Comparative transcriptome analyses on terpenoids metabolism in field- and mountain-cultivated ginseng roots

Beyond genome: Advanced omics progress of Panax ginseng

Ginseng is a perennial herb of the genus Panax in the family Araliaceae as one of the most important traditional medicine. Genomic studies of ginseng assist in the systematic discovery of genes related to bioactive ginsenosides biosynthesis and resistance to stress, which are of great significance in the conservation of genetic resources and variety improvement. The transcriptome reflects the difference and consistency of gene expression, and transcriptomics studies of ginseng assist in screening ginseng differentially expressed genes to further explore the powerful gene source of ginseng. Protein is the ultimate bearer of ginseng life activities, and proteomic studies of ginseng assist in exploring the biosynthesis and regulation of secondary metabolites like ginsenosides and the molecular mechanism of ginseng adversity adaptation at the overall level. In this review, we summarize the current status of ginseng research in genomics, transcriptomics and proteomics, respectively. We also discuss and look forward to the development of ginseng genome allele mapping, ginseng spatiotemporal, single-cell transcriptome, as well as ginseng post-translational modification proteome. We hope that this review will contribute to the in-depth study of ginseng and provide a reference for future analysis of ginseng from a systems biology perspective.

The Integration of the Metabolome and Transcriptome for Dendrobium nobile Lindl. in Response to Methyl Jasmonate

Dendrobium nobile Lindl., as an endangered medicinal plant within the genus Dendrobium, is widely distributed in southwestern China and has important ecological and economic value. There are a variety of metabolites with pharmacological activity in D. nobile. The alkaloids and polysaccharides contained within D. nobile are very important active components, which mainly have antiviral, anti-tumor, and immunity improvement effects. However, the changes in the compounds and functional genes of D. nobile induced by methyl jasmonate (MeJA) are not clearly understood. In this study, the metabolome and transcriptome of D. nobile were analyzed after exposure to MeJA. A total of 377 differential metabolites were obtained through data analysis, of which 15 were related to polysaccharide pathways and 35 were related to terpenoids and alkaloids pathways. Additionally, the transcriptome sequencing results identified 3256 differentially expressed genes that were discovered in 11 groups. Compared with the control group, 1346 unigenes were differentially expressed in the samples treated with MeJA for 14 days (TF14). Moreover, the expression levels of differentially expressed genes were also significant at different growth and development stages. According to GO and KEGG annotations, 189 and 99 candidate genes were identified as being involved in terpenoid biosynthesis and polysaccharide biosynthesis, respectively. In addition, the co-expression analysis indicated that 238 and 313 transcription factors (TFs) may contribute to the regulation of terpenoid and polysaccharide biosynthesis, respectively. Through a heat map analysis, fourteen terpenoid synthetase genes, twenty-three cytochrome P450 oxidase genes, eight methyltransferase genes, and six aminotransferase genes were identified that may be related to dendrobine biosynthesis. Among them, one sesquiterpene synthase gene was found to be highly expressed after the treatment with MeJA and was positively correlated with the content of dendrobine. This study provides important and valuable metabolomics and transcriptomic information for the further understanding of D. nobile at the metabolic and molecular levels and provides candidate genes and possible intermediate compounds for the dendrobine biosynthesis pathway, which lays a certain foundation for further research on and application of Dendrobium.

Transcriptome analysis reveals that jasmonic acid biosynthesis and signaling is associated with the biosynthesis of asperosaponin VI in Dipsacus asperoides

