Pathogenesis of rheumatoid arthritis: a vascular hypothesis

Stroke risk in arthritis: A systematic review and meta-analysis of cohort studies

BACKGROUND AND OBJECTIVE

Stroke is a major contributor to the global burden of disease. Although numerous modifiable risk factors (RF) for stroke have been identified, some remain unexplained. Increasing studies have investigated stroke risk in arthritis, but their results are inconsistent. We aimed to synthesize, quantify, and compare the risk of stroke for the major types of arthritis in cohort studies by using a systematic review and meta-analysis approach.

METHODS

We searched Chinese and English databases to identify relevant studies from inception to April 30, 2020. Only studies adjusting at least for age and sex were included. We calculated pooled effect estimates for relative risk (RR) and 95% confidence interval (CI) and identified potential sources of heterogeneity and publication bias.

RESULTS

A total of 1,348 articles were retrieved, and after an preliminary screening of titles and abstracts, 69 were reviewed for full text, and finally, 32 met the criteria for meta-analysis. Stroke risk in arthritis was significantly increased in studies adjusting for age and sex (RR = 1.36, 95% CI: 1.27-1.46) and for at least one traditional risk factor (RR = 1.40, 95% CI: 1.28-1.54). The results of studies stratified by stroke subtype were consistent with the main finding (ischemic stroke: RR = 1.53, 95% CI: 1.32-1.78; hemorrhagic stroke: RR = 1.45, 95% CI: 1.15-1.84). In subgroup analysis by arthritis type, stroke risk was significantly increased in rheumatoid arthritis (RR = 1.38, 95% CI: 1.29-1.48), ankylosing spondylitis (RR = 1.49, 95% CI: 1.25-1.77), psoriatic arthritis (RR = 1.33, 95% CI: 1.22-1.45), and gout (RR = 1.40, 95% CI: 1.13-1.73) but not osteoarthritis (RR = 1.03, 95% CI: 0.91-1.16). Age and sex subgroup analyses indicated that stroke risk was similar by sex (women: RR = 1.47, 95% CI: 1.31-1.66; men: RR = 1.44, 95% CI: 1.28-1.61); risk was higher with younger age (<45 years) (RR = 1.46, 95% CI: 1.17-1.82) than older age (≥65 years) (RR = 1.17, 95% CI: 1.08-1.26).

CONCLUSIONS

Stroke risk was increased in multiple arthritis and similar between ischemic and hemorrhagic stroke. Young patients with arthritis had the highest risk.

Association between vascular endothelial growth factor receptor 2 rs11941492 C/T polymorphism and Chinese Han patients in rheumatoid arthritis

The aim of the present study was to examine the association between vascular endothelial growth factor receptor 2 (VEGFR2) rs11941492 C/T polymorphism and rheumatoid arthritis (RA) risk in an eastern Chinese Han population. We examined VEGFR2 rs11941492 C/T polymorphism in 615 RA patients and 839 controls in an East Chinese Han population. The power analysis was used for evaluating the reliability of the results. Genotyping was performed using a custom-by-design 48-Plex single nucleotide polymorphism scan Kit. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression.Our results indicated that VEGFR2 rs11941492 C/T polymorphism (TT vs CC, P = .012, OR = 0.61, 95% CI = 0.41-0.89; TT vs CT + CC, P = .017, OR = 0.63, 95% CI = 0.43-0.92) was associated with a significantly decreased risk of RA. The power analysis showed that this study had a power of 98.5% to detect the effect of rs11941492 C/T polymorphism on RA susceptibility, assuming an OR of 0.61. After stratification analysis, a decreased risk of RA was associated with VEGFR2 rs11941492 TT genotype (TT vs CC) among female patients (TT vs CC, P = .007, OR = 0.53, 95% CI = 0.33-0.84), older patients (Yr ≥55) (TT vs CC, P = .039, OR = 0.58, 95% CI = 0.35-0.97), C-reactive protein-positive patients, anti-cyclic citrullinated peptide antibody-negative patients, rheumatoid factor-positive patients (TT vs CT + CC, P = .015, OR = 0.60, 95% CI = 0.39-0.90), functional class III + IV patients, patients with a DAS28 of ≥3.20, and those with an erythrocyte sedimentation rate of <25. However, our results were obtained from only a moderate-sized sample. Studies with larger sample sizes in other ethnic populations are needed to confirm these results. The VEGFR2 rs11941492 genotype is associated with decreased susceptibility to RA.

