User:Immcarle197/Interleukin 1 beta

Furthermore, it has been found that in breast cancer cells, IL-1β activates p38 and p42/22 MAPK pathways which ultimately lead to the secretion of the RANK/RANKL inhibitor osteoprotegerin. Higher osteoprotegerin and IL-1β levels are a characteristic of breast cancer cells with a higher metastatic potential.

Functions of IL-1β in HIV-1 Infections
The human immunodeficiency virus (HIV) infects cells of the immune system, such as macrophages, dendritic cells, and CD4+ T helper cells (TH). The latter can be infected by the virus in various ways with different fates depending on the state of activation of the T helper cell.

Firstly, TH cells can die of viral lysis due to an active infection that produces enough virions to kill the cell. Secondly, CD4+ T cells can be infected by the virus but instead of producing more viral particles, the cell enters a latent phase. In this period, the T helper cells looks identical from the outside but any stressor could lead to the renewed production of HIV and its propagation to new immune cells. Lastly, the TH cell can become abortively infected, where the virus gets detected inside the cell and a programmed cell-death, known as pyroptosis, kills the infected cell. Pyroptosis is mediated via caspase-1 and is characterized by cell lysis and the secretion of IL-1β causing inflammation and attraction of more immune cells. This can create a cycle of CD4+ T cells getting abortively infect with HIV, dying of pyroptosis, new T helper cells arriving to the site of inflammation where they get infected again. The results is the depletion of T helper cells. Even though, levels of IL-1β in blood are not majorly different between HIV positive and negative individuals, studies have shown elevated levels of IL-1β of lymphatic tissue in HIV-infected individuals.

In fact, the gut-associated lymphoid tissue (GALT) has a high density of immune cells as the gut is an interface between symbiotic gut microbes that should remain with the host and pathogenic bacteria that should not gain access into the circulatory system. If HIV-infection leads to the secretion of IL-1βin monocytes and macrophages, it causes inflammation of this area. The mucosal epithelial layer responds to this by producing less or altering the tight junction proteins which makes it easier for pathogenic microbes to move into the lamina propria. Here, the pathogens can further activate local immune cells and amplify the inflammatory response.

Significance of IL-1β in Neuroinflammation
Studies in mice on experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS) research, have found that blocking IL-1β could make the animals resistant to EAE. IL-1β led to the production of an antigen-specific pro-inflammatory subset of T helper cells (TH17). In combination with other cytokines, interleukin-1β can upregulate the production of the cytokine GM-CSF which is correlated to neuroinflammation. Detailed mechanisms on this front are yet too be elucidated.

IL-1β has also been observed in elevated levels of the cerebrospinal fluid and brain tissues of Alzheimer patients. The amyloid-β plaques, that are characteristic of Alzheimer disease, are damage-associated molecular patterns (DAMPs) that are recognized by pattern recognition receptors (RPPs) and lead to the activation of microglia. Consequently, microglia release interleukin-1β among other cytokines. Nevertheless, the significance of IL-1β in Alzheimer disease and the onset of neuroinflammation still remains largely unknown.

Lastly, in vitro studies have shown that IL-1β causes an increase in mitochondrial glutaminase activity. In response, there is excessive glutamate secretion which has a neurotoxic effect.