vitro treated lymphocytes.

HLA and sarcoidosis: new pathogenetic insights.

Many theories have been presented to account for the immunological and epidemiological features of sarcoidosis; several lines of study support the prevailing opinion that an environmental agent, possibly microbial in origin, may cause sarcoidosis in a genetically predisposed host. Many polymorphic genes have been suggested to contribute to this genetic susceptibility: genes encoding angiotensin converting enzyme, vitamin D receptor, and interleukin-1, T-cell receptor genes, Gm and Km immunoglobulin genes and, most relevant, HLA genes (classical and non classical). There is also some evidence of an HLA-associated protection against sarcoidosis. The main action of disease-associated HLA molecules is to present specific antigenic peptides in such a way that the recognizing T-lymphocytes initiate an inflammatory response with peculiar pathological consequences. Other, so-called, non-classical HLA genes coding for proteins involved in antigen processing and presentation, namely TAP, LMP and DM, seem to contribute. Particular alleles of the tumor necrosis factor gene cluster (TNFA, LTA, LTB) are known to be associated with peculiar clinical forms of sarcoidosis. For instance, Löfgren's syndrome, which is an acute form of pulmonary sarcoidosis with frequent spontaneous remission, is marked by the TNFA*2, HLA-DR3 haplotype. How many HLA genes are involved is still unknown, but it is now clear that the HLA region is strongly implicated in the development of sarcoidosis. Probably, the future lies in isolating and sequencing the putative peptide bound to susceptible MHC molecules which, activating reactive T-cells, is responsible for disease initiation and/or exacerbation. However, the investigative approach should not be confined only to genomic sequences: the temporal and spatial expression of gene products, the post-transcriptional modification of the protein products will be fundamental in determining the basic functional context of developing sarcoidosis.

No evidence of autoimmunity in 6-year-old children immunized at birth with recombinant hepatitis B vaccine.

OBJECTIVES: Taking into account that genetic predisposition, marked by human leukocyte antigen (HLA) class I and II genes, augments the probability of developing an autoimmune disorder after a triggering vaccination, as largely debated, we investigated the frequency of autoantibody production after recombinant hepatitis B vaccine (rHBv) in 6-year-old children immunized at birth to evaluate an association between autoimmune disorders and hepatitis B virus vaccination. METHODS: We investigated the presence of autoantibodies in 210 6-year-old children who were immunized at birth with rHBv: 200 showed anti-hepatitis B surface antigen concentrations > or =10 mUI/mL at seroconversion (responders), and 10 were nonresponders. Data were compared with those obtained in 109 unvaccinated children. All participants were screened for the presence of antinuclear antibodies (ANAs), anti-DNA, antimitochondrial, anti-liver/kidney microsomal, antireticulin, anti-smooth muscle (SMA), and antiribosomal antibodies. All participants were also screened for the presence of antithyroid antibodies, such as antithyroglobulin and antiperoxidase, and for antibodies found in type 1 diabetes, such as tyrosine phosphatase (IA-2A) and glutamic acid decarboxylase (GADA). HLA typing was extended to all 10 nonresponders. RESULTS: Autoantibodies were found in 16 of the 200 responders: ANAs were found in 12 (6%), smooth muscle antibodies were found in 4 (2.0%), and antireticulin antibodies and endomysial antibodies were found in 1 girl with ANAs. Antithyroid antibodies, IA-2A, and GADA were not present in any of the participants. No significant difference was found in the frequency of autoantibodies between vaccinated and control children. Three of the 10 nonresponder children were SMA-positive (30% vs 2% of responders); they also carried the supratype HLA-C4AQ0,DRB1*0301,DQB1*02. A family history for autoimmune disorders was present in 3 (18%; 95% confidence interval [CI]: 4.0%-45.6%) of the 16 responder infants with autoantibodies, in 15 (8.4%; 95% CI: 4.6%-13.1%) of responder children without autoantibodies, and in 1 (10%) of the 10 nonsreponder children. CONCLUSIONS: From our data, vaccination with rHBv given during the neonatal period does not seem to increase autoantibody production in a 6-year-old children. Autoantibodies, referred to as natural autoantibodies, can be found in healthy participants, but their significance is unclear. These autoantibodies often cross-react with bacteria or tumor antigens, suggesting their importance in innate immunity. It has been demonstrated in an animal model that self-antigen can promote B-cell accumulation, and that a significant proportion of natural autoantibodies is the product of this self-antigen- dependent process. Consequently, it has been speculated that self-antigens play a positive role in recruiting B cells as a part of innate immunity, but this process carries a potential risk for unregulated growth. Spreading of the immune response is a common theme in organ-specific and systemis autoimmune diseases, and this could be initiated by exogenous agents, in genetically susceptible hosts, owing to molecular mimicry of natural antigen. Moreover, 3 (18%) of the 16 children who had autoantibodies had a family history of autoimmume diseases. Thus, it is apparent that susceptibility to autoimmunity is determined by genetic factors rather than by vaccine challenge. Among all the children considered, only 1 girl (0.5%) developed celiac disease, reflecting the prevalence described in the literature. GADA and IA-2A were not found in our children; this observation is in agreement with data showing that type 1 diabetes risk may not be altered by vaccinations administered during childhood. On the contrary, a high frequency (30%) of autoantibodies, in particular SMA, was observed in the nonresponder children. The 3 SMA-positive children carried the HLA-C4Q0,DRB1*0301,DQB1*02 haplotype, a well-known predisposing factor for autoimmune disorders. On the other hand, the presence of autoantibodies to smooth muscle is known to be common in hepatitis B infection, and, it has been shown that cross-reactive immunity targeting homologous self-protein may partly account for autoantibody production. Although hepatitis B vaccination given during the neonatal period does not increase autoantibody production in 6-year-old immunized children, we deem useful a more prolonged follow-up for these nonresponder children carrying certain HLA haplotypes (such as C4AQ0,DRB1*0301,DQB1*02), particularly because most autoimmune diseases do not develop until later in life.