Group 2 innate lymphoid cells in lung inflammation

Although allergic asthma is a heterogeneous disease, allergen‐specific T helper 2 (Th2) cells producing the key cytokines involved in type 2 inflammation, interleukin‐4 (IL‐4), IL‐5 and IL‐13, are thought to play a major role in asthma pathogenesis. This model is challenged by the recent discovery of group 2 innate lymphoid cells (ILC2) that represent a critical innate source of type 2 cytokines. These ILC2 are activated by epithelial cell‐derived cytokines, including IL‐25 and IL‐33, which have been implicated in the initiation of asthma. In this review, we will discuss recent studies supporting a significant role for ILC2 in lung inflammation, with special attention to allergen‐induced asthma.     

Postoperative changes in collagen synthesis in intestinal anastomoses of the rat: differences between small and large bowel.

Collagen synthesis is an essential feature of anastomotic healing in the intestine. Postoperative collagen synthesis, measured in vitro in intestinal anastomoses was studied from three hours to 28 days after operation. For this purpose, an ileal and a colonic anastomosis were constructed within the same animal and the results in both intestinal segments were compared. In the ileum, collagen synthesis was significantly increased, with respect to unoperated controls, three hours after operation. It remained raised during the period of study, with a maximal 10-fold stimulation four days after operation, and had nearly returned to the preoperative level after four weeks. The general pattern was the same in the colon, although quantitatively different: the increase in synthetic activity was delayed in comparison with the ileum. Maximal stimulation was approximately six-fold. In addition, we calculated the ratio for each rat between anastomotic collagen synthesis and the average value found in non-operated control animals. Postoperative stimulation in the ileum was higher than in the colon in almost every animal examined. The results show that the ileum responds more quickly and strongly to wounding than the colon, at least as far as the production of new collagen is concerned. Possibly, this phenomenon contributes to the lower failure rate apparent for anastomoses in the small bowel.     

Impact of age-associated increase in 2′-O-methylation of miRNAs on aging and neurodegeneration in Drosophila

MicroRNAs (miRNAs) are 20- to ∼24-nucleotide (nt) small RNAs that impact a variety of biological processes, from development to age-associated events. To study the role of miRNAs in aging, studies have profiled the levels of miRNAs with time. However, evidence suggests that miRNAs show heterogeneity in length and sequence in different biological contexts. Here, by examining the expression pattern of miRNAs by Northern blot analysis, we found that Drosophila miRNAs show distinct isoform pattern changes with age. Surprisingly, an increase of some miRNAs reflects increased 2′-O-methylation of select isoforms. Small RNA deep sequencing revealed a global increase of miRNAs loaded into Ago2, but not into Ago1, with age. Our data suggest increased loading of miRNAs into Ago2, but not Ago1, with age, indicating a mechanism for differential loading of miRNAs with age between Ago1 and Ago2. Mutations in Hen1 and Ago2, which lack 2′-O-methylation of miRNAs, result in accelerated neurodegeneration and shorter life span, suggesting a potential impact of the age-associated increase of 2′-O-methylation of small RNAs on age-associated processes. Our study highlights that miRNA 2′-O-methylation at the 3′ end is modulated by differential partitioning of miRNAs between Ago1 and Ago2 with age and that this process, along with other functions of Ago2, might impact age-associated events in Drosophila.     

Museum specimens reveal loss of pollen host plants as key factor driving wild bee decline in The Netherlands

