Preliminary evidence for gut involvement in the pathogenesis of rheumatoid arthritis?

Re-evaluation of dietary interventions in rheumatoid arthritis: can we improve patient conversations around food choices?

Rheumatoid arthritis (RA) is one of over 100 different types of autoimmune conditions. In RA, the cells of the immune system attack the tissue lining the joints, triggering inflammation. A large body of research suggests that the underlying trigger(s) of RA are unique to an individual. For example, increased risk of RA can be driven by smoking tobacco in one individual and mercury exposure in another. Due to the development of next-generation sequencing technology, the critical role of the microbiota in shaping RA risk has been elucidated. Therefore, it is surprising that diet, arguably the most important lever in shaping the gut microbiota, is ineffective in the treatment of RA, even in a sub-set of patients. To attempt to rationalise this apparent paradox, we conducted an umbrella review to address the question as to whether diet can affect outcomes in RA.

Intestinal barrier dysfunction plays an integral role in arthritis pathology and can be targeted to ameliorate disease

Background

Evidence suggests an important role for gut-microbiota dysbiosis in the development of rheumatoid arthritis (RA). The link between changes in gut bacteria and the development of joint inflammation is missing. Here, we address whether there are changes to the gut environment and how they contribute to arthritis pathogenesis.

Methods

We analyzed changes in markers of gut permeability, damage, and inflammation in peripheral blood and serum of RA patients. Serum, intestines, and lymphoid organs isolated from K/BxN mice with spontaneous arthritis or from wild-type, genetically modified interleukin (IL)-10R^−/−or claudin-8^−/−mice with induced arthritis were analyzed by immunofluorescence/histology, ELISA, and flow cytometry.

Findings

RA patients display increased levels of serum markers of gut permeability and damage and cellular gut-homing markers, both parameters positively correlating with disease severity. Arthritic mice display increased gut permeability from early stages of disease, as well as bacterial translocation, inflammatory gut damage, increases in interferon γ (IFNγ)⁺and decreases in IL-10⁺intestinal-infiltrating leukocyte frequency, and reduced intestinal epithelial IL-10R expression. Mechanistically, both arthritogenic bacteria and leukocytes are required to disrupt gut-barrier integrity. We show that exposing intestinal organoids to IFNγ reduces IL-10R expression by epithelial cells and that mice lacking epithelial IL-10R display increased intestinal permeability and exacerbated arthritis. Claudin-8^−/−mice with constitutively increased gut permeability also develop worse joint disease. Treatment of mice with AT-1001, a molecule that prevents development of gut permeability, ameliorates arthritis.

Conclusions

We suggest that breakdown of gut-barrier integrity contributes to arthritis development and propose restoration of gut-barrier homeostasis as a new therapeutic approach for RA.

Funding

Funded by Versus Arthritis (21140 and 21257) and UKRI/MRC (MR/T000910/1).

Serum gut-permeability markers LPB, LPS, and I-FABP are increased in RA

Mice with arthritis have increased gut permeability and intestinal inflammation

Both bacteria and leukocytes are needed to disrupt gut-barrier integrity

Prevention of gut-barrier dysfunction in arthritis ameliorates joint inflammation

Rheumatoid arthritis is an autoimmune disorder characterized by chronic joint inflammation. Accumulating evidence suggests that changes in the composition of the bacteria residing in the gut could be responsible for joint inflammation. Currently, it is unclear how bacteria or their products instruct cells of the immune system to become harmful and induce arthritis. Researchers at University College London have shown that, in arthritis, there is profound damage to the gut lining, which fails to work properly as a barrier, as well as an accumulation in the gut of white blood cells that cause inflammation. The authors show that, in arthritis, bacteria cross the prohibited border of the intestinal lining and that repairing gut permeability defects with specific drugs inhibits joint inflammation.

The role of the gastrointestinal tract in the pathogenesis of rheumatic diseases

Dysregulation of the intestinal epithelial barrier in genetically susceptible individuals may lead to both intestinal and extraintestinal autoimmune disorders. There is emerging literature on the role of microbiota changes in the pathogenesis of systemic rheumatic diseases such as rheumatoid arthritis, spondyloarthropathies, and connective tissue diseases. Although the role of the gastrointestinal tract in the pathogenesis of spondyloartropathies is well defined and many studies underline the importance of gastrointestinal inflammation in modulating local and systemic inflammation, the data are inconclusive regarding the effect of dysbiosis on rheumatoid arthritis and connective tissue diseases. This review aims to summarize current data on the role of the gastrointestinal involvement and intestinal microbiota in the pathogenesis of systemic rheumatic disease.

