Dendritic cells (DCs) play crucial roles in the pathogenesis of rheumatoid arthritis (RA), a prototypic autoimmune disease characterized by chronic synovitis and joint destruction. Conventional ...dendritic cells (cDCs) with professional antigen-presenting functions are enriched in the RA synovium. In the synovium, the cDCs are activated and show both enhanced migratory capacities and T cell activation in comparison with peripheral blood cDCs. Plasmacytoid dendritic cells, another subtype of DCs capable of type I interferon production, are likely to be tolerogenic in RA. Monocyte-derived dendritic cells (moDCs), once called "inflammatory DCs", are localized in the RA synovium, and they induce T-helper 17 cell expansion and enhanced proinflammatory cytokine production. Recent studies revealed that synovial proinflammatory hypoxic environments are linked to metabolic reprogramming. Activation of cDCs in the RA synovium is accompanied by enhanced glycolysis and anabolism. In sharp contrast, promoting catabolism can induce tolerogenic DCs from monocytes. Herein, we review recent studies that address the roles of DCs and their immunometabolic features in RA. Immunometabolism of DCs could be a potential therapeutic target in RA.
The factors controlling the relative contributions of ammonia- (NH3) oxidizing archaea (AOA) and bacteria (AOB) to nitrification and nitrous oxide (N2O) production in soil remain unclear. A study was ...conducted to examine the contributions of AOA and AOB to nitrification, nitrite (NO2−) accumulation, and NO2−-affected N2O production in three non-cropped Oregon soils. Nitrification potential rates in the three soils ranged seven-fold from 0.15 to 1.08 μmol N g−1 d−1, with AOA contributing 64–71% of the total activity. AOA- and AOB-driven NO2− accumulation represented 8–100% of total NO2− + NO3− accumulation, persisted over 48 h, and was accompanied by acetylene-sensitive, ammonium- (NH4+) stimulated N2O production. Ammonium- and NO2−-dependent N2O production occurred when both AOA and AOB, or AOA alone were active. By adding the NO2−-oxidizing bacteria, Nitrobacter vulgaris, to soil slurries to increase NO2−-oxidizing capacity, both NO2− accumulation and N2O production were prevented, while the overall rate of nitrification was unaffected. Yields of N2O-N amounted to 0.05 ± 0.01% of total NO2− + NO3−-N accumulation in the presence of supplemental NH4+, and 0.28 ± 0.11% in the presence of both supplemental NH4+ + NO2−. Regression analysis of the N2O production against NO2− accumulation over 24 h revealed a positive, non-linear relationship for N2O production by both AOA plus AOB and by AOA alone. Values of Vmax ranged 12-fold from 0.05 to 0.62 nmol N2O g−1 d−1, and predicted Km values for NO2− ranged 15-fold from 0.02 to 0.30 μmol NO2− g−1 soil. These findings provide new insights into the impact of NO2− accumulation in soils on N2O production by both AOA and AOB, and show that NO2− accumulation primarily drives N2O formation in these soils, and increases N2O yield by both AOA and AOB.
•Soil AOA- and AOB-driven NO2− accumulation represented 8-100% of total nitrification.•Both AOA- and AOB-driven N2O production were dependent on NO2− accumulation.•Enhancing soil NO2- oxidizing capacity prevents NO2− accumulation and N2O production.•AOA- and AOB-driven N2O yields were influenced by NO2− concentration.•Kinetic parameters were determined for N2O production by AOA and AOB.
An increase in available nitrogen loading in intertidal ecosystems causes eutrophication and macroalgae blooms. Denitrification and anaerobic ammonium oxidation (anammox) lead to the removal of ...bioavailable nitrogen, but few studies have examined this in intertidal sediments. The sediment anammox and denitrification rates in September 2015 and November 2016 were measured using a ¹⁵N tracer technique at two sites, with and without macroalgae, in the hypereutrophic Yatsu tidal flat, eastern Japan. At both sites, the rate of N₂ production via anammox was consistently low compared with that via denitrification, accounting for < 7% of the total N₂ production. In a fed-batch incubation experiment, the anammox rate increased in the surface sediment after 3 months. However, the contribution of anammox to nitrogen removal did not exceed that of denitrification, suggesting that denitrification is the major pathway for conversion of inorganic nitrogen to N₂, and that anammox plays a limited role in nitrogen removal in the Yatsu tidal flat. Denitrification activity measured from August 2012 to January 2017 using the acetylene block method was higher in the sediment with macroalgae than that without. Multiple linear regression analysis revealed that denitrification in the sediment with macroalgae was limited by the nitrogen substrate, likely due to competition with macroalgae for nitrogen. Temperature and H₂S production under macroalgae cover might also affect denitrification. In comparison, the organic carbon content was a key factor regulating heterotrophic denitrification in the sediment without macroalgae. These findings suggest that the occurrence of macroalgae changes the progress of denitrification in intertidal ecosystems.