Nanoparticles' interactions with vasculature in diseases

The ever-growing use of inorganic nanoparticles (NPs) in biomedicine provides an exciting approach to develop novel imaging and drug delivery systems, owing to the ease with which these NPs can be functionalized to cater to various applications. In cancer therapeutics, nanomedicine generally relies on the enhanced permeability and retention (EPR) effect observed in tumour vasculature to deliver anti-cancer drugs across the endothelium. However, such a phenomenon is dependent on the tumour microenvironment and is not consistently observed in all tumour types, thereby limiting drug transport to the tumour site. On the other hand, there is a rise in utilizing inorganic NPs to intentionally induce endothelial leakiness, creating a window of opportunity to control drug delivery across the endothelium. While this active targeting approach creates a similar phenomenon compared to the EPR effect arising from tumour tissues, its drug delivery applications extend beyond cancer therapeutics and into other vascular-related diseases. In this review, we summarize the current findings of the EPR effect and assess its limitations in the context of anti-cancer drug delivery systems. While the EPR effect offers a possible route for drug passage, we further explore alternative uses of NPs to create controllable endothelial leakiness within short exposures, a phenomenon we coined as nanomaterial-induced endothelial leakiness (NanoEL). Furthermore, we discuss the main mechanistic features of the NanoEL effect that make it unique from conventionally established endothelial leakiness in homeostatic and pathologic conditions, as well as examine its potential applicability in vascular-related diseases, particularly cancer. Therefore, this new paradigm changes the way inorganic NPs are currently being used for biomedical applications.

Adenosine and adenosine receptors in the pathogenesis and treatment of rheumatic diseases

Adenosine, a nucleoside derived primarily from the extracellular hydrolysis of adenine nucleotides, is a potent regulator of inflammation. Adenosine mediates its effects on inflammatory cells by engaging one or more cell-surface receptors. The expression and function of adenosine receptors on different cell types change during the course of rheumatic diseases, such as rheumatoid arthritis (RA). Targeting adenosine receptors directly for the treatment of rheumatic diseases is currently under study; however, indirect targeting of adenosine receptors by enhancing adenosine levels at inflamed sites accounts for most of the anti-inflammatory effects of methotrexate, the anchor drug for the treatment of RA. In this Review, we discuss the regulation of extracellular adenosine levels and the role of adenosine in regulating the inflammatory and immune responses in rheumatic diseases such as RA, psoriasis and other types of inflammatory arthritis. In addition, adenosine and its receptors are involved in promoting fibrous matrix production in the skin and other organs, and the role of adenosine in fibrosis and fibrosing diseases is also discussed.

The danger model approach to the pathogenesis of the rheumatic diseases

The danger model was proposed by Polly Matzinger as complement to the traditional self-non-self- (SNS-) model to explain the immunoreactivity. The danger model proposes a central role of the tissular cells' discomfort as an element to prime the immune response processes in opposition to the traditional SNS-model where foreignness is a prerequisite. However recent insights in the proteomics of diverse tissular cells have revealed that under stressful conditions they have a significant potential to initiate, coordinate, and perpetuate autoimmune processes, in many cases, ruling over the adaptive immune response cells; this ruling potential can also be confirmed by observations in several genetically manipulated animal models. Here, we review the pathogenesis of rheumatic diseases such as systemic lupus erythematous, rheumatoid arthritis, spondyloarthritis including ankylosing spondylitis, psoriasis, and Crohn's disease and provide realistic approaches based on the logic of the danger model. We assume that tissular dysfunction is a prerequisite for chronic autoimmunity and propose two genetically conferred hypothetical roles for the tissular cells causing the disease: (A) the Impaired cell and (B) the paranoid cell. Both roles are not mutually exclusive. Some examples in human disease and in animal models are provided based on current evidence.

An observational study of endothelial function in early arthritis

BACKGROUND

Endothelial dysfunction is present in established rheumatoid arthritis, but it is not clear at what stage of the disease this abnormality develops. We set out to determine whether endothelial damage/dysfunction is present in a group of patients with early arthritis (EA) (new onset inflammatory arthritis, EA).

MATERIALS AND METHODS

Eighteen patients with EA, 48 healthy controls and 25 disease controls were recruited. Plasma was obtained for endothelial [von Willebrand factor (vWF) and soluble E-selectin] and angiogenesis markers (vascular endothelial growth factor and its receptor sFlt-1), adhesion molecules (intercellular adhesion molecule 1 and vascular cell adhesion molecule 1) and circulating endothelial cells (CECs, as a marker of endothelial damage). Microvascular endothelial function was assessed using laser Doppler perfusion imaging and macrovascular function using flow-mediated dilatation of the brachial artery.

