Effect of the injection of an extract of Ascaris suum on macrophage activation during the early phase of Mycobacterium bovis BCG infection in C57Bl/6 mice

A life without worms

Worms have co-evolved with humans over millions of years. To survive, they manipulate host systems by modulating immune responses so that they cause (in the majority of hosts) relatively subtle harm. Anthelminthic treatment has been promoted as a measure for averting worm specific pathology and to mitigate subtle morbidities which may include effects on anaemia, growth, cognitive function and economic activity. With our changing environment marked by rapid population growth, urbanisation, better hygiene practices and anthelminthic treatment, there has been a decline in worm infections and other infectious diseases and a rise in non-communicable diseases such as allergy, diabetes and cardiovascular disease. This review reflects upon our age-old interaction with worms, and the broader ramifications of life without worms for vaccine responses and susceptibility to other infections, and for allergy-related and metabolic disease. We touch upon the controversy around the benefits of mass drug administration for the more-subtle morbidities that have been associated with worm infections and then focus our attention on broader, additional aspects of life without worms, which may be either beneficial or detrimental.

Schistosoma mansoni infection reduces the protective efficacy of BCG vaccination against virulent Mycobacterium tuberculosis

We hypothesized that the ability of BCG vaccination to protect against Mycobacterium tuberculosis is less in hosts exposed to chronic helminthes infection compared to unexposed individuals. To test this hypothesis we evaluated the efficacy of BCG vaccination in protecting against M. tuberculosis challenge in Schistosoma mansoni pre-infected mice by analyzing their ability to limit the replication of TB bacilli in the lung and liver and the histology of lung sections. The results show that BCG vaccinated mice with prior S. mansoni infection show significantly higher number of colony forming units of TB bacilli as well as significant reduction in air exchange area in the lung compared to controls. In addition, spleen cells from S. mansoni infected mice were found to produce significantly less IFN-gamma and nitric oxide when stimulated in vitro with PPD and several fold higher soluble egg antigen (SEA) and Concanavalin A induced IL-4 and IL-5 secretion. Taken together, our data show that S. mansoni infection reduces the protective efficacy of BCG vaccination against M. tuberculosis possibly by attenuation of protective immune responses to mycobacterial antigens and/or by polarizing the general immune responses to the Th2 profile.

Low dose chronic Schistosoma mansoni infection increases susceptibility to Mycobacterium bovis BCG infection in mice

The incidence of mycobacterial diseases is high and the efficacy of Bacillus Calmette Guerin (BCG) is low in most areas of the world where chronic worm infections are common. However, if and how concurrent worm infections could affect immunity to mycobacterial infections has not been elucidated. In this study we investigated whether infection of mice with Schistosoma mansoni could affect the ability of the animals to control Mycobacterium bovis BCG infection and the immune response to mycobacterial antigens. BALB/c mice subclinically infected with S. mansoni were challenged with M. bovis BCG via the intravenous route. The ability of the animals to contain the replication of M. bovis BCG in their organs, lung pathology as well as the in vitro mycobacterial and worm antigen induced immune responses were evaluated. The results showed that S. mansoni coinfected mice had significantly higher levels of BCG bacilli in their organs and sustained greater lung pathology compared to Schistosoma uninfected controls. Moreover, Schistosoma infected mice show depressed mycobacterial antigen specific Th1 type responses. This is an indication that chronic worm infection could affect resistance/susceptibility to mycobacterial infections by impairing mycobacteria antigen specific Th1 type responses. This finding is potentially important in the control of TB in helminth endemic parts of the world.

Immunomodulatory activity of Mollugo verticillata L

This article describes the evaluation of immunomodulatory activity of Mollugo verticillata L. (Molluginaceae), a weed plant common in warm and/or wet regions of the American continent. Nitric oxide (NO) release was evaluated in mice peritoneal cell cultures treated in vivo using the ethanolic extract of M. verticillata with and without BCG. The plant extract showed immunostimulatory activity when peritoneal cells were stimulated in vitro with BCG antigen only. However, mice peritoneal cells treated with M. verticillata plus BCG showed a drastic reduction in NO production when they received the additional stimulus in vitro with BCG. Ethanolic extracts of M. verticillata could directly increase NO release by peritoneal cells, but suppress the immune response of these cells when treated with BCG antigen and Mycobacterium tuberculosis whole antigen (TB). Preliminary phytochemical tests allowed the detection of quercetin and triterpenoid glycosides in the ethanolic extract of M. verticillata, and those compounds are probably responsible for the effect of this plant material on the immune system.