Psychoneuroimmunology of stroke

Immunity - a significant pathogenic factor as well as an integral part of the psychoneuroendocrine-immune regulations

Immunity plays an important role in the reactivity of the organism and, in this context, is an essential factor in the pathogenesis of many diseases. Basically, there is no system or organ in the body, whose dysfunction is not related to immunity consequences. In addition, there are also multisystem diseases simultaneously involving multiple body systems. They are not always caused by weak immunity, but also often by modified immune reactions known as overshooting. The essence of all these diseases is a change in the reactivity of the organism where immunity plays an important role. The immunity as such is then part of the systems of neuroendocrine-immune regulation, which have common mediators and receptors. The establishment of psychoneuroimmunology, a relatively new discipline in neuroscience, contributed to a detailed understanding of these mechanisms between central and peripheral nervous system, the endocrine system and the immune system. This research enabled the uncovering of the nature of stress-diseases and impact of other regulatory disturbances on the function of various body organs and systems of the organism as a whole. The aim of this short review is to show complex interconnections of these relationships to better understand the human health and disease.

Atorvastatin Modulates Regulatory T Cells and Attenuates Cerebral Damage in a Model of Transient Middle Cerebral Artery Occlusion in Rats

Regulatory T cells (Tregs) inhibit the activation of the immune response which could down-regulate the systemic and focal activation observed during ischemic stroke. In fact, in animal models, Tregs infiltrate the infarcted brain and reduce the pro-inflammatory cytokine production and infarct volume, mainly in late stages of ischemia. Recently, an expansion and greater suppressive capacity of circulating Tregs after treatment with statins was observed, in addition to their cardio- and neuroprotective actions demonstrated previously. Thus, to determine whether Treg modulation mediated by statins can also be beneficial during stroke, cerebral ischemia was artificially induced in Wistar rats by transient middle cerebral artery occlusion (tMCAO) during 60 minutes with subsequent reperfusion for 7 days. Six hours after surgery, some animals were treated with atorvastatin (ATV, 10 mg/kg) or carboxymethylcellulose as vehicle at the same concentration every other day during 7 days. Some animals were sham operated as control group of surgery. Interestingly, ATV treatment prevented the development of infarct volume, reduced the neurological deficits, and the circulating and cervical lymph node CD25⁺FoxP3⁺ Treg population. Moreover, there was a reduction of glial cell activation, which correlated with decreased circulating Tregs. Remarkably, treatment with ATV induced an increase in the frequency of CD4⁺CD25⁺ T cells, in particular of those expressing CTLA-4, in brain samples. Together, these results suggest that ATV can modulate Tregs in peripheral tissue and favor their accumulation in the brain, where they can exert neuroprotective actions maybe by the reduction of glial cell activation.

Wiki-pi: a web-server of annotated human protein-protein interactions to aid in discovery of protein function

Protein-protein interactions (PPIs) are the basis of biological functions. Knowledge of the interactions of a protein can help understand its molecular function and its association with different biological processes and pathways. Several publicly available databases provide comprehensive information about individual proteins, such as their sequence, structure, and function. There also exist databases that are built exclusively to provide PPIs by curating them from published literature. The information provided in these web resources is protein-centric, and not PPI-centric. The PPIs are typically provided as lists of interactions of a given gene with links to interacting partners; they do not present a comprehensive view of the nature of both the proteins involved in the interactions. A web database that allows search and retrieval based on biomedical characteristics of PPIs is lacking, and is needed. We present Wiki-Pi (read Wiki-π), a web-based interface to a database of human PPIs, which allows users to retrieve interactions by their biomedical attributes such as their association to diseases, pathways, drugs and biological functions. Each retrieved PPI is shown with annotations of both of the participant proteins side-by-side, creating a basis to hypothesize the biological function facilitated by the interaction. Conceptually, it is a search engine for PPIs analogous to PubMed for scientific literature. Its usefulness in generating novel scientific hypotheses is demonstrated through the study of IGSF21, a little-known gene that was recently identified to be associated with diabetic retinopathy. Using Wiki-Pi, we infer that its association to diabetic retinopathy may be mediated through its interactions with the genes HSPB1, KRAS, TMSB4X and DGKD, and that it may be involved in cellular response to external stimuli, cytoskeletal organization and regulation of molecular activity. The website also provides a wiki-like capability allowing users to describe or discuss an interaction. Wiki-Pi is available publicly and freely at http://severus.dbmi.pitt.edu/wiki-pi/.