Pulmonary hypertension (PH) is a serious condition in which there is an abnormally high pressure in the pulmonary arteries that can occur as a complication of connective tissue diseases. Although the ...relationship between PH and systemic lupus erythematosus or systemic sclerosis has been well-characterized, PH rarely occurs in patients with anti-synthetase syndrome (ASS), and little is known about the pathophysiology and clinical outcome of patients with ASS-PH. We herein report a patient with anti-Jo-1-positive ASS complicated by PH and discuss the treatment strategy through a review of previously reported cases.
In southern China, high levels of atmospheric nitrogen (N) are being deposited in forests. Soil acidification and high rates of soil nitrification and subsequent NO3− leaching have been observed in ...the N-saturated forests. We previously did not detect NH3-oxidizing bacteria in non-N-saturated or N-saturated forest soils. However, NH3-oxidizing archaea were present in both soils, more in the saturated ones. The purpose of this study was to investigate the roles of autotrophic NH3-oxidizing archaea and heterotrophic nitrifiers in soil N transformations in N-saturated and non-N-saturated forests in southern China. We investigated the contribution of heterotrophic nitrifiers in the soils by determining the gross nitrification rates with and without an inhibitor of autotrophic nitrification, acetylene (C2H2). We also reevaluated nitrification by NH3-oxidizing archaea by correlating the C2H2-inhibited gross nitrification rates with the abundance of the amoA transcripts of NH3-oxidizing archaea. We further measured the gross NH4+ production rates and analyzed the community composition of the NH3-oxidizing archaea. The results suggest that NH3-oxidizing archaea, rather than heterotrophic nitrifiers and NH3-oxidizing bacteria, are responsible for the nitrification in the N-saturated forest soils. NH3-oxidizing archaea in the soils could be acidophilic, having low amoA diversity, indicating their strong adaptation to the highly acidified soils. The gross NH4+ production rate did not differ between N-saturated and non-N-saturated forests; however, the gross nitrification rate was higher in N-saturated forests. Consequently, the high abundance and NH3 oxidation activity of NH3-oxidizing archaea caused the high rates of nitrification and subsequent leaching of NO3− in the N-saturated forest. This study suggests that acidophilic NH3-oxidizing archaea have a great impact on soil N cycling in N-saturated forests.
•NH3-oxidizing archaea are responsible for nitrification in N-saturated forest soils.•NH3-oxidizing archaea have low amoA diversity and appear to be acidophilic.•Highly abundant NH3-oxidizing archaea causes high rates of nitrification and leaching of NO3−.
Anaerobic ammonium-oxidizing (anammox) bacteria produce dinitrogen gas from nitrite and ammonium under anoxic conditions and significantly contribute nitrogen removal processes in marine ...environments. Distribution and activity of anammox bacteria in a marine water column have been well studied in some oxygen deficient waters such as Black Sea, Arabian Sea, Namibian upwelling and Peruvian upwelling systems. However, the habitable area of anammox bacteria in the Pacific Ocean is still an open question. Here, we report distribution, abundance and phylogeny of anammox bacteria in the water column along the north-south transect (40⁰S to 55⁰N, 170⁰W) of the Pacific Ocean in order to determine their habitable area in the open ocean. Anammox bacteria-specific 16S rRNA gene was detected at 10 locations mostly from oxygen minimum depths (OMD) where dissolved oxygen (DO) concentration ranged from 10.9 to 46.2 µmol Kg-1. Their abundance measured by qPCR ranged from 3.69 ± 1.35 × 102 copies L-1 to 474 ± 15 × 102 copies L-1. The phylogenetic analysis showed that anammox bacteria detected in this study were all related to Candidatus Scalindua species and clustered into three subgroups: the Scalindua brodae/sorokinii cluster, the sediment cluster and the Arabian Sea cluster. Relationship between the abundance of anammox bacteria and DO concentration varied among these 3 clusters, suggesting their difference in oxygen sensitivity. Although rate measurement of anammox reaction using 15N-labeled substrates failed for all OMD samples tested during the cruise, this study unveiled the distribution of anammox bacteria in the open ocean oxygen minimum zone (OMZ) where oxygen deficiency is not extreme but moderate, which provides an insight into the potential distribution of anammox bacteria in marine environments.
Ammonia-oxidizing bacteria (AOB) within the genus Nitrosomonas perform the first step in nitrification, ammonia oxidation, and are found in diverse aquatic and terrestrial environments. Nitrosomonas ...AOB were grouped into six defined clusters, which correlate with physiological characteristics that contribute to adaptations to a variety of abiotic environmental factors. A fundamental physiological trait differentiating Nitrosomonas AOB is the adaptation to either low (cluster 6a) or high (cluster 7) ammonium concentrations. Here, we present physiological growth studies and genome analysis of Nitrosomonas cluster 6a and 7 AOB. Cluster 6a AOB displayed maximum growth rates at ≤ 1 mM ammonium, while cluster 7 AOB had maximum growth rates at ≥ 5 mM ammonium. In addition, cluster 7 AOB were more tolerant of high initial ammonium and nitrite concentrations than cluster 6a AOB. Cluster 6a AOB were completely inhibited by an initial nitrite concentration of 5 mM. Genomic comparisons were used to link genomic traits to observed physiological adaptations. Cluster 7 AOB encode a suite of genes related to nitrogen oxide detoxification and multiple terminal oxidases, which are absent in cluster 6a AOB. Cluster 6a AOB possess two distinct forms of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO) and select species encode genes for hydrogen or urea utilization. Several, but not all, cluster 6a AOB can utilize urea as a source of ammonium. Hence, although Nitrosomonas cluster 6a and 7 AOB have the capacity to fulfill the same functional role in microbial communities, i.e., ammonia oxidation, differentiating species-specific and cluster-conserved adaptations is crucial in understanding how AOB community succession can affect overall ecosystem function.
