Potential Role of Astragaloside IV in the Treatment of Fungal Keratitis

Xiaoshuo Zheng¹, Wenfei Lian², Yang Liu¹

¹Department of Ophthalmology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China.
²Department of Urology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China.

DOI: 10.4236/abb.2022.135012                

Abstract

Fungal keratitis (FK) is a worldwide visual impairment disease. The pathogenesis of fungal keratitis involves fungi, corneal cells, inflammatory cell infiltration, collagen degradation, inflammatory cytokines and their interactions. Accumulated evidence indicated that Astragaloside IV (AS-IV) possesses a broad range of pharmacological properties, such as efficacy in anti-inflammation, alleviating fibrosis, and immunomodulatory effects. This paper summarizes new findings regarding AS-IV in immune and inflammatory diseases and analyzes the perspective application of Astragaloside IV in fungal keratitis.

Keywords

Astragaloside IV, Inflammatory, Immune, Collagen Degradation, Fungal Keratitis

1. Introduction

The cornea acts as a barrier to protect the eyes from external attacks including microbial pathogens. Fungal Keratitis may cause corneal immune inflammation, usually leading to corneal melting and scarring, and severe visual impairment. Antifungal therapy is not effective for some fungal strains, which can cause fungal endophthalmitis and blindness [1] [2] [3] [4]. In addition, apart from fungicide, there is no drug to inhibit the degradation of corneal collagen and inflammation in the treatment of fungal keratitis.

At least three different pathways are involved in the development of fungal keratitis: 1) The recognition of infectious agents by the Toll-like receptor (TLR) system initiates the primary innate immune response and later the adaptive immune response [5] [6]; 2) Degradation of collagen fibers by Matrix Metallo proteins (MMPs) synthesized and secreted by corneal cells (including corneal epithelial cells and corneal stromal fibroblasts) and infiltrating inflammatory cells [7]; 3) Toxic effects of fungal toxins on corneal cells and direct degradation of collagen fibers. New drugs are needed to treat fungi infections which can regulate the function of corneal cells and suppress immune inflammation [8] [9].

Astragalus membranaceus (Fisch) Bge (Huang-Qi) is a well-known herbal medicine with tonic property and has been widely used to treat cancer and other immune disorders in China and Southeast Asia for thousands of years [10]. Astragaloside IV (AS-IV) is considered to be the major bioactive ingredients of Astragalus species. AS-IV initiates the innate and adaptive immune systems by modulating multiple aspects involved in inflammatory process to generate its anti-inflammatory and immunomodulatory effects. As an anti-inflammatory and immunomodulatory agent, the potential role of AS-IV in FK therapy needs to be investigated.

2. Method of Literature Search

Papers and abstracts of relevant studies for this review were obtained from the MEDLINE database. The following search words (inclusive MESH headings) were used: fungal keratitis and TLR, Astragaloside and TLR, fungal keratitis and MMP, Astragaloside and MMP, fungal keratitis and cytokine, Astragaloside and cytokine, fungal keratitis and IL, Astragaloside and IL, fungal keratitis and TNF, Astragaloside and TNF. The search covered publications from 1985 to 2021, and articles published in English.

3. Astragaloside IV and TLR Signaling Pathway

Toll-like receptor (TLR) is a type of transmembrane receptor that acts as the “eye” of primary innate immunity, monitoring and recognizing various pathogen-related molecules, and acting as a bridge between primary innate immunity and adaptive immune response, plays an important role in the identification and defense of pathogens and their products. The expression of TLR2 and TLR4 is significantly increased in fungal infected corneas [11] [12]. Blocking TLR can reduce the corneal inflammation [13]. Aspergillus can up-regulate the expression of TLR2 and TLR4, and increase the production of IL-1 and IL-6 [14]. Anti-TLR2 or anti-TLR4 antibody can inhibit the production of IL-10 by corneal epithelial cells induced by aspergillus [15]. Therefore, TLR and its signal pathway can be used as a target to study the development of fungicide and to research fungal corneal infection in the immune inflammation mechanism.

