Role of inflammasome regulation on immune modulators

Inflammatory responses are essential in eliminating harmful substrates from damaged tissue and inducing recovery.Several cytokines participate in and facilitate this response. Certain cytokines such as interleukin(IL)-1β and IL-18 are initially produced in precursor form in response to toll-like receptor(TLR) ligands and undergo maturation by inflammasomes, which are cytosolic multi-protein complexes containing nucleotide-binding oligomerization domain(NOD)-containing protein 2-like receptors(NLRs). Immune modulators targeting inflammasomes have been investigated to control inflammatory diseases such as metabolic syndrome. However, most immune modulators possessing anti-inflammasome properties attenuate production of other cytokines, which are essential for host defense. In this review, we analyzed the effect of anti-inflammasome agents on the production of cytokines which are not regulated by inflammasome and involving in initial immune responses. As a result, the infiammasome inhibitors are put into three categories: non-effector, stimulator, or inhibitor of cytokine production. Even the stimulator of cytokine production ameliorated symptoms resulting from inflammasome activation in mouse models. Thus, we suggest ideal immune modulators targeting inflammasomes in order to enhance cytokine production while inhibiting cytokine maturation.

Glucose metabolism and neurogenesis in the gerbil hippocampus after transient forebrain ischemia

Recent evidence exists that glucose transporter 3（GLUT3） plays an important role in the energy metabolism in the brain.Most previous studies have been conducted using focal or hypoxic ischemia models and have focused on changes in GLUT3 expression based on protein and m RNA levels rather than tissue levels.In the present study,we observed change in GLUT3 immunoreactivity in the adult gerbil hippocampus at various time points after 5 minutes of transient forebrain ischemia.In the sham-operated group,GLUT3 immunoreactivity in the hippocampal CA1 region was weak,in the pyramidal cells of the CA1 region increased in a time-dependent fashion 24 hours after ischemia,and in the hippocampal CA1 region decreased significantly between 2 and 5 days after ischemia,with high level of GLUT3 immunoreactivity observed in the CA1 region 10 days after ischemia.In a double immunofluorescence study using GLUT3 and glial-fibrillary acidic protein（GFAP）,we observed strong GLUT3 immunoreactivity in the astrocytes.GLUT3 immunoreactivity increased after ischemia and peaked 7 days in the dentate gyrus after ischemia/reperfusion.In a double immunofluorescence study using GLUT3 and doublecortin（DCX）,we observed low level of GLUT3 immunoreactivity in the differentiated neuroblasts of the subgranular zone of the dentate gyrus after ischemia.GLUT3 immunoreactivity in the sham-operated group was mainly detected in the subgranular zone of the dentate gyrus.These results suggest that the increase in GLUT3 immunoreactivity may be a compensatory mechanism to modulate glucose level in the hippocampal CA1 region and to promote adult neurogenesis in the dentate gyrus.

Poly-gamma-glutamic acid from Bacillus subtilis upregulates pro-inflammatory cytokines while inhibiting NLRP3, NLRC4 and AIM2 inflammasome activation

Poly-gamma-glutamic acid(γ-PGA)is a natural,edible and non-toxic polymer synthesized by Bacillus subtilis and is suggested as a safe biomaterial for the use in hydrogels and vaccine adjuvants.However,the effect ofγ-PGA on inflammasome activation has not yet been studied in macrophages.Inflammasomes,which are intracellular multi-protein complexes,promote acute and chronic inflammation via interleukin-1βor interleukin-18 maturation,and they are known targets for metabolic syndromes and cancer.In this study,we observed thatγ-PGA attenuated NLRP3,NLRC4 and AIM2 inflammasome activation,whereas it upregulated pro-inflammatory cytokine expression in human and murine macrophages.Althoughγ-PGA had conflicting effects on cytokine production and maturation,it clearly alleviated the severity of lipopolysaccharide-induced endotoxin shock in an animal model.Thus,we suggestγ-PGA as a candidate to control inflammasome-mediated disorders.