Anemia of Chronic Disease |
treatment
1 Department of Internal Medicine, University of Pavia Medical School and Fondazione IRCCS Policlinico San Matteo, Pavia
2 Clinical Chemistry Laboratory, Fondazione IRCCS Policlinico San Matteo, Pavia
3 Division of Gastroenterology, "L. Sacco" University Hospital, Milan
4 Laboratory of Clinical Epidemiology, Fondazione IRCCS Policlinico San Matteo, Pavia
5 Laboratory of Organ Transplantation, University of Pavia and Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
Correspondence: Gaetano Bergamaschi, Clinica, Medica I, Policlinico San Matteo, Piazzale Golgi, 27100 Pavia, Italy. E-mail: n.bergamaschi{at}smatteo.pv.it
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Design and Methods: In a cross-sectional study 263 out-patients with inflammatory bowel disease (165 with Crohns disease, 98 with ulcerative colitis) were investigated. The influence of time from diagnosis, disease activity, inflammation and the status of iron and hematinic vitamins on the level of hemoglobin and prevalence of anemia were evaluated. In a second group of 27 patients with Crohns disease, undergoing anti-tumor necrosis factor-
treatment with infliximab because of refractory or fistulizing disease, we determined the effects of infliximab on disease activity, hemoglobin, serum erythropoietin levels, iron status and inflammation.
Results: In all, 104 of the 263 patients with inflammatory bowel disease were anemic. Age, gender and azathioprine treatment had no influence on anemia. The prevalence of anemia was highest at diagnosis (65%), decreased during the first 4 years after disease onset, and was stable thereafter. Active disease was associated with higher rates of anemia. At diagnosis most anemic patients had anemia of chronic disease; during follow-up iron deficiency and multifactorial forms of anemia became more prevalent. Eighteen of 27 patients undergoing treatment with infliximab were anemic; most of them had anemia of chronic disease. Infliximab reduced disease activity and improved anemia in 12 patients. This was mediated by an increased production of erythropoietin for the degree of anemia. In vitro infliximab increased the growth of erythroid progenitors from the peripheral blood of patients with active disease.
Conclusions: Anemia is a common problem in out-patients with inflammatory bowel disease; the prevalence and severity of anemia are related to the activity of the bowel disorder. The pathogenesis of anemia changes during the course of the disease, with anemia of chronic disease having a major role at diagnosis and iron deficiency and multifactorial forms of anemia during follow-up. In patients requiring anti-tumor necrosis factor-
treatment, response to therapy improves erythropoiesis.
Key words: anemia, inflammatory bowel, iron deficiency.
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Iron deficiency, due to chronic blood loss and/or reduced iron absorption, and anemia of inflammation (or anemia of chronic disease, ACD) are the most common types of anemia in inflammatory bowel disease, although cobalamin or folate deficiencies, as well as treatment-induced myelosuppression, sometimes have a role.3 In many cases the pathogenesis of anemia is multifactorial, since blood loss, inflammation, malabsorption of several nutrients and use of potentially myelotoxic drugs may occur in the same patient.4 The importance of anemia in inflammatory bowel disease is confirmed by the inclusion of hematocrit and manifestations such as blood in stools or rectal bleeding in scoring systems commonly used to evaluate disease activity in both Crohns disease5 and ulcerative colitis.6,7
Tumor necrosis factor (TNF)-
is a pro-inflammatory cytokine that plays a pathogenic role in immune-mediated diseases including Crohns disease, ulcerative colitis, rheumatoid arthritis, psoriasis, and ankylosing spondylitis.8–11 This led to the development of anti-TNF-
agents for treatment of the above-mentioned conditions. Raised TNF-
levels have been found in the serum of patients with Crohns disease, and recent evidence has implicated TNF-
in the pathogenesis of ACD.12 TNF-
may cause anemia through the inhibition of erythroid progenitors (BFU-E) and through effects on iron metabolism, the latter characterized by iron retention within macrophages and inhibition of intestinal iron absorption.13–15
In the present work we evaluated the prevalence and pathogenesis of anemia in a series of patients with inflammatory bowel disease, mainly focusing on mechanisms related to inflammation and iron deficiency. We also investigated the changes in factors related to iron metabolism and erythropoiesis in a group of patients with Crohns disease undergoing anti-TNF-
treatment.