Making sense of the cause of Crohn's - a new look at an old disease

The cause of Crohn’s disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients’ inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.

Making sense of the cause of Crohn's - a new look at an old disease

The cause of Crohn's disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients' inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.

Gastrointestinal and hepatic manifestations of rheumatoid arthritis

Rheumatoid arthritis (RA), characterized by inflammation of the synovium and surrounding structures, has a prevalence of 0.5-1%. Rheumatoid vasculitis (RV) is an inflammatory condition of the small- and medium-sized vessels that affects up to 5% of patients with RA with intestinal involvement in 10-38% of these cases. Clinically apparent RV of the gastrointestinal (GI) tract, while rare, is often catastrophic, resulting in ischemic ulcers and bowel infarction. Vasculitis of the colon may present as pancolitis clinically similar to ulcerative colitis. Rectal biopsies that include submucosal vessels are positive for vasculitis in up to 40% of cases. Abnormal esophageal motility in RA may result in heartburn and dysphagia. Chronic atrophic gastritis may be associated with hypergastrinemia and hypo- or achlorhydria, promoting small bowel bacterial overgrowth. RA is the most common cause of secondary amyloidosis with GI symptoms in 22% of affected patients. Although amyloid is usually found in the liver, it is rarely evident clinically. Felty's syndrome occurs in less than 1% of patients with RA and is characterized by neutropenia and splenomegaly. The liver may be involved with portal fibrosis or nodular regenerative hyperplasia. Liver histology is abnormal in 92% of RA patients at autopsy, although the changes are usually mild without associated hepatomegaly. Drug-induced liver disease may occur with aspirin, sulfasalazine, and methotrexate. Significant liver damage is rare if the drug is discontinued or the patient is properly monitored. RA can affect both the GI tract and the liver; changes are usually mild except with RV.

Capsule endoscopic diagnosis of nonsteroidal antiinflammatory drug-induced enteropathy

BACKGROUND

Case reports have linked nonsteroidal antiinflammatory drugs (NSAIDs) to a variety of lesions in the small and large bowel including bleeding, protein loss, strictures, increased intestinal permeability, and NSAID enteropathy. We here review the use of wireless capsule endoscopy to quantitate and assess the nature of the small bowel damage caused by NSAIDs when taken short term and in patients on long-term NSAIDs and COX-2 inhibitors.

METHODS

Forty healthy volunteers underwent a baseline capsule endoscopy. After taking diclofenac slow-release 75 mg twice a day for a total of 14 days, both investigations were repeated. A further 120 patients on long-term NSAIDs (more than 3 months) and 40 on COX-2 inhibitors underwent a capsule endoscopy study. Sixty healthy patients acted as controls. Small bowel damage was categorized and quantitated.

RESULTS

Short-term diclofenac: Capsule endoscopy demonstrated new pathology in 27 (68%) of subjects. The most common lesions were mucosal breaks, seen in 16 (40%), which were seen to be bleeding in 2 (5%). Long-term NSAIDs: The main pathology was related to mucosal breaks (29%); 3% had free luminal blood and 2% had strictures. The damage seen in 50% of patients on selective COX-2 inhibitors did not differ significantly (P<0.5) from that seen with NSAIDs.

CONCLUSIONS

Capsule endoscopy demonstrates evidence of macroscopic injury to the small intestine, in up to 68% of volunteers, resulting from 2 weeks ingestion of slow-release diclofenac. Long-term use of NSAIDs and COX-2 inhibitors causes comparable small bowel damage (50%-68%).

Is rheumatoid arthritis a disease that starts in the intestine? A pilot study comparing an elemental diet with oral prednisolone

OBJECTIVES

This pilot study aimed to determine if an elemental diet could be used to treat patients with active rheumatoid arthritis and to compare its effect to that of oral prednisolone.

METHODS

Thirty patients with active rheumatoid arthritis were randomly allocated to 2 weeks of treatment with an elemental diet (n = 21) or oral prednisolone 15 mg/day (n = 9). Assessments of duration of early morning stiffness (EMS), pain on a 10 cm visual analog scale (VAS), the Ritchie articular index (RAI), swollen joint score, the Stanford Health Assessment Questionnaire, global patient and physician assessment, body weight, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and haemoglobin, were made at 0, 2, 4 and 6 weeks.

RESULTS

All clinical parameters improved in both groups (p<0.05) except the swollen joint score in the elemental diet group. An improvement of greater than 20% in EMS, VAS and RAI occurred in 72% of the elemental diet group and 78% of the prednisolone group. ESR, CRP and haemoglobin improved in the steroid group only (p<0.05).

