A genome-wide association study of saturated, mono- and polyunsaturated red blood cell fatty acids in the Framingham Heart Offspring Study

Most genome-wide association studies have explored relationships between genetic variants and plasma phospholipid fatty acid proportions, but few have examined apparent genetic influences on the membrane fatty acid profile of red blood cells (RBC). Using RBC fatty acid data from the Framingham Offspring Study, we analyzed over 2.5 million single nucleotide polymorphisms (SNPs) for association with 14 RBC fatty acids identifying 191 different SNPs associated with at least 1 fatty acid. Significant associations (p<1×10(-8)) were located within five distinct 1MB regions. Of particular interest were novel associations between (1) arachidonic acid and PCOLCE2 (regulates apoA-I maturation and modulates apoA-I levels), and (2) oleic and linoleic acid and LPCAT3 (mediates the transfer of fatty acids between glycerolipids). We also replicated previously identified strong associations between SNPs in the FADS (chromosome 11) and ELOVL (chromosome 6) regions. Multiple SNPs explained 8-14% of the variation in 3 high abundance (>11%) fatty acids, but only 1-3% in 4 low abundance (<3%) fatty acids, with the notable exception of dihomo-gamma linolenic acid with 53% of variance explained by SNPs. Further studies are needed to determine the extent to which variations in these genes influence tissue fatty acid content and pathways modulated by fatty acids.

Rituximab impairs immunoglobulin (Ig)M and IgG (subclass) responses after influenza vaccination in rheumatoid arthritis patients

Rituximab (RTX) treatment in rheumatoid arthritis (RA) patients severely hampers humoral response after influenza vaccination as determined by haemagglutination inhibition assay (HI). It is not known whether HI reflects both immunoglobulin (Ig)M and IgG (subclass) influenza response, and whether IgM antibodies contribute to the low rate of influenza infection seen in RA patients. Twenty RA patients on methotrexate (MTX), 23 on RTX and 28 healthy controls (HC) received trivalent influenza subunit vaccination. Before and 28 days after vaccination, H1N1- and H3N2-specific antibodies were measured by HI and by IgM and IgG (subclass) enzyme-linked immunosorbent assay (ELISA). B cell activating factor (BAFF) levels were determined in serum samples before vaccination. Vaccination induced a significant increase of IgM and IgG (IgG1 and IgG3) antibodies against both strains in the HC and MTX groups (all P < 0·01), but not in the RTX group. HI correlated significantly in all cases with IgG (IgG1) but not with IgM. In RTX late patients (RTX treatment 6-10 months before vaccination), IgG (IgG1 and IgG3) response to vaccination was restored, but not IgM response. BAFF levels were significantly increased in RA-RTX patients and correlated with total IgG levels. Haemagglutination inhibition assay, used as gold standard, detects primarily IgG (IgG1) responses. IgM- and IgG influenza-specific antibodies increase after vaccination in HC and RA patients except in patients on RTX treatment. BAFF levels are increased in both early and late RTX-treated patients, but do not correlate with an influenza-specific antibody response.

Are urinary levels of high mobility group box 1 markers of active nephritis in anti-neutrophil cytoplasmic antibody-associated vasculitis?

The objective of this study is to evaluate urinary high mobility group box 1 (HMGB1) levels as markers for active nephritis in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in comparison with urinary CD4(+) effector memory T cells and urinary monocyte chemoattractant protein-1 (MCP-1). Twenty-four AAV patients with active nephritis and 12 healthy controls (HC) were evaluated. In nine patients, samples were also obtained during remission. Urinary levels of HMGB1 were measured by Western blot. CD4(+) T cells and CD4(+) effector memory T cells (CD4(+) CD45RO(+) CCR7(-) ) were determined in urine and whole blood by flow cytometry. Measurement of urinary levels of MCP-1 and serum HMGB1 levels were performed by enzyme-linked immunosorbent assay (ELISA). AAV patients with active nephritis had higher median intensity of HMGB1 in urine than HC [10·3 (7·05-18·50) versus 5·8 (4·48-7·01); P = 0·004]. Both urinary HMGB1 and MCP-1 levels decreased significantly from active nephritis to remission. The urinary MCP-1/creatinine ratio correlated with Birmingham Vasculitis Activity Score (BVAS) (P = 0·042). No correlation was found between the HMGB1/creatinine ratio and 24-h proteinuria, estimated glomerular filtration rate (eGFR), MCP-1/creatinine ratio, BVAS and serum HMGB1. A positive correlation was found between urinary HMGB1/creatinine ratio and CD4(+) T cells/creatinine ratio (P = 0·028) and effector memory T cells/creatinine ratio (P = 0·039) in urine. Urinary HMGB1 levels are increased in AAV patients with active nephritis when compared with HC and patients in remission, and urinary HMGB1 levels are associated with CD4(+) T cells and CD4(+) effector memory T cells in urine. Measurement of urinary HMGB1 may be of additional value in identifying active glomerulonephritis in AAV patients.

