A pharmaceutical composition for treating tophi

Abstract

This invention relates to the field of pharmaceutical technology for treating gouty tophi, and discloses a pharmaceutical composition for treating gouty tophi, comprising a nuclease for degrading DNA structures. This invention, by introducing a nuclease to directly intervene in the structure of gouty tophi, reduces dependence on single uricase treatment to a certain extent, exhibits weaker immunogenicity, more stable efficacy, and effectively destroys the structure of gouty tophi, solving the problems of strong immunogenicity, unstable efficacy, and difficulty in structural destruction in existing technologies, thereby improving the overall clearance effect of gouty tophi.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical technology for treating gouty tophi, and in particular to a pharmaceutical composition for treating gouty tophi. Background Technology

[0002] Gout is a metabolic disease caused by elevated blood uric acid levels due to purine metabolism disorders, leading to the deposition of monosodium urate (MSU) crystals. As the disease progresses, some patients may develop tophi (tophus), which can deposit in joints, soft tissues, and bone, causing joint damage, deformities, and functional impairment. It is one of the main causes of disability due to gout.

[0003] Currently, treatment for gouty tophi mainly includes uric acid-lowering therapy, anti-inflammatory therapy, and surgical removal. Uric acid-lowering therapy is the foundational approach, including xanthine oxidase inhibitors (such as allopurinol and febuxostat) and uricosuric drugs. However, this type of treatment primarily promotes crystal dissolution indirectly by long-term reduction of blood uric acid levels. The process of clearing existing gouty tophi is slow, often requiring months to years, and some patients may not achieve the treatment goal.

[0004] For patients who do not respond to conventional treatments, uricase preparations are currently used in treatment. Uricase can catalyze the conversion of uric acid into more soluble allantoin, thereby significantly reducing the uric acid load in the body. A representative drug is polyethylene glycol-modified uricase. Phase III randomized controlled clinical trials have shown that after 6 months of pegloticase treatment, approximately 40%–45% of patients experience complete resolution of at least one tophi, but a significant proportion of patients do not respond or have limited efficacy.

[0005] Although uricase preparations have been used to treat refractory gout and tophi, their clinical application still has significant limitations. First, uricase is an exogenous protein with strong immunogenicity. Clinical studies have shown that over 50% of patients develop anti-drug antibodies (ADA), leading to accelerated drug clearance, rebound uric acid levels, and loss of efficacy. Furthermore, antibody production is closely related to infusion reactions, and some patients may experience severe allergic reactions, limiting long-term use. Second, the response rate to uricase therapy is limited; only about 40%–45% of patients maintain sustained efficacy, while the remaining patients show no response or secondary failure. Moreover, the mechanism of action of uricase is mainly to catalyze the breakdown of uric acid; its effect on tophi depends on long-term reduction of serum uric acid levels, thereby indirectly promoting the dissolution of urate crystals, rather than directly destroying the structure of tophi.

[0006] Traditionally, gouty tophi were thought to consist primarily of a urate crystal core and surrounding fibrous tissue. However, recent studies have shown that gouty tophi are not simply crystal deposits, but rather complex, multi-component structures. Schauer et al. discovered that neutrophil extracellular traps (NETs) play a crucial role in gout-related inflammation. Building on this, the inventors, through systematic research on human and animal models of gouty tophi, found that gouty tophi are mainly composed of urate crystals, fibrous septa, and a large amount of amorphous material. This amorphous material is primarily NETs, ​​which are composed of double-stranded DNA, histones (such as CitH3), and neutrophil elastase (NE), forming a dense three-dimensional network structure that constitutes the main structural framework of gouty tophi. The DNA network structure formed by NETs can encapsulate urate crystals and form a physical barrier, potentially limiting the effectiveness of existing uricase therapies in directly targeting the interior of gouty tophi and thus restricting their dissolution efficiency.

[0007] In summary, current uricase therapy suffers from strong immunogenicity, unstable efficacy, and inability to effectively destroy the structure of gouty tophi. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies in uricase therapy, such as strong immunogenicity, unstable efficacy, and inability to effectively destroy the structure of tophi.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A pharmaceutical composition for treating gouty tophi includes a nuclease for degrading DNA structures.