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antibody infliximab (Remicade, Schering Plough, Milan, Italy) either because they were refractory to treatment with steroids (n=10) or because they were affected by fistulizing disease (n=17). None of the patients in this group had been treated with cyclosporine or methotrexate, or received blood transfusions, iron supplementation or erythropoiesis-stimulating agents. No patients had asymptomatic or symptomatic stenoses, strictures, or abscesses at the time of the study. The diagnoses of Crohns disease and ulcerative colitis were based on the usual clinical criteria.16,17 Disease activity was assessed by the Crohns Disease Activity Index (CDAI),5 and by the Clinical Activity Index (CAI).6 A CDAI score of more than 150 in Crohns disease and a CAI score of more than 4 in ulcerative colitis corresponded to active disease. The presence of renal failure, malignancy, connective tissue diseases or hematologic conditions that could cause anemia, other than ACD or nutritional, were criteria for exclusion from the study.
Treatment with infliximab and assessment of patients
The 27 Crohns disease patients undergoing treatment with infliximab received three consecutive infusions of the antibody administered at weeks 0, 2, and 6 at a dose of 5 mg/kg. Concomitant treatment with 5-aminosalicylic acid or sulfasalazine was continued. In the ten steroid-refractory patients steroids were tapered and then discontinued. The CDAI score was determined within 1 week before the first infusion and 14 weeks after beginning therapy. Clinical response was defined as a decrease in CDAI by 70 points or more. Complete remission was defined as a CDAI score of 150 points or less.
Definition of anemia
Anemia was defined by hemoglobin levels lower than 13.0 g/dL for men and 12.0 g/dL for women.18 According to the WHO criteria mild anemia corresponded to a hemoglobin level of 9.5 g/dL or more, moderate anemia to a hemoglobin of 8 g/dL or more, but less than 9.5 g/dL, and severe anemia to a hemoglobin of less than 8.0 g/dL. The diagnosis of ACD required a low transferrin saturation (< 16%) with normal or increased serum ferritin concentration (> 100 µg/L). Iron-deficiency anemia was characterized by the presence of anemia associated with low serum ferritin (<10 µg/L for females, <15 µg/L for males) or with a transferrin saturation less than 16% together with serum ferritin levels less than 30 µg/mL. The association of iron-deficiency anemia and ACD was characterized by a transferrin saturation of less than 16% and a serum ferritin between 30 and 100 µg/mL inclusive.19,20 These diagnostic criteria were previously suggested and validated by several authors.19–21 In this work we did not use the soluble transferrin receptor to log serum ferritin ratio as an indicator of iron-deficiency anemia in the presence of inflammation. However, given the different behavior of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in these groups of patients, and the intermediate behavior of patients with the association of iron-deficiency anemia and ACD, we believe that the number of possible mis-diagnoses was low and did not influence the general results of our study.
In patients treated with infliximab, a major hematologic response was defined as the normalization of the hemoglobin level or a hemoglobin increase of 1.0 g/dL or more; a minor hematologic response was represented by a hemoglobin increase of 0.5 to 0.9 g/dL.
Laboratory investigations
All patients underwent clinical evaluation and determination of complete blood cell counts, body iron status, serum levels of folate and vitamin B12, CRP and ESR. In a subgroup of 39 unselected patients (22 with Crohns disease and 17 with ulcerative colitis) and in 29 healthy controls serum prohepcidin concentration was determined. In patients treated with infliximab serum erythropoietin concentration was determined immediately before the first infusion and at week 14 of therapy. The following commercial kits were used for these determinations: the EPO ELISA—Medac (Hamburg, Germany) and the pro-Hepcidin ELISA Kit from DRG (Heidelberg, Germany).
In vitro assays were performed to evaluate the effect of infliximab on the growth of peripheral blood BFU-E from ten patients with untreated active Crohns disease and ten age-matched healthy volunteers. For these assays, 5x105 peripheral blood mononuclear cells were seeded in 30 mm plastic dishes in 1 mL methylcellulose (StemCell Inc., Vancouver, Canada) containing 30% fetal bovine serum (HyClone, Logan, UT, USA), 10 ng/mL interleukin-3, 10 ng/mL granulocyte-monocyte colony-stimulating factor, 50 ng/mL stem cell factor, and 1 U/mL human erythropoietin (all from PeproTech EC Ltd., London, UK) and cultured with infliximab, 100 µg/mL, its isotype-matched control (human IgG1, Sigma-Aldrich, Poole, UK) or 10 ng/mL recombinant human TNF-
(R&D Systems, Abingdon, UK). After 14 days of incubation at 37°C in 5% CO2, the number of BFU-E was scored according to standard criteria.