AS-IV can downregulate TLR4/NF-kappaB signaling pathway and inhibits myocardial cell apoptosis and protected myocardial cells [16] [17] [18]. On memory impairment induced by transient cerebral ischemia and reperfusion in mice, AS-IV significantly reduces the expression of TLR4 and its downstream adaptor proteins and subsequently inhibits NF-kappaB phosphorylation [19]. In Lung Tissue, AS-IV significantly attenuates the level of TLR4 and inhibits neutrophil infiltration and activation in lung tissue [20] [21], and similar results were seen in the heart, aorta, kidney and liver [20]. In the unilateral ureteral obstruction (UUO) model mouse, AS-IV significantly reduces the Pro-inflammatory cytokines and lps-induced epithelial cells, and at the same time, TLR4 and NF-kappaB, CyrillicB signaling pathway are also inhibited in vivo and in vitro [22]. In recent studies, As-IV has a similar effect on the reproductive system. Administration with As-IV restrains the high expression of TLR-4 in a rat preeclampsia-like model [23] and in macrophages co-cultured with ovarian cancer cells [24]. In addition, AS-IV can also promote the proliferation of bone marrow mesenchymal stem cells (MSCs) and inhibit the increased expression of TLR4 induced by high glucose [25].

4. Astragaloside IV and Matrix Metalloproteinase

Research has shown that Matrix metalloproteinase (MMPS) are enzymes that play an important role in the development of corneal ulcers. Excessive degradation of collagen fibers in corneal stroma leads to corneal ulcer. Matrix metalloproteinase-1 (MMP-1) is mainly responsible for the degradation of type I collagen fibers. The degradation of type I collagen fibers by MMP-2 and-9 occurs after type I collagen fibers are lysed by MMP-1 and subsequent denaturation of three-dimensional collagen chains [26]. MMP-2 can degrade the basement membrane of epithelial cells and promote the development of corneal ulcer [27]. The expression of MMP-2 and MMP-9 were significantly increased in fungal infected corneas [28] [29]. Thus, inhibition of MMPS production and action during fungal corneal infection may inhibit the progression of corneal ulcers.

AS-IV could markedly reverse the UVA irradiation-induced increase of MMP-1 release in fibroblasts, which prevents collagen reduction and increases dermal thickness in photoaging skin [30] [31] [32] [33]. AS-IV inhibits platelet-derived growth factor (PDGF)-BB-stimulated vascular smooth muscle cells (VSMCs) proliferation and migration and inhibits the up-regulation of MMP-2 [34]. The up-regulations of MMP-9 which are related to cerebral vasogenic edema or cytotoxic edema can be inhibited significantly by AS-IV administration [35]. AS-IV can also suppress the expression of MMP-13 in osteoarthritispatients-derived chondrocytes [36]. Besides, AS-IV could regulate the expression of MMP-2, reduce the formation of collagen fibers, which plays an important role in hepatic fibrosis [37].

AS-IV has also been found to play a role in tumor research. AS-IV reduces MMP and inhibits PC12 cell apoptosis induced by oxidative injury [38]. The migration and invasion characteristics that are related to inflammatory response play important roles in the development of lung cancer. Xudong Cheng’s study suggests that AS-IV can significantly decrease the levels of MMP-2, MMP-9 and suppress the migration and invasion ability of A549 cells [39]. Similar findings have been reported in breast cancer, glioma, vulvar squamous cell carcinoma (VSCC), ovarian cancer [24] [40] [41] [42].

In particular, in 2021 Ramesh Babu Kasetti published an AS-IV article on ocular disease, and the study showed the antifibrotic effects of AS-IV are mediated via inhibition of NF-kappaB and modulation of MMPs [43]. This findings may encourage more ophthalmologists to join AS-IV studies related to ophthalmic diseases.

5. Astragaloside IV and Inflammatory Cytokines

Among inflammatory cytokines, interleukin (IL) plays an important role in the formation of corneal ulcer. The expression of IL in the corneas of fungal infection was significantly increased [44]. Our previous work has demonstrated that IL-1 stimulates the production of MMP-1, -2, -3 and-9 in corneal stromal fibroblasts and promotes the degradation of corneal collagen [45].

Under the stimulation of inflammatory cytokines, corneal epithelial cells and corneal stromal fibroblasts can produce various inflammatory cytokines, chemokines and adhesion factors, which can promote the aggregation of neutrophil and aggravate the inflammatory reaction of cornea [46] [47].

