Importance Of Phagocytosis Research Articles

Alantolactone Enhances the Phagocytic Properties of Human Macrophages and Modulates Their Proinflammatory Functions

Aim of the StudyPhagocytosis is a crucial element of innate immune defense involved in bacterial killing. The aim of our study was to evaluate the influence of alantolactone on phagocytosis and cytokines release by THP1-derived macrophages. We assessed whether antimicrobial compound alantolactone (a sesquiterpene lactone present in Inula helenium L.) is able to stimulate immune functions of macrophages by increase of S. aureus uptake, phagosome acidification and further stimulation of phago-lysosomes formation. Simultaneously, we tested influence of alantolactone on cytokines/chemokines production and p65 NF-κB concentration. The activity of alantolactone was compared with clarithromycin at concentration 20 µM.MethodsThe cytotoxicity of alantolactone as well as S. aureus uptake, pH of phagosomes and phago-lysosomes fusion were analysed with flow cytometry. Reactive oxygen species and superoxide production were evaluated spectrophotometrically. The efficiency of phagocytosis was evaluated via quantifying viable bacteria (CFU). The effect on p65 protein concentration and cytokine production by macrophages were measured by enzyme-linked immunosorbent assay (ELISA).ResultsAlantolactone enhanced phagocytosis via increase of S. aureus uptake, acidification of phagosomes, and later stimulation of phago-lysosomes fusion. Alantolactone treatment resulted in ROS and superoxide production decrease. Furthermore, alantolactone inhibited production of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 as well as decreased p65 concentration, the subunit responsible for NF-κB activation and cytokine production and simultaneously stimulated release of anti-inflammatory mediators (IL-10 and TGF-β).ConclusionResults of our study indicate that alantolactone enhances clearance of S. aureus, and simultaneously modulates immune response, preventing collateral damage of the surrounding tissues. Considering the importance of phagocytosis in the pathogen killing, alantolactone may have a great potential as the supportive treatment of S. aureus infections. Further in vivo studies are warranted to confirm this hypothesis.

Abstract 9: Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) deficiency Attenuates Phagocytic Activities of Microglia and Exacerbates Ischemic Damage in Experimental Stroke

Clearing cellular debris after brain injury represents an important mechanism to re-attain tissue homeostasis and promote functional recovery. Triggering receptor expressed by myeloid cells-2 (TREM2) is involved in the innate immune system, and carries out surveillance functions by binding and phagocytosing pathogens. TREM2 is expressed on macrophages and microglia, and promotes the phagocytosis of apoptotic brain cells. Deficiency of functional TREM2 leads to accelerated dementia, and mutations in the TREM2 gene have been linked to Alzheimer’s. Here we explore the significance of TREM2 in a in-vitro and in-vivo stroke model. Cultures of neurons and microglia were subjected to OGD. TREM2-knockout (KO) and wildtype (WT) mice were subjected to permanent distal middle cerebral artery occlusion ischemic model. TREM2 knockdown in microglia by siRNA led to decreased transformation to an amoeboid morphology following co-culture and OGD exposure, but no effect on overall neuron death. OGD-exposed and nuclear lysates from neurons led to TREM2 signaling. In vivo, phagocytosis and infarcted brain tissue resorption was observed in wild-type mice by 14d, but no phagocytosis and little infarcted brain resorption was seen in TREM2 KO mice (p < 0.01)(Fig). TREM2 KO mice also had worsened neurological recovery (p < 0.05), and decreased viable brain tissue in the ipsilateral hemisphere. Numbers of activated microglia and macrophages in KO mice were decreased compared to WT, and oil red staining to identify foamy macrophages was nearly absent in the KO brains. These findings establish the relevance of TREM2 in phagocytosis of the infarcted brain and emphasize the importance of phagocytosis in neurological outcome following experimental stroke.

Nutrient limitation of bacterioplankton, autotrophic and mixotrophic phytoplankton, and heterotrophic nanoflagellates in Lake Örträsket

Enrichment experiments with P and N were conducted in humic Lake Örträsket in northern Sweden. The composition of the microplankton community showed a dominance by bacterioplankton, followed by mixotrophic and potentially mixotrophic phytoplankton, heterotrophic nanoflagellates, and autotrophic phytoplankton. Bacterioplankton was P limited for most of the ice‐free period, and phytoplankton biomass and primary production mostly increased after enrichment with N, but not with P. The dominant group of phytoplankton, the mixotrophic flagellates, was stimulated by N but not by P, while obligate autotrophic species were stimulated only by P+N. It is suggested that N limitation in mixotrophic species is induced by grazing of P‐rich bacteria. The results suggest that primary productivity in humic lakes can be limited by N and indicate the importance of phagocytosis as a means of nutrition in phytoplankton. A link is suggested to exist in humic lakes whereby heterotrophic bacterioplankton, which use humic compounds as their principal energy source, can transfer energy and nutrients to potentially autotrophic organisms, with subsequent utilization by other components of the food web.

The Erwin Neter Memorial Lecture: looking to the future of medical laboratory immunology, a personal view.

The Erwin Neter Memorial Lecture: looking to the future of medical laboratory immunology, a personal view.

Welding fumes and chromium compounds in cell transformation assays

Fumes generated from mild steel and stainless steel welding were collected on paper filters and tested in the BHK and SHE cell transformation assays. Fumes from the manual metal arc welding of stainless steel (MMA/SS) had a toxic and transforming effect attributable to their Cr(VI) content. The fumes from metal inert gas stainless steel (MIG/SS) welding also had a toxic effect but this was 2-3 times greater than that expected from their soluble Cr(VI) content based on the activity of soluble Cr(VI) from pure chromium compounds. When collected in an impinger, the fumes from MIG/SS were found to contain approximately 10 times the soluble Cr(VI) content of samples collected on filters. This additional Cr(VI), when collected in a water impinger, also exhibited a greater toxicity compared with that found for the additional Cr(VI) collected in an impinger filled with growth medium. This comparison implies the presence of a short-lived biologically active Cr(VI) species usually lost in conventional sampling techniques. It also implies that there is a detoxification step associated with the formation of Cr(VI) organic complexes. Relatively insoluble Cr(VI) compounds showed a higher toxic and transforming effect in the BHK assay than could be ascribed to the soluble Cr(VI) content of the medium, indicating the importance of phagocytosis as a pathway for the uptake of Cr(VI) and other toxic substances from particulates.

The production of immunity to vaccinia virus by mixtures of immune serum and virus and the importance of phagocytosis in antivaccinial immunity

The production of immunity to vaccinia virus by mixtures of immune serum and virus and the importance of phagocytosis in antivaccinial immunity