EFFECTS OF SPECIFIC ELECTRIC FIELD STIMULATION ON THE RELEASE AND ACIVITY OF SECRETED ACID PHOSPHATASES FROM LEISHMANIA TARENTOLAE AND IMPLICATIONS FOR THERAPY
The use of specific electric field stimulation to affect release and activity of select enzymes is not well established. We have now reported that enzymes (secreted acid phosphatases) implicated in infectivity of the Leishmania parasitic protozoan are affected by electric field stimulation. These data have implications for a new therapeutic direction for treatment of cutaneous leishmaniasis.
Published 2018 in Pathogens
authors: Benjamin M. Dorsey+, Cynthia L. Cass#, David L. Cedeño#, Ricardo Vallejo#, and Marjorie A. Jones+*
+Department of Chemistry, Illinois State University, Normal, IL 61790-4160
# Millennium Pain Center, Bloomington, IL 61704-0303
Leishmaniasis is a neglected tropical disease with 1.6 million new cases reported each year. However, there are few safe, effective, and affordable treatments provided to those affected by this disease . Still under-appreciated as potential pharmaceutical targets, especially for cutaneous leishmaniasis infections, are the two isozymes of secreted acid phosphatase (SAP). These enzymes are involved in the survival of the parasite in the sand fly vector, and in infecting host macrophages [2-4]. While the application of electric or electromagnetic fields as a medicinal therapeutic is not new , the utility of electric field application for the treatment of leishmaniasis is under studied . Studies involving effects of electric fields on the cell secretion of SAP or the activity of SAP that has been secreted prior to electrical stimulation have not yet been reported. This work is the first report on the effect of specific electric fields on the activity of Leishmania tarentolae secreted acid phosphatases and the modulation of this secretion from the cells. In addition, the kinetic constants for the enzyme isoforms were determined as a function of days in culture and removal of carbohydrate from the glycosylated enzymes, using a glycosidase, was shown to affect these kinetic constants.
Electrical pulses were produced by an arbitrary waveform generator (Siglent) that was coupled to signal isolators (World Precision Instruments) using the following parameters: frequency of 50 Hz (400 µs pulse width) or 10,000 Hz (30 µs pulse width), current amplitudes of 100 µA, 150 µA, 200 µA, 250 µA, 300 µA, 400, or 500 µA, and waveform polarity of cathodic monophasic, anodic monophasic, or symmetric biphasic pulses. Of these, the monophasic cathodic electric field resulted in the largest effects on secreted acid phosphatase activity.
The application of a 10,000 Hz, monophasic cathodic electric field, with amplitudes ranging from 100 to 500 µA, to L. tarentolae supernatant or pellet followed by the assessment of SAP activity resulted in different effects in both the supernatant and pellet activity that were statistically different from their controls. The greatest effect in supernatant activity was observed from the 500 µA pulse (300% increase in activity compared to control). There was an apparent non-linear trend in the activation of the supernatant activity from 300 to 500 µA, where the application of larger pulse amplitudes (current) leads to more activity. The greatest effect on pellet activity was also observed from the application of the 500 µA pulse (64% decrease in activity compared to control), however no apparent trends were observed in the pellet group, under these conditions.
One corollary that could be drawn from this study is that electric field therapy could be implemented through inexpensive, readily available electrical stimulator devices that could be applied to humans or domestic animals. In contrast to drug therapies, we anticipate that these devices could have fewer side effects, and have a minimal risk of developing resistance to the therapy. Whether leishmaniasis treatment with a mild electric field followed by the application of a topical therapy is more effective than just the topical treatment alone remains to be determined in future studies.
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