[0010] This invention introduces nucleases to directly intervene in the structure of gouty tophi, which reduces the dependence on single uricase treatment to a certain extent. It has weaker immunogenicity, more stable efficacy, and effectively destroys the structure of gouty tophi, solving the problems of strong immunogenicity, unstable efficacy, and difficulty in destroying the structure in existing technologies, thereby improving the overall clearance effect of gouty tophi.

[0011] Preferably, the nuclease is a deoxyribonuclease.

[0012] Preferably, the pharmaceutical composition for treating gouty tophi further includes uricase, wherein the volume ratio of the nuclease to uricase is (1-2):1.

[0013] Preferably, the concentration of the nuclease is 1200 U / mL-1600 U / mL.

[0014] Preferably, the concentration of the uricase is 30 U / mL to 50 U / mL.

[0015] The uricase is either PEG-modified uricase or recombinant uricase.

[0016] Optionally, the pharmaceutical composition may be administered via local injection.

[0017] Optionally, the pharmaceutical composition for treating gouty tophi is screened using a mouse MSU crystal induction model.

[0018] Optionally, the method for constructing the mouse MSU crystal induction model includes the following steps: 1) Anesthetize male mice aged 6-8 weeks; 2) MSU crystal suspension was injected into the right paw of mice, while PBS was injected into the left paw as a control. 3) After a predetermined time is given, MSU crystals can form tophi-like deposits in the foot model; The method for constructing the mouse MSU crystal induction model also includes step 4), which specifically involves monitoring joint swelling.

[0019] The beneficial effects of the present invention include at least the following: 1) This invention is the first to intervene in the DNA network structure of gouty tophi, which is centered on neutrophil extracellular traps (NETs). Nucleases can degrade the DNA backbone in NETs, ​​thereby disrupting the stability of gouty tophi at the structural level and promoting their depolymerization, thus overcoming the shortcomings of existing uricases that only act on uric acid components; 2) This invention utilizes nucleases that can directly act on the main structural components of gouty tophi, causing the dense deposits to depolymerize, which is beneficial to the overall regression of gouty tophi. Compared with the indirect dissolution method that relies solely on uricase to lower uric acid levels, nucleases provide a more direct pathway of action. 3) In this invention, nucleases are used as the primary mechanism of action, which can reduce the intensity or dependence on exogenous uricase to a certain extent, thereby helping to reduce the risk of uricase-related immunogenicity. In comparison, nucleases have homologous enzymes in the human body, and their immunogenicity risk is relatively low. 4) This invention utilizes a treatment method that primarily employs nucleases, combined with uricase as an adjunct, to target both the structural framework (DNA / NETs) and urate components of gouty tophi, achieving synergistic intervention at different targets. Nucleases promote structural depolymerization, while uricases degrade uric acid components; the two complement each other in their mechanisms of action, jointly promoting the clearance of gouty tophi. Attached Figure Description

[0020] Figure 1 This is a diagram showing the DNA staining markers of tophi prepared in vitro in the in vitro experiments of this invention; Figure 2The images show visual representations of tophi prepared in vitro in this invention after treatment with nuclease and uricase alone and in combination. Figure 3 Immunofluorescence staining image of tophi on the foot of a mouse obtained by dissection 48 hours after the establishment of the mouse model of gout in the mouse experiment of this invention; Figure 4 Images of gouty tophi after dissection in the Ctrl group at different time points (d0 to d8) after the establishment of a gout model in the foot in mouse experiments of this invention. Figure 5 Images of gouty tophi after dissection in the DNase group at different time points (d0 to d6) after the establishment of a gout model in the foot in mouse experiments of this invention. Figure 6 This is a semi-quantitative area analysis statistical chart of residual tophi in the paw anatomical diagram of mice in the Ctrl group of the present invention. Figure 7 This is a semi-quantitative area analysis statistical chart of residual tophi in the paw anatomical diagram of the DNase group mice in the mouse experiment of this invention. Figure 8 Images of gouty tophi after dissection in the URI group at different time points (d4 to d8) after the foot gout model was established in the mouse experiment of this invention; Figure 9 Images of gouty tophi after dissection in the DNase+URI group at different time points (d3 to d7) after pediculum gout modeling in mouse experiments of this invention. Figure 10 This is a semi-quantitative area analysis statistical chart of residual tophi in the paw anatomical diagram of mice in the URI group of the present invention. Figure 11 This is a semi-quantitative area analysis statistical chart of residual tophi in the paw anatomical diagram of mice in the DNase+URI group in the mouse experiment of this invention. Figure 12 This is a graph showing the changes in the swelling index of each group during the mouse experiment of this invention. Figure 13 This is a statistical chart showing the number of days for the degradation of tophi in each intervention group during the mouse experiment of this invention. Detailed Implementation

