Infection with human immunodeficiency virus (HIV) brings numerous harms, not least a dysbiosis leading to:
- microbial translocation
- chronic immune activation
- changes in tryptophan metabolism
These toxic effects are felt by the central nervous system (CNS) and are poorly understood.
Concerning tryptophan–an essential (not made by the body) amino acid provided by diet– an enzyme indolamine-2,3-dioxygenase (IDO) breaks it down into substances which damage the CNS, causing cognitive problems and even contributing to the depletion of vital CD4 T cells.
A team of researchers in Italy led by Carolina Scagnolari suspected a link between high levels of immune activation markers in the cerebrospinal fluid (CSF) of HIV-1 infected patients and the over-expression of the enzyme IDO at the gut mucosal surface.
They initiated a small study—ten HIV-1-positive patients successfully treated with antiretrovirals.
All patients received a multistrain probiotic powder supplement twice a day for six months. The supplement contained high concentrations of lactobacillus, streptococcus and bifidobacterium strains.
Neopterin levels in CSF were measured as a marker of the expression of brain immune activation.
Results after 6 months of high concentration multistrain probiotic supplementation:
- Significant decrease in CSF neopterin levels recorded in all HIV-1-positive patients
- Significant reductions of IDO mRNA expression in the gut-associated lymphoid tissue (GALT) recorded in all HIV-1-positive patients
The authors suggest that “The opportunity to reduce the activation of the IDO pathway through this probiotic product could break the vicious gut–brain circle and in this manner prevent the neurocognitive impairment observed in HIV-1-positive patients.”
As this was a small trial, a larger trial may confirm a positive effect for probiotic supplements in reducing immune activation and cognitive impairment in these HIV patients.
The full study was published in the International Journal of Molecular Sciences in October of 2016.