Dipsacus asperoides is a perennial herb, the roots of which are abundant in asperosaponin VI, which has important medicinal value. However, the molecular mechanism underlying the biosynthesis of asperosaponin VI in D. asperoides remains unclear. In present study, a comprehensive investigation of asperosaponin VI biosynthesis was conducted at the levels of metabolite and transcript during root development. The content of asperosaponin VI was significantly accumulated in two-leaf stage roots, and the spatial distribution of asperosaponin VI was localized in the xylem. The concentration of asperosaponin VI gradually increased in the root with the development process. Transcriptome analysis revealed 3916 unique differentially expressed genes (DEGs) including 146 transcription factors (TFs) during root development in D. asperoides. In addition, α-linolenic acid metabolism, jasmonic acid (JA) biosynthesis, JA signal transduction, sesquiterpenoid and triterpenoid biosynthesis, and terpenoid backbone biosynthesis were prominently enriched. Furthermore, the concentration of JA gradually increased, and genes involved in α-linolenic acid metabolism, JA biosynthesis, and triterpenoid biosynthesis were up-regulated during root development. Moreover, the concentration of asperosaponin VI was increased following methyl jasmonate (MeJA) treatment by activating the expression of genes in the triterpenoid biosynthesis pathway, including acetyl-CoA acetyltransferase (DaAACT), 3-hydroxy-3-methylglutaryl coenzyme A synthase (DaHMGCS), 3-hydroxy-3-methylglutaryl coenzyme-A reductase (DaHMGCR). We speculate that JA biosynthesis and signaling regulates the expression of triterpenoid biosynthetic genes and facilitate the biosynthesis of asperosaponin VI. The results suggest a regulatory network wherein triterpenoids, JA, and TFs co-modulate the biosynthesis of asperosaponin VI in D. asperoides.

Investigation of the pharmacological effect and mechanism of mountain-cultivated ginseng and garden ginseng in cardiovascular diseases based on network pharmacology and zebrafish experiments

Ginseng (Panax ginseng C.A. Mey) is a kind of perennial herb of the Panax genus in the Araliaceae family. The secondary metabolites of mountain-cultivated ginseng (MCG) and garden ginseng (GG) vary greatly due to their different growth environments. To date, the differences in their pharmacological effects on cardiovascular diseases (CVDs) and their clinical applications remain unclear. To distinguish between the components of MCG and GG, ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) was performed. Next, the relationship between the expression of metabolites and the categories of the sample were analyzed using supervised partial least squares discriminant analysis and orthogonal partial least squares discriminant analysis. A network-based pharmacology approach was developed and applied to determine the underlying mechanism of different metabolites in CVD. In the present study, the role of MCG and GG in angiogenesis and their protective effects on damaged blood vessels in a vascular injury model of zebrafish were investigated. Using UPLC-Q-TOF/MS, 11 different metabolites between MCG and GG were identified. In addition, 149 common target genes associated with the metabolites and CVD were obtained; these targets were related to tumor protein P53, proto-oncogene tyrosine-protein kinase Src, human ubiquitin-52 amino acid fusion protein, ubiquitin-40S ribosomal protein S27a, polyubiquitin B, signal transducer and activator of transcription 3, isocitrate dehydrogenase 1, vascular endothelial growth factor A, glycose synthase kinase-3B, and coagulation factor II and were associated with the regulation of the phosphoinositide 3-kinase-Akt signaling pathway, the tumor necrosis factor signaling pathway, and the hypoxia-inducible factor-1 (HIF-1) signaling pathway, which play important roles in the curative effect in CVD treatment. Both types of ginseng can promote the growth of the subintestinal vessel plexus and protect injured intersegmental vessels through the HIF-1α/vascular endothelial growth factor signaling pathway in a dose-dependent manner. In addition, MCG has a stronger impact than GG. This is the first time metabolomics and network pharmacology methods were combined to study the difference between MCG and GG on CVDs, which provides a significant theoretical basis for the clinical treatment of CVD with two kinds of ginseng.

Integrated transcriptome and metabolome analyses revealed regulatory mechanisms of flavonoid biosynthesis in Radix Ardisia

Background

Radix Ardisia (Jab Bik Lik Jib) is a common Miao medicine and is widely distributed in the Guizhou region of southern China. The botanical origin of Radix Ardisia includes the dry root and rhizome of Ardisia Crenata Sims (ACS) or Ardisia Crispa (Thunb.) A.DC. (AC), which are closely related species morphologically. However, the secondary metabolites in their roots are different from one another, especially the flavonoids, and these differences have not been thoroughly explored at the molecular level. This project preliminarily identified regulatory molecular mechanisms in the biosynthetic pathways of the flavonoids between ACS and AC using a multi-omics association analysis.

Methods

In this study, we determined the total levels of saponin, flavonoid, and phenolic in Radix Ardisia from different origins. Integrated transcriptome and metabolome analyses were used to identify the differentially expressed genes (DEGs) and differentially expressed metabolites (DEM). We also performed conjoint analyses on DEGs and DEMs to ascertain the degree pathways, and explore the regulation of flavonoid biosynthesis.