RESULTS

von Willebrand factor and CECs (both P < 0.05) were significantly elevated in EA suggesting endothelial dysfunction and damage but were unrelated to classical laboratory markers of inflammation C-reactive protein, erythrocyte sedimentation rate or IL6. No other biomarkers was elevated in EA. Microvascular and macrovascular abnormalities were confined to endothelium-independent (smooth muscle cell) responses.

CONCLUSIONS

Endothelial damage/dysfunction is present early in the course of inflammatory arthritis but is not directly related to inflammation markers.

The endotheliome: a new concept in vascular biology

As the importance of the endothelium is becoming increasingly recognised, additional tools are needed to assess its functions. Separate studies have looked at different aspects of vascular biology primarily focusing on the central role of the endothelium, i.e. secretion/release of molecules in the plasma, physiological action on other cells, and the presence of endothelial cells themselves in the circulation. Targeting and protecting the endothelium is a promising therapeutic strategy for modifying a number of disease processes but 'ideal' methods to monitor this treatment, like many other tools for assessing endothelial activity, remain elusive. We suggest that a broader view of the endothelium is important, and with it the concept of the assessment of overall vascular function, which fuses different aspects of endothelial activity into a unifying concept. In the present document we review the current understanding of endothelial biology and the methods of its assessment, and hypothesise that a more multifactorial approach to the endothelium will be a crucial determinant of outcomes and treatment strategies for different diseases. This we describe as the 'endotheliome'.

Inflammation and Microvascular and Macrovascular Endothelial Dysfunction in Rheumatoid Arthritis: Effect of Treatment

Objective.

To determine whether abnormalities in microvascular and macrovascular function in rheumatoid arthritis (RA) are associated with plasma markers [von Willebrand factor (VWF)] of endothelial dysfunction and inflammation [C-reactive protein (CRP)] and whether the abnormalities would be altered by treatment. Endothelial dysfunction and inflammation in RA may contribute to adverse cardiovascular events. Although endothelial dysfunction in RA has been demonstrated by altered plasma markers, the relationships with macrovascular and microvascular function are relatively unexplored.

Methods.

We recruited 66 patients with chronic RA, 48 community controls (CC), and 25 patients with diabetes and hypertension as a disease control group (DC). Subjects had venous blood sampled for plasma markers, and underwent laser Doppler perfusion imaging of forearm skin (to assess microvascular circulation) following acetylcholine and sodium nitroprusside iontophoresis, to assess endothelium-dependent and endothelium-independent responses, respectively. Brachial artery flow-mediated dilatation assessed endothelial dysfunction in a macrovascular bed. A subgroup of 29 patients with RA were assessed pretherapy and after 2–4 weeks of antirheumatic therapy.

Results.

As expected, patients with RA had higher CRP, erythrocyte sedimentation rate (ESR), and VWF. Endothelium-independent vasoreactivity was abnormal in RA, and this correlated negatively with CRP. All aspects of microvascular function were abnormal in the DC compared to the CC. Macrovascular function was preserved in RA but was abnormal in the DC group. Four weeks of antiinflammatory therapy reduced CRP and ESR but had no effect on any vascular function index in the patients with RA.

Conclusion.

Patients with RA have abnormal endothelium-independent microvascular function that correlates with inflammation but is not altered by short-term antiinflammatory therapy.

The vasculature in rheumatoid arthritis: cause or consequence?

The expansion of the synovial lining of joints in rheumatoid arthritis (RA) necessitates an increase in the vascular supply to the synovium, to cope with the increased requirement for oxygen and nutrients. New blood vessel formation -'angiogenesis'- is recognized as a key event in the formation and maintenance of the pannus in RA, suggesting that targeting blood vessels in RA may be an effective future therapeutic strategy. Although many pro-angiogenic factors have been demonstrated to be expressed in RA synovium, vascular endothelial growth factor (VEGF) has been demonstrated to a have a central involvement in the angiogenic process in RA. Nevertheless, it is unclear whether angiogenesis - whether driven by VEGF and/or other factors - should be considered as a 'cause' or 'consequence' of disease. This ongoing 'chicken vs. egg' debate is difficult, as even the success of angiogenesis inhibition in models of RA does not provide a direct answer to the question. This review will focus on the role of the vasculature in RA, and the contribution of different angiogenic factors in promoting disease. Although no data regarding the effectiveness of anti-angiogenic therapy in RA have been reported to date, the blockade of angiogenesis nevertheless looks to be a promising therapeutic avenue.

