Microbial Immune Evasion Employing Suppressor of Cytokine Signaling (SOCS) Proteins

Cytokines mediate communication between cells of the immune system and are of crucial importance to induce an appropriately regulated immune response to invading pathogens. Cytokine receptor signaling has to be tightly controlled to balance anti-microbial and tissue-destructive effects, both of which are inherently associated with cytokinemediated inflammation. Suppressor of cytokine signaling (SOCS) proteins have been identified as intracellular, inducible feedback inhibitors which limit the signal magnitude of cytokines employing Janus kinase (Jak) and signal transducer and activator of transcription (STAT) pathways. Interfering with cytokine receptor signaling has been shown to be a promising strategy used by various microbial pathogens to evade otherwise detrimental immune responses. To this, microbes make use of a variety of different means. Recent reports now indicate that certain bacteria, viruses and parasites have also learned to use the host's inhibitory SOCS proteins for manipulating cytokine receptor signaling, especially to circumvent the actions of interferon. Progress in the field of microbial immune evasion mediated by SOCS proteins is discussed in this review. Modulating the host's SOCS system therefore could also be a promising new approach for molecular therapeutic strategies.