Immunity is known to be sexually dimorphic. This dimorphism may be attributed to the action of different hormones. Aluminum is a component of several vaccines and acts as an adjuvant of immunogenicity. The activation of the Nalp3 inflammasome plays a role in aluminum’s adjuvancy. Estrogen affects immune cells by regulating the expression of genes involved in immune-related mechanisms; such as the modulation of cytokine secretion. We hypothesized that estrogen modulates the aluminum-induced secretion of IL-1β and IL-18. Using an ex vivo mouse macrophage model this study examined: (i) the effects of estrogen on Nalp3 inflammasome genes expression and (ii) the estrogen receptor involved in the modulation of these genes. Our results indicate that estrogen up-regulates Nalp3 gene expression via ERα/β heterodimerization, and caspase-1 activity may be indirectly modulated due to the up-regulation of SPI-6 via ERβ.

<p>Innate immunity has received impressive attention in the past decade owing to the discovery of the Toll like receptors (TLRs) and the NOD-like receptors (NLRs). While the TLRs specialize in fighting microbes at the cell surface, the NLRs complement by detecting and responding to intracellular microbes. Recently, the non-microbe sensing NLR called inflammasomes, have been identified, which senses metabolic stress as well as certain pathogenic microbes and elicits host’s inflammatory response. <strong></strong></p><p>The NLR, NALP3 (formerly known as cryopyrin) forms a large cytoplasmic complex called the ‘inflammasome’ when NALP3, activated by a stimuli, associates with the adaptor proteins ASC and CARD-8. This interaction leads to the activation of pro-inflammatory caspase-1 which subsequently results in the formation of Interleukin (IL)-1β and IL-18. Mutations in the gene encoding NALP3, termed <em>NLRP3</em> can lead to its constitutive activation resulting in an uncontrolled production of IL-1β. These mutations have been implicated in hereditary inflammatory diseases, often grouped under cryopyrin associated periodic syndromes (CAPS).</p><p>This thesis describes a patient with a long history of arthritis and antibiotic resistant fever, but without the typical symptoms of CAPS. The patient was found to be a heterozygous carrier of two common polymorphisms Q705K in <em>NLRP3 </em>and C10X in the <em>CARD-8</em>. Experimental studies showed elevated levels of caspase-1 and IL-1β in the patient, and a total clinical remission was achieved by IL-1β blockade. These two polymorphisms combined, were found to occur in approximately 4% of the control population, suggesting the possibility of a genetic predisposition for inflammation in these individuals. Therefore, a cohort of rheumatoid arthritis (RA) patients, where elevated IL-1β could be one of the reasons behind chronic inflammation, was investigated. We found that carrying the combined polymorphisms resulted in increased RA susceptibility and a more severe disease course. Hypothetically, this subgroup of patients might benefit from IL-1β blockade. Additional studies are warranted to elucidate the functional effects of the two polymorphisms and to determine whether they identify a subgroup of patients that could benefit from IL-1 targeted therapy. Given the structural similarity of NALP3 to other NALPs, the possibility of involvement of the alternative, homologous genes cannot be eliminated.</p>

Innate immunity has received impressive attention in the past decade owing to the discovery of the Toll like receptors (TLRs) and the NOD-like receptors (NLRs). While the TLRs specialize in fighting microbes at the cell surface, the NLRs complement by detecting and responding to intracellular microbes. Recently, the non-microbe sensing NLR called inflammasomes, have been identified, which senses metabolic stress as well as certain pathogenic microbes and elicits host’s inflammatory response. The NLR, NALP3 (formerly known as cryopyrin) forms a large cytoplasmic complex called the ‘inflammasome’ when NALP3, activated by a stimuli, associates with the adaptor proteins ASC and CARD-8. This interaction leads to the activation of pro-inflammatory caspase-1 which subsequently results in the formation of Interleukin (IL)-1β and IL-18. Mutations in the gene encoding NALP3, termed NLRP3 can lead to its constitutive activation resulting in an uncontrolled production of IL-1β. These mutations have been implicated in hereditary inflammatory diseases, often grouped under cryopyrin associated periodic syndromes (CAPS). This thesis describes a patient with a long history of arthritis and antibiotic resistant fever, but without the typical symptoms of CAPS. The patient was found to be a heterozygous carrier of two common polymorphisms Q705K in NLRP3 and C10X in the CARD-8. Experimental studies showed elevated levels of caspase-1 and IL-1β in the patient, and a total clinical remission was achieved by IL-1β blockade. These two polymorphisms combined, were found to occur in approximately 4% of the control population, suggesting the possibility of a genetic predisposition for inflammation in these individuals. Therefore, a cohort of rheumatoid arthritis (RA) patients, where elevated IL-1β could be one of the reasons behind chronic inflammation, was investigated. We found that carrying the combined polymorphisms resulted in increased RA susceptibility and a more severe disease course. Hypothetically, this subgroup of patients might benefit from IL-1β blockade. Additional studies are warranted to elucidate the functional effects of the two polymorphisms and to determine whether they identify a subgroup of patients that could benefit from IL-1 targeted therapy. Given the structural similarity of NALP3 to other NALPs, the possibility of involvement of the alternative, homologous genes cannot be eliminated.

Metal ions released from implantable biomaterials have been associated with adverse biological reactions that can limit implant longevity. Previous studies have shown that, in macrophages, Co2+, Cr3+, and Ni2+ can activate the NLR family pyrin domain-containing protein 3 (NLPR3) inflammasome, which is responsible for interleukin(IL)-1β production through caspase-1. Furthermore, these ions are known to induce oxidative stress, and inflammasome priming is known to involve nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. However, the mechanisms of inflammasome activation by metal ions remain largely unknown. The objectives of this thesis were to determine if, in macrophages: 1. IL-1β release induced by metal ions is caspase-1-dependent; 2. caspase-1 activation and IL-1β release induced by metal ions are oxidative stress-dependent; and 3. IL-1β release induced by metal ions is NF-κB signaling pathway-dependent. Lipopolysaccharide (LPS)-primed murine bone-marrow-derived macrophages were exposed to Co2+, Cr3+, or Ni2+, with or without an inhibitor of caspase-1, oxidative stress, or NF-κB. Culture supernatants were analyzed for active caspase-1 (immunoblotting) and/or IL-1β (ELISA). Overall, results showed that while both Cr3+ and Ni2+ may be inducing inflammasome activation, Cr3+ is likely a more potent activator, acting through oxidative stress and the NF-κB signaling pathway. Further elucidation of the activation mechanisms may facilitate the development of therapeutic approaches to modulate the inflammatory response to metal ions, and thereby increase implant longevity.