Dear Editor, We have read with great interest the article by Peters et al. concerning the changes on lipid profile during infliximab and corticosteroid treatment in patients with rheumatoid arthritis (RA) (1). Recently, we performed a similar longitudinal study over time using a different TNF blocker – namely etanercept. In this prospective study 22 RA female patients were analyzed. Patients received during the study etanercept ( 25 mg twice weekly), stable doses of non-steroidal anti-inflammatory drugs, prednisolone (<7.5 mg/die) and methotrexate (MTX: 10 mg/week). A control group included 20 RA patients with baseline stable therapy (prednisone: <7.5 mg/die and MTX: 10 mg/week).

The concentrations of total cholesterol, high density lipoprotein (HDL)-cholesterol, triglyceride (TG), lipoprotein (a) [Lp(a)] were determined by ELISA before the administration of etanercept treatment and after 12, 24, 36 and 48 weeks from the starting dosage. Low density lipoprotein (LDL)-cholesterol value was calculated with the Friedewald formula. Concerning the results, the study showed that DAS-28 score decreased significantly from baseline to week 12 (5.5±1.6 vs 3.2±1.5), week 24 (2.9±1.8,), week 36 (2.3±1.1) and week 48 (2.1±0.8, p<0.01 for all), in etanercept treated patients. Similar DAS-28 score significant decrease was observed in RA controls from baseline to week 12, 24, 36 and 48 (from 5.5±2.1 to 3.9±2.1, 3.3±1.8, 2.9±1.8 and 2.6±1.1, p<0.01). Since etanercept dramatically improved the outcome of RA, the prednisone dose was gradually decreased from a baseline median dose of 7.5 to 3.4 mg/day. In etanercept treated patients, total cholesterol and HDL-cholesterol levels were found in concentrations of 4.76±0.26 mmol/ L and 0.88±0.06 mmol/L at baseline; interestingly total cholesterol and HDL-cholesterol levels were found significantly increased at 12 and 24 weeks when compared to baseline values (4.84±0.32 mmol/ L, p<0.01 and 4.91±0.36 mmol/ L, p<0.001) and (0.96±0.09 mmol/ L, p<0.05 and 1.08±0.11 mmol/ L, p<0.01). However, at 48 weeks, total cholesterol and HDL-cholesterol levels approached again baseline levels (4.81±0.32 mmol/ L and 0.94±0.05 mmol/ L, respectively). In contrast, TG, Lp(a) concentrations and atherogenic index (calculated using the following formula: total / HDL cholesterol) were not significantly changed during anti-TNFá treatment at every time.

Interestingly, no significant changes were observed in the RA untreated etanercept group in lipid profile when compared with baseline. During the treatment with etanercept, lipid levels were compared with changes in prednisone dose at different points after adjustment for age. The effects of etanercept treatment on the changes in prednisone dose were observed as changes in total cholesterol and HDL-cholesterol levels. Recent studies have found increased levels of total cholesterol and LDL- cholesterol levels, but also increased HDL-cholesterol concentrations and no modification of triglycerides and atherogenic index after six month of anti-TNF therapy (4-6). Therefore, our observations, in agreement with those of Peters et al., show that etanercept treatment increases total cholesterol and HDL-cholesterol levels after 24 weeks; these parameters returned to baseline levels under low dose prednisone reduction (1). In conclusion, these results seem to support a possible interference of TNFá blockers (i.e. infliximab or etanercept) with some of the mechanisms implicated in the development of atherosclerosis at least in patients with RA, through anti- inflammatory and anti-atherogenic effects exerted on lipid profile.

References

1. Peters MJL, Vis M, van Halm VP, Wolbink GJ, Voskuyl AE, Lems WF, et al. Changes in lipid profile during infliximab and corticosteroid treatment in rheumatoid arthritis. Ann Rheum Dis 2007;66:958-961.

2. Gonzalez-Gay MA,De Matias M, Gonzalez-Juanatey C, et al. Anti-tumor necrosis factor-alpha blockade improves insulin resistance in patients with rheumatoid arthritis. Clin Exp Rheumatol 2006;24:83-86.

3. Kiortis DN, Mavridis AK, Vasakos S, Nikas SN, Drosos AA. Effects of infliximab treatment on insulin resistance in patients with rheumatoid arthritis and ankylosing spondylitis. Ann Rheum Dis 2005;64:765-6.

4. Seriolo B, Paolino S, Ferrone C, Cutolo M. Effects of etanercept or infliximab treatment on lipid profile and insulin resistance in patients with refractory rheumatoid arthritis Clin Rheumatol 2007 Jul 24; [Epub ahead of print]

5. Allanore Y, Kahan A, Sellam J, Ekindjian OG, Borderie D. Effects of repeated infliximab therapy on serum lipid profile in patients with refractory rheumatoid arthritis. Clin Chim Acta 2006;365:143-8.

6. Seriolo B, Paolino S, Sulli A, Fasciolo D, Cutolo M. Effects of anti-TNF-á treatmenton lipid profile in patients with active rheumatoid arthritis. Ann N Y Acad Sci 2006;1069:414-9.