Results

The total flavonoid and phenolic levels in ACS were significantly higher than in AC (P < 0.05). There were 17,685 DEGs between ACS vs. AC, 8,854 were upregulated and 8,831 were downregulated. Based on this, we continued to study the gene changes in the flavonoid biosynthesis pathway, and 100 DEGs involving flavonoid biosynthesis were differentially expressed in ACS and AC. We validated the accuracy of the RNA-seq data using qRT-PCR. Metabolomic analyses showed that 11 metabolites were involved in flavonoid biosynthesis including: Naringenin, Luteolin, Catechin, and Quercetin. A conjoint analysis of the genome-wide connection network revealed the differences in the types and levels of flavonoid compounds between ACS and AC. The correlation analysis showed that Naringenin, Luteolin, Catechin, and Quercetin were more likely to be key compounds in the flavonoid biosynthesis pathway also including 4CL, AOMT, CHS, CHI, DFR, F3'5'H, FLS, and LAR.

Conclusions

This study provides useful information for revealing the regulation of flavonoid biosynthesis and the regulatory relationship between metabolites and genes in the flavonoid biosynthesis pathway in Radix Ardisia from different origins.

Nanoemulsions prepared from mountain ginseng-mediated gold nanoparticles and silydianin increase the anti-inflammatory effects by regulating NF-κB and MAPK signaling pathways

In order to increase the bioavailability of mountain ginseng (MG), gold nanoparticles (MG-AuNPs) were biologically synthesized from MG extract, and an oil-in-water (O/W) nanoemulsion (SMG-AuNEs) was prepared from MG-AuNPs and a phytochemical silydianin. The physical stability of SMG-AuNEs were monitored and optimized in terms of particle size, pH value, zeta potential, and polydispersity index. The chemicostructural properties of the prepared MG-AuNPs and SMG-AuNEs were characterized using various spectrometric and microscopic analyses, such as EDX spectroscopy, FT-IR spectroscopy, and TEM. The effect of both nanomaterial samples on the anti-inflammatory activity and their underlying mechanism was compared in LPS-stimulated RAW 264.7 cells. SMG-AuNEs did not show toxic effects against RAW 264.7 macrophages, HaCaT keratinocytes, and normal dermal fibroblasts. SMG-AuNEs exhibited significantly higher inhibition of pro-inflammatory genes and proteins, including IL-1β, IL-6, and TNF-α, compared with those of MG-AuNPs and silydianin. Western blotting analysis revealed that the MAPK and NF-κB signalings were highly inhibited by SMG-AuNEs treatment. Hence, this study shows that nano-emulsification of gold nanoparticles prepared from MG is a useful method for augmenting the anti-inflammatory potential of MG. This study may serve as a foundation for using MG as a functional ingredient in anti-inflammatory agents. Our results may implicate the use of nanoemulsions to develop new anti-inflammatory products using MG.

Effects of growth years on ginsenoside biosynthesis of wild ginseng and cultivated ginseng

Background

Ginsenoside, as the main active substance in ginseng, has the function of treating various diseases. However, the ginsenosides content of cultivated ginseng is obviously affected by the growth years, but the molecular mechanism is not clear. In addition, there are significant differences in morphology and physiology between wild ginseng and cultivated ginseng, and the effect of growth years on ginsenoside synthesis not yet understood in wild ginseng.

Results

Transcriptome sequencing on the roots, stems and leaves of cultivated ginseng and wild ginseng with different growth years was performed in this study, exploring the effect of growth years on gene expression in ginseng. The number of differentially expressed genes (DEGs) from comparison groups in cultivated ginseng was higher than that in wild ginseng. The result of weighted gene co-expression network analysis (WGCNA) showed that growth years significantly affected the gene expression of Mitogen-activated protein kinases (MAPK) signaling pathway and terpenoid backbone biosynthesis pathway in cultivated ginseng, but had no effects in wild ginseng. Furthermore, the growth years had significant effects on the genes related to ginsenoside synthesis in cultivated ginseng, and the effects were different in the roots, stems and leaves. However, it had little influence on the expression of genes related to ginsenoside synthesis in wild ginseng. Growth years might affect the expression of genes for ginsenoside synthesis by influencing the expression of these transcription factors (TFs), like my elob lastosis (MYB), NAM, ATAF1 and 2, and CUC2 (NAC), APETALA2/ethylene-responsive factor (AP2/ERF), basic helix-loop-helix (bHLH) and WRKY, etc., thereby affecting the content of ginsenosides.

