Antonio López-Vázquez

Interaction between ERAP1 and HLA-B27 in ankylosing spondylitis implicates peptide handling in the mechanism for HLA-B27 in disease susceptibility

Ankylosing spondylitis is a common form of inflammatory arthritis predominantly affecting the spine and pelvis that occurs in approximately 5 out of 1,000 adults of European descent. Here we report the identification of three variants in the RUNX3, LTBR-TNFRSF1A and IL12B regions convincingly associated with ankylosing spondylitis (P < 5 × 10−8 in the combined discovery and replication datasets) and a further four loci at PTGER4, TBKBP1, ANTXR2 and CARD9 that show strong association across all our datasets (P < 5 × 10−6 overall, with support in each of the three datasets studied). We also show that polymorphisms of ERAP1, which encodes an endoplasmic reticulum aminopeptidase involved in peptide trimming before HLA class I presentation, only affect ankylosing spondylitis risk in HLA-B27–positive individuals. These findings provide strong evidence that HLA-B27 operates in ankylosing spondylitis through a mechanism involving aberrant processing of antigenic peptides.

NKG2D ligands: key targets of the immune response.

NKG2D is an activating receptor expressed by NK and T cells. NKG2D ligands show a restricted expression in normal tissues, but they are frequently overexpressed in cancer and infected cells. The binding of NKG2D to its ligands activates NK and T cells and promotes cytotoxic lysis of the cells expressing these molecules. The mechanisms involved in the expression of the ligands of NKG2D play a key role in the recognition of stressed cells by the immune system and represent a promising therapeutic target for improving the immune response against cancer or autoimmune disease. In this review, we analyse the recent advances in understanding the regulation of NKG2D ligand expression and their therapeutic implications.

TNF-α− 308A promoter polymorphism is associated with enhanced TNF-α production and inflammatory activity in Crohn's patients with fistulizing disease

OBJECTIVE:Tumor necrosis factor-α (TNF-α) plays a key role in the inflammatory response and pathogenesis of Crohns disease (CD). TNF-α− 308A polymorphism within the TNF-α gene promoter has been associated with enhanced TNF-α production in vitro. The aim of this study was to investigate the effect of TNF-α promoter polymorphism at −308 on the susceptibility and phenotypic expression of fistulizing CD.METHODS:The distribution of −308 TNF-α genotypes was analyzed in 50 patients with fistulizing CD and 100 healthy matched controls. TNF-α, interleukin-1β, and interleukin-6 serum levels were measured by ELISA. Serum amyloid-A, C-reactive protein, α1-antitrypsin, α1-acid glycoprotein, and haptoglobin were measured by nephelometry.RESULTS:No significant differences were found in the allele frequencies of the polymorphism between patients and controls. However, compared with −308GG patients, those carrying −308AG had a significant increase of serum levels of TNF-α (58 ± 79 vs 8 ± 19 pg/ml, p < 0.001), interleukin-1β (36 ± 45 vs 16 ± 20 pg/ml, p = 0.048), and acute phase proteins (APPs). −308A carriers had also a higher frequency of arthritis (66% vs 26%, p = 0.039). The logistic regression model showed that the patients carrying −308A polymorphism had a relative risk for developing arthritis of 5.45 (95% CI = 1.1–25.6). No other clinical or analytical findings were predictive for the risk of development of arthritis.CONCLUSIONS:TNF-α− 308A polymorphism is associated with enhanced TNF-α production, more intense inflammatory activity, and an increased risk for arthritis susceptibility in CD patients with fistulizing disease.

Protective Effect of the HLA-Bw4I80 Epitope and the Killer Cell Immunoglobulin-Like Receptor 3DS1 Gene against the Development of Hepatocellular Carcinoma in Patients with Hepatitis C Virus Infection

The aim of the present study was to investigate, in 152 Spanish patients infected with hepatitis C virus (HCV), the possibility that killer cell immunoglobulin-like receptors (KIRs) influence progression to hepatocellular carcinoma. KIRs are related to the activation and inhibition of natural killer cells and may play an important role in the innate response against infection with such viruses as HCV. We found that the human leukocyte antigen-Bw4I80 epitope and the KIR3DS1 gene were more frequent in HCV carriers than in patients with hepatocellular carcinoma. Moreover, these associations were not independent of each other--the KIR3DS1/Bw4I80 genotype clearly was also more frequent in HCV carriers (odds ratio, 24.22).