To the editor,

We read with interest the article by Hjardem E et al which reported the experiences of switching between TNF-antagonists from the Danish patient registry, DANIBO. We would like to draw the authors’ attention to data published from our group 2 years ago which both highlights some aspects relevant to the current report and which provides some insights into the mechanisms involved. Non-response is seen either as a primary phenomenon i.e. no response at the first point of assessment (usually 12 weeks using standard response criteria) or secondary non-response - loss of an initial demonstrable response. We described primary non-response in detail in a cohort of over 200 patients on infliximab (Buch MH, et al, A&R 05). Furthermore, distinctsub-groups of primary non-response were identified based on the presence or lack of CRP suppression, with the latter group demonstrating significantly high response rates upon switching to etanercept (68% ACR20, 51% ACR50). These observations have been confirmed in a larger cohort (Buch MH et al, Arth Rheum 07). The basis for such contrasting responses has been discussed and explored previously with a representative case suggesting a role for lymphotoxin-alpha, targeted by etanercept but not infliximab (Buch MH et al, ARD 04). We have also recently illustrated that secondary non-response occurs to a significant extent in a cohort of initial infliximab responders (Buch MH et al, Rheum 07). We suggested the kinetics of secondary non-response implies a pharmacokinetic basis for failure and showed that such patients demonstrate a higher response rate to adalimumab (Buch MH et al Arth Rheum abstract 05); probably by overcoming potential HACA issues. Thus the observations by Hjardem E et al have been well-described previously in a more homogeneous cohort and with the benefit of more stringent classification. Furthermore, tailored therapeutic intervention has revealed possible underlying basis for such non-response.

Dear Editor, I read with interest the manuscript, by Girgis et al (1) on the role of sitaxsentan in the treatment of patients with pulmonary arterial hypertension associated with connective tissue diseases. The main conclusion is that sitaxsentan, a selective endothelin-A receptor antagonist, produced a significant improvement in six-minute walk distance, functional class, and quality of life in this group of patients.

The authors are to be congratulated on highlighting this group of patients and they have done a good job of outlining the potential shortcomings of a small post-hoc analysis. As described by the authors, patients with pulmonary hypertension associated with scleroderma are known to have very poor outcomes despite vasodilator therapy (2-4), as such this finding can have significant implications. The bulk of data in this arena though, comes from patients with pulmonary hypertension related to scleroderma (2-4) and there is very little information on treatment responses in patients with pulmonary hypertension related to other connective tissue diseases.

We have recently reported that patients with systemic lupus erythematosus and pulmonary hypertension may have a much more favorable short- and long-term response to vasoactive therapy (5). Similar findings have also been reported previously in smaller case series (6,7). In contrast to patients with scleroderma, there are also reports of severe pulmonary hypertension in patients with systemic lupus erythematosus responding to immunosuppressive therapy (8,9). It is not unreasonable to assume that response to therapy and outcomes in patients with pulmonary hypertension related to different diseases may be different and, in view of their distinctly different responses, perhaps we should avoid grouping them together under the rubric of “pulmonary hypertension associated with connective tissue diseases”. The small sample size may not have allowed the authors to do so, however, it would be interesting to contrast the response to therapy in patients with scleroderma and systemic lupus erythematosus among their cohort since a sizable proportion of the patients had systemic lupus erythematosus. I would argue in favor of tempered enthusiasm until further studies confirm that patients with pulmonary hypertension associated with scleroderma have short- and long-term outcomes, similar to patients with idiopathic pulmonary arterial hypertension, on vasoactive therapy.

References

1. Girgis RE, Frost AE, Hill NS, Horn EM, Langleben D, Mclaughlin VV, Oudiz RJ, Robbins IM, Seibold JR, Shapiro S, Tapson VF, Barst RJ. Selective endothelin A receptor antagonism with sitaxsentan for pulmonary arterial hypertension associated with connective tissue disease. Ann Rheum Dis 2007 Epub ahead of print.

2. Denton CP, Humbert M, Rubin L, Black CM. Bosentan treatment for pulmonary arterial hypertension related to connective tissue diseases: a subgroup analysis of the pivotal clinical trials and their open-label extensions. Ann Rheum Dis 2006;65:1336-1340.

3. Oudiz RJ, Schilz RJ, Barst RJ, Galie N, Rich S, Rubin LJ, et al. Treprostinil, a prostacyclin analogue, in pulmonary arterial hypertension associated with connective tissue diseases. Chest 2004;126:420-427.

4. Girgis RE, Mathai SC, Krishnan JA, Wigley FM, Hassoun PM. Long-term outcome of bosentan treatment in idiopathic pulmonary arterial hypertension and pulmonary arterial hypertension associated with scleroderma spectrum of diseases. J Heart Lung Transplant 2005;24:1626-1631.