The role of substance P in microvascular responses in murine joint inflammation

1. Rheumatoid arthritis is a serious, inflammatory disease of the distal joints that has a possible neurogenic component underlying its pathology. 2. Substance P (SP), an endogenous neuropeptide that acts upon the neurokinin 1 (NK(1)) receptor, is released from sensory nerves and is involved in neurogenic inflammation. 3. In this study, we have developed novel techniques to determine the contribution of SP to microvascular responses in a model of complete Freund's adjuvant (CFA)-induced arthritis in NK(1) knockout mice. 4. Detailed analysis in normal mice revealed that CFA (20 microg i.art.)-induced plasma extravasation was raised from 18 to 72 h, when compared with intravascular volume. By comparison, knee swelling was sustained for 3 weeks. Neutrophil accumulation mirrored plasma extravasation. SP (10 pmol i.art.) caused significant acute plasma extravasation, but not other parameters, in wild type (WT), but not NK(1) knockout mice. CFA (10 microg i.art.) induced a significantly decreased intravascular volume, presumably due to decreased blood flow, at early time points (5 and 7 h) in WT but not NK(1) knockouts. Otherwise, similar responses in WT and NK(1) knockout mice were observed. However, injection of SP into CFA-pretreated joints caused a significant enhancement of plasma extravasation and knee swelling in the WT but not NK(1) knockouts. 5. In conclusion, the present study has used novel techniques in WT and NK(1) knockout mice to show that SP can modulate vascular tone and permeability in the inflamed joint via activation of the NK(1) receptor and that SP-induced responses are more pronounced where pre-existing inflammation is present.

Endothelial dysfunction in rheumatoid arthritis: influence of HLA-DRB1 alleles

Cardiovascular disease is the commonest cause of premature mortality in rheumatoid arthritis (RA) patients. Vascular endothelial injury is the primary event in atherosclerosis. It has been associated with endothelial dysfunction. We have recently observed that actively treated RA patients had endothelial dysfunction. HLA-DRB1 shared epitope alleles, in particular HLA-DRB1*0404, seem to be implicated in the development of endothelial dysfunction. These results underline the influence of genetic factors in the risk of atherosclerosis in RA patients.

Effect of Different Methods of Thermotherapy on Skin Microcirculation

OBJECTIVE

The purpose of the study was to compare the effects of different methods of thermotherapy on skin microcirculation, skin temperature, and core temperature in patients with rheumatoid arthritis and in healthy persons.

DESIGN

In 20 patients with rheumatoid arthritis and 20 healthy controls, the skin microcirculation was measured by means of laser-Doppler flowmetry before, at the end of, and 30 mins after completion of local thermotherapy (infrared light, paraffin, peat) in the lumbar area. In addition, skin and core temperature were recorded at the same point in time. The influence of previous intake of acetylsalicylic acid on skin microcirculation during thermotherapy was investigated. The controlled trial was conducted in an air-conditioned laboratory.

RESULTS

All methods caused a significant increase in skin microcirculation (flow and vasomotion), skin temperature, and core temperature. The skin temperature showed the highest increase when infrared light was applied. The microcirculation became more intense when paraffin fango was used. There were no differences between the reactions of rheumatoid arthritis patients and healthy persons. The additional intake of 500 mg acetylsalicylic acid before treatment did not affect skin temperature or skin microcirculation. A tendency toward a sinusoidal rhythmization of vasomotion was detected.

CONCLUSIONS

The effects of the three methods of thermotherapy differ quantitatively due to their physical attributes. The effects on circulation differ depending on the method chosen, and this is significant when selecting the least stressful method for a particular patient. Rheumatoid arthritis patients and healthy controls have the same increase of skin microcirculation in the lumbar area. Findings in the distal limbs might differ. All used therapies cause a rhythmization of the vasomotion and, as a consequence, a qualitative improvement of the microcirculation.

Comparison of soluble adhesion molecules in juvenile idiopathic arthritis between the active and remission stages

OBJECTIVE

To determine the serum levels of soluble adhesion molecules in patients with juvenile idiopathic arthritis (JIA), and to determine whether the levels of these molecules differ between active disease and remission in the same JIA subtype, and whether differences in these levels exist between controls and the three JIA subtypes.

METHODS

The serum levels of soluble E-selectin (sE-selectin) and soluble intercellular adhesion molecule-1 (sICAM-1) were determined by enzyme linked immunosorbent assay (ELISA) in 40 patients with JIA (12 systemic, 13 polyarticular, and 15 oligoarticular) who had active disease or were in clinical remission and 16 healthy controls. Differences in the levels of adhesion molecules of the same JIA subtype during different disease activity were determined by the paired t test, and differences between the disease and control groups were calculated by one way analysis of variance. A value p<0.01 was considered significant.