Polymorphism in MICA rather than HLA-B/C genes is associated with psoriatic arthritis in the Jewish population

The aim of this study was to examine whether the association of psoriatic arthritis (PsA) with human leukocyte antigen (HLA) class I genes is secondary to linkage disequilibrium with a nearby gene. We examined a sample of the Jewish population to investigate whether HLA-B/C and DR polymorphism is associated with susceptibility, or whether other closely related class I loci, such as the major histocompatibility complex class I chain-related gene A (MICA) and tumor necrosis factor (TNF), might play a role in disease development. Comparisons of different populations with different HLA profiles would be of value in identifying the candidate genes involved in PSA. Fifty-two patients with PsA and 73 random matched controls from a Jewish population were selected and DNA typed by polymerase chain reaction-single-strand oligonucleotide probe (PCR-SSOP) (HLA-C), PCR sequence-specific primers (PCR-SSP) (HLA-B, -DR), radioactive PCR (MICA-TM polymorphism in the transmembrane region), and PCR-RFLP (TNF). Some findings can be concluded from the study: (1) the frequency of HLA-B*5701, B*3801, B*39, B*27, Cw*0602, Cw*07, DRB1*0402, and DRB1*0701 were not found to be significantly increased in PsA; (2) no significant differences of TNFalpha promoter alleles at positions -308 and -238 were found between PsA and healthy controls; (3) the trinucleotide repeat polymorphism MICA-A9 was present at a higher frequency in PsA patients, (p(c) < 0.009, RR = 3.34, EF = 0.39); and (4) MICA-A9 polymorphism was found in linkage disequilibrium with HLA-B alleles (B*5701, B*3801) described to be associated with PsA in Caucasians. These results suggest that the MICA gene or other nearby gene(s) may be involved in the development of PsA, and it would thus appear that psoriasis vulgaris (PsV) and PsA are associated with different MHC susceptibility genes.

High serum tumor necrosis factor-α levels are associated with lack of response to infliximab in fistulizing Crohn’s disease

OBJECTIVES:Infliximab, a chimeric monoclonal antibody directed against tumor necrosis factor-α (anti-TNF-α), has been effective in the treatment of patients with active Crohns disease and with fistulas. We investigated the effect of infliximab on circulating cytokines and acute phase proteins in patients with fistulas to determine the clinical response to anti-TNF-α.METHODS:A total of 36 patients with fistulizing Crohns disease were selected for study. Serum from patients was drawn before the infusion on day 0 and at wk 2, 4, 6, 8, and 10 after completion of treatment. Circulating concentrations of TNF-α, interleukin-1β (IL-1β), and IL-6 were measured by ELISA. The functional activity of circulating TNF-α was assessed by the WEHI 164 TNF-α bioassay. Acute phase proteins were also determined.RESULTS:Elevated TNF-α, IL-1β, IL-6, and acute phase proteins were observed in patients with Crohns disease. Of the patients with fistulas, 22 (61.1%) responded to treatment. Before receiving infliximab, higher levels of serum TNF-α were found in patients who did not respond to infliximab compared with those who did (median interquartile range 26, 0–245 pg/ml; n = 14 vs 0, 0–22 pg/ml, n = 22). Patients showed no change in circulating levels of TNF-α during the course of the study.CONCLUSIONS:This treatment produces a clinical improvement in about two-thirds of CD patients with fistulas. The circulating levels of TNF-α are associated with the response to infliximab and could help to identify patients who would benefit from anti-TNF-α treatment.

Relationship between functional ability in older people, immune system status, and intensity of response to CMV.

Shorter survival in the elderly has been associated with deterioration of the immune system and also with functional disability. To analyze the relationship between functional and immune impairment in older individuals, we studied 100 elderly who lived in a nursing home, were age matched, and grouped according to their functional status. We characterized cell subpopulations by flow cytometry, quantified TREC by RT–PCR, and measured the T-cell proliferation and activation response (IFN-γ by ELISPOT, CD69) against anti-CD3 and CMV. Specific antibody titers against influenza virus and CMV were determined by ELISA. Individuals with worse functional status had significantly higher levels of NK cells and fewer B cells. These poorly functioning elders also had a significantly lower proportion of CD4+ T cells, increased CD8+ T cells, and a decreased CD4/CD8 ratio. TREC levels in CD4+ T cells were significantly lower in individuals with a high disability. Lower TREC levels correlated with a lower frequency of naïve T-cell subpopulations (CD45RA+CCR7+) and higher percentages of effector cells (CD45RA−CCR7−). The functionally impaired group had lower anti-CD3 responses, but gradually increased responses against CMV. Similarly, the higher CMV titers were found in elderly with worse functional status. On the contrary, the functional response in vivo, and the titer of antibodies generated after vaccination against influenza virus, was higher in individuals with better performance status. In summary, we concluded that the functional decline of elderly individuals was clearly associated with the aging of their immune system, and the intensity of the response to CMV.

Cd8dim and Nkg2d Expression Defines Related Subsets of Cd4+ T cells in Hiv-infected Patients With Worse Prognostic Factors