5. Heresi GA, Minai OA. Lupus-associated pulmonary hypertension: long-term response to vasoactive therapy. Resp Med 2007, doi:10.1016/j.rmed.2007.05.020

6. Robbins IM, Gaine SP, Schilz R, Tapson VF, Loyd JE. Epoprostenol for treatment of pulmonary hypertension in patients with systemic lupus erythematosus. Chest 2000;117:14-18.

7. Horn EM, Barst RJ, Poon M. Epoprostenol for treatment of pulmonary hypertension in patients with systemic lupus erythematosus. Chest 2000;118:1229-1230.

8. Karmochkine M, Wechsler B, Godeau P, Brenot F, Jagot JL, Simmoneau G. Improvement of severe pulmonary hypertension in a patients with SLE. Ann Rheum Dis 1996;55:561-562.

9. Gonzalez-Lopez L, Cardona-Munoz EG, Celia A, et al. Therapy with intermittent pulse cyclophosphamide for pulmonary hypertension associated with systemic lupus erythematosus. Lupus 2004;13:105-112.

Dear Editor, In the article by Matulis et al, published online on 20 July 2007 the authors state in their discussion that “Compared with the ELISA test used in our study the IFN-gamma ELISPOT test was previously reported to have lower rates of indeterminate results (1). These differences may, among other reasons, be explained by differences in the concentrations of the mitogen PHA between the two test systems”. Can the authors please provide the PHA concentrations used in the QuantiFERON-TB Gold and IFN-gamma ELISPOT (T-SPOT.TB) assays and explain if they are indeed different.

We agree with the authors statement “the elevation of PHA concentrations to lower the rates of indeterminate results will not per se lead to a more accurate test: T-lymphocytes may respond to the strong unspecific stimulus, but not to tuberculosis specific peptides”. The authors continue “the performance of IFN gamma assays using higher PHA concentrations in the positive control reaction of the test may therefore be overestimated.” The authors are suggesting that an assay system that elevates PHA concentrations will have lower indeterminate rates. However, this would also allow the assay to report results in individuals who may not respond to tuberculosis-specific peptides. In some cases these subjects will be falsely negative. Therefore, following the author’s logic, an assay system where the PHA concentration has been increased to lower the numbers of indeterminates would result in lower sensitivity.

The authors imply that the IFN-ELISPOT assay system (T-SPOT.TB) has been modified in this way, which would explain the previously reported lower rates of indeterminate results compared to the IFN-ELISA system (QuantiFERON TB Gold). However, if this were the case, the lower indeterminate rates associated with the T-SPOT.TB system would also result in a reduced ability to identify infected subjects (lower sensitivity). However, previous studies have shown that T-SPOT.TB has BOTH lower indeterminates AND higher sensitivity than QFN-Gold1 (1,2,3).

This is consistent with the fact that the ELISPOT assay methodology is orders of magnitude more sensitive than the ELISA methodology (4,5,6) in detecting antigen-specific T cell response.

In conclusion, indeterminate results should be reviewed along with the sensitivity of a particular assay system since increasing the PHA concentration in order to reduce the rate of indeterminate results will directly decrease the sensitivity of that assay.

References

1. Ferrara G, Losi M, D’Amico R, Roversi P, Piro, Meacci M, Meccugni B, Marchetti Dori I, Andreani A, Bergamini B, Mussini C, Rumpianesi F, Fabbri L, Richeldi L (2006) Use in routine clinical practice of two commercial blood tests for diagnosis of infection with Mycobacterium tuberculosis: a prospective study. Lancet 2006;367:1328–34.

2. Lee JY, Choi HJ, Park I-N, Hong S-B, Oh Y-M, Lim C-M, Lee SD, Koh Y, Kim WS, Kim DS, Kim WD, and Shim TS. Comparison of two commercial interferon-ã assays for diagnosing Mycobacterium tuberculosis infection. Eur Respir J 2006;28:24–30.

3. Goletti D, Carrara D, Vincenti D, Saltini D, Busi Rizzi E, Schinina V, Ippolito G, Amicosante M and Girardi E. Accuracy of an immunediagnostic assay based on RD1 selected epitopes for active tuberculosis in a clinical setting: a pilot study. Clin Microbiol Infect 2006 10.1111/j.1469-0691.

4. Tanguay S, Killion JJ. Direct comparison of ELISPOT and ELISA-based assays for detection of individual cytokine-secreting cells. Lymphokine Cytokine Res 1994;13(4):259-63.

5. Tassignon J, Burny W, Dahmani S, Zhou L, Stordeur P, Byl B, De Groote D. Monitoring of cellular responses after vaccination against tetanus toxoid: comparison of the measurement of IFN-gamma production by ELISA, ELISPOT, flow cytometry and real-time PCR. 1. J Immunol Methods 2005;305(2):188-98. Epub 2005 Aug 31.

6. Ekerfelt C. Ernerudh J. Jenmalm MC. Detection of spontaneous and antigen-induced human interleukin-4 responses in vitro: comparison of ELISPOT, a novel ELISA and real-time RT-PCR. J Immunol Methods 2002;260(1-2):55-67.

Chris Granger is an employee of Oxford Immunotec, the manufacturer of T-SPOT.TB.