RESULTS

During the same disease stage (active or in remission), systemic JIA was associated with a significantly higher sE-selectin level than the oligoarticular JIA subtype, whereas this was not found for sICAM-1. Although the mean levels of sE-selectin and sICAM-1 in active systemic and polyarticular JIA were higher than those in remission, this did not reach statistical significance. The levels of sE-selectin and sICAM-1 of the three JIA subtypes, in both the active stage and clinical remission, were still significantly higher than in normal controls.

CONCLUSIONS

Systemic JIA is associated with a higher sE-selectin level than oligoarticular JIA both in active disease and in clinical remission. This may explain why the morbidity of systemic JIA is greater than that of oligoarticular JIA-namely, owing to increased endothelial cell activation. As significantly higher levels of sE-selectin and sICAM-1 were found in the active and remission stages of the three JIA subtypes compared with those in the control group, JIA may recur even when clinical remission has been achieved.

Angiogenesis in rheumatoid arthritis

The expansion of the synovial lining of joints in rheumatoid arthritis (RA) and the subsequent invasion by the pannus of underlying cartilage and bone necessitate an increase in the vascular supply to the synovium, to cope with the increased requirement for oxygen and nutrients. The formation of new blood vessels - termed 'angiogenesis' - is now recognised as a key event in the formation and maintenance of the pannus in RA. This pannus is highly vascularised, suggesting that targeting blood vessels in RA may be an effective future therapeutic strategy. Disruption of the formation of new blood vessels would not only prevent delivery of nutrients to the inflammatory site, but could also lead to vessel regression and possibly reversal of disease. Although many proangiogenic factors are expressed in the synovium in RA, the potent proangiogenic cytokine vascular endothelial growth factor (VEGF) has been shown to a have a central involvement in the angiogenic process in RA. The additional activity of VEGF as a vascular permeability factor may also increase oedema and hence joint swelling in RA. Several studies have shown that targeting angiogenesis in animal models of arthritis ameliorates disease. Our own study showed that inhibition of VEGF activity in murine collagen-induced arthritis, using a soluble VEGF receptor, reduced disease severity, paw swelling, and joint destruction. Although no clinical trials of anti-angiogenic therapy in RA have been reported to date, the blockade of angiogenesis - and especially of VEGF - appears to be a promising avenue for the future treatment of RA.

Endothelial cell activation, injury, damage and dysfunction: separate entities or mutual terms?

The loss of well-regulated endothelial cell functioning is followed by adverse changes in a variety of physiological systems, such as the expression of adhesion molecules, maintenance of adequate blood vessel tone and haemostasis. Therefore, a full understanding of endothelial cell biology is essential if the losses of normal function of these systems are to be avoided. The viewpoint presented in this paper suggests that a spectrum between endothelial cell health and disease can be drawn: midway between these two extremes is immunological activation (by, for example, cytokines), which is reversible. Endothelial cell damage or injury (which may be the result of chronic inflammatory activation, hypercholesterolaemia, and/or smoking) are invariably associated with clinical conditions such as hypertension and oedema (and, ultimately, thrombosis and infarction), and are more difficult to reverse. A better understanding of the events, including apoptosis, that lead to vascular dysfunction may be useful in developing our understanding of vascular biology.

An adenoviral vector regulated by hypoxia for the treatment of ischaemic disease and cancer

Recombinant adenoviral vectors have a number of advantages for gene therapy, including transduction of a range of dividing and non-dividing cell types. However, this broad range may be a disadvantage if non-target cells are transduced and are adversely affected by expression of the transferred gene. Here we describe a novel adenoviral vector in which transcription of the transgene is restricted to the patho-physiological condition of low oxygen tension (hypoxia). Hypoxia activates the expression of a number of genes, principally via the stabilisation of members of the bHLH/PAS family of transcription factors that bind to a con- sensus DNA sequence, the hypoxia response element (HRE). We have configured an optimised HRE expression cassette into an adenoviral vector, AdOBHRE. A range of cell types, including primary human skeletal muscle, when transduced with AdOBHRE display a low basal level of transgene expression that is highly induced in hypoxia to levels equivalent to that obtained from the CMV promoter. The AdOBHRE vector could be exploited for transcriptionally targeted gene therapy for the treatment of diseases such as cancer, peripheral arterial disease, arthritis and anaemia where tissue hypoxia is a cardinal feature.

