YIV-906 potentiated anti-PD1 action against hepatocellular carcinoma by enhancing adaptive and innate immunity in the tumor microenvironment

YIV-906 (PHY906) is a standardized botanical cancer drug candidate developed with a systems biology approach—inspired by a traditional Chinese herbal formulation, historically used to treat gastrointestinal symptoms including diarrhea, nausea and vomiting. In combination with chemotherapy and/or radiation therapy, preclinical and clinical results suggest that YIV-906 has the potential to prolong survival and improve quality of life for cancer patients. Here, we demonstrated that YIV-906 plus anti-PD1 could eradicate all Hepa 1–6 tumors in all tumor bearing mice. YIV-906 was found to have multiple mechanisms of action to enhance adaptive and innate immunity. In combination, YIV-906 reduced PD1 or counteracted PD-L1 induction caused by anti-PD1 which led to higher T-cell activation gene expression of the tumor. In addition, YIV-906 could reduce immune tolerance by modulating IDO activity and reducing monocytic MDSC of the tumor. The combination of anti-PD1 and YIV-906 generated acute inflammation in the tumor microenvironment with more M1-like macrophages. YIV-906 could potentiate the action of interferon gamma (IFNg) to increase M1-like macrophage polarization while inhibiting IL4 action to decrease M2 macrophage polarization. Flavonoids from YIV-906 were responsible for modulating IDO activity and potentiating IFNg action in M1-like macrophage polarization. In conclusion, YIV-906 could act as an immunomodulator and enhance the innate and adaptive immune response and potentiate anti-tumor activity for immunotherapies to treat cancer.


YIV-906 enhanced anti-PD1 action to inhibit Hepa1-6 tumor growth in vivo and demonstrated
tumor-specific vaccine-like effect. YIV-906 alone had no effect on Hepa1-6 tumor growth in vivo (P > 0.05) (Fig. 1A,B). Anti-PD1 alone started to slow down tumor growth of Hepa 1-6 on day 4 (Fig. 1A,B). Some tumors were shrunk on day 8 and 40% tumors were below detection limit at the end of the experiment (Fig. 1A,B).
Tumors responded to the YIV-906 plus anti-PD1 in as soon as 2 days with all tumors disappearing following 7-days of treatment (P < 0.001) (Fig. 1A,B). Without further treatment up to 21 days later, no tumors re-appeared in the YIV-906 plus anti-PD1 combination group. YIV 906 plus anti-PD1 did not induce the animals' body weight loss (Fig. 1C) and did not caused histological changes of normal liver tissues (Fig. 1D) as comparing to the control or single treatment groups. This suggested that YIV-906 plus anti-PD1 did not cause adverse side effect to animals while this treatment can selectively cure Hepa 1-6 tumors in vivo (Fig. 1A,B). When Hepa 1-6 cells were re-implanted into the "cured" mice no tumor growth was found, while naïve mice had tumor growth (data not shown). When CMT167 cells (small cell lung carcinoma) or Pan02 (Pancreatic Ductal Adenocarcinoma) were implanted into the "cured" mice after being re-challenged with Hepa 1-6, CMT167 or Pan02 tumor growth could be observed. This behavior suggested YIV-906 in combination with anti-PD1 could create a tumor-specific vaccine-like effect.
Combination of YIV-906 and anti-PD1 reduced immune suppression by reducing the PD1 and PDL1 protein expression of Hepa 1-6 tumor. Since tumor shrinking happened on day 4 following YIV-906 plus anti-PD1, we compared apoptosis and DNA damage of tumors at this time point. YIV-906 plus anti-PD1 could significant increased levels of cleaved caspase 9 and DNA breakage (P-H2AX-ser139) (Fig S2A, D, E). The above result supported that YIV-906 enhanced anti-PD1 action to lead to more cell death and tumor shrinkage.