Statistical analysis
Continuous variables were compared by the Students t-test, the F test (one-way analysis of variance), the Mann-Whitney U test, the Wilcoxon test and the Kruskal-Wallis test. For categorical variables the
2 test and Fishers exact test were used. Correlations between continuous variables were expressed by Pearsons correlation coefficient or Spearmans R test. Data are reported as means ± 1 SD. P values less than 0.05 are considered statistically significant.
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Table 1. Summary of demographic and clinical characteristics of patients with inflammatory bowel disease in the anemia evaluation cohort.
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Figure 1. Temporal trend of hemoglobin (Hb) concentration in patients with inflammatory bowel disease during the first 4 years from diagnosis. Hb increases with time and the prevalence of anemia decreases.
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Figure 2. Correlations between disease activity indices and hemoglobin in patients with inflammatory bowel disease. The correlation between CDAI and hemoglobin is less significant when the contribution of hematocrit to the score is removed (modified CDAI, central panel).
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Table 3. Data on iron status, disease activity and inflammation in 27 patients with Crohns disease treated with infliximab.
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Table 2. Causes of anemia in inflammatory bowel disease.
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Infliximab treatment of patients with Crohns disease
The clinical features and treatment results for the 27 patients with Crohns disease undergoing treatment with infliximab are shown in Table 3. Eighteen patients were anemic before starting infliximab and most of them (n=12) had ACD. Nineteen of the 27 patients had a clinical improvement after 14 weeks of treatment: 18 had a complete response and one had a partial response (Table 3). Hematologic responses were observed in 12 patients (10 major responses and 2 minor responses), and were already apparent 2 weeks after the first infusion of infliximab. In all, the mean CDAI value was significantly reduced after 14 weeks of treatment and, in responsive patients, this was associated with increased hemoglobin concentration and reduced serum ferritin and ESR (Table 3). The log of serum erythropoietin [log(Epo)] concentration negatively correlated with hemoglobin (r=–0.576, P=0.0001; regression equation: log(Epo)=–0.107x Hb+2.421), although the difference between erythropoietin values before and after treatment with infliximab was significant only in responsive patients. When the ratio between the observed log(Epo) and the log(Epo) predicted according to the regression equation was considered (Epo O/P ratio), higher post-treatment values were observed but, again, the difference was statistically significant only for responding patients (0.85±0.26 before treatment, 1.08±0.15 following treatment with infliximab, P=0.022; Table 3).
In vitro evaluation of erythropoiesis
To assess the influence of infliximab on erythropoiesis, we cultured hematopoietic progenitors from the peripheral blood of ten patients with active Crohns disease and evaluated the effect of infliximab on the number of BFU-E after 14 days of culture in semisolid medium. As shown in Figure 3, the mean number of BFU-E in the presence of infliximab (97.2±14.4) was significantly higher than that of colonies cultured with a control IgG1 (51.5±12.7; P=0.010). In contrast, TNF-
significantly reduced the number of BFU-E (17.6±6.2; P<0.001). BFU-E growth and response to in vitro treatment with infliximab were not different between healthy volunteers and patients with active Crohns disease (data not shown).
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Figure 3. Growth of peripheral blood erythroid progenitors (BFU-E) from untreated patients with active Crohns disease (n=10). The effect of TNF- , infliximab and its isotype control (human IgG1) is shown. *indicates a difference between the IgG1 and the infliximab samples (P=0.010); **indicates a difference between the TNF- and the other samples (P<0.001).
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9.5 g/dL) but, since the study population included only out-patients, we probably missed some cases of more severe anemia that required hospitalization. We observed a peculiar temporal trend in the prevalence and pathogenesis of anemia, characterized by higher rates of anemia at diagnosis followed by a progressive decrease during the subsequent 4 years. In the same period of time there was a mild increase in the mean hemoglobin level. According to our diagnostic criteria, inflammation was the main cause of anemia at diagnosis, and this is in agreement with the observation that diagnosis was characterized by higher indices of inflammation. The increasing frequency of iron-deficiency anemia during follow-up, associated with a reduced incidence of ACD, may be related to chronic intestinal blood loss and/or iron malabsorption which can take months to years in order to induce iron deficiency and anemia.
Inflammation is known to inhibit iron absorption, and subjects with active Crohns disease have impaired oral iron absorption associated with increased urinary excretion of hepcidin,22 the liver-derived peptide that inhibits iron absorption.23 We measured serum prohepcidin concentration as a substitute for hepcidin; prohepcidin levels were higher in patients with inflammatory bowel disease than in normal subjects and correlated with CRP and the CDAI score. Although the prohepcidin assay has been considered a poor indicator of hepcidin synthesis, these correlations suggest a link between abnormal iron homeostasis, inflammation and disease activity in inflammatory bowel disease. We, therefore, suggest that, in addition to directly causing ACD, recurrent flares of inflammation over a period of years substantially reduce iron absorption in patients with inflammatory bowel disease and lead to an iron deficiency that may persist during periods of disease remission.
