| 1. |
- Abate Waktola, Ebba Abate, et al.
(author)
-
Polymorphisms in CARD8 and NLRP3 are associated with extrapulmonary TB and poor clinical outcome in active TB in Ethiopia
- 2019
-
In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- Innate immunity is a first line defense against Mycobacterium tuberculosis infection where inflammasome activation and secretion of the pro-inflammatory cytokine IL-1beta, plays a major role. Thus, genetic polymorphisms in innate immunity-related genes such as CARD8 and NLRP3 may contribute to the understanding of why most exposed individuals do not develop infection. Our aim was to investigate the association between polymorphisms in CARD8 and NLRP3 and active tuberculosis (TB) as well as their relationship to treatment outcome in a high-endemic setting for TB. Polymorphisms in CARD8 (C10X) and NLRP3 (Q705K) were analysed in 1190 TB patients and 1990 healthy donors (HD). There was a significant association between homozygotes in the CARD8 polymorphism and extrapulmonary TB (EPTB), which was not the case for pulmonary TB or HDs. Among TB-patients, there was an association between poor treatment outcome and the NLRP3 (Q705K) polymorphism. Our study shows that inflammasome polymorphisms are associated with EPTB and poor clinical outcome in active TB in Ethiopia. The practical implications and determining causal relationships on a mechanistic level needs further study.
|
|
| 2. |
- Blomgran, Robert, et al.
(author)
-
Common Genetic Variations in the NALP3 Inflammasome Are Associated with Delayed Apoptosis of Human Neutrophils
- 2012
-
In: PLOS ONE. - San Francisco, USA : Public Library of Science. - 1932-6203. ; 7:3
-
Journal article (peer-reviewed)abstract
- Background: Neutrophils are key-players in the innate host defense and their programmed cell death and removal are essential for efficient resolution of inflammation. These cells recognize a variety of pathogens, and the NOD-like receptors (NLRs) have been suggested as intracellular sensors of microbial components and cell injury/stress. Some NLR will upon activation form multi-protein complexes termed inflammasomes that result in IL-1 beta production. NLR mutations are associated with auto-inflammatory syndromes, and our previous data propose NLRP3 (Q705K)/CARD-8 (C10X) polymorphisms to contribute to increased risk and severity of inflammatory disease by acting as genetic susceptibility factors. These gene products are components of the NALP3 inflammasome, and approximately 6.5% of the Swedish population are heterozygote carriers of these combined gene variants. Since patients carrying the Q705K/C10X polymorphisms display leukocytosis, the aim of the present study was to find out whether the inflammatory phenotype was related to dysfunctional apoptosis and impaired clearance of neutrophils by macrophages. less thanbrgreater than less thanbrgreater thanMethods and Findings: Patients carrying the Q705K/C10X polymorphisms displayed significantly delayed spontaneous as well as microbe-induced apoptosis compared to matched controls. Western blotting revealed increased levels and phosphorylation of Akt and Mcl-1 in the patients neutrophils. In contrast to macrophages from healthy controls, macrophages from the patients produced lower amounts of TNF; suggesting impaired macrophage clearance response. less thanbrgreater than less thanbrgreater thanConclusions: The Q705K/C10X polymorphisms are associated with delayed apoptosis of neutrophils. These findings are explained by altered involvement of different regulators of apoptosis, resulting in an anti-apoptotic profile. Moreover, the macrophage response to ingestion of microbe-induced apoptotic neutrophils is altered in the patients. Taken together, the patients display impaired turnover and clearance of apoptotic neutrophils, pointing towards a dysregulated innate immune response that influences the resolution of inflammation. The future challenge is to understand how microbes affect the activation of inflammasomes, and why this interaction will develop into severe inflammatory disease in certain individuals.
|
|
| 3. |
- Eklund, Daniel, 1984-, et al.