CONCLUSIONS

An elemental diet for 2 weeks resulted in a clinical improvement in patients with active rheumatoid arthritis, and was as effective as a course of oral prednisolone 15 mg daily in improving subjective clinical parameters. This study supports the concept that rheumatoid arthritis may be a reaction to a food antigen(s) and that the disease process starts within the intestine.

Determining small bowel integrity following drug treatment

Intestinal integrity is maintained by a delicate balance between mucosal defence and luminal aggressors that cause damage if exposed to the mucosa. The intestinal barrier function appears to be the gatekeeper for controlling this balance. It is becoming increasingly clear that if the intestinal barrier is disrupted the consequences are low grade intestinal inflammation which carry with it the risk of significant blood and protein loss both of which may cause clinical management problems. We review the strength and weaknesses of methods for assessing small bowel function that are useful for assessing drug-induced intestinal toxicity. There are a number of imaging methods for assessing intestinal integrity but these do not provide functional information. Intestinal permeability measurements have been optimized for specificity and there are now ways of measuring intestinal permeability regionally, but marker analyses continue to be cumbersome. Recent developments of faecal inflammatory markers make it a matter of routine to assess this in any routine chemical pathology laboratory. Bleeding, protein loss and other complications of inflammation can also be measured with good specificity, but again the methods are cumbersome. Using a combination of functional and imaging techniques it is now possible to characterize and define with precision, the small bowel side-effects of drugs, the best example being the small bowel side-effects of nonsteroidal anti-inflammatory drugs (NSAIDs).

A comparative experimental study of the effects of diclofenac and ketoprofen on the small-bowel mucosa of canines

The aim of this experimental study was to investigate the effect of diclofenac sodium and ketoprofen, two non-steroidal anti-inflammatory drugs (NSAIDs) with different excretion pathways, and the role of other enteric factors during simultaneous administration of these drugs on the development of mucosal lesions of the small intestine in canines. Twenty-five animals were divided into three groups. Group I included 10 canines, 5 with diclofenac sodium (group Ia) and 5 with ketoprofen administration (group Ib). Group II included 5 animals in which a segment of ileum was surgically isolated from the rest of the small intestine. Group III included 10 animals in two subgroups of 5; a segment of ileum was surgically isolated in both subgroups; groups IIIa received diclofenac and group IIIb ketoprofen. Histological examination of the specimens taken revealed macroscopic and microscopic mucosal lesions in 5/5 animals in group Ia, whereas none of the 5 animals in group Ib had any lesions. Group II did not reveal any mucosal lesions. Three out of 5 animals (60%) administered diclofenac in group IIIa had intestinal mucosal lesions, but none of the 5 revealed lesions in the isolated loop of ileum. No lesions were observed in the isolated loop or in the rest of the intestinal mucosa in the animals in group IIIb. Our results suggest that NSAIDs produce intestinal mucosal lesions not only when administered per mouth but also after intramuscular administration. Diclofenac, unlike ketoprofen, was responsible for the development of lesions in the intestinal mucosa. The role of drugs and/or their metabolites in the intestine and certain other factors must still be determined.

Bowel inflammation and the spondyloarthropathies

The concept of spondyloarthropathies gathers together a group of chronic diseases in which not only the locomotor system is involved but also other organs, especially the gastrointestinal tract. In humans, ileocolonoscopic studies demonstrated the presence of inflammatory gut lesions in all the diseases in the spondyloarthropathy group; their presence varied in the different diseases between 20% and 70%. The inflammation could be related to specific disease features in the spondyloarthropathies. Further research supports the hypothesis of subclinical inflammatory bowel disease in some patients with spondyloarthropathy, in which the locomotor inflammation was the only clinical manifestation. The link between gut inflammation and arthropathy has also been demonstrated in animal models, notably the human leukocyte antigen B27 transgenic rats. The temporal relationship between activity and severity of colonic involvement and flares of peripheral arthritis directs treatment of choice. For all forms of enterogenic arthropathies, nonsteroidal anti-inflammatory drugs remain the acute treatment form. Caution is in order, however, because of their possible harmful effects on intestinal integrity, permeability, and even on gut inflammation.