The essential function of anti-PD1 is to restore cytotoxic T-cell function by inhibiting the co-inhibitory pathways of T cells through interrupting the interactions between PD1-PDL1 18 . As expected, anti-PD1 induced the number of activated T cells (GranyzmeB + /CD3 +) of Hepa 1-6 tumors ( Fig. 2A). The number of activated T cell and Treg upon anti-PD1 treatment was not affected by the co-treatment of YIV-906 (Fig. 2B). Interestingly, the combination treatment did induce more T cell activation related genes in Hepa 1-6 tumors (Fig. 2C), suggesting that the function of T cells could be enhanced. We wondered if YIV-906 had an impact on PD1 and PDL1 protein expression leading to stronger T cell function. Results indicated that Anti-PD1 or YIV-906 alone did not change the PD1 tumor proteins (Fig. 2D). Compared to the control group or anti-PD1 alone group, YIV-906 plus anti-PD1 could significantly decrease PD1 tumor proteins (P = 0.02 or 0.003, respectively) following 4-day treatments (Fig. 2D). This result partially helps explain why less anti-PD1 combined with YIV-906 was required to have similar anti-tumor activity versus taking a higher dosage of anti-PD1 alone. Additionally, anti-PD1, but not YIV-906-only treatment, did significantly increase PDL-1 tumor protein (P = 0.01) but this increase could be counteracted by combining YIV-906 and anti-PD1 (P = 0.008) (Fig. 2E). These results suggested that YIV-906 might facilitate anti-PD1 action in overcoming tumor resistance to immune surveillance and lead to a stronger  20 . IDO could be a key resistance factor to anti-PD1 therapy 20,21 . We found that YIV-906 could modulate IDO activity in cell cultures (Fig. 3A). After using purified E.coli glucuronidase (GU) to remove glucuronoside from chemicals to mimic the condition happening in lower GI, YIV-906GU had stronger IDO inhibition than YIV-906 (Fig. 3A). Baicalein was shown to be the most potent compound among the flavonoids (Fig. 3A). It was found that YIV-906 or YIV-906/anti-PD1 had lower kynurenine/tryptophan ratio of Hepa 1-6 tumor (Fig. 3B). This suggested that YIV-906 could modulate IDO activity in vivo. Furthermore, we found that anti-PD1 plus YIV-906 treatment reduced monocytic MDSC of Hepa 1-6 tumor (Fig. 3C). Modulation of IDO by YIV-906 could be an additional mechanism action to reduce immune tolerance and facilitate the action of Anti-PD1.
YIV-906 plus anti-PD1 treatment induced macrophage infiltration and polarized to a higher M1-like macrophage signature in Hepa 1-6 tumors. The combination of YIV-906 plus anti-PD1, but not YIV906 alone or anti-PD1 alone, could significantly induce macrophage infiltration in Hepa 1-6 tumors after 4-days of treatment (Fig. 4A,B). This could be attributed to the increase of MCP1(CCL2), a monocyte chemoattractant protein, of tumors in the YIV-906 plus Anti-PD1 treatment group where MCP1 was higher than that of the anti-PD1 only group (P < 0.05) ( Fig. 4C and S4A). Depending on the tissue microenvironment, mac- www.nature.com/scientificreports/ rophages can be differentiated into two distinct phenotypes: M1 (tumor rejection) and M2 (tumor promotion). Based on bio-statistical analysis, YIV-906 plus anti-PD1 treatment had tumor environment favoring M1-like macrophages (Fig. 4E,F). Western blot analysis further confirmed that the iNOS protein (a M1 marker) but not ARG protein (a M2 marker) was substantially increased following YIV-906 plus anti-PD1 treatment ( Fig. 4D and S5A-C). This result also suggested that YIV-906 plus anti-PD1 treated tumors were highly inflamed. It is known that IFNg helps polarize macrophages into the M1-like state. We found that INFg mRNA expression of tumors was significantly induced by YIV-906 plus anti-PD1 treatment ( Fig. 4E and S6C). Therefore, the enhanced infiltration of M1-like macrophages induced by YIV-906 plus Anti-PD1, could be an additional mechanism aiding against Hepa1-6 tumor growth.
In contrast to IFNg, YIV-906 or YIV-906GU inhibited IL4 action by suppressing IRF4 expression, a key transcription factor of the IL4 signaling pathway (Fig. 5C, S11 and S12). This also led to down-regulation of Arg protein in BMDM (Fig. 5C, S11 and S12). The decrease of IFR4 and Arg protein could be attributed to downregulation of their mRNA by YIV-906 or YIV-906GU in the presence of IL4 (Fig. 5A).
Our results demonstrated that YIV-906 or YIV-906GU could also potentiate IFNg action by stimulating P-Jak1/2 and P-Stat2 phosphorylation while inhibiting IL4 action by down-regulating IFR4 protein of BMDM. The modality could explain how multiple mechanisms of YIV-906 can work to polarize macrophages into the M1-like phenotype. The immuno-modulatory effect of the above activities could be explained by the sugar moiety of chemicals present in YIV-906, specifically the aglycone chemicals which appear most active.