(author)
-
Human Gene Variants Linked to Enhanced NLRP3 Activity Limit Intramacrophage Growth of Mycobacterium tuberculosis
- 2014
-
In: Journal of Infectious Diseases. - Cary, USA : Oxford University Press. - 0022-1899 .- 1537-6613. ; 209:5, s. 749-753
-
Journal article (peer-reviewed)abstract
- Activation of the NLRP3 inflammasome and subsequent generation of interleukin 1 beta is initiated in macrophages upon recognition of several stimuli. In the present work, we show that gain-of-function gene variants of inflammasome components known to predispose individuals to inflammatory disorders have a host-protective role during infection with Mycobacterium tuberculosis. By isolation of macrophages from patients and healthy blood donors with genetic variants in NLRP3 and CARD8 and subsequent infection of the cells with virulent M. tuberculosis, we show that these gene variants, combined, are associated with increased control of bacterial growth in human macrophages.
|
|
| 4. |
- Schoultz, Ida, et al.
(author)
-
Combined polymorphisms in genes encoding the inflammasome components NALP3 and CARD8 confer susceptibility to Crohn's disease in Swedish men
- 2009
-
In: American Journal of Gastroenterology. - : Wolters Kluwer. - 0002-9270 .- 1572-0241. ; 104:5, s. 1180-1188
-
Journal article (peer-reviewed)abstract
- OBJECTIVES: Crohn's disease (CD) is characterized by overproduction of proinflammatory cytokines like interleukin (IL)-1beta. Production of mature IL-1beta is dependent on a caspase-1-activating protein complex called the NALP3 inflammasome, composed of NALP3, ASC, and CARD8. NALP3 shares structural similarities with Nod2, and both of these proteins are required for bacteria-induced IL-1beta secretion. The combination of the polymorphisms CARD8 (C10X)and NALP3 (Q705K) was recently shown to be associated with rheumatoid arthritis.Our aim was to investigate whether these combined polymorphisms play a role in the susceptibility to CD. METHODS: The study included 498 CD patients in two cohorts from different regions and 742 control individuals from a Swedish population. DNA was isolated from whole blood. Polymorphisms of (Q705K) NALP3 and (C10X) CARD8, as well as the Nod2 variants, R702W and G908R, were genotyped using the Taqman single nucleotide polymorphism assay. The Nod2 frameshift mutation, L1007fs, was detected by Megabace SNuPe genotyping. RESULTS: Our results show that men who have both the C10X and Q705K alleles in CARD8 and NALP3, and who express wild-type alleles of Nod2 are at an increased risk of developing CD (odds ratio, OR: 3.40 range: 1.32-8.76); P = 0.011). No association with these polymorphisms was found in women (OR: 0.89 (range: 0.44-1.77); P = 0.74). CONCLUSIONS: We suggest a role for combined polymorphisms in CARD8 and NALP3 in the development of CD in men, with obvious sex differences in the genetic susceptibility pattern. These findings give further support to the importance of innate immune responses in CD.
|
|
| 5. |
|
|
| 6. |
- Schoultz, Ida, 1979-, et al.
(author)
-
Ubiquitination and degradation of the Crohn’s Disease associated protein Nod2involves the E2 enzyme UBE2G2
-
Other publication (other academic/artistic)abstract
- Background: Mutations predisposing to Crohn’s disease (CD) have been mapped to the CARD15/Nod2 locus,which encodes a cytoplasmic receptor hereafter referred to as Nod2, a member of the NACHT-LRR (NLR) familyof pattern recognition receptors. The binding of bacterial muramyl dipeptide (MDP) to Nod2 triggers theactivation of the nuclear factor-κB (NFκB) pathway, thereby inducing a number of pro-inflammatory genes. Themost common variant of Nod2 associated with CD is the frame shift mutation L1007fs, which results in atruncated form of the protein unable to respond to MDP. Despite active research, little is known about howNod2 is regulated. The aim of this study was to investigate if the cellular Nod2 protein level is regulated by theubiquitin-proteasome pathway. Material and Methods/Results: Nod2 was shown to be subjected to rapid turnover in the colorectal cancer cellline SW480 as measured by immunoprecipitation following inhibition of protein synthesis with cyklohexamide.Immunoprecipitation of Nod2 also revealed co-precipitation of ubiquitin, suggesting that Nod2 wasubiquitinated. In line with this observation, inhibition of the proteasome using MG-132 or lactacystin, resultedin increased levels of Nod2 in the cells. UBE2G2, an E2 enzyme, thus conferring specificity of ubiquitin binding,was identified to have affinity for the CARD domain of Nod2. Activation of Nod2 with MDP enhanced itsubiquitination, and increasing amounts of UBE2G2 in the cells abrogated NF-κB-activation, suggesting thatubiquitination of Nod2 may be important for the resolution of the inflammatory signal. Conclusion: Taken together, our results show that the cellular level of Nod2 protein is regulated via theubiquitin-proteasome pathway, suggesting that Nod2-driven inflammation may be resolved through rapiddegradation of Nod2. Consequently, not only polymorphisms in Nod2 directly, but also in genes regulatingNod2 protein levels may contribute to the susceptibility to Crohn’s disease.
|
|
| 7. |
- Verma, Deepti, et al.