Influence of anti-rheumatic drugs on gut permeability and on the gut associated lymphoid tissue

There is great interest in the association between intestinal inflammation and the various arthropathies. However, most studies assessing intestinal function in these diseases are confounded by the fact that non-steroidal anti-inflammatory drugs (NSAIDs) have profound effects on the small intestine. Hence NSAIDs cause quite distinct and severe biochemical damage during drug absorption (uncoupling of mitochondrial oxidative phosphorylation proving to be most important) which results in increased intestinal permeability. All commonly used NSAIDs, apart from aspirin and nabumetone, are associated with increased intestinal permeability in man. Whilst reversible in the short term, it may take months to improve following prolonged NSAID use. Increased intestinal permeability appears to be the central mechanism of converting the biochemical damage to an inflammatory tissue reaction (NSAID enteropathy). The inflammatory enteropathy is not, however, unique to NSAIDs but similar changes are found with other permeability breakers. In intestinal infections and in diseases associated with reduced mucosal defence, suggesting that the small intestinal inflammation represents a common final pathway for a number of intestinal injuries. Spondylarthropathies are associated with a high prevalence of terminal ileitis, but as most patients have been receiving NSAIDs it has been difficult to dissociate the effects of NSAIDs on intestinal function from that of the ileitis itself. Nevertheless, two studies suggest that increased intestinal permeability in spondylarthropathies occur independently of NSAID ingestion. Whilst these findings may have implications for the development of arthritis, the permeability changes in spondylarthropathy do not differ quantitatively or qualitatively from that of NSAIDs or other permeability breakers. NSAID enteropathy can be differentiated from spondylarthropathic enteropathy by differences in location of disease and lack of predilection of certain HLA types. However, as the two may coexist both enteroscopy and ileocolonoscopy may be necessary for this distinction.

Evidence for differential effects of sulphasalazine on systemic and mucosal immunity in rheumatoid arthritis

OBJECTIVE

To study the effects of sulphasalazine (SASP) on the systemic and mucosal humoral immune systems in patients with rheumatoid arthritis (RA).

METHODS

Serum concentrations of interleukin 6 (IL-6), class and subclass specific IgG, IgA and IgM, IgA and IgG antigliadin antibodies and rheumatoid factors (RF) of IgG, IgA (including IgA1 and IgA2 subclasses) and IgM isotypes were measured before and 16 weeks after sulphasalazine (SASP) therapy in 15 female and three male patients with RA. Amounts of immunoglobulins in saliva and jejunal fluid were measured as estimates of mucosal humoral immunity.

RESULTS

Serum concentrations of IgA and IgG decreased significantly during SASP therapy and correlated with reduced concentrations of IL-6. In addition, levels of circulating IgA RF, IgA anti-gliadin antibodies and IgM RF decreased significantly after the treatment. In contrast, immunoglobulin levels in saliva and jejunal fluid were unaltered.

CONCLUSION

SASP exerts powerful but selective inhibitory effects on systemic immunoglobulin production, whereas no effects on mucosal immunoglobulin production were observed. The decreased systemic B cell activity may be mediated by downregulation of the production of IL-6, a cytokine with Ig switching properties.

Evidence of a local intestinal immunomodulatory effect of sulfasalazine in rheumatoid arthritis

OBJECTIVE

To analyze whether the intestinal mucosa in rheumatoid arthritis (RA) is immunologically abnormal and whether sulfasalazine (SSZ) possesses any local intestinal immunoregulatory effect.

METHODS

Lymphocyte subpopulations and HLA-DR expression were evaluated in biopsy specimens from the duodenal-jejunal mucosa and in peripheral blood samples obtained from 17 patients with RA, both before and after 16 weeks of SSZ treatment. The same mucosal assays were also performed in 7 controls.

RESULTS

The mucosa of the small intestine in RA patients showed no differences in morphology, HLA-DR expression, or the amounts and distribution of CD3+, CD4+, CD8+, and gamma/delta + lymphocytes compared with the control group. However, there was a reduction in mucosal CD3+ and gamma/delta + lymphocyte numbers after SSZ therapy, which did not correspond to a change in peripheral blood CD3+ lymphocyte number. SSZ treatment also tended to diminish the peripheral blood CD4+:CD8+ cell ratio (P = 0.05).

CONCLUSION

No signs of inflammation or immunologic abnormalities were seen in RA duodenal-jejunal mucosa. In this part of the intestine, however, SSZ exerted immunoregulatory effects that were not encountered in the peripheral blood.

Intestinal toxicity of non-steroidal anti-inflammatory drugs

We review the adverse effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the small and large intestine. NSAIDs cause small intestinal inflammation in 65% of patients receiving the drugs long-term. The clinical implications of NSAID-induced enteropathy are that patients bleed and lose protein from the inflammatory site, contributing to iron deficiency and hypoalbuminemia, respectively. Some patients develop intestinal strictures, which may require surgery, and the occasional one may develop discrete ulcers with perforations. There are a number of therapeutic options available to treat the enteropathy and the attendant complications, including antibiotics, sulphasalazine and misoprostol. The colon, by comparison, is only rarely affected by NSAIDs, but colitis is well recognized and NSAIDs may be an important factor in diverticular complications and the relapse of inflammatory bowel disease. There is an association between NSAID intake and appendicitis in the elderly.