Flavonoids play key roles of YIV-906 in potentiating IFNg action to polarize macrophages into M1-like type. The key YIV-906GU components responsible for potentiating the IFNg action on macrophages were investigated. Of the four herb ingredients in YIV-906GU: G, P, S and Z, results indicated that G, P, S, in the presence of IFNg, could increase iNOS/Arg mRNA expression ratio (S > P > G) (Fig. 6A). Consistently   www.nature.com/scientificreports/ the formulations without G, P or S (-G, -P, -S) completely lost the IFNg potentiation property (Fig. 6A). These results indicated that G, P, Z could also play a role in the IFNg potentiation or interact with S to enhance IFNg action. In addition, key flavonoids (baicalein wogonin, chrysin, oroxylin A and baicalin) of S 22,23 could increase the IFNg action to increase iNOS/Arg mRNA expression ratio (Fig. 6B). Most importantly, the amount of wogonin and oroxylin A in the tumors was higher in the YIV-906 plus anti-PD1 group compared to the YIV-906 alone group (Fig. 6C, Table S2). Thus, these flavonoid compounds naturally present in component S of YIV-906 could be the active ingredients, along with others, contributing to the IFNg potentiation that polarizes macrophages to the M1-like phenotype in Hepa 1-6 tumors.

Discussion
Many current immune therapies for cancer are trying to convert "cold tumors" into "hot tumors" so that revived immune cells could attack tumor cells. Immune check point antibodies, such as anti-PD1, anti-PD-L1, anti-CTLA4 have led to breakthroughs for the treatment of many tumor types; However, tumor types such as HCC, pancreatic and colon cancers have had relatively low response rates to these antibodies. Currently hundreds of remedies are being tested to see if they can further improve the efficacy of these immune check point antibodies. Many of these new remedies are designed to target a specific target (vs multiple targets) of the immune cycle. Up to date, there have been no major breakthroughs in these combination clinical trials. Here, we reported that YIV-906, a botanical immunomodulator with a systems biology effect, could potentiate anti-PD1 action against Hepa 1-6 tumor growth by promoting both adaptive and innate immunity through multiple mechanisms of actions.
For adaptive immunity, we found YIV-906 plus anti-PD1 could decrease PD1 tumor proteins and inhibited PDL-1 expression induced by anti-PD1. This could foster a more favorable tumor microenvironment for T cell activation. In addition, we found that YIV-906 could modulate IDO activity and leading to a decrease of MDSC of Hepa 1-6 tumor. We identified that flavonoids of S herb played a key role in modulating IDO activity. This result was supported by a previous report 24 . IDO inhibitors were reported to enhance the action of anti-PD1, anti-PD-L1, anti-CTLA4 on different types of animal tumors 20,21,25 . BMS-986205, with less side effects compared to Epacadostat which had serious adverse effects 26 and failed in clinical trials 27 , is still being tested in combination with Nivolumab as first or second line therapy for liver cancer (NCT03695250).
In addition to adaptive immunity, YIV-906 also enhances the innate immune response. YIV-906 plus anti-PD1 could attract more M1-like macrophage infiltration which could be partly due to the induction of MCP1 in the tumors. Interestingly, YIV-906 also increased M1-like macrophage tumor infiltration when combined with irinotecan (CPT-11) or Sorafenib 13,14 . There is increasing evidence to support M1-like macrophages in tumors could enhance the efficacy of chemotherapy and target therapies 13,28,29 . It has also been reported that M1-like macrophages phenotype help T cells re-activation under immune checkpoint blockade therapy 30 . PD1 expression was found to dictate macrophage polarization. M2 macrophages, which have high PD1 expression and low phagocytic activity, promote tumor growth and are not favorable for immunotherapy 31 . In contrast, low PD1 expression favors M1-like macrophages that have high phagocytic activity and could increase immune check point blockade therapy action 31,32 . A recent report demonstrated that anti-PD1 could help switch macrophage polarity states from M2 to M1-like phenotypes in lung cancer 33 . Our result also indicated that anti-PD1 alone increased the probability of M1-like macrophage in the tumor microenvironment by 40%. Most importantly YIV-906 combined with anti-PD1 could further enhance M1-like macrophages and the innate immune response in the tumor microenvironment. YIV-906 plus anti-PD1 even further decreased PD1 proteins in tumor tissues which subsequently created favorable conditions for M1-like macrophage polarization 31 . The decrease in PD1 protein levels in the YIV-906 plus anti-PD1 group also explains why lower dosages (by 1/3), of anti-PD1 combined with YIV-could also achieve the same anti-tumor activity for higher doses of anti-PD1.
