Post-resolution macrophages shape long-term tissue immunity and integrity in a mouse model of pneumococcal pneumonia

Resolving inflammation is thought to return the affected tissue back to homoeostasis but recent evidence supports a non-linear model of resolution involving a phase of prolonged immune activity. Here we show that within days following resolution of Streptococcus pneumoniae-triggered lung inflammation, there is an influx of antigen specific lymphocytes with a memory and tissue-resident phenotype as well as macrophages bearing alveolar or interstitial phenotype. The transcriptome of these macrophages shows enrichment of genes associated with prostaglandin biosynthesis and genes that drive T cell chemotaxis and differentiation. Therapeutic depletion of post-resolution macrophages, inhibition of prostaglandin E2 (PGE2) synthesis or treatment with an EP4 antagonist, MF498, reduce numbers of lung CD4+/CD44+/CD62L+ and CD4+/CD44+/CD62L-/CD27+ T cells as well as their expression of the α-integrin, CD103. The T cells fail to reappear and reactivate upon secondary challenge for up to six weeks following primary infection. Concomitantly, EP4 antagonism through MF498 causes accumulation of lung macrophages and marked tissue fibrosis. Our study thus shows that PGE2 signalling, predominantly via EP4, plays an important role during the second wave of immune activity following resolution of inflammation. This secondary immune activation drives local tissue-resident T cell development while limiting tissue injur

A critical evaluation of the fish early-life stage toxicity test for engineered nanomaterials: experimental modifications and recommendations

There are concerns that regulatory toxicity tests are not fit for purpose for engineered nanomaterials (ENMs) or need modifications. The aim of the current study was to evaluate the OECD 210 fish, early-life stage toxicity test for use with TiO2 ENMs, Ag ENMs, and MWCNT. Both TiO2 ENMS (≤160 mg l(-1)) and MWCNT (≤10 mg l(-1)) showed limited acute toxicity, whilst Ag ENMs were acutely toxic to zebrafish, though less so than AgNO3 (6-day LC50 values of 58.6 and 5.0 µg l(-1), respectively). Evidence of delayed hatching, decreased body length and increased muscle width in the tail was seen in fish exposed to Ag ENMs. Oedema (swollen yolk sacs) was also seen in fish from both Ag treatments with, for example, mean yolk sac volumes of 17, 35 and 39 µm(3) for the control, 100 µg l(-1) Ag ENMs and 5 µg l(-1) AgNO3 treatments, respectively. Among the problems with the standard test guidelines was the inability to maintain the test solutions within ±20 % of nominal concentrations. Pronounced settling of the ENMs in some beakers also made it clear the fish were not being exposed to nominal concentrations. To overcome this, the exposure apparatus was modified with the addition of an exposure chamber that ensured mixing without damaging the delicate embryos/larvae. This allowed more homogeneous ENM exposures, signified by improved measured concentrations in the beakers (up to 85.7 and 88.1 % of the nominal concentrations from 10 mg l(-1) TiO2 and 50 µg l(-1) Ag ENM exposures, respectively) and reduced variance between measurements compared to the original method. The recommendations include: that the test is conducted using exposure chambers, the use of quantitative measurements for assessing hatching and morphometrics, and where there is increased sensitivity of larvae over embryos to conduct a shorter, larvae-only toxicity test with the ENMs

Wpływ warunków hodowli na parametry hematologiczne i podatność karpia na eksperymentalny stres manipulacyjny

The effects of rearing conditions on hematology and susceptibility of common carp to experimental manipulation stress. The aim of present study was to compare hematological values in pond-reared and hatchery-reared common carp, and their hematological alterations following experimental manipulation. Two groups of carp: pond, and hatchery-reared juveniles were subjected to experimental manipulation – transfer of each fi sh for three hours to separate, aerated but confi ning aquaria. Blood was sampled and hematological parameters were evaluated (erythrocyte and leukocyte counts, hemoglobin concentration, hematocrit, metabolic activity of phagocytes), and differential erythrocyte and leukocyte counts were calculated in the smears. Prior to stress, pond fi sh showed higher erythrocyte count and hemoglobin concentration, lower erythrocyte volume, and higher leukocyte count and phagocyte activity comparing to the hatchery fi sh. Reaction of both groups of fi sh to manipulation also differed. Pond fi sh showed erythrocyte swelling, and strong leukopenia (lymphopenia and neutropenia), and a decrease in phagocyte activity, while in hatchery fi sh increase in erythrocyte count and phagocyte activity took place. Rearing conditions signifi cantly affected hematological parameters of fi sh, pond-reared carp showing higher oxygen transport and immunological capacities comparing to the hatchery-reared ones. Pond fi sh showed also higher susceptibility to stress

Sezonowe zmiany parametrów hematologicznych u młodocianych karpi w warunkach laboratoryjnych

Annual changes in hematological parameters of common carp juveniles under laboratory conditions. The aim of the study was to evaluate the changes of the values of hematological parameters of carp juveniles in annual cycle under stable laboratory conditions. Some parameters showed distinct rhythms of changes, e.g. 2 peaks of hematocrit occurred in II and VIII, of hemoglobin concentration in I and VI, while erythrocyte count showed maximum in II. The largest erythrocytes were observed in VIII, and the smallest in XII. Leukocyte count showed two peaks in XII and III. Maximum lymphocyte frequency occurred in III and minimum in XI, while percentage of neutrophils showed the reverse pattern. Oxidative metabolic activity of phagocytes peaked in III, while minimum occurred in XI–XII and VI–VII. Thrombocyte count was highest in XII, and lowest in VII. The obtained results revealed that the values of hematological parameters in carp considerably changed during the year despite little alterations in environmental factors. Some of these changes, e.g. increase in oxidative activity of phagocytes in spring and increase in hemoglobin level in summer were similar to those that occur in fi sh under natural conditions. Another changes, such as increase in erythrocyte size or decrease in leukocyte count suggest long-term adjustment to the laboratory environment