High mobility group box1 (HMGB1) in relation to cutaneous inflammation in systemic lupus erythematosus (SLE)

Summary

Photosensitivity is characteristic of systemic lupus erythematosus (SLE). Upon ultraviolet B (UVB) exposure, patients develop inflammatory skin lesions in the vicinity of sunburn cells (SBCs). High mobility group box 1 (HMGB1) is released from apoptotic and activated cells and exerts inflammatory actions through ligation to its receptors.

Methods

Eleven SLE patients and 10 healthy controls (HCs) were exposed to UVB. Skin biopsies were taken before and at one, three and 10 days after irradiation. Sections were stained for SBC, HMGB1, CD3, CD68, interferon-induced protein MxA and cleaved caspase 3. In vitro experiments with UVB-irradiated keratinocytes were also performed. Higher numbers of cells that had released HMGB1 were seen in the skin of SLE patients compared to HCs before and after irradiation. HMGB1-negative nuclei correlated with the presence of SBCs, and with the number of cleaved caspase 3 positive cells in lupus skin.

Results

HMGB1 release is increased in the skin of SLE patients compared to HCs. Upon UVB exposure, HMGB1 release further increases in SLE patients and is related to the number of apoptotic cells. Our data suggest that HMGB1, probably released from apoptotic keratinocytes, contributes to the development of inflammatory lesions in the skin of SLE patients upon UVB exposure.

[Effect of periodontal treatment on rheumatoid arthritis and vice versa]

The pathogenesis of periodontitis and of rheumatoid arthritis show remarkable similarities. There is a distinct degree of co-existence between the 2 diseases. The prevalence of periodontitis is more pronounced in rheumatoid arthritis patients and the prevalence of rheumatoid arthritis is more pronounced in periodontitis patients. At present, a positive influence of periodontal treatment on the rheumatoid arthritis disease activity or of rheumatoid arthritis drug treatment on periodontitis is not sufficiently supported by clinical research. Periodontitis may play a role in unsatisfactory therapy response in some rheumatoid arthritis patients.

Hypoxia inducible factor-1-alpha (HIF-1alpha) is related to both angiogenesis and inflammation in rheumatoid arthritis

OBJECTIVES

Despite the important role of the transcription factor HIF-1alpha in angiogenesis and inflammation, only a few studies on HIF-1alpha expression have been performed in RA patients. The aim of the present study was to identify the layer in synovial tissue of RA patients where HIF1a is expressed and to find out whether HIF-1alpha expression is related to both angiogenesis and inflammation in synovium from RA patients.

METHODS

A reproducible staining method for HIF-1alpha was developed. HIF-1alpha -positive cells were quantified in synovial tissue from patients with RA. As control we used synovial tissue from patients with osteoarthritis (OA). The number of HIF-1alpha-positive cells was compared with the number of blood vessels present and was correlated with the amount of inflammation. The amount of inflammation was determined by counting inflammatory cells, by estimating the proliferation marker Ki67 in inflamed tissue, and by using a recently published synovitis score which gives an accurate estimate of the amount of inflammation present.

RESULTS

HIF-1alpha was expressed weakly in the lining layer and strongly in the sublining layer in RA synovial tissue. In contrast, HIF-1alpha was only weakly expressed in OA synovial tissue. The number of HIF-1alpha -positive cells correlated strongly with the number of blood vessels in RA synovial tissue and with inflammatory endothelial cell infiltration (blood vessels), cell proliferation (Ki67) and the synovitis score.