Phlogistic properties of peptidoglycan-polysaccharide polymers from cell walls of pathogenic and normal-flora bacteria which colonize humans

PG-PS polymers which can induce experimental chronic inflammation in joints and other tissues can be isolated from the cell walls of human pathogens, such as group A streptococci, as well as from certain indigenous bacterial species which colonize the human intestinal tract. The structural and biological properties that are required for cell wall fragments to express this remarkable activity are still not well defined, but polymer size, resistance to tissue enzymes, and capacity to sustain activation of complement, macrophages, neutrophils, and T cells are properties associated with the most active preparations. There is increasing evidence that PG-PS structures with arthropathogenic activity occur in the human intestinal lumen and that these polymers can be translocated systemically. These observations support the concept that PG-PS, derived from a variety of bacterial species, can be part of the etiology of rheumatoid arthritis and other chronic inflammatory diseases. Since the PG component provides a common element to which all individuals are exposed, it follows that susceptibility is related to efficiency of disposal of bacterial cell wall debris, as well as to cytokine networks and immune cell function (51).

Variation in the serum IgA concentration and the production of IgA in vitro in rheumatoid arthritis treated by sulfasalazine

Sulfasalazine is an efficient treatment for rheumatoid arthritis (RA), but its mode of action is not known. In RA, a correlation has been demonstrated between disease activity and the secretion of immunoglobulin A (IgA) by peripheral blood lymphocytes (PBL) in culture. Furthermore, the IgA-producing cells of the peripheral blood have been shown to originate from the mucous-associate lymphoid tissue (MALT). We studied the variations in the total IgA concentration in the serum of RA patients, and the secretion of IgA by PBL after 7 days culture in vitro, before and after treatment with sulfasalazine. A significant decrease in the serum IgA concentration was obtained, but there was no modification of the spontaneous increase in the in vitro IgA synthesis by circulating mononuclear cells. Our results suggested that the decrease in serum IgA concentration after treatment with sulfasalazine was not linked to a decrease in the IgA secretion by PBL. This does not favour a direct effect of sulfasalazine on the mucous-associated lymphoid tissue.

Side effects of nonsteroidal anti-inflammatory drugs on the small and large intestine in humans

BACKGROUND

It is not widely appreciated that nonsteroidal anti-inflammatory drugs (NSAIDs) may cause damage distal to the duodenum. We reviewed the adverse effects of NSAIDs on the large and small intestine, the clinical implications and pathogenesis.

METHODS

A systematic search was made through Medline and Embase to identify possible adverse effects of NSAIDs on the large and small intestine.

RESULTS

Ingested NSAIDs may cause a nonspecific colitis (in particular, fenemates), and many patients with collagenous colitis are taking NSAIDs. Large intestinal ulcers, bleeding, and perforation are occasionally due to NSAIDs. NSAIDs may cause relapse of classic inflammatory bowel disease and contribute to serious complications of diverticular disease (fistula and perforation). NSAIDs may occasionally cause small intestinal perforation, ulcers, and strictures requiring surgery. NSAIDs, however, frequently cause small intestinal inflammation, and the associated complications of blood loss and protein loss may lead to difficult management problems. The pathogenesis of NSAID enteropathy is a multistage process involving specific biochemical and subcellular organelle damage followed by a relatively nonspecific tissue reaction. The various possible treatments of NSAID-induced enteropathy (sulphasalazine, misoprostol, metronidazole) have yet to undergo rigorous trials.

CONCLUSIONS

The adverse effects of NSAIDs distal to the duodenum represent a range of pathologies that may be asymptomatic, but some are life threatening.

Glucose and citrate reduce the permeability changes caused by indomethacin in humans

Nonsteroidal anti-inflammatory drug (NSAID)-induced increased intestinal permeability appears to be a prerequisite for NSAID enteropathy. It has been suggested that early metabolic events leading to the permeability changes may involve inhibition of glycolysis and the tricarboxylic acid cycle, in which case the coadministration of glucose and citrate (the substrates for these metabolic pathways) with indomethacin may afford some protection. The present study, using a combined intestinal absorption-permeability test including 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and [51Cr]ethylene-diaminetetraacetic acid (EDTA) as test probes and the differential urine excretion ratio of [51Cr]-EDTA/L-rhamnose, showed that indomethacin (50 + 75 mg) increased intestinal permeability. A formulation of indomethacin containing 15 mg glucose and 15 mg citrate to each milligram of indomethacin did not increase intestinal permeability significantly above baseline values. When given alone with indomethacin, neither glucose nor citrate (45 mg to each milligram of indomethacin) had any protective effects. Pharmokinetic studies showed that the effects of glucose and citrate cannot be explained on the basis of altered drug absorption. These results suggest a new approach to reducing the small intestinal side effects of NSAIDs.

