This is due in part to an innate feedback mechanism inherited from non-malignant prostate epithelial cells, enabling them to adapt to varying levels of steroid.
Even in a castrate-sensitive cell, ligand depletion triggers an innate feedback response leading to increased transcription of the AR gene (Wolf et al, 1993; Cai et al, 2011; Knuuttila et al, 2014; Wyatt et al, 2014).
In our study, we focused more exclusively on epithelial cells and the effects of positive chemokine feedback on the innate immune response of these cells.
In the immune system, miR-146a/b upregulation provides negative feedback on the innate immune system by targeting IRAK1 and TRAF6 [ 44].
The IL-25-mediated collaborative interactions between eosinophils/basophils and Th2 memory cells perhaps propagate a positive feedback loop between innate effector and adaptive immunity, leading to the amplification of allergic inflammation.
This miRNA would appear to be a master regulator for several aspects of immunity, including the regulation of cytokines, such as tumor necrosis factor-alpha (TNF-α), functioning in the negative feedback control of innate immunity in Toll-like receptor (TLR) signaling, and is involved with T-cell activation and is highly expressed in mature human memory T cells [ 41].
Specifically, it contributes to controlling the overproduction of cytokines, such as TNF-α, and it functions as a negative feedback control of innate immunity in toll-like receptor (TLR) signaling during recurrent bacterial infection by establishing endotoxin tolerance [ 33] and cross-tolerance [ 34].
DUSP1 appears to be a major feedback regulator of the innate immune response, and to play a critical role in preventing septic shock and multi-organ dysfunction during pathogenic infection [36].
We speculate that strong, early innate immune responses could result in feedback responses, in an attempt to restore homeostasis.
This potentially fatal innate immune reaction consists of positive feedback loops between cytokines and immune and tissue cells, resulting in highly elevated levels of cytokines in the blood, multiorgan failure, and death (Osterholm 2005).
Interestingly, TLR-dependent induction of miR-101 appears to provide positive feedback loop control of innate immune responses through miR-101-mediated suppression of MAPK phosphatase 1, an inhibitory regulator of TLR-signalling pathways [ 119].
