| 1. |
- Davidsson, Lisa, et al.
(författare)
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In Vivo Transmigrated Human Neutrophils Are Highly Primed for Intracellular Radical Production Induced by Monosodium Urate Crystals.
- 2020
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Ingår i: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 21:11
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Tidskriftsartikel (refereegranskat)abstract
- Gout is an inflammatory disease caused by monosodium urate (MSU) crystals. The role of neutrophils in gout is less clear, although several studies have shown neutrophil extracellular trap (NET) formation in acutely inflamed joints of gout patients. MSU crystals are known to induce the production of reactive oxygen species (ROS) and NET formation in neutrophils isolated from blood, but there is inconclusive knowledge on the localization of ROS production as well as whether the ROS are required for NET formation. In this report we demonstrate that MSU crystals activate human neutrophils to produce ROS exclusively in intracellular compartments. Additionally, in vivo transmigrated neutrophils derived from experimental skin chambers displayed markedly increased ROS production as compared to resting blood neutrophils. We also confirmed that MSU stimulation potently induced NET formation, but this response was not primed in in vivo transmigrated neutrophils. In line with this we found that MSU-triggered NET formation was independent of ROS production and proceeded normally in neutrophils from patients with dysfunctional respiratory burst (chronic granulomatous disease (CGD) and complete myeloperoxidase (MPO) deficiency). Our data indicate that in vivo transmigrated neutrophils are markedly primed for oxidative responses to MSU crystals and that MSU triggered NET formation is independent of ROS production.
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| 2. |
- Khamzeh, Arsham, et al.
(författare)
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High levels of short-chain fatty acids secreted by Candida albicans hyphae induce neutrophil chemotaxis via free fatty acid receptor 2
- 2024
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press. - 1938-3673 .- 0741-5400. ; 115:3, s. 536-546
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Tidskriftsartikel (refereegranskat)abstract
- Candida albicans belongs to our commensal mucosal flora and in immune-competent individuals in the absence of epithelial damage, this fungus is well tolerated and controlled by our immune defense. However, C. albicans is an opportunistic microorganism that can cause different forms of infections, ranging from superficial to life-threatening systemic infections. C. albicans is polymorphic and switches between different phenotypes (e.g. from yeast form to hyphal form). C. albicans hyphae are invasive and can grow into tissues to eventually reach circulation. During fungal infections, neutrophils in particular play a critical role for the defense, but how neutrophils are directed toward the invasive forms of fungi is less well understood. We set out to investigate possible neutrophil chemoattractants released by C. albicans into culture supernatants. We found that cell-free culture supernatants from the hyphal form of C. albicans induced both neutrophil chemotaxis and concomitant intracellular calcium transients. Size separation and hydrophobic sorting of supernatants indicated small hydrophilic factors as responsible for the activity. Further analysis showed that the culture supernatants contained high levels of short-chain fatty acids with higher levels from hyphae as compared to yeast. Short-chain fatty acids are known neutrophil chemoattractants acting via the neutrophil free fatty acid receptor 2. In line with this, the calcium signaling in neutrophils induced by hyphae culture supernatants was blocked by a free fatty acid receptor 2 antagonist and potently increased in the presence of a positive allosteric modulator. Our data imply that short-chain fatty acids may act as a recruitment signal whereby neutrophils can detect C. albicans hyphae.
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| 3. |
- Sanchez Klose, Felix Peter, 1989, et al.
(författare)
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A rare CTSC mutation in Papillon-Lefèvre Syndrome results in abolished serine protease activity and reduced NET formation but otherwise normal neutrophil function.
- 2021
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Papillon-Lefèvre Syndrome (PLS) is an autosomal recessive monogenic disease caused by loss-of-function mutations in the CTSC gene, thus preventing the synthesis of the protease Cathepsin C (CTSC) in a proteolytically active form. CTSC is responsible for the activation of the pro-forms of the neutrophil serine proteases (NSPs; Elastase, Proteinase 3 and Cathepsin G), suggesting its involvement in a variety of neutrophil functions. In PLS neutrophils, the lack of CTSC protease activity leads to inactivity of the NSPs. Clinically, PLS is characterized by an early, typically pre-pubertal, onset of severe periodontal pathology and palmoplantar hyperkeratosis. However, PLS is not considered an immune deficiency as patients do not typically suffer from recurrent and severe (bacterial and fungal) infections. In this study we investigated an unusual CTSC mutation in two siblings with PLS, a 503A>G substitution in exon 4 of the CTSC gene, expected to result in an amino acid replacement from tyrosine to cysteine at position 168 of the CTSC protein. Both patients bearing this mutation presented with pronounced periodontal pathology. The characteristics and functions of neutrophils from patients homozygous for the 503A>G CTSC mutation were compared to another previously described PLS mutation (755A>T), and a small cohort of healthy volunteers. Neutrophil lysates from patients with the 503A>G substitution lacked CTSC protein and did not display any CTSC or NSP activity, yet neutrophil counts, morphology, priming, chemotaxis, radical production, and regulation of apoptosis were without any overt signs of alteration. However, NET formation upon PMA-stimulation was found to be severely depressed, but not abolished, in PLS neutrophils.