Enumeration of IgA producing cells by the enzyme linked immunospot (ELISPOT) technique to evaluate sulphasalazine effects in inflammatory arthritides

Numbers of IgA producing cells in peripheral blood were determined by the enzyme linked immunospot (ELISPOT) technique in 15 patients with inflammatory arthritides receiving sulphasalazine treatment. The numbers of IgA producing cells decreased significantly after the first three weeks of treatment. In 11 of the patients this decrease persisted, whereas a subsequent increase was seen in the four others; in two of these latter patients this increase coincided with a temporary withdrawal of the sulphasalazine treatment. A reduction of serum concentrations of IgA and haptoglobin was seen after three months' treatment. Eleven of the patients had a subjective improvement in their joint disease during the first three months of treatment. Analysis of circulating cells committed for IgA secretion may constitute one way of assessing gut associated immunity indirectly, and the present data suggest that sulphasalazine has a rapid effect on lymphocytes possibly originating from the gut and that such an effect precedes improvement in laboratory parameters and clinical symptoms in arthritic diseases.

Importance of local versus systemic effects of non-steroidal anti-inflammatory drugs in increasing small intestinal permeability in man

Increased small intestinal permeability caused by non-steroidal anti-inflammatory drugs (NSAIDs) is probably a prerequisite for NSAID enteropathy, a source of morbidity in patients with rheumatoid arthritis. This increased small intestinal permeability may be a summation of a local effect during drug absorption, a systemic effect after absorption, and a local effect of the drug excreted in bile, but the relative contribution made by these factors is unknown. We assessed the effect of indomethacin and nabumetone on intestinal permeability. The principal active metabolite of nabumetone, 6-methoxy-2-naphthylacetic acid, is not subject to appreciable enterohepatic recirculation. Twelve volunteers were studied before and after one week's ingestion of indomethacin (150 mg/day) and nabumetone (1 g/day) with a combined absorption/permeability test. Neither drug had a significant effect on the permeation of 3-0-methyl-D-glucose, D-xylose, and L-rhamnose. Indomethacin increased the permeation of radioactive 51chromium ethylenediaminetetra-acetic acid (51Cr EDTA) significantly from baseline (mean (SEM) 0.63 (0.09)% v 1.20 (0.14)%, p less than 0.01) but nabumetone did not (0.70 (0.10)% p greater than 0.1). These results were supported by the 51Cr EDTA/L-rhamnose urine excretion ratios, which reflect changes in intestinal permeability. They suggest that NSAIDs increase intestinal permeability during absorption or after biliary excretion and that the systemic effect is of minor importance.

Treatment of non-steroidal anti-inflammatory drug induced enteropathy

Non-steroidal anti-inflammatory drug induced small intestinal inflammation may have an adverse effect on the joints of patients with rheumatoid arthritis. We therefore assessed small intestinal and joint inflammation in patients with rheumatoid arthritis before and after three to nine months' treatment with sulphasalazine (n = 40) and other second line drugs (n = 20), while keeping the dosage of non-steroidal anti-inflammatory drug at the same level. Sulphasalazine significantly decreased the mean (SD) faecal excretion of 111indium labelled leucocytes from 2.39 (2.22)% to 1.33 (1.13)% (normal less than 1%, p less than 0.01) and improved the joint inflammation as assessed by a variety of parameters. There was no significant correlation between the effects of sulphasalazine treatment on the intestine and the joints. Treatment with other second line drugs had no significant effect on the faecal excretion of 111indium (1.58 (1.04)% and 1.86 (1.51)%, respectively) but improved joint inflammation significantly. The lack of correlation between the intestinal and joint inflammation and their response to treatment suggests that the two are not causally related.

Intestinal mucosal permeability and rheumatological diseases

Rheumatological disorders frequently have gastrointestinal manifestations and, conversely, intestinal disorders frequently have rheumatological manifestations. The possibility of altered intestinal permeability in arthritic patients may provide the bridge needed to link the two organ systems. The normal intestine absorbs nutrients and excludes the remaining material. If the intestine were less discriminating or 'leaky' then material normally excluded would be able to cross the intestinal mucosa into the lamina propria. An inflammatory response to these antigens, be they dietary, bacterial, or viral in origin, could produce either local or systemic disease. This would depend upon the type of immunological response and the cross-reactivity between the host's antigens and the absorbed antigens. This theory could account for the postulated relationship between intestinal abnormalities and the pathogenesis of some forms of arthritis.