Vasculitis associated with connective tissue disease

Vasculitis, one of the clinical features shared by connective tissue diseases, should be considered when signs and symptoms are observed that may result from tissue ischaemia due to damaged vessels. The lesions seem to result from specific and non-specific immunopathogenic mechanisms targeted at the vascular endothelium. Because of the therapeutic implications it is the physician's responsibility to document its presence and the extent of organ involvement. Prompt institution of immunosuppressive drugs may be lifesaving. On the other hand there are some forms of vasculitis accompanying connective tissue disease which are entirely benign. Patients with infarctions of extremities and progressive functional disturbances of the central nervous system or internal organs because of vasculitis should be treated with high dosages of corticosteroids in combination with cytostatic drugs. Remissions are frequently obtained within three to six months of initiation of treatment and can be maintained with a less aggressive treatment regimen.

Increased capillary permeability in systemic sclerosis: help or hindrance?

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Activation of the transcription factor nuclear factor-kappaB in human inflamed synovial tissue

OBJECTIVE

The transcription factor nuclear factor kappaB (NF-kappaB) has been implicated in the inflammatory response and is known to be activated by a process involving reactive oxygen intermediates. The purpose of the present study was to demonstrate the presence and distribution of activated NF-kappaB in synovium samples from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and from autopsy subjects with no known history of arthritis.

METHODS

Immunohistochemical staining was performed using both polyclonal and monoclonal "activity-specific" antibodies to the Rel-A (p65) subunit of NF-kappaB (anti-Rel-A nuclear location sequences). Histologic features of inflammation were also scored.

RESULTS

Both antibodies demonstrated positive staining of synovial tissue, with a cellular distribution that was nuclear. The staining was associated with specific cell types within the tissue, in particular, type A synoviocytes and vascular endothelium. Notably, lymphoid aggregates were unstained. Using the monoclonal antibody, a further study was carried out to investigate the distribution of staining in tissues from patients with different disease activities and clinical diagnoses, as well as in normal control tissue obtained at autopsy. Patients with acute RA more commonly showed vessel staining (P = 0.05) and, conversely, showed less frequent staining of the synovial lining (P < 0.005) compared with OA patients. Synovial tissue from controls exhibited either no staining or only weak staining in the synovial lining.

CONCLUSION

The activation of NF-kappaB in vascular endothelium and type A synovial lining cells is a feature of synovial tissue from both RA and OA patients. The distribution of this staining appears to be related to the clinical diagnosis.

New agents for scintigraphy in rheumatoid arthritis

Radiopharmaceuticals have been used as investigative tools for the detection and treatment of arthritis activity in rheumatoid arthritis (RA) since the 1950s. Against the background of the pathophysiology of RA, the current status of joint scintigraphy and possible future developments are reviewed. Both non-specific (radiolabelled leucocytes and technetium-99m labelled human immunoglobulin) and specific targeting radiopharmaceuticals (including radiolabelled antibodies) are considered. The use of radiopharmaceuticals in the detection of arthritis activity has the advantages of allowing direct imaging of joints by means of whole-body scintigraphy and of joints that are difficult to assess clinically or radiographically. Promising results have been obtained with radiolabelled anti-CD4 and anti-E-selectin antibodies and with somatostatin receptor imaging, but more data are available regarding 99mTc-IgG scintigraphy, which differentiates between the various degrees of arthritis activity and thus facilitates the choice of antirheumatic drug. Newer promising approaches to the imaging of RA include the use of radiolabelled J001 and cytokines, though studies on these are limited at present.

Hormonal and pregnancy relationships to rheumatoid arthritis: convergent effects with immunologic and microvascular systems

OBJECTIVE

To review sex hormones and rheumatoid arthritis (RA) and the interrelationships between hormonal, immunological, and vascular systems.

DATA SOURCES

Publications detailing serum sex hormone levels and their HLA interactions, steroidogenesis, pregnancy, and therapeutic uses of sex hormones in RA.

STUDY SELECTION

Controlled studies of sex hormone levels in RA patients not previously treated with glucocorticoids.

DATA EXTRACTION

Mean (+/- SD) serum levels of dehydroepiandrosterone sulfate (DHEAS), testosterone (T), and estradiol (E2).

DATA SYNTHESIS

Mean (+/- SD) levels were collated into tables for women with pre-versus postmenopausal onsets of disease and men. Data were also ordered across all study groups by increasing mean levels of the control subjects. Pooled data were summarized statistically, and major sources of variation between the studies were identified.