Evidence for declining populations of both wild and managed bees has raised concern about a potential global pollination crisis. Strategies to mitigate bee loss generally aim to enhance floral resources. However, we do not really know whether loss of preferred floral resources is the key driver of bee decline because accurate assessment of host plant preferences is difficult, particularly for species that have become rare. Here we examine whether population trends of wild bees in The Netherlands can be explained by trends in host plants, and how this relates to other factors such as climate change. We determined host plant preference of bee species using pollen loads on specimens in entomological collections that were collected before the onset of their decline, and used atlas data to quantify population trends of bee species and their host plants. We show that decline of preferred host plant species was one of two main factors associated with bee decline. Bee body size, the other main factor, was negatively related to population trend, which, because larger bee species have larger pollen requirements than smaller species, may also point toward food limitation as a key factor driving wild bee loss. Diet breadth and other potential factors such as length of flight period or climate change sensitivity were not important in explaining twentieth century bee population trends. These results highlight the species-specific nature of wild bee decline and indicate that mitigation strategies will only be effective if they target the specific host plants of declining species.Pollinating insects such as bees play an essential role in the pollination of wild plants (1) and crops (2). However, reported population declines in both wild and managed bees (3–5) have raised concerns about loss of pollination services and triggered interest in identifying the underlying causes for bee decline (6). Land use change and agricultural intensification are major drivers of biodiversity loss in general (7, 8) and are considered the most important environmental drivers of loss of wild bee diversity in particular (6, 9). It is generally believed that these drivers affect bees, which depend on floral resources in both their larval and adult life stages, through repercussions on the availability of floral resources in contemporary anthropogenic landscapes (9–11), but, so far, scientific evidence that loss of floral resources is driving bee decline is lacking. Nevertheless, current strategies to mitigate bee decline focus primarily on enhancing floral resources (12). To prioritize and develop effective mitigation strategies, it is essential to identify the mechanisms underlying bee population trends and assess whether these are mediated by floral resources.Although bees as a group are declining, individual species show more variable responses, with some species declining sharply while others remain stable or even increase under current land use change and agricultural intensification (3, 4, 13). These differential responses can be used to disentangle the effects of floral resource availability from those of other potential factors affecting bee population trends. The proportion of the floral resources in contemporary anthropogenic landscapes that can be used for forage by a bee species depends on its diet breadth and host plant preference, and it may be expected that species that have declined have a narrower diet breadth and prefer host plants that have declined (14, 15). However, diet breadth and host plant preference of bee species is difficult to assess. Presently observed host plant use does not necessarily reflect actual preference, as preferred host plants may have gone locally extinct and bees that have declined may have become restricted in their food choice in their remaining habitats (15). In addition, if host plant use is measured for more individuals of abundant, widespread species than for rare ones, an apparent link between diet breadth and population trend may simply arise as a sampling artifact (16). Furthermore, the relationship between host plant use and population trend may be confounded by species’ rarity prior to the onset of major environmental changes (17), as rarity in itself increases susceptibility to stochastic events (18) and has been shown to be one of the most important factors predicting population decline in various taxa (19–21). Surprisingly, to our knowledge, none of the studies that have so far examined the relationship between diet breadth and/or host plant preference and bee population trends have taken species’ initial rarity into account (e.g., refs. 3, 4, 15, and 22). Other factors, such as body size (4, 23), phenology (4, 22), and sensitivity to climate change (4, 24, 25) may be associated with bee decline as well, and, to date, the relative importance of diet breadth and pollen host plant preference in explaining bee population trends remains unclear.Here we solve this problem by analyzing historical pollen preferences of wild bees (15). Bees are generally more selective in their choice of food plants when foraging for pollen (source of protein and minerals for both larvae and adults) than nectar (source of energy) (26, 27). Distributional changes in plant species from which pollen is collected therefore probably exerts a larger influence on bee populations than changes in nectar plants. We investigate whether and to what extent loss of preferred floral resources drives bee population trends in The Netherlands, one of the most human-modified and intensively farmed countries in the world. Over the course of the twentieth century, agriculture has intensified in The Netherlands (Fig. S1) and the area of seminatural habitat preferred by bees has diminished to only one-fifth of the area at the beginning of the twentieth century (Fig. S2). More than half of the bee species are currently on the national Red List (28). As such, this country is a particularly suitable study area to identify critical factors associated with bee population decline.We assessed pollen host plant use of bee species independently from their population trends by analyzing pollen loads on the bodies of bee specimens that were collected before 1950 (15), before the onset of agricultural intensification in The Netherlands. Altogether, our analysis included trend and trait data of 57 bee species in 10 genera and 4 subfamilies (Table S1). We calculated population trend indices for bee species and their host plants (period 1902–1949 vs. 1975–1999) using extensive national species distribution datasets (13, 29). Linear mixed models, with bee subfamily as a random factor to account for phylogeny, and a multimodel inference approach were used to examine the relationship between bee population trends and pollen host plant use, simultaneously taking into account differences in species’ rarity before the onset of agricultural intensification and other factors that have been proposed to explain bee population trends.     

Long-Term Results after Video-Assisted Thoracic Surgery for Spontaneous Pneumothorax

Objective: Analysis of the long-term results of video-assisted thoracic surgery (VATS) for spontaneous pneumothorax in patients treated in two surgical centres from May 1994 until December 2000.

Methods: A cohort of 86 patients was studied retrospectively. For final analysis, 74 patients undergoing 76 VATS procedures were included.

Results: Sixty-three procedures for primary spontaneous pneumothorax (PSP) and 13 procedures for secondary spontaneous pneumothorax (SSP) were performed. In 78.9% (n = 60) blebs or bullae were resected with an endostapler device. In 2.6% (n = 2) an apical fibrotic zone was resected. In 71.1% (n = 54) a subtotal pleurectomy was performed combined with an abrasion in 41 cases. In 21.1% (n = 16) a total pleurectomy and in 7.8% (n = 6) an abrasion was performed. Operative mortality was 1.3% (n = 1) and total operative morbidity 25.4% in the PSP group and 76.9% in the SSP group. Mean follow-up was 36 months. The global recurrence rate was 5.3% (n = 4), being 4.8% (n = 3) in the PSP group and 7.7% (n = 1) in the SSP group. Recurrences occurred at 1 (n = 2), 2 (n = 1) and 16 (n = 1) months after the initial operation. The incidence of postoperative neuralgia was 17.1% (n = 13). One patient needed analgesics for the neuralgia.

Conclusion: VATS treatment of spontaneous pneumothorax proves to be effective. In cases of SSP, VATS treatment is feasible but a higher morbidity rate should be anticipated.     

Systemic CD4+ and CD8+ T-cell cytokine profiles correlate with GOLD stage in stable COPD

Chronic obstructive pulmonary disease (COPD) is associated with pulmonary and systemic inflammation. Both CD4+ and CD8+ T-lymphocytes play a key role in COPD pathogenesis, but cytokine profiles in circulating T-lymphocytes have not been well characterised. Here we report the analysis of peripheral blood T-cells from 30 stable COPD patients and 10 healthy never-smokers for interferon (IFN)-γ, interleukin (IL)-4, tumour necrosis factor (TNF)-α and the T-helper 17 cytokines IL-17A, IL-17F and IL-22 by intracellular flow cytometry. We found significantly increased proportions of IFN-γ+ and TNF-α+ CD8+ T-cells in COPD patients, when compared with healthy controls. This was most evident in patients with less severe disease. In contrast, expression profiles in circulating CD4+ T-cells were similar in COPD patients and healthy controls for all cytokines tested, except for IL-17F. COPD patients with more severely reduced diffusing capacity had lower proportions of IL-17A+ CD4+ T-cells. Proportions of IL-22+ cells in the CD4+ memory T-cell population were significantly increased in active smokers, when compared with past smokers. Collectively, this comprehensive cytokine analysis of circulating T-cells in COPD patients revealed a correlation for CD8+ T-cells between Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage and IFN-γ or TNF-α expression, but not for CD4+ T-cells.