Since the main site of iron and folate24 absorption is the duodenum, malabsorption and deficiencies of these nutrients could be a consequence of upper gastrointestinal involvement. Upper gastrointestinal involvement in inflammatory bowel disease is considered a rare complication occurring in 0.5 to 4% of patients,25 but some pediatric studies report gastro-duodenal involvement in up to 40% of patients with Crohns disease, often in a subclinical form.26,27 Thus, compared to the situation at diagnosis, when anemia is usually due to isolated ACD or iron-deficiency anemia, the course of inflammatory bowel disease is characterized by an impairment of erythropoiesis due to a variety of mechanisms, as suggested by the increasing frequency of cases of anemia due to different combinations of iron-deficiency anemia, ACD and vitamin deficiencies observed during the follow-up. We do not routinely treat inflammatory bowel disease patients with iron and/or vitamin supplements, unless the diagnostic work-up performed following a diagnosis of anemia shows a specific hematinic deficiency, since the safety of iron supplementation for the prevention of anemia in inflammatory bowel disease is still a matter of discussion. This may partially explain the trend we observed in the prevalence of iron-deficiency anemia and the higher prevalence of anemia in our study than in others.28–30
In the present study anemia was related to disease activity in both Crohns disease and ulcerative colitis (Figure 2). Greater disease activity in anemic patients with Crohns disease has been previously reported.28 Since the CDAI value is influenced by hematocrit, this result is not unexpected. However, using a modified CDAI (the CDAI score calculated without considering the hematocrit), the correlation with hemoglobin was preserved, but only in ten patients (11% of the population with active disease) did anemia have a determinant role for the classification of patients within the active disease group. Thus, in most cases the definition of active disease does not depend on the presence of anemia which, however, remains an expression of more active and severe disease.
Anti-TNF-
therapy is being increasingly used in inflammatory bowel disease to treat patients with steroid refractory or fistulizing disease (at least in Crohns disease); the treatment specifically targets one of the main inflammatory pathways involved in the pathogenesis of tissue damage.10,11 Since TNF-
is a negative regulator of erythropoiesis and contributes to ACD,12 we investigated how TNF-
neutralization with infliximab affects anemia and iron status parameters in vivo and modulates the in vitro growth of erythroid progenitor cells (BFU-E). ACD was the most common form of anemia in patients undergoing infliximab treatment. In these patients infliximab improved anemia through the control of inflammation and disease activity, as suggested by the reduction in ESR, serum ferritin and CRP in responsive patients. This was confirmed by the increased post-therapy Epo O/P ratio in responding patients, and indicates that infliximab makes erythropoietin production more adequate for the level of hemoglobin, thus allowing more efficient bone marrow stimulation.
Interleukin-6, rather than TNF-
, is a mediator of hepcidin production and abnormal iron homeostasis in inflammation; whether infliximab directly modulates interleukin-6 or hepcidin production, and through this pathway improves erythropoiesis in inflammatory bowel disease, is presently unknown. In vitro infliximab increased the growth of BFU-E from peripheral blood, as already shown for bone marrow-derived BFU-E in a study involving patients with rheumatoid arthritis.13 This suggests that infliximab can modulate erythropoiesis at different levels. At variance with the study by Papadaki et al.13 we found that infliximab enhanced the growth of BFU-E also from peripheral blood of normal subjects; further studies are needed to clarify the mechanism of BFU-E stimulation exerted by infliximab.
The online version of this article has a Supplementary Appendix.
GB was the principal investigator and takes primary responsibility for the paper; he co-ordinated the research and wrote the paper. ADS, GBP and GRC co-ordinated the research and wrote the paper, RA, EB and VR performed the laboratory work for this study. SA, PB, AC, PC, KM, and AM recruited the patients.
The authors reported no potential conflicts of interest.
Received for publication April 14, 2009. Revision received August 20, 2009. Accepted for publication August 21, 2009.
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antibody therapy. Blood 2002;100 2: 474–82.
regulates iron transport and transporter expression in human intestinal epithelial cells. FEBS Lett 2004;573 1–3: 195–201.[CrossRef][Web of Science][Medline]Related Article
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