Fig. 1

The interplay of local and systemic processes leading to pneumonia in stroke patients. Stroke-associated pneumonia is influenced by systemic and local mechanisms. Locally, there are pulmonary alterations due to stroke itself and the inflammatory processes that develop. BALF inflammation, lung inflammation, and edema seem to be the principal alterations, although there are some discrepancies between studies. On a systemic level, various represented processes lead to 3 main alterations that cause systemic immunosuppression after stroke: an increase of the T-helper (Th) 2/Th1 cytokine ratio; a reduction of the lymphocyte counts in the spleen, thymus, and blood; and a decrease of the antimicrobial defense mechanisms of neutrophils and monocytes. SNS sympathetic nervous system, iNKT invariant natural killer T cells, PNS parasympathetic nervous system, ACh acetylcholine, HPA hypothalamic–pituitary–adrenal, HMGB-1 high motility group box-1, sCD163 soluble cluster of differentiation 163, MZ marginal zone, FasL Fas ligand, BALF bronchoalveolar lavage fluid. Parts of this figure were supported by Servier Medical Art with permission under the Creative Commons Attribution 3.0 Unported License