(author)
-
Gene polymorphisms in the NALP3 inflammasome are associated with interleukin-1 production and severe inflammation : relation to common inflammatory diseases?
- 2008
-
In: Arthritis and Rheumatism. - New York, NY : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 58:3, s. 888-894
-
Journal article (peer-reviewed)abstract
- OBJECTIVE: NALP3, ASC, and TUCAN are components of the NALP3 inflammasome, which triggers caspase 1-mediated interleukin-1beta (IL-1beta) release. Activating mutations in the gene encoding NALP3 (NLRP3) have recently been linked to familial periodic fever syndromes. We undertook this study to determine whether a patient with arthritis and antibiotic-resistant fever carried mutations in the genes encoding the NALP3 inflammasome. METHODS: Genetic analysis of NLRP3 and the gene encoding TUCAN (CARD-8) was performed on genomic DNA from the patient and from a population-based collection of DNA (806 subjects). For in vitro studies of IL-1beta production and caspase 1 activity, blood was obtained from the patient at different time points after administration of anakinra, an IL-1 receptor antagonist, as well as from 5 healthy age- and sex-matched control subjects. RESULTS: Mutation analysis of the patient's genes encoding NALP3, ASC, and TUCAN revealed variations in the NLRP3 (Q705K) and CARD-8 (C10X) genes. The allele frequencies of these single-nucleotide polymorphisms (SNPs) in the population were 6.5% and 34%, respectively. The elevated activity of caspase 1 and the high levels of IL-1beta measured in samples from the patient returned to normal levels after treatment with anakinra. CONCLUSION: Our results indicate that the patient's symptoms were due to elevated levels of IL-1beta, since treatment with anakinra effectively abolished the symptoms. The compound SNPs may explain the increased IL-1beta levels and inflammatory symptoms observed, but further studies are needed to reveal a functional relationship. The prevalence of the polymorphisms (4% of the population carry both SNPs) in the general population may suggest a genetic predisposition for common inflammatory disorders.
|
|
| 8. |
- Verma, Deepti, et al.
(author)
-
The Q705K polymorphism in NLRP3 is a gain-of-function alteration leading to excessive interleukin-1β and IL-18 production
- 2012
-
In: PLOS ONE. - San Fransisco, USA : Public Library of Science. - 1932-6203. ; 7:4
-
Journal article (peer-reviewed)abstract
- Background: The Q705K polymorphism in NLRP3 has been implicated in several chronic inflammatory diseases. In this study, we determine the functional role of this commonly occurring polymorphism using an in-vitro system.Methods / Principle findings: NLRP3-WT and NLRP3-Q705K were retrovirally transduced into the human monocytic cell line THP-1, followed by the assessment of IL-1β and IL-18 levels in the cell culture supernatant. THP-1 cells expressing the above NLRP3 variants were sorted based upon Green Fluorescent Protein (GFP) expression. Cytokine response to alum (one of the most widely used adjuvants in vaccines) in the cells stably expressing NLRP3-WT and NLRP3-Q705K were determined. IL-1β and IL-18 levels were found to be elevated in THP-1 cells transduced with NLRP3-Q705K compared to the NLRP3-WT. Upon exposure to alum, THP-1 cells stably expressing NLRP3-Q705K displayed an increased production of IL-1β, IL-18 and TNF-α, in a caspase-1 and IL-1 receptor-dependent manner.Conclusions: Collectively, these findings show that the Q705K polymorphism in NLRP3 is a gain-of-function alteration leading to an overactive NLRP3 inflammasome. The option of IL-1β blockade may be considered in patients with chronic inflammatory disorders that are unresponsive to conventional treatments.
|
|