In temperate forest ecosystems, accelerated freeze–thaw cycles caused by winter climate change are expected to affect nitrogen (N) cycling in soils. Net N mineralization and nitrification rates were ...investigated via incubations of sieved soils transplanted from ten temperate forest ecosystems to two northern Japan sites with natural snowfall gradients. This was done to address: 1) how freeze–thaw cycles affect N mineralization and nitrification in temperate forest soils; 2) whether freeze–thaw cycles change the soil N transformation rates in the following growing season; and 3) which soil characteristics affect the response of the N transformation rates to freeze–thaw cycles. The effect of freeze–thaw cycles on inorganic N and dissolved organic carbon productions differed among soils, that is, some soils produced more inorganic N and dissolved organic carbon in the conditions imposed by freeze thaw cycles than in the non-frozen treatment but the others did not. The response to the freeze–thaw cycles was explained by soil microbial activity (gross N mineralization and nitrification rate) and soil fertility (inorganic N pools in the early spring and water soluble ions). Freeze–thaw cycles significantly increased N transformation rates in the following growing season, suggesting that winter climate change might also affect nutrient availability for vegetation and soil microbes in the growing season. The magnitude and frequency of freeze–thaw cycles were considered to be important indicators of N transformation rates during the growing season, suggesting that the higher intensity of freeze–thaw cycles in the original locations of soils changed the microbial communities and functions with high tolerance to freeze–thaw cycles; this resulted in greater N transformation rates in the following growing season. Microbial activity, soil fertility and climate patterns in the original locations of soils are believed to have an effect on the response to winter climate change and to cause large variability of soil response of N transformation rates to freeze–thaw cycles in both the dormant and growing seasons.
•Freeze–thaw effects were studied for ten soils using a natural snowfall gradient.•The effect of FTC on N mineralization differed among soils in the dormant season.•Nitrification and mineralization increased during the growing season after FTC.•The differences in the response to FTC among soils was explained by soil characteristics.
Abstract
Nitrification has been believed to be performed only by autotrophic ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) until the recent discovery of ammonia-oxidizing ...archaea (AOA). Meanwhile, it has been questioned whether AOB are significantly responsible for NH3 oxidation in acidic forest soils. Here, we investigated nitrifying communities and their activity in highly acidified soils of three subtropical forests in southern China that had received chronic high atmospheric N deposition. Nitrifying communities were analyzed using PCR- and culture (most probable number)-based approaches. Nitrification activity was analyzed by measuring gross soil nitrification rates using a 15N isotope dilution technique. AOB were not detected in the three forest soils: neither via PCR of 16S rRNA and ammonia monooxygenase (amoA) genes nor via culture-based approaches. In contrast, an extraordinary abundance of the putative archaeal amoA was detected (3.2 × 108–1.2 × 109 g soil−1). Moreover, this abundance was correlated with gross soil nitrification rates. This indicates that amoA-possessing archaea rather than bacteria were predominantly responsible for nitrification of the soils. Furthermore, sequences of the genus Nitrospira, a dominant group of soil NOB, were detected. Thus, nitrification of acidified subtropical forest soils in southern China could be performed by a combination of AOA and NOB.
To elucidate the effect of macroalgae blooms on dissimilatory nitrate reduction pathways (denitrification, anammox, and DNRA) in sediments of the hypereutrophic Yatsu tidal flat, eastern Japan, ...sediment denitrification, anammox, and DNRA rates were measured using a 15N tracer technique at two sites affected and unaffected by macroalgae (Ulva) blooms and in incubation experiments with and without Ulva. Anammox was insignificant at both sites and in both experiments. The denitrification rate was consistently higher than the DNRA rate, and its contributions to the total dissimilatory nitrate reduction were 82% and 85% at sites affected and unaffected by Ulva, respectively. In a sediment incubation experiment with Ulva, the contribution of DNRA had increased to approximately 30% on day 7, which is when the sulfide concentration was the highest. Sulfide produced by sulfate reduction during macroalgae blooms inhibited denitrification and did not change the DNRA, and consequently increased the DNRA contribution. On day 21, after reaching the peak sulfide concentration during the late macroalgae collapse, the DNRA contribution decreased to 15%. These results indicated that the DNRA contribution was greater during the macroalgae blooms than at the collapse, although denitrification dominated DNRA regardless of the macroalgal status. Therefore, vigorous macroalgae cover and sulfide production under the macroalgae cover had an important impact on the nitrogen dynamics.
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