Conclusions

This study complemented the gaps in the genetic information of wild ginseng in different growth periods and helped to clarify the potential mechanisms of the effect of growth years on the physiological state in wild ginseng and cultivated ginseng, which also provided a new insight into the mechanism of ginsenoside regulation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08570-0.

Comparative transcriptome mining for terpenoid biosynthetic pathway genes in wild and cultivated species of Plantago

Plantagos are important economical and medicinal plants that possess several bioactive secondary metabolites, such as phenolics, iridoids, triterpenes, and alkaloids. Triterpenoids are the ubiquitous and dynamic secondary metabolites that are deployed by plants for chemical interactions and protection under biotic/abiotic stress. Plantago ovata, a cultivated species, is the source of psyllium, while Plantago major, a wild species, has significant therapeutic potential. Wild species are considered more tolerant to stressful conditions in comparison to their cultivated allies. In view of this, the present study aimed to decipher the terpenoid biosynthetic pathway operative in P. ovata and P. major using a comparative transcriptomics approach. Majority of terpenoid biosynthetic genes were observed as upregulated in P. major including rate limiting genes of MVA (HMGR) and MEP (DXR) pathways and genes (α-AS, BAS, SM, and CYP716) involved in ursolic acid biosynthesis, an important triterpenoid prevalent in Plantago species. The HPLC output further confirmed the higher concentration of ursolic acid in P. major as compared to P. ovata leaf samples, respectively. In addition to terpenoid biosynthesis, KEGG annotation revealed the involvement of differentially expressed unigenes in several metabolic pathways, aminoacyl-tRNA biosynthesis, biosynthesis of antibiotics, and biosynthesis of secondary metabolites. MYB was found as the most abundant transcription factor family in Plantago transcriptome. We have been able to generate valuable information which can help in improving terpenoid production in Plantago. Additionally, the present study has laid a strong foundation for deciphering other important metabolic pathways in Plantago.

LC-MS/MS targeting analysis of terpenoid metabolism in Carya cathayensis at different developmental stages

Terpenoid metabolism at different developmental stages of Carya cathayensis was elucidated based on LC-MS/MS analysis and multi-omics. Terpenoid metabolites 2-hydroxy-1,4-naphoquinone and 3-hydroxybenzoic acid reached the maximum at 105 days after pollination (DAP) (P2 stage). To reveal the complex mechanism of C. cathayensis embryogenesis in relation to terpenoid metabolites (90-165 DAP), a metabolomic and transcriptional co-expression analysis was conducted. Based on RNA-Seq analysis, 679 genes of 1144 terpenoid biosynthesis were differentially expressed. Six terpenoid metabolites and 86 differentially expressed genes related to terpenoquinone metabolism were identified. Comprehensive analysis of metabolome and transcriptional data revealed that terpenoquinone accumulated in the early phase was active in the later phase. Overall, we profiled the transcriptome and metabolome changes in C. cathayensis during the developmental phase to investigate the metabolic pathways and candidate genes underlying the changes at different growth stages.

Comparative transcriptome analysis of Alpinia oxyphylla Miq. reveals tissue-specific expression of flavonoid biosynthesis genes

BACKGROUND

Alpinia oxyphylla Miq. is an important edible and medicinal herb, and its dried fruits are widely used in traditional herbal medicine. Flavonoids are one of the main chemical compounds in A. oxyphylla; however, the genetic and molecular mechanisms of flavonoid biosynthesis are not well understood. We performed transcriptome analysis in the fruit, root, and leaf tissues of A. oxyphylla to delineate tissue-specific gene expression and metabolic pathways in this medicinal plant.

RESULTS

In all, 8.85, 10.10, 8.68, 6.89, and 8.51 Gb clean data were obtained for early-, middle-, and late-stage fruits, leaves, and roots, respectively. Furthermore, 50,401 unigenes were grouped into functional categories based on four databases, namely Nr (47,745 unigenes), Uniprot (49,685 unigenes), KOG (20,153 unigenes), and KEGG (27,285 unigenes). A total of 3110 differentially expressed genes (DEGs) and five distinct clusters with similar expression patterns were obtained, in which 27 unigenes encoded 13 key enzymes associated with flavonoid biosynthesis. In particular, 9 DEGs were significantly up-regulated in fruits, whereas expression of 11 DEGs were highly up-regulated in roots, compared with those in leaves.

