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- Kerkman, Priscilla, et al.
(författare)
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Generation of plasma cells and CD27-IgD- B cells during hantavirus infection is associated with distinct pathological findings
- 2021
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Ingår i: Clinical & Translational Immunology (CTI). - : John Wiley & Sons. - 2050-0068. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Human hantavirus infections can cause haemorrhagic fever with renal syndrome (HFRS). The pathogenic mechanisms arenot fully understood, nor if they affect the humoral immune system. The objective of this study was to investigate humoral immune responses to hantavirus infection and to correlate them to the typical features of HFRS: thrombocytopenia and transient kidney dysfunction.Methods: We performed a comprehensive characterisation of longitudinal antiviral B-cell responses of 26 hantavirus patients and combined this with paired clinical data. In addition, we measured extracellular adenosine triphosphate (ATP)and its breakdown products in circulation and performed in vitro stimulations to address its effect on B cells.Results: We found that thrombocytopenia was correlated to an elevated frequency of plasmablasts in circulation. In contrast, kidney dysfunction was indicative of an accumulation of CD27-IgD- B cells and CD27/low plasmablasts. Finally, we provide evidence that high levels of extracellular ATP and matrix metalloproteinase 8 can contribute to shedding of CD27 during human hantavirus infection.Conclusion: Our findings demonstrate that thrombocytopenia and kidneydysfunction associate with distinctly different effects on the humoral immune system. Moreover, hantavirus-infectedindividuals have significantly elevated levels of extracellular ATP incirculation.
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| 2. |
- Tadala, Lalitha, et al.
(författare)
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Infection-induced membrane ruffling initiates danger and immune signaling via the mechanosensor PIEZO1
- 2022
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Ingår i: Cell Reports. - : Elsevier. - 2211-1247. ; 40:6
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Tidskriftsartikel (refereegranskat)abstract
- Microorganisms are generally sensed by receptors recognizing microbial molecules, which evoke changes in cellular activities and gene expression. Bacterial pathogens induce secretion of the danger signal ATP as an early alert response of intestinal epithelial cells, initiating overt inflammation. However, what triggers ATP secretion during infection is unclear. Here we show that the inherently mechanosensitive plasma membrane channel PIEZO1 acts as a sensor for bacterial entry. PIEZO1 is mechanically activated by invasion-induced membrane ruffles upstream of Ca2+ influx and ATP secretion. Mimicking mechanical stimuli of pathogen uptake with sterile beads equally elicits ATP secretion. Chemical or genetic PIEZO1 inactivation inhibits mechanically induced ATP secretion. Moreover, chemical or mechanical PIEZO1 activation evokes gene expression in immune and barrier pathways. Thus, mechanosensation of invasion-induced plasma membrane distortion initiates immune signaling upon infection, independently of detection of microbial molecules. Hence, PIEZO1-dependent detection of infection is driven by physical signals instead of chemical ligands.
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| 3. |
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| 4. |
- Tadala, Lalitha, 1991-
(författare)
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Role of extracellular ATP in immune mechanisms against infections
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inflammation is driven either by infection with pathogens or sterile stimuli, such as tissue damage or autoimmune diseases. Upon tissue damage, ATP is released passively from the dead or compromised cells. During stress, ATP can be secreted from the cells. Extracellular ATP (eATP) acts as an endogenous danger signal. An increase in eATP is sensed by cell surface purinergic receptors and regulates the onset and resolution of inflammation. Extracellular ATP is an important inflammatory mediator during sterile inflammation. On the other hand, the role of eATP is poorly studied during infection, both bacterial and viral. In this thesis, I present the molecular mechanisms underlying ATP secretion during bacterial infections and the role of eATP in human hantaviral infections.During infection with certain enteropathogenic Gram-negative bacteria, intestinal epithelial cells secrete ATP via connexin hemichannels as an alert signal to activate the immune system, which triggers acute inflammation in the gut. However, neither what triggers ATP secretion nor the molecular mechanisms of ATP secretion were known. Pharmacological, genetic, and microscopy-based evidence shows that during invasive bacterial infections, the plasma membrane ruffles act as mechanical immune stimuli and activate the inherently mechanosensitive plasma membrane channel PIEZO1. Mechanically activated PIEZO1 leads to the influx of Ca2+ ions and concurrent ATP secretion. In addition, PIEZO1 also activates protective transcriptional responses. Thus, PIEZO1 acts as a sensor for invasive infection using mechanical stimuli, unlike the so-far-described immune sensors of infection, which all recognize microbial components by chemical interaction.During human hantavirus infection, the humoral immune responses are poorly studied. Our collaborators found that atypical B cells, which do not have the surface marker CD27, show increased frequency in a cohort of hantavirus-infected patients. CD27 shedding in murine lymphocytes had been previously linked to eATP-dependent activation of a purinergic receptor7. To test whether ATP levels in the circulation of hantavirus-infected patients are elevated, an approach to perform same-day eATP quantifications in human plasma was developed. This assay was used to establish the normal eATP concentration in plasma in a cohort of healthy volunteers and to show that eATP levels are elevated in the acute and convalescent stages of hantavirus infection. Further, the addition of ATP to isolated human B cells recapitulated the observed CD27 shedding via a metallomatrix proteinase-8-dependent (MMP8) mechanism. Together, these projects provide evidence for the importance of eATP in bacterial and viral infectious diseases.
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