Seronegative arthritis and the bowel

In this chapter we have outlined the seronegative spondarthritides associated with bowel disease, excluding those discussed in separate chapters. Although, traditionally, Crohn's disease and ulcerative colitis have been dealt with separately in any discussion of seronegative arthritides, they have been discussed together here for the following reasons. Despite being pathologically distinct they show remarkable similarity in extraintestinal manifestations including any associated arthritis. Any observed differences in prevalence rates of arthritis may be secondary to the relative difficulty in diagnosing Crohn's disease, and most of the important prevalence studies were done before the more sophisticated techniques to investigate the bowel became available. This may in part explain the dramatic increase in the world-wide incidence of Crohn's disease seen in the last 30 years, particularly through the 1970s, but which has fallen off recently (Miller et al, 1974). It would seem that the body has a limited means of expressing disease processes. The final common pathway of a number of quite distinct disease entities is the concept of the seronegative spondarthritides. Exactly how the microbiological, immunogenetic and molecular factors interact to produce a particular disease end-point is currently not clearly defined, but with the increasingly sophisticated means to investigate the body at a cellular level the explanations may soon be at hand. Further controlled family studies are also needed to define the genetic relationships more precisely. We may then be able to piece the jigsaw puzzle together.

IgA rheumatoid factor and IgG dietary protein antibodies are associated in rheumatoid arthritis

This study sought to determine whether patients with rheumatoid arthritis (RA) were immunologically sensitised to dietary protein (DP). Using an enzyme linked immunosorbent assay (ELISA), antibodies to milk and wheat proteins were measured in 93 unselected out-patients with classical or definite RA. Of these 93, 53 had raised levels of IgG antibodies to one or both dietary proteins (DP). In the DP antibody positive group, 48 patients (90%) also had raised levels of IgA rheumatoid factor (measured by ELISA) while only 7 (17%) of the 40 DP antibody negative patients had detectable IgA RF; P less than 0.02. There was no association between IgM rheumatoid factor and dietary protein antibodies. These results demonstrate that in RA, raised levels of IgA RF are associated with an increased IgG response to antigens which enter the body through the gastrointestinal tract. A breakdown in gastrointestinal tolerance to dietary antigens may play a role in the immunopathogenesis of RA in these patients who might therefore benefit from dietary manipulation.

Misoprostol reduces indomethacin-induced changes in human small intestinal permeability

This study examined whether indomethacin-induced increases in small intestinal permeability in man are prevented by concomitant administration of a prostaglandin analog (misoprostol). Twelve male volunteers were tested as baseline, following misoprostol alone (200 micrograms, at -16, -12, -8.5, -4, -1.5, and +4 hr); following indomethacin alone (75 mg, at -8; 50 mg, -1 hr); and following coadministration of misoprostol and indomethacin as specified above. A 100-ml test solution containing 3-O-methyl glucose (0.2 g), D-xylose (0.5 g), L-rhamnose (1.0 g), and [51Cr]EDTA (100 microCi) was ingested at 8 AM, and a 5-hr collection made for marker analysis to assess active and passive carrier-mediated transport and trans- and intercellular permeation, respectively. Indomethacin increased the permeation of [51Cr]EDTA selectively, and this increase was significantly reduced by the coadministration of misoprostol. These changes were mirrored by changes in [51Cr]EDTA-L-rhamnose urine excretion ratios, which indicates that paracellular permeability was specifically altered. This study supports the suggestion that NSAIDs alter intestinal permeability by a mechanism involving reduced prostaglandin synthesis and indicates that coadministration of misoprostol with NSAIDs may reduce the frequency and severity of NSAID-induced small intestinal inflammation.

The changing gastrointestinal side effect profile of non-steroidal anti-inflammatory drugs. A new approach for the prevention of a new problem

The most serious side effects of non-steroidal anti-inflammatory drugs (NSAIDs) involve gastroduodenal perforations and massive haemorrhage. It is becoming increasingly clear, however, that it is the small intestine that bears the main brunt of NSAID-related gastrointestinal toxicity. Hence 70% of patients receiving NSAIDs in the long term have evidence of small-intestinal inflammation, and the same patients lose blood and protein as a consequence. Many patients have asymptomatic ileal dysfunction and occasionally may develop unique small-intestinal strictures necesitating surgery. The pathogenesis of the intestinal inflammation is beginning to emerge. There are data to support that an imbalance between prostaglandins and leukotrienes is important in disrupting small-intestinal integrity during drug absorption. Furthermore, a simple mixture of glucose and citrate with indomethacin appears to minimize the damage. Whether this overcomes a metabolic block caused by NSAIDs and replenishes ATP levels or acts by scavenging oxygen free radicals is unknown, but our further understanding of the mechanism may revolutionize our approach to prevention of the gastrointestinal toxicity of NSAIDs.