CONCLUSION

The DEGs and metabolic pathway related to flavonoids biosynthesis were identified in root, leaf, and different stages of fruits from A. oxyphylla. These results provide insights into the molecular mechanism of flavonoid biosynthesis in A. oxyphylla and application of genetically engineered varieties of A. oxyphylla.

The dehiscence process in Panax ginseng seeds and the stigmasterol biosynthesis pathway in terms of metabolomics

Background

Ginseng, officially known as Panax ginseng Meyer, has been traditionally used as a medicinal herb, particularly in Asia. Ginseng is propagated from seeds; however, seed germination is challenging, especially in its natural environment on farms. The seeds typically exhibit morphophysiological dormancy and require release from both morphological and physiological dormancy before germination. Although some studies have proposed methods for increasing seed germination rates, the underlying mechanisms of its dormancy release process remain unclear. Here, we investigated metabolic alterations during dehiscence in P. ginseng to determine their potential roles in dormancy release.

Methods

We compared the ginseng seed metabolome before and after dehiscence and the ginsenoside and phytosterol compositions of the seeds in both periods in the presence of related enzymes.

Results

After seed dehiscence, the sugar, amino acid, and squalene concentrations were significantly altered, phytosterols associated with the stigmasterol biosynthesis pathway were increased, while ginsenoside and brassinosteroid levels were not significantly altered. In addition, squalene epoxidase, cycloartenol synthase, 24-methylenesterol C-methyltransferase, and the stigmasterol biosynthesis pathway were activated.

Conclusion

Overall, our findings suggest that morphological activities that facilitate ginseng seed growth are the primary phenomena occurring during the dehiscence process. This study improves the understanding of P. ginseng germination processes and promotes further research of its germination and cultivation.

Defensive functions of volatile organic compounds and essential oils from northern white-cedar in China

BACKGROUND

Plants are known to emit diverse volatile organic compounds (VOCs), which may function as signaling substances in plant communication with other organisms. Thuja occidentalis, which is widely cultivated throughout China, releases aromatic VOCs into the air in winter and early spring. The relationship of this cultivated plant with its neighboring plants is necessary for the conservation of biodiversity.

RESULTS

(-)-α-thujone (60.34 ± 5.58%) was found to be the major component in VOCs from the Shenyang population. The essential oils (EOs) from the Kunming and Shenyang populations included the major components (-)-α-thujone, fenchone, (+)-β-thujone, and (+)-hibaene, identified using GC-MS analyses. (-)-α-thujone and (+)-hibaene were purified and identified by NMR identification. EOs and (-)-α-thujone exhibited valuable phytotoxic activities against seed germination and seedling growth of the plants Taraxacum mongolicum and Arabidopsis thaliana. Moreover, the EOs displayed potent inhibitory activity against pathogenic fungi of maize, including Fusarium graminearum, Curvularia lunata, and Bipolaris maydis, as well as one human fungal pathogen, Candida albicans. Quantitative analyses revealed high concentrations of (-)-α-thujone in the leaves of T. occidentalis individuals from both the Shenyang and Kunming populations. However, (-)-α-thujone (0.18 ± 0.17 μg/g) was only detected in the rhizosphere soil to a distance of 0.5 m from the plant.

CONCLUSIONS

Taken together, our results suggest that the phytotoxic effects and antifungal activities of the EOs and (-)-α-thujone in T. occidentalis certainly increased the adaptability of this plant to the environment. Nevertheless, low concentrations of released (-)-α-thujone indicated that reasonable distance of T. occidentalis with other plant species will impair the effects of allelochemical of T. occidentalis.