The combination not only eradicated the Hepa 1-6 tumors in every mouse, it also mimicked tumor-specific vaccine-like behavior as demonstrated by selective rejection of re-implanted Hepa 1-6 tumors and the growth of implanted CMT167 or Pan02 tumors. Some studies suggest that boosting innate immunity could increase tumor vaccine effect. A recent report demonstrated that exosomes secreted by M1-like macrophages can potentiate cancer vaccine-like properties through Th1 cytokine induction 34 resulting in a proinflammatory tumor climate. A separate study reporting that M1-like macrophages function by aiding CD8 T cell differentiation into memory T cells 35 . Our next step would be to investigate the extent exosomes or T-cells play in the vaccine mimicking behavior.
IFNg plays an important role in macrophage M1-like polarization. YIV-906 could potentiate the IFNg activity to turn up the signaling transduction response to a higher level; as anti-PD1 alone could activate T cells which released IFNg in tumor, adding YIV-906 could further amplify the IFNg signal and enhance M1-like macrophage polarization. Another unique property of YIV-906 was the inhibitory activity demonstrated on the M2 inducer, IL4, through down-regulation of IFR4. When treated with the combination of YIV-906 and anti-PD1, the dual effect of promoting M1-like polarity while inhibiting the M2 state ensures the dominance of M1-like macrophages in tumor tissues. Currently, there was no other therapeutic agents that can have these synergistic systems biology properties.
We identified Scutellaria baicalensis Georgi (S) as the key herb ingredient that is most likely responsible for promoting M1-like macrophage polarization. This result was consistent with our previous study of the effects of YIV-906 in combination therapy with anti-cancer drugs CPT-11 or sorafenib. Similar elevated predominantly M1-like macrophage signals were observed, as well as the enhanced anti-tumor activity of the combination 13,36 . Flavonoids were identified as the active compounds in S that promotes M1-like macrophage polarization. The flavonoid baicalin's ability to induce repolarization of tumor-associated macrophages to M1-like phenotype was demonstrated by others 37 . Most importantly, we detected baicalein, wogonin and oroxylin A in the Hepa 1-6 tumor and they could potentiate IFNg in the tumor to polarize macrophages into M1-like. www.nature.com/scientificreports/ In conclusion, YIV-906 enhanced the anti-tumor activity of anti-PD1. The action is due to its ability to promote both adaptive and innate immunity. Flavonoids from Scutellaria baicalensis Georgi (S) were identified as one of the major active compounds responsible for modulating IDO activity, which regulated MDSC function and potentiated IFNg action to polarize macrophages into M1-like type. It could be interesting to investigate other herbs or herbal formulations containing S or flavonoids on anti-PD1 actions. YIV-906 component herbs G, P, Z might also contribute to the activity of YIV-906 and this is under current investigation. The potential use of YIV-906 as an immunomodulatory enhancer of tumor microenvironment in combination with Anti-PD1, or other immune check point antibodies, for the treatment of HCC or other type of cancers should be explored further in the clinic. Currently, a phase II international clinical trial for using YIV-906 (600 mg (3 capsules) BID, 4 days on 3 days off) plus sorafenib (400 mg BID, daily) had be initialized to target HBV positive hepatocellular carcinoma (NCT04000737). As similar scheduling and dosing (up to 2400 mg, BID) of YIV-906 had been used for several clinical trials with no detection of YIV-906 associated toxicity of patients [8][9][10][11] , similar scheduling and dosing of YIV-906 could be combined with anti-PD1 treatments in the future clinical trials.