[0021] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0022] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used in this invention are conventional in the art and can be obtained through conventional commercial means; unless otherwise specified, the methods used in this invention are conventional methods in the art.

[0023] In this invention, the CitH3 fluorescent primary antibody is a product of Novus Biologicals, Inc., USA.

[0024] In this invention, the CitH3 fluorescent secondary antibody used was DyLight 488 goat anti-rabbit IgG and DyLight 594 goat anti-mouse IgG, both purchased from Abbkine in Wuhan, China.

[0025] In this invention, the dsDNA fluorescent primary antibody is a product of Abcam, Inc., USA.

[0026] The analysis of variance (ANOVA) in this invention, also known as variance analysis, is mainly used to "test whether the difference between the means of two or more samples is significant".

[0027] In this invention, DAPI (4',6-diamidinyl-2-phenylindole) is a blue fluorescent dye that can bind strongly to DNA and is widely used in cell nuclear staining during fluorescence microscopy.

[0028] The DAPI used in this invention is from Zhongke Ruitai (Beijing) Biotechnology Co., Ltd.

[0029] In this invention, the SYTOX Green nucleic acid dye is a product of Thermo Fisher Scientific, Inc., USA.

[0030] In this invention, the deoxyribonuclease used is a product of Sigma-Aldrich, Inc.

[0031] In this invention, the MSU crystals used are products of Beijing Asrell Biotechnology Co., Ltd.

[0032] The products of Shandong Huian Chemical Co., Ltd. are used in this invention.

[0033] The uricase used in this invention is a product of Shanghai Enzyme-Link Biotechnology Co., Ltd.

[0034] In this invention, Lymphoflot is a product of California Bio-Rad, Hercules, Inc.

[0035] In this invention, the isoflurane used is a product of Forane, Abbott, Chicago, IL.

[0036] The C57BL / 6 mice used in this invention were purchased from Shanghai Slack Laboratory Animal Co., Ltd.

[0037] In this invention, Lymphoflot is a commercially available, ready-to-use separation medium based on the density gradient centrifugation principle for separating lymphocytes and peripheral blood mononuclear cells from blood samples. Its core working principle utilizes the density differences among different blood cells. Similar to the classic Ficoll-Hypaque method, Lymphoflot, as a pre-prepared separation medium, can rapidly and effectively obtain highly active target cells.

[0038] In this invention, peripheral blood neutrophils are the most numerous and functionally crucial type of white blood cells in the human immune system.

[0039] In this invention, whole blood is blood drawn directly from blood vessels without undergoing any other operations other than centrifugation and anticoagulation, thus preserving the original components and proportions of the blood.

[0040] Hypotonic lysis, as described in this invention, is a technique that utilizes osmotic pressure differences to disrupt cell membranes and release cell contents. Its core principle is to induce cells to absorb water, swell, and eventually rupture in a hypotonic environment.

[0041] ImageJ, mentioned in this invention, is an open-source image processing and analysis software based on Java, developed by the National Institutes of Health (NIH) in the United States, and widely used in fields such as biomedicine, materials science, and physics.

[0042] In this invention, PBS (phosphate buffer saline) is a commonly used buffer solution in biological experiments. It is prepared by mixing disodium hydrogen phosphate (Na2HPO4), potassium dihydrogen phosphate (KH2PO4), sodium chloride (NaCl) and other components in a specific ratio. The pH value is usually maintained at 7.2-7.4, and the osmotic pressure is similar to that of human body fluids.