Peptides as Potential Biomarkers for Authentication of Mountain-Cultivated Ginseng and Cultivated Ginseng of Different Ages Using UPLC-HRMS

The growth conditions and age of Panax ginseng are vital for determining the quality of the ginseng plant. However, the considerable difference in price according to the cultivation method and period of P. ginseng leads to its adulteration in the trade market. We herein focused on ginseng peptides and the possibility of these peptides to be used as biomarker(s) for discrimination of P. ginseng. We applied an ultraperformance liquid chromatography-high resolution mass spectrometry-based peptidomics approach to characterize ginseng peptides and discover novel peptide biomarkers for authentication of mountain-cultivated ginseng (MCG). We identified 52 high-confidence peptides and screened 20 characteristic peptides differentially expressed between MCG and cultivated ginseng (CG). Intriguingly, 6 differential peptides were expressed significantly in MCG and originated from dehydrins that accumulated during cold or drought conditions. In addition, 14 other differential peptides that were significantly expressed in CG derived from ginseng major protein, an essential protein for nitrogen storage. These biological associations confirmed the reliability and credibility of the differential peptides. Additionally, we determined several robust peptide biomarkers for discrimination of MCG through a precise selection process. These findings demonstrate the potential of peptide biomarkers for identification and quality control of P. ginseng in addition to ginsenoside analysis.

Optimization of flash extraction, separation of ginsenosides, identification by HPLC-FT-ICR-MS and determination of rare ginsenosides in mountain cultivated ginseng

In this paper, we used the flash extraction method (FEM) to extract ginsenosides from mountain cultivated ginseng (MCG), optimized the FEM process by response surface methodology (RSM), and separated 23 kinds of ginsenosides from MCG, including rare ginsenoside Rg₃, 20(R/S)-Rg₂, Rk₃, 20(S)-Rh₂, 20(R)-Rh₁, F₁ and Rg₆. Among them, notoginsenoside R₁ was isolated from MCG for the first time. Additionally, we established an HPLC-FT-ICR-MS method to accurately identify 20 ginsenosides in MCG, and quantitatively analyzed the differences in the content of rare ginsenosides in MCG and Garden-Cultivated Ginseng (CG) by HPLC-UV. The results showed that the chemical components of MCG and CG were similar, but the ginsenoside content of MCG was double that of CG. Notably, the content of ginsenoside 20 (S)-Rh₂ and 20 (R)-Rh₁ had the largest difference, and the content in MCG was 33 and 24 times higher than that in CG, respectively. Through quantitative analysis, we clarified the reason why the activity of MCG is stronger than that of CG, which provided a theoretical basis for clinical application and further research of MCG.

23 ginsenosides, including rare ginsenosides, were separated from MCG by flash extraction technique. Through quantitative analysis, we found that the content of rare ginsenosides in MCG was higher than that in CG.

Ginsenoside metabolite compound-K regulates macrophage function through inhibition of β-arrestin2

Ginsenoside metabolite compound-K (C-K), which is an active metabolite of ginsenoside in vivo, can produce anti-inflammatory affects by activating glucocorticoid receptors (GRs) to inhibit the expression of β-arrestin2. Studies have shown that C-K can inhibit the function of immune cells including macrophage polarization and phagocytosis. However, the mechanism by which C-K regulates macrophage polarization is currently unclear. Toll-like receptors (TLRs) are the pattern recognition receptors on the membrane of immune cells, with TLR4 being especially important in polarization of macrophages. The Gαi-mediated activation of nuclear factor-κB (NF-κB) by TLR4 promotes inflammation and phagocytosis in macrophages by increasing the proportion of type I phenotypic macrophages (M1). Whether C-K inhibits the signal transduction of TLR4-Gαi-NF-κB and how that effects macrophage polarization regulation in murine models of RA is not reported. The coupling of G proteins with receptors is regulated by β-arrestin2, but it has been unclear whether C-K modulates the TLR4 interaction with G proteins by inhibiting the expression of β-arrestin2. To explore these questions, the collagen-induced arthritis (CIA) mouse model was employed, and mice were treated with C-K (112 mg/kg/day). The results depict that C-K treatment inhibits macrophage phagocytosis and reduces the proportion of M1. C-K decreases the overexpressed β-arrestin2, Gαi, TLR4 and NF-κB in macrophages of CIA mice, while increasing the expression of Gαs. Furthermore, C-K promotes TLR4-Gαs coupling and inhibits TLR4-Gαi coupling through β-arrestin2 regulation in macrophages, leading to a decrease in the proportion of M1 to M2 macrophages and improved outcomes in CIA mice.