AS-IV inhibits the production of IL, TNF-α and NO in macrophages and Microglia [48] [49] [50] [51]. In LPS-induced acute kidney injury, AS-IV reduces the production of TNF-α and IL-6 in Plasma and activates the ERK Signal Pathway [52].

In addition, there are many experimental studies have confirmed AS-IV inhibits the production of inflammatory cytokines (including IL-1, IL-6, IL-8, IL-10 and TNF-α, etc) in the heart, lungs, brain, ovary, placenta, necrotizing enterocolitis, arthritis and so on [17] [19] [20] [21] [23] [24] [36] [53] [54] [55] [56].

6. Conclusion

Fungal keratitis is very stubborn. In addition to antifungal therapy, developing drugs which can inhibit the degradation of corneal collagen and immune inflammation is needed to prevent the development of ulcers. Toll-like receptor (TLR) plays a key role in innate immune responses in corneal infection. Corneal collagen fibrils serve as the basal component of the corneal stroma, the degradation of corneal collagen by MMPs activated by cytokines and chemokines may lead to the corneal ulcer. Therefore, inhibition of immune inflammation associated with TLR, MMPS and cytokine, and thus reducing the degradation of corneal collagen is considered a potential target for treatment of the corneal ulcer [57] [58]. This review shows that AS-IV can affect TLR signal path, MMPs and the expression of inflammatory cytokines in the heart, lungs, brain, liver, kidneys, ovaries, skin and other organs. AS-IV has definite immunomodulatory and anti-inflammatory effects, which have potential value in the treatment of fungal keratitis to inhibit the degradation of corneal collagen and suppress the immune inflammation.

Acknowledgements

Foundations: Supported by Guangdong Provincial Bureau of traditional Chinese medicine (project No.: 20191073; applicant: Zheng Xiao-shuo).

Conflicts of Interest

The authors declare no conflicts of interest regarding the publication of this paper.

References

[1]	Leal Jr., S.M. and Pearlman, E. (2012) The Role of Cytokines and Pathogen Recognition Molecules in Fungal Keratitis—Insights from Human Disease and Animal Models. Cytokine, 58, 107-111. https://doi.org/10.1016/j.cyto.2011.12.022
[2]	FlorCruz, N.V., Peczon, I.V. and Evans, J.R. (2012) Medical Interventions for Fungal Keratitis. Cochrane Database of Systematic Reviews, 2, CD004241. https://doi.org/10.1002/14651858.CD004241.pub3
[3]	Chhablani, J. (2011) Fungal Endophthalmitis. Expert Review of Anti-Infective Therapy, 9, 1191-1201. https://doi.org/10.1586/eri.11.139
[4]	Kawakami, H., Inuzuka, H., Mochizuki, K., Takahashi, N., Muto, T., Ohkusu, K., Yaguchi, T. and Nishimura, K. (2012) Clinical Manifestations, Treatment and Outcome of Ocular Infections Caused by Paecilomyces Species. Journal of Japanese Ophthalmological Society, 116, 613-622.
[5]	Lin, Z. and Xie, X. (2010) The Delayed Response of Toll-Like Receptors May Relate to Pseudomonas aeruginosa Keratitis Exacerbating Rapidly at the Early Stages of Infection. European Journal of Clinical Microbiology & Infectious Diseases, 29, 231-238. https://doi.org/10.1007/s10096-014-2222-8
[6]	Zhang, H., Chen, H., Niu, J., Wang, Y. and Xie, L. (2009) Role of Adaptive Immunity in the Pathogenesis of Candida albicans Keratitis. Investigative Ophthalmology & Visual Science, 50, 2653-2659. https://doi.org/10.1167/iovs.08-3104
[7]	Nagano, T., Hao, J., Nakamura, M., et al. (2001) Stimulatory Effect of Pseudomonal Elastase on Collagen Degradation by Cultured Keratocytes. Investigative Ophthalmology & Visual Science, 42, 1247-1253.
[8]	Guarro, J. (2011) Lessons from Animal Studies for the Treatment of Invasive Human Infections Due to Uncommon Fungi. Journal of Antimicrobial Chemotherapy, 66, 1447-1466. https://doi.org/10.1093/jac/dkr143
[9]	Pereira Gonzales, F. and Maisch, T. (2012) Photodynamic Inactivation for Controlling Candida albicans Infections. Fungal Biology, 116, 1-10. https://doi.org/10.1016/j.funbio.2011.10.001
[10]	Qi, Y., Gao, F., Hou, L. and Wan, C. (2017) Anti-Inflammatory and Immunostimulatory Activities of Astragalosides. The American Journal of Chinese Medicine, 45, 1157-1167. https://doi.org/10.1142/S0192415X1750063X
[11]	Yuan, X., Mitchell, B. and Wilhelmus, K. (2009) Expression of Matrix Metalloproteinases during Experimental Candida albicans Keratitis. Investigative Ophthalmology & Visual Science, 50, 737-742. https://doi.org/10.1167/iovs.08-2390
[12]	Jie, Z., Wu, X. and Yu, F. (2009) Activation of Toll-Like Receptors 2 and 4 in Aspergillus fumigatus Keratitis. Innate Immunity, 15, 155-168. https://doi.org/10.1177/1753425908101521
[13]	Sun, Y. and Pearlman, E. (2009) Inhibition of Corneal Inflammation by the TLR4 Antagonist Eritoran tetrasodium (E5564). Investigative Ophthalmology & Visual Science, 50, 1247-1254. https://doi.org/10.1167/iovs.08-2628
[14]	Guo, H. and Wu, X. (2009) Innate Responses of Corneal Epithelial Cells against Aspergillus fumigatus Challenge. FEMS Immunology and Medical Microbiology, 56, 88-93. https://doi.org/10.1111/j.1574-695X.2009.00551.x
[15]	Nishida, T., Ueda, A., Fukuda, M., Mishima, H., Yasumoto, K. and Otori, T. (1988) Interactions of Extracellular Collagen and Corneal Fibroblasts: Morphologic and Biochemical Changes of Rabbit Corneal Cells Cultured in a Collagen Matrix. In Vitro Cellular & Developmental Biology, 24, 1009-1014. https://doi.org/10.1007/BF02620874
[16]	Yang, J., Wang, H.X. and Zhang, Y.J. (2013) Astragaloside IV Attenuates Inflammatory Cytokines by Inhibiting TLR4/NF-Small Ka, CyrillicB Signaling Pathway in Isoproterenol-Induced Myocardial Hypertrophy. Journal of Ethnopharmacology, 150, 1062-1070. https://doi.org/10.1016/j.jep.2013.10.017
[17]	Lu, M., Tang, F. and Zhang, J. (2015) Astragaloside IV Attenuates Injury Caused by Myocardial Ischemia/Reperfusion in Rats via Regulation of Toll-Like Receptor 4/Nuclear Factor-κB Signaling Pathway. Phytotherapy Research, 29, 599-606. https://doi.org/10.1002/ptr.5297
[18]	Zhao, Y., Liu, Z. and Zhang, H. (2018) Astragaloside Protects Myocardial Cells from Apoptosis through Suppression of the TLR4/NF-κB Signaling Pathway. Experimental and Therapeutic Medicine, 15, 1505-1509. https://doi.org/10.3892/etm.2017.5535
[19]	Li, M., Li, H. and Fang, F. (2017) Astragaloside IV Attenuates Cognitive Impairments Induced by Transient Cerebral Ischemia and Reperfusion in Mice via Anti-Inflammatory Mechanisms. Neuroscience Letters, 639, 114-119. https://doi.org/10.1016/j.neulet.2016.12.046
[20]	Zhang, W.J. and Frei, B. (2015) Astragaloside IV Inhibits NF-κB Activation and Inflammatory Gene Expression in LPS-Treated Mice. Mediators of Inflammation, 2015, Article ID: 274314. https://doi.org/10.1155/2015/274314
[21]	Zhang, L.Y., Yi, P.F. and Guo, X. (2016) Astragaloside IV Inhibits the Inflammatory Injury of Chicken Type II Pneumocytes Induced by Avian Pathogenic Escherichia coli. Inflammation, 39, 1660-1669. https://doi.org/10.1007/s10753-016-0400-9
[22]	Zhou, X., Sun, X. and Gong, X. (2017) Astragaloside IV from Astragalus membranaceus Ameliorates Renal Interstitial Fibrosis by Inhibiting Inflammation via TLR4/NF-κB in Vivo and in Vitro. International Immunopharmacology, 42, 18-24. https://doi.org/10.1016/j.intimp.2016.11.006
[23]	Tuerxun, D., Aierken, R. and Zhang, Y.M. (2021) Astragaloside IV Alleviates Lipopolysaccharide-Induced Preeclampsia-Like Phenotypes via Suppressing the Inflammatory Responses. The Kaohsiung Journal of Medical Sciences, 37, 236-244. https://doi.org/10.1002/kjm2.12313
[24]	Wang, X., Gao, S. and Song, L. (2021) Astragaloside IV Antagonizes M2 Phenotype Macrophage Polarization-Evoked Ovarian Cancer Cell Malignant Progression by Suppressing the HMGB1-TLR4 Axis. Molecular Immunology, 130, 113-121. https://doi.org/10.1016/j.molimm.2020.11.014
[25]	Li, M., Yu, L. and She, T. (2012) Astragaloside IV Attenuates Toll-Like Receptor 4 Expression via NF-κB Pathway under High Glucose Condition in Mesenchymal Stem Cells. European Journal of Pharmacology, 696, 203-209. https://doi.org/10.1016/j.ejphar.2012.09.033
[26]	Kim, H., Shang, T., Chen, Z., Pflugfelder, S. and Li, D. (2004) TGF-β1 Stimulates Production of Gelatinase (MMP-9), Collagenases (MMP-1, -13) and Stromelysins (MMP-3, -10, -11) by Human Corneal Epithelial Cells. Experimental Eye Research, 79, 263-274. https://doi.org/10.1016/j.exer.2004.05.003
[27]	Fini, M.E., Girard, M.T. and Matsubara, M. (1992) Collagenolytic/Gelatinolytic Enzymes in Corneal Wound Healing. Acta Ophthalmologica, 70, 26-33. https://doi.org/10.1111/j.1755-3768.1992.tb02165.x
[28]	Mitchell, B., Wu, T., Chong, E., Pate, J. and Wilhelmus, K. (2007) Expression of Matrix Metalloproteinases 2 and 9 in Experimental Corneal Injury and Fungal Keratitis. Cornea, 26, 589-593. https://doi.org/10.1097/ICO.0b013e318033b504
[29]	Boveland, S., Moore, P., Mysore, J., et al. (2010) Immunohistochemical Study of Matrix Metalloproteinases-2 and -9, Macrophage Inflammatory Protein-2 and Tissue Inhibitors of Matrix Metalloproteinases-1 and -2 in Normal, Purulonecrotic and Fungal Infected Equine Corneas. Veterinary Ophthalmology, 13, 81-90. https://doi.org/10.1111/j.1463-5224.2009.00757.x
[30]	Yang, B., Ji, C. and Chen, X. (2011) Protective Effect of Astragaloside IV against Matrix Metalloproteinase-1 Expression in Ultraviolet-Irradiated Human Dermal Fibroblasts. Archives of Pharmacal Research, 34, 1553-1560. https://doi.org/10.1007/s12272-011-0918-1
