Potential of thalidomide and thalidomide analogues as immunomodulatory drugs in leprosy and leprosy reactions

What is New in the Pathogenesis and Management of Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is a manifestation of type II lepra reaction, seen in lepromatous or borderline lepromatous leprosy. Although it is a common reaction encountered in clinical practice, there are an increasingly large number of newer updates in the pathophysiology and management of this condition. The treatment options have expanded far beyond just thalidomide and steroids and now extends to TNF-α inhibitors, thalidomide analogs, tenidap, cyclosporine A, plasma exchange, and even IVIG amongst others. These updates and the current knowledge of ENL are summarized in this review.

Serological responses to prednisolone treatment in leprosy reactions: study of TNF-α, antibodies to phenolic glycolipid-1, lipoarabinomanan, ceramide and S100-B

BACKGROUND

Corticosteroids have been extensively used in the treatment of immunological reactions and neuritis in leprosy. The present study evaluates the serological response to steroid treatment in leprosy reactions and neuritis.

METHODS

Seven serological markers [TNF-α, antibodies to Phenolic glycolipid-1 (PGL-1 IgM and IgG), Lipoarabinomannan (LAM IgG1 and IgG3), C2-Ceramide and S100 B] were analyzed longitudinally in 72 leprosy patients before, during and after the reaction. At the onset of reaction these patients received a standard course of prednisolone. The levels of the above markers were measured by Enzyme linked immunosorbent assay (ELISA) and compared with the individuals own value in the month prior to the reaction and presented as percentage increase.

RESULTS

One month before the reaction individuals showed a varying increase in the level of different markers such as TNF-α (53%) and antibodies to Ceramide (53%), followed by to PGL-1 (51%), S100B (50%) and LAM (26%). The increase was significantly associated with clinical finding of nerve pain, tenderness and new nerve function impairment. After one month prednisolone therapy, there was a fall in the levels [TNF-α (60%), C2-Ceramide (54%), S100B (67%), PGL-1(47%) and LAM (52%)] with each marker responding differently to steroid.

CONCLUSION

Reactions in leprosy are inflammatory processes wherein a rise in set of serological markers can be detected a month before the clinical onset of reaction, some of which remain elevated during their action and steroid treatment induces a variable fall in the levels, and this forms the basis for a variable individual response to steroid therapy.

Leprosy therapy, past and present: can we hope to eliminate it?

Leprosy remains an important problem globally. Timely detection of new cases and prompt treatment with MDT continue to be the main intervention strategies. We review the various issues related to classification, treatment, drug resistance and the possible steps to eliminate the disease in the near future. The need for newer anti leprosy agents has been felt and various agents like fluroquinolones, macrolides and minocycline have all been tried in various combinations and duration. Uniform MDT in all leprosy patients might be a logical one too. Drug resistance can be identified by PCR based DNA sequence analysis which saves much time. Drugs like thalidomide analogues, pentoxifylline, selective cytokine inhibitory drugs have proved effective in controlling type-2 reaction in leprosy patients. New drugs for leprosy reactions are still needed. Far from being eliminated as a public health problem, leprosy still causes a considerable long term morbidity in both developing and developed world. New treatment and the optimal length of MDT requires further research. We need genome based technology to address the unresolved issues of transmission of M. leprae.

Transport of thalidomide by the human intestinal caco-2 monolayers

Studies in patients have indicated that the oral absorption of thalidomide is considerably variable at high doses (>200 mg/day). The aim of this study was to investigate the transport of racemic thalidomide using human colon cancer cell line (Caco-2) monolayers, which have been widely used to investigate drug permeability. A typical 21-day protocol was used to prepare Caco-2 monolayers. Thalidomide was determined by a validated high performance liquid chromatography method with ultraviolet detection. The integrity of Caco-2 monolayer was confirmed when the transepithelial electrical resistance (TEER) exceeded 300 Ohmz . cm2, and the leakage of 14C-manitol was <1% per hour. Uptake of thalidomide by Caco-2 cells was very limited (up to 2.1%). The transport of thalidomide appeared to be linear up to 1 hr. Our study indicated that the permeability coefficients (Papp) of thalidomide at 2.5-300 microM from the apical (AP) to basolateral (BL) and from BL to AP side was 2-6 x 10(-5) cm/sec, with a marked decrease in Papp values from AP to BL at increased thalidomide concentration. The transport of thalidomide was sodium-, temperature- and pH-dependent, as replacement of extracellular sodium chloride or reducing temperature and apical pH can result in significant decreases in the Papp values. Additional data indicated that transport of thalidomide is energy-dependent, as it was significantly (P < 0.05) inhibited by the ATP inhibitors, sodium azide and 2,4-dinitrophenol. In addition, DL-glutamic acid, cytidine, diprodomole, papaverine, quinidine, and cyclophosphamide significantly (P < 0.05) inhibited the transport of thalidomide, while the P-glycoprotein inhibitor verapamil and other nucleosides and nucleotides such as thymidine and guanine had no effect. These results indicated that thalidomide was rapidly transported by Caco-2 monolayers, and this might involve a saturable energy-dependent transporter.