CONCLUSIONS

HIF-1alpha expression is strongest in the sub-lining layer of RA synovium and is related to both angiogenesis and inflammation in synovium from RA patients. These results thus suggest that HIF-1alpha could serve as an important new therapeutic target in RA, targeting both angiogenesis and inflammation.

p38 Mitogen-Activated Protein Kinase (MAPK) in Rheumatoid Arthritis

The importance of p38 MAPK inhibitors as new drug for rheumatoid arthritis is reflected by the large number of compounds that has been developed over the last years. In this review new insights such as non-stressful activation of p38 MAPK, and the role of p38 MAPK in regulation of NF-kappaB recruitment are also discussed.

Differential influence of p38 mitogen activated protein kinase (MAPK) inhibition on acute phase protein synthesis in human hepatoma cell lines

BACKGROUND

Inhibition of intracellular signal transduction is considered to be an interesting target for treatment in inflammation. p38 MAPK inhibitors, especially, have been developed and are now in phase II clinical trials for rheumatoid arthritis (RA).

OBJECTIVE

To investigate the influence of p38 MAPK inhibition on acute phase protein (APP) production, which is dependent on both JAK/STAT and p38 MAPK pathways.

METHODS

The effects of p38 MAPK inhibition on APP production and mRNA expression in four human hepatoma cell lines was investigated, after stimulation with interleukin (IL)6 and/or IL1beta or tumour necrosis factor alpha.

RESULTS

Two out of four cell lines produced C reactive protein (CRP), especially after combined IL6 and IL1beta stimulation. CRP production was significantly inhibited by the p38 MAPK specific inhibitor RWJ 67657 at 1 micromol/l, which is pharmacologically relevant. Fibrinogen production was also inhibited at 1 micromol/l in all cell lines. Serum amyloid A (SAA) was produced in all four lines. In contrast with CRP, SAA production was not inhibited by RWJ 67657 at 1 micromol/l.

CONCLUSION

Production and mRNA expression of CRP and fibrinogen, but not SAA production and mRNA expression, were significantly inhibited by p38 MAPK specific inhibitor in hepatoma cell lines. For p38 MAPK inhibitor treatment in RA SAA might be a better marker of disease activity than CRP and fibrinogen, because SAA is not directly affected by p38 MAPK inhibition.

BRAF screening as a low-cost effective strategy for simplifying HNPCC genetic testing

BACKGROUND

According to the international criteria for hereditary non-polyposis colorectal cancer (HNPCC) diagnostics, cancer patients with a family history or early onset of colorectal tumours showing high microsatellite instability (MSI-H) should receive genetic counselling and be offered testing for germline mutations in DNA repair genes, mainly MLH1 and MSH2. Recently, an oncogenic V600E hotspot mutation within BRAF, a kinase encoding gene from the RAS/RAF/MAPK pathway, has been found to be associated with sporadic MSI-H colon cancer, but its association with HNPCC remains to be further clarified.

METHODS

BRAF-V600E mutations were analysed by automatic sequencing in colorectal cancers from 206 sporadic cases with MSI-H and 111 HNPCC cases with known germline mutations in MLH1 and MSH2. In addition, 45 HNPCC cases showing abnormal immunostaining for MSH2 were also analysed.

RESULTS

The BRAF-V600E hotspot mutation was found in 40% (82/206) of the sporadic MSI-H tumours analysed but in none of the 111 tested HNPCC tumours or in the 45 cases showing abnormal MSH2 immunostaining.

CONCLUSIONS

Detection of the V600E mutation in a colorectal MSI-H tumour argues against the presence of a germline mutation in either the MLH1 or MSH2 gene. Therefore, screening of these mismatch repair (MMR) genes can be avoided in cases positive for V600E if no other significant evidence, such as fulfilment of the strict Amsterdam criteria, suggests MMR associated HNPCC. In this context, mutation analysis of the BRAF hotspot is a reliable, fast, and low cost strategy which simplifies genetic testing for HNPCC.

Effects of RWJ 67657, a p38 mitogen activated protein kinase (MAPK) inhibitor, on the production of inflammatory mediators by rheumatoid synovial fibroblasts

OBJECTIVE

To investigate the effect of the p38 mitogen activated protein kinase (MAPK) inhibitor RWJ 67657 on inflammatory mediator production by rheumatoid synovial fibroblasts (RSF).

