| 1. |
- Andersson, Henrik, et al.
(författare)
-
Apoptotic neutrophils augment the inflammatory response to Mycobacterium tuberculosis infection in human macrophages
- 2014
-
Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 9:7
-
Tidskriftsartikel (refereegranskat)abstract
- Macrophages in the lung are the primary cells being infected by Mycobacterium tuberculosis (Mtb) during the initial manifestation of tuberculosis. Since the adaptive immune response to Mtb is delayed, innate immune cells such as macrophages and neutrophils mount the early immune protection against this intracellular pathogen. Neutrophils are short-lived cells and removal of apoptotic cells by resident macrophages is a key event in the resolution of inflammation and tissue repair. Since anti-inflammatory activity is not compatible with effective immunity to intracellular pathogens, we therefore investigated how uptake of apoptotic neutrophils modulates the function of Mtb-activated human macrophages. We show that Mtb infection exerts a potent proinflammatory activation of human macrophages with enhanced gene activation and release of proinflammatory cytokines and that this response was augmented by apoptotic neutrophils. The enhanced macrophage response is linked to apoptotic neutrophil-driven activation of the NLRP3 inflammasome and subsequent IL-1β signalling. We also demonstrate that apoptotic neutrophils not only modulate the inflammatory response, but also enhance the capacity of infected macrophages to control intracellular growth of virulent Mtb. Taken together, these results suggest a novel role for apoptotic neutrophils in the modulation of the macrophage-dependent inflammatory response contributing to the early control of Mtb infection.
|
|
| 2. |
- Eklund, Daniel, 1984-, et al.
(författare)
-
Vitamin D enhances IL-1β secretion and restricts growth of Mycobacterium tuberculosis in macrophages from TB patients
- 2013
-
Ingår i: International journal of mycobacteriology. - Netherlands : Wolters Kluwer. - 2212-5531. ; 2:1, s. 18-25
-
Tidskriftsartikel (refereegranskat)abstract
- The emergence of multidrug-resistant strains of Mycobacterium tuberculosis (MTB), the bacterium responsible for tuberculosis (TB), has rekindled the interest in the role of nutritional supplementation of micronutrients, such as vitamin D, as adjuvant treatment. Here, the growth of virulent MTB in macrophages obtained from the peripheral blood of patients with and without TB was studied. The H37Rv strain genetically modified to express Vibrio harveyi luciferase was used to determine the growth of MTB by luminometry in the human monocyte-derived macrophages (hMDMs) from study subjects. Determination of cytokine levels in culture supernatants was performed using a flow cytometry-based bead array technique. No differences in intracellular growth of MTB were observed between the different study groups. However, stimulation with 100nM 1,25-dihydroxyvitamin D significantly enhanced the capacity of hMDMs isolated from TB patients to control the infection. This effect was not observed in hMDMs from the other groups. The interleukin (IL)-1β and IL-10 release by hMDMs was clearly increased upon stimulation with 1,25-dihydroxyvitamin D. Furthermore, the 1,25-dihydroxyvitamin D stimulation also led to elevated levels of TNF-α (tumor necrosis factor-alpha) and IL-12p40. It was concluded that vitamin D triggers an inflammatory response in human macrophages with enhanced secretion of cytokines, as well as enhancing the capacity of hMDMs from patients with active TB to restrict mycobacterial growth.
|
|
| 3. |
- Persson, Alexander, 1978-, et al.
(författare)
-
Apoptotic neutrophils activates the inflammatory response in macrophages –increased capacity to handle intracellular infection
-
Annan publikation (populärvet., debatt m.m.)abstract
- Inflammation is essential to eradicate invading pathogens but an uncontrolled inflammation may develop into chronic inflammation and extensive tissue destruction unable of effectively controlling infections. At the site of infection, macrophages are the major regulators of the inflammatory response through balanced release of pro- or anti-inflammatory cytokines and therefore a key cell in the resolution of inflammation. Neutrophils effectively phagocytose and kill pathogens but they are short-lived and removal of these dead cells by macrophages is a key event in the resolution of inflammation and tissue repair. However, down-regulation of the immune response by apoptotic cells would in the presence of pathogens be detrimental to the host. In contrast to resolution of inflammation, we show that in the presence of microbial stimuli, apoptotic neutrophils in fact exert a potent pro-inflammatory activation of macrophages. This augmentation of the pro-inflammatory response is dependent on uptake of the apoptotic cells by the macrophage. In addition to secretion of TNF-α, presence of apoptotic neutrophils enhanced the capacity of the stimulated macrophages to kill intracellular Mycobacterium tuberculosis. This presents a novel role for apoptotic neutrophils in the modulation of the macrophage-dependent inflammatory response, and control of intracellular infections.