[0043] GraphPad Prism 10.1, used in this invention, is a statistical analysis and graphing software widely used in scientific research.

[0044] The cofocusing laser scanning microscope used in this invention employs the Leica STELLARIS 5.

[0045] This invention relates to the Student's t-test, primarily used for normally distributed samples with small sample sizes (e.g., n) and unknown population standard deviation σ. The t-test uses t-distribution theory to infer the probability of differences occurring, thereby comparing whether the difference between two means is significant. It is considered alongside the F-test and chi-square test.

[0046] This invention discloses a pharmaceutical composition for treating gouty tophi, comprising a nuclease for degrading DNA structures.

[0047] In some embodiments, the nuclease is a deoxyribonuclease.

[0048] In some embodiments, the pharmaceutical composition for treating tophi further includes uricase, wherein the volume ratio of the nuclease to uricase is (1-2):1.

[0049] In some embodiments, the concentration of the nuclease is 1200 U / mL-1600 U / mL.

[0050] In some embodiments, the concentration of the uricase is 30 U / mL to 50 U / mL.

[0051] In some embodiments, the uricase is a PEG-modified uricase or a recombinant uricase.

[0052] In some of these embodiments, the pharmaceutical composition is administered via local injection.

[0053] In some embodiments, the pharmaceutical composition for treating gouty tophi is screened using a mouse MSU crystal induction model. The method for constructing the mouse MSU crystal induction model includes the following steps: 1) Anesthetize 6-8 week old male C57BL / 6 mice; 2) MSU crystal suspension was injected into the right paw of mice, while PBS was injected into the left paw as a control. 3) After a predetermined time is given, MSU crystals can form tophi-like deposits in the foot model; 4) Monitor joint swelling.

[0054] In some of these embodiments, the booking time is 8 hours.

[0055] Example 1: The present invention discloses a pharmaceutical composition for treating gouty tophi, comprising a nuclease for degrading DNA structures, wherein the nuclease is a deoxyribonuclease.

[0056] The drug composition is administered via local injection.

[0057] Example 2: The present invention discloses a pharmaceutical composition for treating gouty tophi, comprising a nuclease and a uricase, wherein the nuclease is used to degrade DNA structure, and the nuclease is a deoxyribonuclease.

[0058] The volume ratio of the nuclease to uricase is 1:1. The concentration of the nuclease is 1600 U / mL.

[0059] The concentration of the uricase is 50 U / mL. The uricase is modified with PEG.

[0060] The drug composition is administered via local injection.

[0061] Example 3: The present invention discloses a pharmaceutical composition for treating gouty tophi, comprising a nuclease and a uricase, wherein the nuclease is used to degrade DNA structure, and the nuclease is a deoxyribonuclease.

[0062] The volume ratio of the nuclease to uricase is 2:1. The concentration of the nuclease is 1200 U / mL.

[0063] The concentration of the uricase is 30 U / mL. The uricase used is recombinant uricase.

[0064] The drug composition is administered via local injection.

[0065] A. Construction of the tophi model: Tophi-like structures were constructed in vitro using a co-culture system of monosodium urate (MSU) crystals and high-density neutrophils.

[0066] The specific construction method is as follows: 1) Isolate fresh human peripheral blood neutrophils from heparinized (20 U / mL) blood of healthy blood donors (NHD); 2) Using the Lymphoflot density gradient centrifugation method, carefully transfer whole blood to the upper layer of the Lymphoflot solution and centrifuge at 1400 rpm for 30 min in unbraked mode. 3) Carefully remove plasma, monocytes, and the Lymphoflot layer. Remove the neutrophil-rich layer above the red blood cells (erythrocytes) and perform two hypotonic lysis procedures on the red blood cells; 4) Neutrophils and MSU crystals (0.6 mg / million cells) were incubated at 37°C for 24 h; 5) Inducing the formation of NET-rich deposits to mimic the structure of tophi.

[0067] B. Construction of the mouse MSU crystal induction model: The pharmaceutical composition for treating gouty tophi of the present invention was screened using a mouse MSU crystal induction model.

[0068] The method for constructing a mouse MSU crystal induction model includes the following steps: 1) