Differential effects of infliximab on absolute circulating blood leucocyte counts of innate immune cells in early and late rheumatoid arthritis patients.

Anti-tumour necrosis factor (TNF) biologics have revolutionized therapy of rheumatoid arthritis (RA). We compared the effects of infliximab on numbers of circulating leucocyte subsets in early RA (disease/symptom duration of ≤1 year) and late RA patients (>1 year). A control group consisted of early RA patients treated with a combination of methotrexate (MTX) and methylprednisolone. Blood samples were obtained at baseline (pre-therapy) from all RA patients, divided into three groups: (i) late RA receiving infliximab/MTX, (ii) early RA-infliximab/MTX, (iii) early RA-steroid/MTX, and also from follow-up patients at 2 and 14 weeks. Significant differences in absolute counts of monocytes and granulocytes were observed between healthy controls and RA patients. At baseline CD14(bright) monocytes and CD16(+) granulocytes were increased in both early RA and late RA patients. CD4(+) T cells, CD8(+) T cells and B cells were all increased at baseline in early RA, but not in late RA. At 2 weeks following infliximab treatment decreased granulocytes were observed in both early and late RA and decreased natural killer (NK) cells in late RA. CD16(+) granulocytes and NK cells were also decreased at 14 weeks post-infliximab in early RA. Biotinylated infliximab was used to detect membrane-associated TNF (mTNF)-expressing leucocytes in RA patients. CD16(+) granulocytes, NK cells and CD14(dim) monocytes all expressed higher levels of mTNF in RA patients. In summary infliximab is associated with decreased CD16(+) granulocyte and NK cell counts, possibly through binding of mTNF. Differential effects of infliximab between early and late RA suggest that pathogenic mechanisms change as disease progresses.

A novel TNFRSF1A splice mutation associated with increased nuclear factor kappaB (NF-kappaB) transcription factor activation in patients with tumour necrosis factor receptor associated periodic syndrome (TRAPS).

OBJECTIVE: To characterise and investigate the functional consequences of a novel TNFRSF1A splice site mutation causing tumour necrosis factor receptor associated periodic syndrome (TRAPS) in a 16-year-old male patient and his mother. METHODS: Mutational DNA screening was performed in the patient and his mother. Western blotting was used to analyse protein expression levels of TNFR1. A multiplex bead immunoassay was used to quantify serum levels of range of cytokines, and an ELISA-based transcription factor assay to measure nuclear factor (NF)-kappaB transactivation. Serum levels of soluble TNFR1 (sTNFR1) were measured by ELISA and fluorescence-activated cell sorting (FACS) analysis used to measure monocyte TNFR1 cell surface expression. RESULTS: A novel mutation, c.472+1G>A (C158delinsYERSSPEAKPSPHPRG), involving a splice site in intron 4 of TNFRSF1A, was found in the proband and affected mother leading to a 45 nucleotide insertion of intronic DNA into the mRNA, resulting in an in-frame insertion of 15 amino acids in the mature TNFR1 protein and a deletion of a cysteine residue C129 (158) in cysteine rich domain (CRD)3. The patients had reduced serum sTNFR1 and surface expression levels of TNFR1, with marked increases in pro- and anti-inflammatory cytokine. Their peripheral blood mononuclear cells (PBMC) had increased basal NF-kappaB activation compared with healthy controls and also had increased p50 nuclear expression following tumour necrosis factor (TNF) stimulation compared with PBMC from healthy controls, as well as T50M (T79M) and C88R (C117R) patients with TRAPS and patients with rheumatoid arthritis (RA). CONCLUSION: A novel, TRAPS causing, TNFRSF1A splice site mutation is associated with decreased sTNFR1 levels, cell surface and whole cell extract expression and increased NF-kappaB transcription factor activation.

TNF and TNFR polymorphisms in severe sepsis and septic shock: a prospective multicentre study.

Tumour necrosis factor (TNF) is an important pro-inflammatory cytokine produced in sepsis. Studies examining the association of individual TNF single nucleotide polymorphisms with sepsis have produced conflicting results. This study investigated whether common polymorphisms of the TNF locus and the two receptor genes, TNFRSF1A and TNFRSF1B, influence circulating levels of encoded proteins, and whether individual polymorphisms or extended haplotypes of these genes are associated with susceptibility, severity of illness or outcome in adult patients with severe sepsis or septic shock. A total of 213 Caucasian patients were recruited from eight intensive care units (ICU) in the UK and Australia. Plasma levels of TNF (P = 0.02), sTNFRSF1A (P = 0.005) and sTNFRSF1B (P = 0.01) were significantly higher in those who died on ICU compared to those who survived. There was a positive correlation between increasing soluble receptor levels and organ dysfunction (increasing SOFA score) (sTNFRSF1A R = 0.51, P < 0.001; sTNFRSF1B R = 0.53, P < 0.001), and in particular with the degree of renal dysfunction. In this study, there were no significant associations between the selected candidate TNF or TNF receptor polymorphisms, or their haplotypes, and susceptibility to sepsis, illness severity or outcome. The influence of polymorphisms of the TNF locus on susceptibility to, and outcome from sepsis remains uncertain.

Allelic variants in genes associated with hereditary periodic fever syndromes as susceptibility factors for reactive systemic AA amyloidosis.

We investigated the hypothesis that low-penetrance mutations in genes (TNFRSF1A, MEFV and NALP3/CIAS1) associated with hereditary periodic fever syndromes (HPFs) might be risk factors for AA amyloidosis among patients with chronic inflammatory disorders, including rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), Crohn's disease, undiagnosed recurrent fevers and HPFs themselves. Four of 67 patients with RA plus amyloidosis had MEFV variants compared with none of 34 RA patients without amyloid (P value=0.03). The E148Q variant of MEFV was present in two of the three patients with TNF receptor-associated periodic syndrome (TRAPS) complicated by amyloid in two separate multiplex TRAPS families containing 5 and 16 affected members respectively, and the single patient with Muckle-Wells syndrome who had amyloidosis was homozygous for this variant. The R92Q variant of TNFRSF1A was present in two of 61 JIA patients with amyloidosis, and none of 31 nonamyloidotic JIA patients. No HPF gene mutations were found in 130 healthy control subjects. Although allelic variants in HPFs genes are not major susceptibility factors for AA amyloidosis in chronic inflammatory disease, low-penetrance variants of MEFV and TNFRSF1A may have clinically significant proinflammatory effects.

Hyper IgD syndrome (HIDS) associated with in vitro evidence of defective monocyte TNFRSF1A shedding and partial response to TNF receptor blockade with etanercept.

Hereditary periodic fever syndromes comprise a group of distinct disease entities linked by the defining feature of recurrent febrile episodes. Hyper IgD with periodic fever syndrome (HIDS) is caused by mutations in the mevalonate kinase (MVK) gene. The mechanisms by which defects in the MVK gene cause febrile episodes are unclear and there is no uniformly effective treatment. Mutations of the TNFRSF1A gene may also cause periodic fever syndrome (TRAPS). Treatment with the TNFR-Fc fusion protein, etanercept, is effective in some patients with TRAPS, but its clinical usefulness in HIDS has not been reported. We describe a 3-year-old boy in whom genetic screening revealed a rare combination of two MVK mutations producing clinical HIDS as well as a TNFRSF1A P46L variant present in about 1% of the population. In vitro functional assays demonstrated reduced receptor shedding in proband's monocytes. The proband therefore appears to have a novel clinical entity combining Hyper IgD syndrome with defective TNFRSF1A homeostasis, which is partially responsive to etanercept.

Genetic susceptibility to fibrocalculous pancreatic diabetes in Bangladeshi subjects: a family study.

Fibrocalculous pancreatic diabetes (FCPD) is an uncommon cause of diabetes, seen mainly in developing countries. A family-based study was carried out in 67 Bangladeshi families, consisting of a proband with FCPD and both parents, to determine whether an association exists between FCPD susceptibility and either the major histocompatiblity complex (MHC) or insulin gene (INS) loci. HLA-DQB1 typing was done using allele-specific primers, and INS was typed using the restriction enzyme HphI. Three microsatellites (TNFa, TNFc and TNFd), from within and flanking the TNF-LT locus, were used for MHC Class IV typing and a PCR-RFLP assay was used to define the -308G/A TNF promoter polymorphism. The extended transmission disequilibrium test (ETDT) was used for statistical analysis. An overall association was observed between FCPD and HLA-DQB1 (P = 0.003), that was largely due to a positive association with HLA-DQB1*0302 and a negative association with HLA-DQB1*0202. Although no association was found between FCPD and TNF-LT microsatellite markers a trend was observed for TNFc (P = 0.037, Pc = 0.15). No association was found between FCPD and INS (P = 0.26). This study confirms an association between FCPD and the MHC using a family-based study design and the stringent ETDT analysis; a novel protective association was found with HLA-DQB1*0202 in Bangladeshi FCPD subjects. The genetic susceptibility to FCPD has features both similar and dissimilar to T1DM.

Hereditary periodic fever syndromes.

Hereditary periodic fever syndromes are defined by recurrent attacks of generalised inflammation for which no infectious or auto-immune cause can be identified. For most of these disorders, the molecular basis has recently been elucidated. This has opened the prospect of novel therapeutic approaches. Familial Mediterranean fever (FMF) is caused by mutations in the MEFV gene. Pathogenesis is poorly understood. The clinical severity is in part related to the mutations involved. Tumour necrosis factor receptor-1-associated periodic syndrome (TRAPS) is caused by mutations in the TNFRSF1A gene. This results in decreased serum levels soluble TNF-receptor leading to inflammation due to unopposed TNF-alpha action. Results of treatment with recombinant TNF-receptor analogues are promising. The hyper IgD periodic fever syndrome (HIDS) is caused by mutations in the MVK gene, leading to mevalonate kinase deficiency. The pathogenesis remains unclear. Muckle-Wells syndrome (MWS) and familial cold urticaria (FCU) are probably allelic disorders. The gene has been located, but not identified.

TNF and TNFR biology in health and disease.

Many insights have been gained into cytokine-regulated control of inflammatory processes and host defence in recent years. Evidence has also gradually accumulated that cytokine cascades play a central role in events regulating cell death and differentiation. Further developments include an understanding that the biological effects of the tumor necrosis factor-alpha (TNF-alpha or TNFSF) cytokine may be regulated by soluble TNF receptor binding and that modulation of receptor levels may permit physiological inhibition of TNF action. There has been a gradual realisation of the value of TNF/TNFR ratios as predictors of disease outcome, and the discovery of functional regulatory polymorphisms of the TNF gene and mutations of TNFRSF1A (TNFR1 receptor) have led to conceptual breakthroughs in our understanding of the genetic control of inflammation. However the exact mechanisms by which TNFRSF1A mutations give rise to disease susceptibility are not yet well understood. Over the past 10 years these concepts have been used as the basis for successful anti-TNF therapy of autoimmune diseases like rheumatoid arthritis (RA) and Crohn's disease.

Tumour necrosis factor 5' promoter single nucleotide polymorphisms influence susceptibility to rheumatoid arthritis (RA) in immunogenetically defined multiplex RA families.

Tumour necrosis factor (TNF) plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA) and it has been shown that the TNF-lymphotoxin (TNF-LT) region influences susceptibility to RA. To investigate the role of the TNF-LT locus further, inheritance of TNF 5' promoter alleles was determined in multiplex RA families. Six previously defined TNF promoter single nucleotide polymorphisms (SNPs) (-238, -308, -376, -857, -863, -1031) were observed in these families and in addition, a heretofore undocumented adenine (A) to cytosine (C) substitution at position -572 relative to the transcription start site was defined. TNF 5' promoter SNPs were found to co-segregate with specific TNF microsatellite haplotypes. In particular, the SNP -308A allele was found to be inherited with the TNF a2, b3, c1, d1, e3 (H2) microsatellite haplotype (P < 0.001) which had previously been found to be associated with RA in individuals heterozygous for the HLA-DR 'shared epitope' (SE). When the data were stratified by the presence of the SE with further stratification according to SE DR subtypes and analysed by transmission disequilibrium test (TDT) for which offspring were assumed independent, the -308A and -857T alleles were found to be associated with RA in patients carrying the SE (P = 0.0076 and 0.0063 respectively). The data were further stratified to analyse for association in individuals homozygous or heterozygous for SE alleles. Results showed that the -308A allele was significantly associated with RA susceptibility in individuals heterozygous for the SE (P < 0.001) with the significance only occurring in patients carrying HLA-DR4 (P < 0.001), while the -857T allele was significant in individuals homozygous for the SE (P = 0.0039). Further analysis using the pedigree disequilibrium test (PDT) which conservatively adjusts for all sources of familial correlation except that conferred by linkage disequilibrium still indicated a significant role for the -308A and -857T alleles. These data provide evidence that TNF promoter SNPs may play an independent role in RA susceptibility in specific immunogenetically-defined groups of RA patients.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) in a Dutch family: evidence for a TNFRSF1A mutation with reduced penetrance.

Mutations of the tumor necrosis factor receptor 1 (TNFRSF1A) gene underly susceptibility to a subset of autosomal dominant recurrent fevers (ADRFs). We report on a two-generation six-member Dutch family in which a novel R92P mutation and reduced plasma TNFRSF1A levels were found in all the children, including two who are unaffected. However, only the daughter proband and father exhibited a typical TNF-receptor associated periodic syndrome (TRAPS) phenotype. PCR-RFLP analysis revealed that the mutation was not present in 120 control chromosomes from unaffected Dutch individuals. As this R92P mutation is present in two unaffected carriers it appears to be less penetrant than previously reported TNFRSF1A mutations involving cysteine residues in the extracellular domains.

Pancreatitis in fibrocalculous pancreatic diabetes mellitus is not associated with common mutations in the trypsinogen gene.

BACKGROUND: A distinct type of pancreatitis associated with diabetes, termed fibrocalculous pancreatic diabetes (FCPD), has been reported in tropical developing countries including Bangladesh. The molecular basis for autosomal dominant hereditary pancreatitis (HP) has recently been attributed to mutations in exons 2 and 3 of the trypsinogen gene. We have investigated the hypothesis that mutations in the aforementioned exons of this gene might also predispose to FCPD. METHODS: Seventy Bangladeshi and 50 South Indian unrelated FCPD patients and seven South Indian families with FCPD probands were studied. Pancreatic calcification was confirmed by abdominal X-ray, ultrasound and/or ERCP. Established mutations of exons 2 and 3 of the trypsinogen gene were studied in these subjects by PCR-RFLP analysis and DNA sequencing. RESULTS: The mutations found in hereditary pancreatitis were not observed in this collection of FCPD subjects, and complete DNA sequencing of exons 2 and 3 of the fourth cationic trypsinogen gene also excluded any new mutations. CONCLUSIONS: These results indicate that chronic pancreatitis of FCPD is unlikely to be caused by common mutations in the trypsinogen gene.

An autosomal dominant periodic fever associated with AA amyloidosis in a north Indian family maps to distal chromosome 1q.

OBJECTIVE: To investigate genetic susceptibility in the first Indian family identified as having an autosomal dominantly inherited periodic fever syndrome. The inflammatory disease was characterized chiefly by arthralgia, skin rashes, and AA amyloidosis. METHODS: Markers from known periodic fever susceptibility loci were investigated in 7 affected and 11 healthy members of a north Indian family. These included the TNFRSF1A locus (formerly known as TNFRI), which is involved in autosomal dominant tumor necrosis factor receptor-associated periodic syndrome on chromosome 12p13, the familial Mediterranean fever locus (MEFV) on chromosome 16p13, the hyperimmunoglobulinemia D and periodic fever syndrome (HIDS) locus on chromosome 12q24, and the Muckle-Wells syndrome/familial cold urticaria (MWS/FCU) locus on distal chromosome 1q44. RESULTS: Linkage to both TNFRSF1A and MEFV was definitively excluded, and DNA sequencing of these genes revealed no mutations. Furthermore, there was no evidence of linkage to the HIDS locus. In contrast, significant logarithm of odds scores for 5 markers from the MWS/FCU region were obtained in this family, and the disease segregated with the same haplotype in all affected members. CONCLUSION: We have identified an inherited inflammatory disease in a north Indian family with clinical features overlapping some of those of MWS and FCU. The susceptibility gene maps to distal chromosome 1q44, a region already implicated in both MWS and FCU. Different mutations in the same (or a closely related) gene may be responsible for an inflammatory disease with a broad phenotype among diverse ethnic populations.

TNFRSF1A mutations and autoinflammatory syndromes.

The autoinflammatory syndromes are systemic disorders characterized by apparently unprovoked inflammation in the absence of high-titer autoantibodies or antigen-specific T lymphocytes. One such illness, TNF-receptor-associated periodic syndrome (TRAPS), presents with prolonged attacks of fever and severe localized inflammation. TRAPS is caused by dominantly inherited mutations in TNFRSF1A (formerly termed TNFR1), the gene encoding the 55 kDa TNF receptor. All known mutations affect the first two cysteine-rich extracellular subdomains of the receptor, and several mutations are substitutions directly disrupting conserved disulfide bonds. One likely mechanism of inflammation in TRAPS is the impaired cleavage of TNFRSF1A ectodomain upon cellular activation, with diminished shedding of the potentially antagonistic soluble receptor. Preliminary experience with recombinant p75 TNFR-Fc fusion protein in the treatment of TRAPS has been favorable.

Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes.

Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation. In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal. Leukocytes bearing a C52F mutation showed increased membrane TNFR1 and reduced receptor cleavage following stimulation. We propose that the autoinflammatory phenotype results from impaired downregulation of membrane TNFR1 and diminished shedding of potentially antagonistic soluble receptor. TNFR1-associated periodic syndromes (TRAPS) establish an important class of mutations in TNF receptors. Detailed analysis of one such mutation suggests impaired cytokine receptor clearance as a novel mechanism of disease.

Cytokine gene polymorphism in human disease: on-line databases.

The pathologies of many infectious, autoimmune and malignant diseases are influenced by the profiles of cytokine production in pro-inflammatory (TH1) and anti-inflammatory (TH2) T cells. Interindividual differences in cytokine profiles appear to be due, at least in part, to allelic polymorphism within regulatory regions of cytokine gene. Many studies have examined the relationship between cytokine gene polymorphism, cytokine gene expression in vitro, and the susceptibility to and clinical severity of diseases. A review of the findings of these studies is presented. An on-line version featuring appropriate updates is accessible from the World Wide Web site, http://www.pam.bris.ac.uk/services/GAI/cytokine4.htm.

Modelling the major histocompatibility complex susceptibility to RA using the MASC method.

To explain the association between HLA-DRB1 gene and rheumatoid arthritis (RA), two main hypotheses have been proposed. The first, the shared epitope hypothesis, assumes a direct role of DRB1 in RA susceptibility. The second hypothesis assumes a recessive disease susceptibility gene in linkage disequilibrium with DRB1. To investigate these two hypotheses, we analysed data on the HLA-DRB1 and TNF-LT loci in 49 affected sib-pairs. We used the Marker Association Segregation Chi-square (MASC) method in which the genotype distribution of markers among index cases and the haplotype sharing in affected sib-pairs are jointly taken into account. With DRB1 data alone, both hypotheses were shown to fit but with analysis of TNF data, both hypotheses were strongly rejected. Thus the TNF data provided additional information for a better understanding of genetic susceptibility to RA than was previously possible using only HLA-DR data. A theoretical standpoint is addressed here on the advisability of using different linked markers in a candidate region for modelling the contribution of this region in disease susceptibility.

Genetic variability in the tumor necrosis factor-lymphotoxin region influences susceptibility to rheumatoid arthritis.

The major histocompatibility complex class III tumor necrosis factor-lymphotoxin (TNF-LT) region (6p21.3) was investigated as a possible susceptibility locus for rheumatoid arthritis (RA). Inheritance of five TNF microsatellite markers was determined in 50 multiplex families. Overall, 47 different haplotypes were observed. One of these, the TNF a6, b5, c1, d3, e3 (H1) haplotype, was present in 35.3% of affected, but in only 20.5% of unaffected, individuals (P < .005). This haplotype accounted for 21.5% of the parental haplotypes transmitted to affected offspring and only 7.3% not transmitted to affected offspring (P = .0003). The TNF a6 and TNF c1 alleles were individually associated with RA (P = .0005 and .0008, respectively), as were the HLA-DRB1 "shared epitope" (SE) (P = .0001) and HLA-DRB1*0401 (P = .0018). Both univariate and bivariate conditional logistic regression analysis showed significant effects of TNF c1 and SE in increasing risk to RA (P < .001). Stratification by the presence of SE indicated an independent effect of the TNFc1 allele (P = .0003) and the HLA A1, B8, DR3 extended haplotype (always TNFa2, b3, c1, d1, e3) (P = .0027) in SE heterozygotes, while the H1 haplotype was associated with RA in SE homozygotes (P = .0018). The TNF-LT region appears to influence susceptibility to RA, distinct from HLA-DR.