Ankylosing spondylitis: current approaches to treatment

Effects of levofloxacin and doxycycline on interleukin-6 production of Chlamydia trachomatis-infected human synovial fibroblasts

BACKGROUND

A large amount (80,000-100,000 pg/ml) of interleukin-6 (IL-6) was detected in cultures of human synoviocytes infected with Chlamydia trachomatis. In this study, we investigated the effect of antibiotics on the IL-6 production of C. trachomatis-infected human fibroblast-like synovial cells (HFLS).

METHODS

The minimum inhibitory concentrations of levofloxacin and doxycycline against C. trachomatis were determined in either HFLS or HeLa 229 cells. The number of live Chlamydia was also examined. IL-6 in the supernatants of infected cultures was quantified by capture ELISA.

RESULTS

The production of IL-6 was suppressed to as low as 1,800 pg/ml in the infected HFLS treated with levofloxacin or doxycycline immediately or early after infection. In HFLS treated with levofloxacin and doxycycline, the IL-6 levels decreased to 37,000 and 21,000 pg/ml, respectively, 48 h after infection, and levofloxacin was thus found to be less effective than doxycycline. In addition, the number of viable C. trachomatis in the infected cultures treated with levofloxacin 24 h after infection was higher than when treated with doxycycline.

CONCLUSIONS

The early administration and proper selection of antibiotics is important for the suppression of inflammatory cytokine production. These findings indicate that antibiotic therapy will not only work in treating infections but might also be useful in treating reactive arthritis secondary to the infection.

Resistance to antifolates

The antifolates were the first class of antimetabolites to enter the clinics more than 50 years ago. Over the following decades, a full understanding of their mechanisms of action and chemotherapeutic potential evolved along with the mechanisms by which cells develop resistance to these drugs. These principals served as a basis for the subsequent exploration and understanding of the mechanisms of resistance to a variety of diverse antineoplastics with different cellular targets. This section describes the bases for intrinsic and acquired antifolate resistance within the context of the current understanding of the mechanisms of actions and cytotoxic determinants of these agents. This encompasses impaired drug transport into cells, augmented drug export, impaired activation of antifolates through polyglutamylation, augmented hydrolysis of antifolate polyglutamates, increased expression and mutation of target enzymes, and the augmentation of cellular tetrahydrofolate-cofactor pools in cells. This chapter also describes how these insights are being utilized to develop gene therapy approaches to protect normal bone marrow progenitor cells as a strategy to improve the efficacy of bone marrow transplantation. Finally, clinical studies are reviewed that correlate the cellular pharmacology of methotrexate with the clinical outcome in children with neoplastic diseases treated with this antifolate.

Bacteria-Triggered reactive arthritis: implications for antibacterial treatment

Reactive arthritis (ReA) is definitely caused by an infection. Several observations suggest that the triggering microbe may persist in the tissues of the patient for a prolonged time. The obvious conclusion is to consider antibacterial treatment. In two instances antibacterial agents are of definite value: in the primary and secondary prevention of rheumatic fever and for early eradication of Borrelia burgdorferi in order to prevent development of the arthritis associated with Lyme disease. Altogether, clinical and experimental data exist to indicate that if antibacterial treatment of ReA can be started very early during the pathogenetic process, the disease can be prevented or the prognosis improved. In fully developed ReA, the value of antibacterial agents is less certain. All available evidence indicates that short term antibacterial treatment has no effect on the prognosis and final outcome of ReA, and the results with long term administration of antibacterials are also overall poor. In some instances sulfasalazine appears useful, rather as a result of its antirheumatic effect or influence on an underlying inflammatory bowel disease than its action as an antibacterial agent. Tetracyclines have also been found to have an effect on ReA, but again, this is probably due to their anti-inflammatory action rather than any antibacterial effect.