Association between villous atrophy in rheumatoid arthritis and a rheumatoid factor and gliadin-specific IgG

93 patients with rheumatoid arthritis (RA) were examined for histological or other evidence of gut abnormalities. 44 had raised levels of IgG to gliadin, and of these 38 (86%) were also positive for IgA rheumatoid factor (RF). 24 patients (15 with raised levels of IgA RF and wheat protein IgG [AB+] and 9 with normal levels of both antibodies [AB-]) underwent jejunal biopsy. 6 of the AB+ and 1 of the AB- patients had villous atrophy. The AB+ group had lower villous surface/volume ratio and small intestinal lactase concentrations than did the AB- group or age-matched controls. There was no significant difference between the two groups of RA patients in disease severity or treatment regimen. The findings suggest that the gut may play a more important part in the immunopathogenesis of some cases of RA than in others, and that the former may be identified by raised levels of IgA RF and wheat protein IgG.

Co-trimoxazole in rheumatoid arthritis: a comparison with sulphapyridine

The antirheumatoid activity of sulphasalazine and sulphapyridine may result from their antibacterial properties. The second line activity of sulphamethoxazole, in the form of cotrimoxazole (CTZ), has been investigated by treatment of 13 patients with RA for 24 weeks with CTZ (480 mg three times a day). The drug was found to be poorly tolerated, only five of the thirteen patients recruited completing the study. High circulating concentrations of sulphamethoxazole were found, with mean (SD) steady state serum concentrations reaching 54.02 (23.38) micrograms/ml. A significant reduction in serum IgM from 280 to 130 IU/l was observed, but otherwise disease activity remained unchanged or deteriorated throughout the course of the study. In contrast, patients with RA treated with sulphapyridine (1.25 g a day) showed improvement in disease activity. The results argue against an antibacterial mechanism of action for sulphasalazine and sulphapyridine in rheumatoid arthritis, unless this occurs at a site inaccessible to sulphamethoxazole.

The pathogenesis and consequence of non steroidal anti-inflammatory drug induced small intestinal inflammation in man

Non steroidal anti-inflammatory drugs (NSAID's) have recently been shown to cause small intestinal inflammation in the majority of patients receiving these on a regular basis for more than one year. The development of inflammation is preceded by an NSAID effect to increase small intestinal permeability. Increased intestinal permeability is shown to be related to drug potency to inhibit cyclooxygenase and the effect is systemically mediated rather than a local irritant one. More recently, increased intestinal permeability due to NSAID's has been reduced by concomitant prostaglandin administration, showing that prostaglandins are essential for maintaining intestinal integrity in man. It is proposed that altered intestinal permeability allows the mucosa to be exposed to bacterial degradation products or other toxins and together with reduced chemotaxic response and altered neutrophil function due to NSAID's, this series of events leads to bacterial invasion of the mucosa which is evident by the techniques of 111Indium leucocyte scans and faecal collections. The consequence of such inflammation is that it may explain intestinal perforations and strictures which are occasionally seen in subjects on NSAID's. Most patients with NSAID-induced small intestinal inflammation may be bleeding from the intestine, loosing protein and some have ileal dysfunction. The small intestine may be a greater source of morbidity than the stomach, in patients receiving NSAID's.

It is wise to prescribe NSAIDs with modern gastroprotective agents?

The administration of non-steroidal anti-inflammatory drugs (NSAIDs) leads to mucosal lesions in the upper gastrointestinal tract. Furthermore, NSAIDs increase the risk of ulcer bleeding and perforation, but the overall risk of fatal complications is relatively small (about 21 per one million prescriptions). Therefore, in asymptomatic patients, it is not justified to prescribe NSAIDs together with gastroprotective agents. The following recommendations can be given with respect to the management of peptic lesions in patients taking NSAIDs: (i) Fibre endoscopy should be performed even when there are relatively mild symptoms since mucosal lesions in rheumatic patients under NSAIDs produce minor or no symptoms. (ii) "Modern" NSAIDs might produce less gastric lesions than aspirin. (iii) Rheumatic patients with peptic disorders should be treated with an H2-antagonist. (iv) After complications such as ulcer bleeding or after rapid recurrence of peptic lesions, maintenance treatment with an H2-antagonist is advisable.