|
|
| 4. |
- Persson, Alexander, et al.
(författare)
-
Induction of apoptosis in human neutrophils by Mycobacterium tuberculosis is dependent on mature bacterial lipoproteins
- 2009
-
Ingår i: Microbial Pathogenesis. - : Elsevier BV. - 0882-4010 .- 1096-1208. ; 47:3, s. 143-150
-
Tidskriftsartikel (refereegranskat)abstract
- Modulation of immune cell apoptosis is a key evasion strategy utilized by Mycobacterium tuberculosis (Mtb). To be able to multiply within macrophages, the bacterium delays apoptosis and down-regulates pro-inflammatory activation in these cells, whereas apoptosis is rapidly induced in the potently bactericidal neutrophils. Initial host-pathogen interactions between neutrophils and Mtb, subsequently leading to apoptosis, need to be investigated to understand the early features during Mtb infections. Opsonized Mtb were readily phagocytosed, and the immuno-mediated phagocytosis triggered early activation of anti-apoptotic Akt in the neutrophils but the bacteria still induced apoptosis to the same extent as non-phagocytosed Mtb. Mtb-induced apoptosis was strictly dependent on NADPH oxidase-generated reactive oxygen species, compounds shown to damage lysosomal granules. Despite this, we found no involvement of damaged azurophilic granules in Mtb-induced apoptosis in human neutrophils. Instead, the Mtb-induced apoptosis was p38 MAPK dependent and induced through the mitochondrial pathway. Moreover, Mtb deficient of mature lipoproteins lacked the determinants required for induction of neutrophil apoptosis. These results show that Mtb exert a strong intrinsic capacity to induce apoptosis in neutrophils that is capable of overcoming the anti-apoptotic signaling in the cell.
|
|
| 5. |
|
|
| 6. |
- Persson, Hans Lennart, et al.
(författare)
-
Alveolar macrophages from patients with tuberculosis exhibit reduced capacity of restricting growth of Mycobacterium tuberculosis: a pilot study of vitamin D stimulation in vitro
- 2013
-
Ingår i: Microbiology Discovery. - United Kingdom : Herbert Publications PVT LTD. - 2052-6180. ; 1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The role of vitamin D supplementation as adjuvant treatment of tuberculosis (TB) has lately attracted increasing interest. Our aim was to investigate the capacity of alveolar macrophages (AMs) from patients with or without exposure to TB to control intracellular growth of virulent Mycobacterium tuberculosis (Mtb). Methods: AMs were freshly harvested from the bronchoalveolar lavage fluid of 7 patients with a history of TB (4 patients with previous TB and 3 patients with current TB) and 4 non-TB subjects. The H37Rv strain, genetically modified to express Vibrio harveyi luciferase, was used to determine the growth of Mtb by luminometry in the AMs from study subjects. Cytokine levels in culture supernatants were determined using a flow cytometry-based bead array technique. Results: AMs from patients with a TB history were less efficient in restricting Mtb growth. Stimulation with 100 nM1, 25-dihydroxyvitamin D (1,25D3) did not significantly influence the capacity of AMs from any study subjects to control the infection. Out of the cytokines evaluated (TNF-α, IL-1β, IL-10 and IL-12p40) only TNF-α demonstrated detectable levels in culture supernatants, but did not respond to stimulation with 1,25D3. Conclusions: We conclude that AMs of TB-patients show reduced ability to control mycobacterial growth in vitro, and, that AMs in this pilot study do no respond to 1, 25D3-stimulation. The former observation supports the concept that innate immunity is crucial for the control of TB infection.
|
|