[31]	Liu, X. and Min, W. (2011) Protective Effects of Astragaloside against Ultraviolet A-Induced Photoaging in Human Fibroblasts. Journal of Chinese Integrative Medicine, 9, 328-332. https://doi.org/10.3736/jcim20110315
[32]	Chen, B., Li, R. and Yan, N. (2015) Astragaloside IV Controls Collagen Reduction in Photoaging Skin by Improving Transforming Growth Factor-β/Smad Signaling Suppression and Inhibiting Matrix Metalloproteinase-1. Molecular Medicine Reports, 11, 3344-3348. https://doi.org/10.3892/mmr.2015.3212
[33]	Niu, Y., Chen, Y. and Xu, H. (2020) Astragaloside IV Promotes Antiphotoaging by Enhancing the Proliferation and Paracrine Activity of Adipose-Derived Stem Cells. Stem Cells and Development, 29, 1285-1293. https://doi.org/10.1089/scd.2020.0092
[34]	Chen, Z., Cai, Y. and Zhang, W. (2014) Astragaloside IV Inhibits Platelet-Derived Growth Factor-BB-Stimulated Proliferation and Migration of Vascular Smooth Muscle Cells via the Inhibition of p38 MAPK Signaling. Experimental and Therapeutic Medicine, 8, 1253-1258. https://doi.org/10.3892/etm.2014.1905
[35]	Li, M., Ma, R.N. and Li, L.H. (2013) Astragaloside IV Reduces Cerebral Edema Post-Ischemia/Reperfusion Correlating the Suppression of MMP-9 and AQP4. European Journal of Pharmacology, 715, 189-195. https://doi.org/10.1016/j.ejphar.2013.05.022
[36]	Li, H., Peng, Y. and Wang, X. (2019) Astragaloside Inhibits IL-1β-Induced Inflammatory Response in Human Osteoarthritis Chondrocytes and Ameliorates the Progression of Osteoarthritis in Mice. Immunopharmacology and Immunotoxicology, 41, 497-503. https://doi.org/10.1080/08923973.2019.1637890
[37]	Yuan, X., Gong, Z. and Wang, B. (2018) Astragaloside Inhibits Hepatic Fibrosis by Modulation of TGF-β1/Smad Signaling Pathway. Evidence-Based Complementary and Alternative Medicine, 2018, Article ID: 3231647. https://doi.org/10.1155/2018/3231647
[38]	Huang, X.P., Liu, X.D. and Deng, C.Q. (2012) Effects of the Combination of Active Component Extracts from Astragalus membranaceus and Panax notoginseng on Apoptosis, Reactive Oxygen Species and Mitochondrial Membrane Potential of PC12 Cells with Oxidative Injury. Journal of Chinese Integrative Medicine, 10, 1127-1134. https://doi.org/10.3736/jcim20121009
[39]	Cheng, X., Gu, J. and Zhang, M. (2014) Astragaloside IV Inhibits Migration and Invasion in Human Lung Cancer A549 Cells via Regulating PKC-α-ERK1/2-NF-κB Pathway. International Immunopharmacology, 23, 304-313. https://doi.org/10.1016/j.intimp.2014.08.027
[40]	Jiang, K., Lu, Q. and Li, Q. (2017) Astragaloside IV Inhibits Breast Cancer Cell Invasion by Suppressing Vav3 Mediated Rac1/MAPK Signaling. International Immunopharmacology, 42, 195-202. https://doi.org/10.1016/j.intimp.2016.10.001
[41]	Li, B., Wang, F. and Liu, N. (2017) Astragaloside IV Inhibits Progression of Glioma via Blocking MAPK/ERK Signaling Pathway. Biochemical and Biophysical Research Communications, 491, 98-103. https://doi.org/10.1016/j.bbrc.2017.07.052
[42]	Zhao, Y.Y. and Zhang, H.Y. (2021) Astragaloside IV Inhibits Cell Invasion and Metastasis in Vulvar Squamous Cell Carcinoma through the TGF-β1/FAK/AKT Signaling Pathway. Ginekologia Polska, 93, 179-184. https://doi.org/10.5603/GP.a2021.0113
[43]	Kasetti, R.B., Maddineni, P. and Kodati, B. (2021) Astragaloside IV Attenuates Ocular Hypertension in a Mouse Model of TGFβ2 Induced Primary Open Angle Glaucoma. International Journal of Molecular Sciences, 22, Article No. 12508. https://doi.org/10.3390/ijms222212508
[44]	Leema, G., Muralidharan, A.R., Annadurai, T., Kaliamurthy, J., Geraldine, P. and Thomas, P. (2013) Oxidative Stress in Experimental Rodent Corneas Infected with Aflatoxigenic and Onaflatoxigenic Aspergillus flavus. Cornea, 32, 867-874. https://doi.org/10.1097/ICO.0b013e3182867d87