CONCLUSIONS

Serum DHEAS, an adrenal androgen, was impressively decreased among women with premenopausal onset of RA. One study showed such deficiency years before disease onset. Serum T was somewhat decreased in the premenopausal onset group, but could be explained by decreased peripheral conversion of the lower levels of adrenal androgens. Women with postmenopausal onset of RA had modestly decreased serum DHEAS levels overall, but no difference in serum T, compared with controls. Male RA cases had consistently decreased serum levels of T, but not of DHEAS. Serum E2 was comparable in all RA versus control groups. The complex biology of pregnancy was interpreted as an example of vital interactions between hormonal, immunological, and vascular systems, as they may relate to the physiopathology of RA. The major age, sex, and hereditable determinants of RA were compared within a composite table of estimated relative risks. Elucidation of the interacting risk factors offers promising avenues of research in this complex disease.

Presence of foam cells containing oxidised low density lipoprotein in the synovial membrane from patients with rheumatoid arthritis

OBJECTIVE

Increased concentrations of lipid peroxidation products have been described in the serum and synovial fluid from patients with rheumatoid arthritis. A large proportion of the unsaturated lipids in human extracellular fluids is a component of low density lipoprotein (LDL). The oxidative modification of LDL, and its subsequent uptake by macrophages, has been implicated in the pathogenesis of atherosclerosis, but not of rheumatoid arthritis. This study aimed to assess whether oxidatively modified LDL was present in the rheumatoid synovium.

METHODS

A polyclonal antiserum raised in rabbits against oxidised LDL (o-LDL) was used to perform an immunohistochemical study of a series of synovial biopsy specimens from patients with rheumatoid arthritis.

RESULTS

Collections of positively stained macrophages, arranged in a linear fashion and with the morphological characteristics of foam cells--that is, 'fatty streaks', were identified around blood vessels within the intimal connective tissue. In addition, scattered, positively stained foam cells were present in association with deposits of fibrin. These staining patterns were absent from control synovial membranes (traumatic knee injuries).

CONCLUSIONS

The findings in all rheumatoid patients studied suggest that atherosclerosis and rheumatoid arthritis have analogous pathogenetic features.

Raised plasma renin and prorenin in rheumatoid vasculitis

The value of plasma renin and its inactive precursor, prorenin, were examined as a marker for vasculitis in rheumatoid arthritis (RA). Plasma renin and prorenin rise when the renin-angiotensin system is activated; an isolated increase of prorenin may be a marker for microvascular complications in diabetes mellitus. Renin concentrations in plasma obtained from 34 patients with RA (seven with vasculitis, 27 controls) were measured under standard conditions, before and five days after stopping non-steroidal anti-inflammatory drugs; creatinine clearance was also measured. At first the median renin concentration in the patients with vasculitis was 19 (range 12-63) mU/l (normal less than 61 mU/l) and in the controls 9 (3-43) mU/l. The median prorenin concentration in patients with vasculitis was 233 (144-428) mU/l (normal less than 358 mU/l) and in the controls 144 (25-364) mU/l. Renin and prorenin concentrations increased significantly in both groups after withdrawal of nonsteroidal anti-inflammatory drugs. The creatinine clearance was similar in both groups and did not correlate with renin concentrations. In conclusion, it was found that, unlike patients with diabetes mellitus, patients with RA with vasculitis had slightly raised concentrations of both renin and prorenin. These findings signal activation of the renin-angiotensin system and might indicate early cardiac or renal involvement by vasculitis.

Perivascular infiltration in normal skin of patients with rheumatoid arthritis: association with rheumatoid factors and HLA-DR antigens

The relation between immunohistological findings in biopsy specimens of apparently normal skin, HLA antigens, and rheumatoid factors (RF) was studied in 120 patients with rheumatoid arthritis (RA), selected for treatment with D-penicillamine. Perivascular infiltration (PVI) of more than three mononuclear cells was present in 77 (68%) of 114 patients, accompanied usually by the presence of IgM or C3, or both, in immunofluorescence studies. The number of perivascular cells was associated significantly with the titre of circulating RF. A weak relation of both perivascular cellular infiltration and RF with HLA-DR3 and DR4 did not reach statistical significance. It is concluded that the histological presence of perivascular inflammation is associated mainly with deposition of RF. It is suggested that the first is merely an epiphenomenon of the latter. PVI was not prognostic for the occurrence of the clinical syndrome of rheumatoid vasculitis. For practical purposes skin biopsies do not appear to be useful in the evaluation of individual patients with RA.