METHODS

RSF were pretreated with RWJ 67657 and stimulated with TNF alpha and/or IL-1 beta. Protein levels and mRNA expression of MMP-1, MMP-3, TIMP-1, IL-6, and IL-8 were determined, as was mRNA expression of COX-2 and ADAMTS-4.

RESULTS

MMP-3 production was significantly inhibited at 1 microM RWJ 67657 and MMP-1 production at 10 microM, while TIMP-1 production was not inhibited. Inhibition of IL-6 and IL-8 protein production was seen at 0.1 microM RWJ 67657. Expression profiles of mRNA were in accordance with protein production. Inhibition of COX-2 mRNA expression occurred at 0.01 microM RWJ 67657.

CONCLUSIONS

RWJ 67657 inhibits major proinflammatory mediator production in stimulated RSF at pharmacologically relevant concentrations. These findings could have important relevance for the treatment of rheumatoid arthritis.

Constitutive NF-kappaB DNA-binding activity in AML is frequently mediated by a Ras/PI3-K/PKB-dependent pathway

In the present study, we aimed to elucidate the mechanism responsible for constitutive NF-kappaB DNA-binding activity in AML cells. Intervening in aberrant signaling pathway provides a rational approach for in vivo targeting of AML cells. Constitutive NF-kappaB DNA-binding activity was observed in 16 of 22 (73%) investigated AML cases and was, in general, associated with resistance to spontaneous apoptosis. Indeed, inhibition of NF-kappaB activity by the NF-kappaB inhibitor SN-50 peptide resulted in enhanced chemotherapy-induced apoptosis. In the majority of cases, constitutive NF-kappaB activity was mediated by a Ras/PI3 kinase (PI3-K)/protein kinase B (PKB)-mediated pathway. The PI3-K inhibitor Ly294002 and the Ras inhibitor L-744832 both inhibited PKB phosphorylation and NF-kappaB DNA-binding activity. The constitutive activation of Ras GTP-ase was caused by mutations in the gene encoding for N-Ras in 29% of the cases. The constitutive NF-kappaB activity could so far not be ascribed to the autocrine production of growth factors or to mutations in the Flt3 receptor, since anti-GM-CSF, -IL-1, -IL6, -TNFalpha or the tyrosine kinase inhibitor AG1296 did not affect the NF-kappaB DNA-binding activity. The present study demonstrates that Ras activation is an important pathway for triggering the NF-kappaB pathway in AML cells.

Serum matrix metalloproteinase 3 levels in comparison to C-reactive protein in periods with and without progression of radiological damage in patients with early rheumatoid arthritis

OBJECTIVE

To evaluate serum matrix metalloproteinase 3 (MMP-3) levels in comparison to C-reactive protein (CRP) in periods with and without progression of radiological damage in patients with early rheumatoid arthritis (RA).

METHODS

Thirty-two patients with RA and radiological progression (> or = 5 points according to the Sharp/van der Heijde method) during 6 months followed by a 6-month period without radiological progression (< or = 1 point) were selected from a prospective follow-up study of early RA patients. Serum MMP-3 levels, CRP, the erythrocyte sedimentation rate (ESR), disease activity index (DAS), swollen joint count (SJC), tender joint count (TJC), and Ritchie articular index (RAI) were measured monthly and results were transformed into mean values for the 6-month periods.

RESULTS

During the period with radiological progression the mean serum MMP-3 correlated significantly with the mean CRP (r = 0.68, p < 0.001), ESR (r = 0.54, p = 0.001) and swollen joint count (r = 0.48, p = 0.006). In the period without radiological progression the mean serum MMP-3 only correlated with the mean CRP (r = 0.44, p = 0.012). Individual changes--expressed in percentages (%)--between the two periods showed a decrease in both the mean serum MMP-3 and CRP in 19 and an increase in 3 patients, in parallel with other markers of disease activity in these patients (69% of cases). The individual change (%) in mean serum MMP-3 or CRP did not correlate with the difference in radiological progression between the two periods.

CONCLUSIONS

Serum MMP-3 and CRP are closely related and there seems to be no difference between serum MMP-3 and CRP with regard to the monitoring of the progression of radiological damage.