Materials and methods
Animal studies. Details of animal studies can be found in our previous reports 13,15 . Briefly, Hepa 1-6 cells (about 2 × 10 6 cells in 100 μl phosphate-buffered saline) were transplanted subcutaneously into 8-week-old female C57BL6 mice (Charles River Laboratories, Wilmington, MA). Body weight, tumor size, and mortality of the mice were monitored daily. After 10-14 days, mice with tumor sizes of 180 mm 3 were selected. Tumor volume was examined by using the formula length × width 2 × π/6. Each group consisted of seven mice. YIV-906 was administered orally for 7 days (500 mg/kg po, twice per day), while anti-PD1 was administered intraperitoneal on day zero (200ug/mice). In the control groups, mice were administered water orally. On Day 0, YIV-906 was administered 30 min prior to anti-PD1 administration. All animal experiments were carried out in accordance with the relevant guidelines and regulations approved Yale University Institutional Animal Care and Use Committee (IACUC) protocol. Animal experimental protocols were approved by Yale University Institutional Animal Care and Use Committee (IACUC). Animal studies were carried out in compliance with the ARRIVE guidelines.
Immunohistochemistry. After 4-day treatments, mice were terminated by cervical dislocation two days or four days after initiation of drug treatment (see above). Details of immunohistochemistry protocol can be found in our previous reports 13,15 . Intestinal and colon tissues were removed, fixed in formalin, embedded in paraffin, and sectioned into 10 μm. The sections were mounted on Superfrost slides, dewaxed with xylene, and gradually hydrated. Antigen retrieval was achieved by 10 mM Sodium citrate pH6.0 with 0.02% Tween-20 under steaming for 30 min. The source and dilution of primary antibody are listed in supplementary methods. The primary antibodies were diluted using Tris-HCl buffer containing 1% BSA and 0.5% Tween-20 and were incubated at room temperature for one hour. As a negative control, a set of slides was processed without primary antibody. Superpicture immunohistochemistry detection kit (Invitrogen, Inc.) was used for detection. The slides were counterstained with hematoxylin and mounted. The antibodies used were: Cleaved Caspase-3 (#9664, Cell Signaling Technology, Inc.), Cleaved Caspase-8 (#9496, Cell Signaling Technology, Inc. Danvers, MA), Cleaved Caspase-9 (#ab52298, Abcam, Cambridge, England), F4/80 (#ab16911, Abcam).

Flow cytometry analysis.
Tumor tissues (200 mg) were cut into small pieces in 0.5 ml RPM1 640 culture medium. Liberase was added to dissociate the connected tumor cells at room temperature for 15 min. Dissociated cells were passed through a cell strainer (70um). After spinning down the cells at 1000 g centrifugation for 10 min, red blood cells were lysed with 1 ml BD pharm lyse on ice. Cells were collected at 1000 g centrifugation for 10 min. 2 × 10 6 cells were used for each staining sample. Cells were resuspended in RPM1 640 with 3% FBS. Anti-mouse CD16/CD32 clone 2.4G2 (BD Pharmingen, #553142) was used to block Fc receptors on cells. Total T cells were stained by Anti-CD3-PE (BD Pharmingen, clone 145-2c11, #553064) for 30 min on ice. Fixation/ Permeabilized (eBioscience) was used to fix and permeabilize cells. Then activated cytotoxic T cells was further stained with Anti-Granzyme B-pacific blue (BioLegend, clone GB11, #515408) and T regulatory cells were stained with Anti-FOX3P-APC (eBioscience, clone FJK16s, #17-5773-83). The stained cells were washed and analyzed by flow cytometry LSR II (BD Canto II, New Jersey, USA). Details of flow cytometry analysis can be found in our previous report 38 . Western blot. BMDM or RAW 264.7 cells (American Type Culture Collection) were cultured RPMI supplemented with 5% FBS in 37 °C incubator with 5% CO 2 . 2 × 10 6 cells were seeded in 12-well plate. After drug treatment, cells were lysed in 0.3 ml protein loading buffer (for 20 ml buffer, 10% SDS 4 ml, Tris-HCL pH 6.8 0.75 ml, 10% glycerol 5 ml, β-mercaptoethanol 0.5 ml, and bromophenol blue) for each well, and sonicated for 30 s to break DNA. Then cell extracts were electrophoresed through Mini PROTEAN TGX Precast gels (12%, 15 well comb, 15 µl/well Cat. #456-1046) in a running buffer (10 × , Tris 30 g, Glycine 144 g, SDS 10 g, with DD H 2 O) and transferred to the nitrocellulose membrane (Bio-Rad Laboratories, Inc) in a transfer buffer (Tris 30 g, Glysine 144 g, SDS 0.5 g). After blot transfer, membrane was cut into two parts with approximate size of 3 cm (height) x 9 cm (wide) to fit into a blocking chamber. The upper part of the membrane will be used for probing target proteins with specific antibodies (as following), the lower part of the membrane will be used for probing actin or Histone 2 (H3) as protein loading control for normalization. The membrane was blocked and probed in TBS-T buffer (TBST + 1% Tween, AB14330-01000, American Bioanalytical) containing non-fat milk 1 (Table S1) and the rest of primers that could be found in our previous reports 13,15 . Isolation of bone marrow derived monocytes (BMDMs) and macrophage differentiation. Bone marrow cells were collected from tibias and femurs of 10-week-old C57Bl/6 mice were cultured with complete RPMI-1640 medium (supplemented with 5% Fetal Bovine Serum and 1% Penn/Strep) in the presence of murine M-CSF (10 ng/ml) for 7 days to allow differentiation of monocytes into macrophages 39 . Macrophage were cultured in 5% FBS RPMI-1640 medium with IFNg (10 ng/ml) to induce polarization to M1-like macrophage while M2-like macrophage were induced by IL4 (20 ng/ml).