The past several years have seen substantial developments in the use of alternative specimens for drug analysis. The use of oral fluid has been found to offer significant promise when detection of relatively recent use of drugs is sought in a relatively noninvasive manner. Although there are a number of factors that affect drug concentration in oral fluid, there appears to be a reasonable correlation between blood and oral fluid concentrations of drugs. Collection techniques can artificially affect production of oral fluid and its subsequent pH. These need to be understood, as does local absorption of drug, in situations where drug may be present in the oral cavity (eg, smoking or sublingual absorption). Nevertheless, it is essential that devices used to collect oral fluid are checked to ensure reasonable stability and recovery of absorbed drug. The most common applications include workplace testing for drugs of abuse, particularly post-incident, and roadside detection of illicit drugs. Therapeutic drug monitoring has been shown to be useful for a number of drugs that have traditionally been measured in plasma/serum.CD4+ T lymphocytes expressing CD8dim (DP: CD4+ CD8dim) or NKG2D represent cytotoxic effector populations, which have been involved in viral infections and chronic diseases. The frequency of DP cells was analyzed by flow cytometry in 300 consecutive HIV-infected patients and 50 healthy controls. NKG2D expression and memory/effector markers in CD4+ T cells were also studied, in addition to virologic and genetic factors involved in DP T-cell expansion. HIV-infected patients showed a significantly higher frequency of DP cells than controls, mainly in patients with advanced disease. Expansion of DP cells was related to NKG2D appearance in CD4+ T cells and was predicted by CD4+ CD28null T-cell levels. Cells expressing CD8dim and NKG2D+ cells are closely related populations with a similar pattern of surface markers, perforin expression, and responses to activation. We also found that these subsets seem to share an ontogenic relationship and TcR oligoclonality. In this way, cytomegalovirus infection and certain HLA alleles, such as DR7, conditioned the expansion of DP cells. Their common ontogenic origin and oligoclonality, possibly due to repeated encounters with the same antigen, could result in a limitation of the repertoire of responder cells and in a worse prognosis of HIV infection.

Contribution of KIR3DL1/3DS1 to ankylosing spondylitis in human leukocyte antigen-B27 Caucasian populations

Killer cell immunoglobulin-like receptors (KIRs) and humaAn leukocyte antigen (HLA) loci are both highly polymorphic, and some HLA class I molecules bind and trigger cell-surface receptors specified by KIR genes. We examined whether the combination of KIR3DS1/3DL1 genes in concert with HLA-B27 genotypes is associated with susceptibility to ankylosing spondylitis (AS). Two HLA-B27-positive Caucasian populations were selected, one from Spain (71 patients and 105 controls) and another from the Azores (Portugal) (55 patients and 75 controls). All were typed for HLA-B and KIR (3DS1 and 3DL1) genes. Our results show that in addition to B27, the allele 3DS1 is associated with AS compared with B27 controls (p < 0.0001 and p < 0.003 in the Spanish population and Azoreans, respectively). We also observed that the association of KIR3DS1 to AS was found in combination with HLA-B alleles carrying Bw4-I80 in trans position in the Spanish population (30.9% in AS versus 15.2% in B27 controls, p = 0.02, odds ratio (OR) = 2.49) and in Azoreans (27.2% in AS versus 8.7% in B27 controls, p = 0.01, OR = 4.4 in Azoreans). On the other hand, 3DL1 was decreased in patients compared with B27 controls (p < 0.0001 in the Spanish population and p < 0.003 in Azoreans). The presence of this allele in combination with Bw4-I80 had a protective effect against the development of AS in the Spanish population (19.7% in AS, 35.2% in B27 controls; p = 0.03, OR = 0.45). The presence of KIR3DS1 or KIR3DL1 in combination with HLA-B*27s/HLA-B Bw4-I80 genotypes may modulate the development of AS. The susceptibility to AS could be determined by the overall balance of activating and inhibitory composite KIR-HLA genotypes.

HLA-B27 alone rather than B27-related class I haplotypes contributes to ankylosing spondylitis susceptibility

Characterization of non-B27 susceptibility genes will be required to know the pathogenesis of AS. The aim of this study was to examine whether ankylosing spondylitis (AS) susceptibility is controlled by B27 alone rather than B27 haplotypes and, whether other closely related class I loci, such as MICA and TNFA genes might play a role in AS. Three hundred eleven B27-positive samples from Caucasoid, Asian, and African populations were selected and genotypes were carried out by PCR/SSOP (HLA-B27 and HLA-C), PCR/SSP (MICA-TM polymorphism in the transmembrane region), PCR/SSCP (MICA alleles), and PCR-RFLP (TNF-alpha). Of these, 161 were AS patients, chosen in order to investigate the contribution of TNFA and MICA loci to AS in HLA-B27 positive individuals. Some findings can be concluded from the study: (a) No significant differences of TNF-alpha promoter alleles at position -308 and -238 (A/G) were found between AS patients and B27 matched alleles from healthy controls; (b) strong linkage disequilibrium was found between the B27 and the MICA alleles. The MICA-A4 was found to be in association with B*2705,02,03 and 08; MICA-A5 with B*2704 and B*2707 and MICA-A.5.1 with B*2706; (c) no significant differences of MICA alleles were found between AS and controls carrying the B27-associated alleles, and therefore no evidence is provided for an additional role of MICA gene in AS susceptibility; (d) there are a striking correlations between the structure of B27 extended haplotypes (from MICA region to HLA-C) and the ethnic distribution of these subtypes. The results of differential linkage disequilibrium with HLA-B27 subtypes suggest that B27 itself remains the primary gene for AS susceptibility, and TNFA and MICA are not involved in the pathogenesis of the disease.