[45]	Lu, Y., Fukuda, K. and Liu, Y. (2004) Dexamethasone Inhibition of IL-1-Induced Collagen Degradation by Corneal Fibroblasts in Three-Dimensional Culture. Investigative Ophthalmology & Visual Science, 45, 2998-3004. https://doi.org/10.1167/iovs.04-0051
[46]	Kumagai, N., Fukuda, K., Fujitsu, Y., Lu, Y., Chikamoto, N. and Nishida, T. (2005) Lipopolysaccharide-Induced Expression of Intercellular Adhesion Molecule-1 and Chemokines in Cultured Human Corneal Fibroblasts. Investigative Ophthalmology & Visual Science, 46, 114-120. https://doi.org/10.1167/iovs.04-0922
[47]	Li, D., Zhou, N., Zhang, L., Ma, P. and Pflugfelder, S. (2010) Suppressive Effects of Azithromycin on Zymosan-Induced Production of Proinflammatory Mediators by Human Corneal Epithelial Cells. Investigative Ophthalmology & Visual Science, 51, 5623-5629. https://doi.org/10.1167/iovs.09-4992
[48]	Xu, H., You, C., Zhang, R., Gao, P. and Wang, Z. (2007) Effects of Astragalus Polysaccharides and Astragalosides on the Phagocytosis of Mycobacterium Tuberculosis by Macrophages. The Journal of International Medical Research, 35, 84-90. https://doi.org/10.1177/147323000703500108
[49]	Wang, B. and Chen, M.Z. (2014) Astragaloside IV Possesses Antiarthritic Effect by Preventing Interleukin 1β-Induced Joint Inflammation and Cartilage Damage. Archives of Pharmacal Research, 37, 793-802. https://doi.org/10.1007/s12272-014-0336-2
[50]	Li, C., Yang, F., Liu, F., Li, D. and Yang, T. (2018) NRF2/HO-1 Activation via ERK Pathway Involved in the Anti-Neuroinflammatory Effect of Astragaloside IV in LPS Induced Microglial Cells. Neuroscience Letters, 666, 104-110. https://doi.org/10.1016/j.neulet.2017.12.039
[51]	He, Y.X., Shi, H.L. and Liu, H.S. (2015) Astragaloside IV Regulates STAT1/IκB/NF-κB Signaling Pathway to Inhibit Activation of BV-2 Cells. China Journal of Chinese Materia Medica, 40, 124-128.
[52]	Zhou, W., Chen, Y. and Zhang, X. (2017) Astragaloside IV Alleviates Lipopolysaccharide-Induced Acute Kidney Injury Through Down-Regulating Cytokines, CCR5 and p-ERK, and Elevating Anti-Oxidative Ability. Medical Science Monitor, 23, 1413-1420. https://doi.org/10.12659/MSM.899618
[53]	Wang, S.G., Xu, Y. and Xie, H. (2015) Astragaloside IV Prevents Lipopolysaccharide-Induced Injury in H9C2 Cardiomyocytes. Chinese Journal of Natural Medicines, 13, 127-132. https://doi.org/10.1016/S1875-5364(15)60016-4
[54]	Cai, Z., Liu, J. and Bian, H. (2016) Astragaloside IV Ameliorates Necrotizing Enterocolitis by Attenuating Oxidative Stress and Suppressing Inflammation via the Vitamin D3-Upregulated Protein 1/NF-κB Signaling Pathway. Experimental and Therapeutic Medicine, 12, 2702-2708. https://doi.org/10.3892/etm.2016.3629
[55]	Xu, H., Wang, C.Y. and Zhang, H.N. (2016) Astragaloside IV Suppresses Inflammatory Mediator Production in Synoviocytes and Collageninduced Arthritic Rats. Molecular Medicine Reports, 13, 3289-3296. https://doi.org/10.3892/mmr.2016.4923
[56]	Chen, T., Wang, R. and Jiang, W. (2016) Protective Effect of Astragaloside IV against Paraquat-Induced Lung Injury in Mice by Suppressing Rho Signaling. Inflammation, 39, 483-492. https://doi.org/10.1007/s10753-015-0272-4
[57]	Benaud, C., Dickson, R.B. and Thompson, E.W. (1998) Roles of the Matrix Metalloproteinases in Mammary Gland Development and Cancer. Breast Cancer Research and Treatment, 50, 97-116. https://doi.org/10.1023/A:1006061115909
[58]	Zhou, H., Kimura, K., Orita, T., Nishida, T. and Sonoda, K.H. (2012) Inhibition by Medroxyprogesterone Acetate of Interleukin-1β-Induced Collagen Degradation by Corneal Fibroblasts. Investigative Ophthalmology & Visual Science, 53, 4213-4219. https://doi.org/10.1167/iovs.11-8822