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| 4. |
- Sanchez Klose, Felix Peter, 1989
(författare)
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Neutrophil Serine Proteases in Health and Disease
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neutrophils are filled with many antimicrobial agents, including the neutrophil serine proteases (NSPs); a group of proteases including Elastase, Proteinase 3, and Cathepsin G. Synthesized as inactive proforms, the NSPs are activated through proteolytic processing by Cathepsin C (CTSC). The NSPs have been demonstrated to degrade microbes in vitro. Therefore, NSPs have been described as crucial for microbial killing and are also believed to be critical for NETosis, a neutrophil-specific type of cell death capable of ensnaring extracellular microbes. Periodontitis is a destructive inflammation of the tooth supporting tissues initiated by colonizing bacteria. Neutrophils are abundantly present in the gingival crevice and more are recruited during periodontitis. Certain defects in neutrophil functions, like the Papillon-Lefèvre Syndrome (PLS), are associated with severe forms of periodontitis. PLS is a rare autosomal recessive loss-of-function mutation in the CTSC gene. The subsequent absence of CTSC activity in PLS neutrophils, results in absence of NSP activity. Interestingly, patients with PLS do not typically display increased susceptibility to opportunistic infections. The cardinal symptom of PLS is instead a rapidly progressing periodontitis with prepubertal onset. By studying PLS neutrophils, this thesis shows that NSP activity is indeed important for certain but not all types of NETosis (paper I). The work also demonstrates that PLS neutrophils from two families with distinct CTSC mutations, are indeed devoid of CTSC as well as NSP activities (paper II). Despite this, PLS neutrophils appeared to function normally with the exception of NETosis. To explain how lack of NSP activity results in periodontitis, it was hypothesised that NSPs may regulate inflammation by the cleavage of cytokines. In vitro, it was shown that whereas normal neutrophils were capable of degrading certain cytokines, PLS neutrophils were unable to do so (paper III). Most notably, IL-17A, IL-23, CCL20, and RANKL, all of potential importance for driving periodontal pathology, were quite susceptible to NSP-mediated cleavage. Other cytokines, e.g., IL-17F and CCL2, were resistant to NSP mediated cleavage indicating that degradation was not indiscriminate. In conclusion, this thesis shows that NSP activity is important for certain types of NET formation, but otherwise dispensable for basic neutrophil function. It also demonstrates that NSP activity may be able to regulate inflammatory processes and could help to explain the aggressive periodontal pathology seen in patients with PLS.
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| 5. |
- Sundqvist, Martina, et al.
(författare)
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Severe chronic non-bacterial osteomyelitis in combination with total MPO deficiency and responsiveness to TNFα inhibition
- 2023
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- We describe a female patient suffering from severe chronic non-bacterial osteomyelitis (CNO) with systemic inflammation and advanced malnutrition and complete deficiency of myeloperoxidase (MPO). CNO is a rare autoinflammatory bone disorder associated with dysregulation of the innate immune system. MPO deficiency is a genetic disorder with partial or complete absence of the phagocyte peroxidase MPO. MPO deficiency has no established clinical phenotype but reports indicate increased susceptibility to infection and chronic inflammation. The patient’s symptoms began at 10 years of age with pain in the thighs, systemic inflammation and malnutrition. She was diagnosed with CNO at 14 years of age. Treatment with nonsteroidal anti-inflammatory drugs, corticosteroids, bisphosphonates or IL1-receptor antagonists (anakinra) did not relieve the symptoms. However, the patient responded instantly and recovered from her clinical symptoms when treated with TNFα blockade (adalimumab). Three years after treatment initiation adalimumab was withdrawn, resulting in rapid symptom recurrence. When reintroducing adalimumab, the patient promptly responded and went into remission. In addition to clinical and laboratory profiles, neutrophil functions (reactive oxygen species, ROS; neutrophil extracellular traps, NETs; degranulation; apoptosis; elastase activity) were investigated both in a highly inflammatory state (without treatment) and in remission (on treatment). At diagnosis, neither IL1β, IL6, nor TNFα was significantly elevated in serum, but since TNFα blockade terminated the inflammatory symptoms, the disease was likely TNFα-driven. All neutrophil parameters were normal both during treatment and treatment withdrawal, except for MPO-dependent intracellular ROS- and NET formation. The role of total MPO deficiency for disease etiology and severity is discussed.
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