Cytokine analysis by cytometric bead array.
IDO activity assay. 2 × 10 6 HEK293 cells were transfected with mouse IDO (2 µg/10 cm plate) (OriGene Technologies, Inc., Rockville, MD, Ido1 (NM_008324)) or without IDO DNA as negative control using lipofectamine 3000 for 48 h. For one plate, 1 ml PBS was used to collect cells into a 2 ml tube. Cells were spin down at 3500 rpm 1 min. Cells were then sonicated in ice cold 1 ml PB buffer pH 6.5. Cell lysis was clarified by centrifuging at 12000 rpm for 5 min at 4 °C. 25 µl cell lysis will be mixed with 25 µl herbal extract at desired concentration and 50 µl reaction buffer: (PB buffer 100 mM pH 6.5) every 10 ml add 70 mg Vitamin C, 10 µl methylene blue (2.5%), 100 µl catalase (20 mg/ml), 250 µl of 500 mM l-tryptophan. Mixture was incubated for 1.5 h at 37 °C in water bath. Trichloroacetic acid 30% 25 µl will be added and incubated at 50 °C for 1 h. Finally, Enrlich 0.8% (80 mg/10 ml in acetic acid) 100 µl was added. Absorbance at 540 nm will be measure 40 . Optical density at 540 nm (Yellow) has positive correlation to the amount of kynurenine 40 .

LC-MS detection.
Each tumor sample were homogenized in 200 μL acetronitrile/methanol/water(2/2/1, v/v/v) and 1 mm glass beads (BioSpec Products, Bartlesville, OK) for 30 s at 3500 rpm twice. The homogenate was then centrifuged at 12,000 rpm for 15 min at 4 °C. The supernatant was dried down in a Speedvac. The residue of each tumor sample was re-dissolved in 100 µL of acetonitrile, and vortexed at 3000 rpm for 3 min. The solution was then centrifuged at 12,000 rpm at 4 ℃ for 15 min, and 2 μL supernatant was injected into the UPLC-QTOF system for analysis. All sample analyses were performed on an ACQUITY ultra-performance liquid chromatography (UPLC) system coupled with a quadrupole-time of flight (Q-TOF) MS instrument (UPLC Xevo G2-XS QTOF MS, Waters Corp., Milford, MA, USA) with an electrospray ionization (ESI) source. Separation was carried out on a Waters ACQUITY BEH C18 column (2.1 X100 mm id, 1.7 μ m) with a guard column (Waters ACQUITY BEH C18 column (2.1 X5 mm id, 1.7 μ m)). The mobile phase consisted of acetonitrile (A) and water containing 0.1% formic acid (B) using a gradient elution of 5% A at 0-2 min, 5-10% A at 2-3 min, 10-17% A at 3-10 min, 17 www.nature.com/scientificreports/ was performed on a Water Xevo G2-XS QTOF. The scan range was from 50 to 1000 Da. For negative electrospray mode, the capillary voltage and cone voltage were set at 2.5 kV and 60 V, respectively. The desolation gas was set to 800 L/h at a temperature of 500 C; The cone gas was set to 50 L/h at a temperature of 120 C; Data acquisition was achieved using MS E , and the collision energy was 15-60 V.
Statistical analysis. Data were analyzed by one-or two-way analysis of variance (ANOVA) (GraphPad