Immune complexes in sera from patients with rheumatoid vasculitis induce polymorphonuclear cell-mediated injury to endothelial cells

The ability of sera from 11 patients with rheumatoid arthritis (RA) complicated by leukocytoclastic vasculitis (RV) to induce injury to cultured monolayers of human umbilical vein endothelial cells (HEC) was investigated. Injury was assessed in vitro using assays of cell lysis and cell detachment. Sera from patients with RV produced neither direct injury to HEC monolayers nor indirect injury when cocultured with HEC and normal peripheral blood polymorphonuclear cells (PMN). However, immune complexes (Icx) isolated from these sera induced nonlytic PMN-mediated HEC detachment. The inhibitory effect of serum on PMN-mediated HEC detachment induced by Icx could be attributed both to a different response of PMN to Icx present in serum compared to isolated Icx and to the presence of protease inhibitors in serum. The results of this study show that sera from patients with RV do not contain factors that can injure HEC directly and provide further support for the hypothesis that Icx and PMN play important roles in the pathogenesis of immune vascular injury.

Influence of atmospheric factors on the rheumatic diseases

There appears to be ample evidence to conclude that various meteorological factors do exert a significant impact on some people with various rheumatic diseases. The data is, however, crude relative to our general understanding. Most of this research on RA has dealt with the primary signs and symptoms of inflammation. We know, however, many of the chemical mediators of inflammation. It seems like a logical progression of research to determine the effects of the meteorological/atmospheric factors of concern on these specific intrinsic mediators of inflammation. In general, gout can be very well controlled through medication. The evidence suggests, however, that we may gain a much better understanding of how atmospheric factors such as temperature can effect the body through changes in its physico-chemical processes by using Gout as a model. The work with SLE has already yielded useful applications. Sun screening pharmaceuticals have been quite successful in reducing exacerbations of symptoms. But we don't know why only some people are photosensitive. The previous research on the effects of atmospheric factors on the rheumatic diseases has illustrated key issues in methodology: large sample sizes are critical, objective and quantifiable disease variables are important, the variables measured must be specific to the questions investigated, the diseases investigated must be as specifically and accurately defined as possible, and the various aspects of 'weather' to be investigated must be specifically defined and quantified. It is apparent that there is much more important and useful work to be performed before we can understand the effects of atmospheric factors on the rheumatic diseases.

Rheumatoid arthritis: clinical features and pathogenetic mechanisms

Rheumatoid arthritis is a disorder characterized by chronic inflammation affecting predominantly articular tissues, leading in some instances to disruption of the normal structure and function of the joint. In some patients extra-articular manifestations are also present. In the joints, the pathologic lesion consists of synovial cell proliferation with infiltration by inflammatory cells. The complex interaction among these cells is likely responsible for the connective tissue abnormalities that characterize the rheumatoid lesion. The factors responsible for inducing the inflammatory process are unknown.

Multifactorial pathogenesis: ought we to classify disease or treat the individual's causes of disease?

Added to the uniqueness of most of us imparted by HLA, our individual differences in the expression of other genetic traits, foetal period steroid imprints on brain and other functions, and regulators shared by body and mind indicate that each one of us (except most monozygotic twins) is born as a unique individual whole (I). Mechanisms suspected to be contributing ones in classified synovitides appear to correspond to individually exaggerated or depressed modes of response by physiological mechanisms linked to our unique individual wholes (II). If we upgrade the importance of influences of combinations of 'contributing' mechanisms, the importance of the alleged unknown fundamental causes of these diseases diminishes (III). This broad interpretation of 'multifactorial pathogenesis' can probably be applied to many common types of disease (IV), implying that disease classifications may poorly reflect the individual's causes of disease (V). There is reason to challenge modern concepts about disease (VI).

Laminin and vascular proliferation in rheumatoid arthritis

Laminin is a high molecular weight basement membrane structural glycoprotein. In rheumatoid arthritis and other arthropathies immunoreactive laminin was prominent in synovial blood vessel basement membranes and acted as a marker for them. It codistributed with collagen type IV. Immunohistological reactivity to laminin showed extensive vascular proliferation in rheumatoid arthritis together with basement membrane reduplication, which was confirmed ultrastructurally. Parallel histological studies showed vascular proliferation was predominantly in the subintimal rheumatoid synovium, where it was related to connective tissue proliferation but not to the inflammatory cell infiltrate. Vascular proliferation was also seen in relation to connective tissue changes in biopsies from cases of haemophilic arthritis, osteoarthritis, and meniscal tears. We suggest connective tissue activation is non-specific reaction associated with vascular proliferation. This involves laminin and other structural proteins. It occurs in rheumatoid arthritis and other arthropathies but is distinct from inflammatory cell infiltration.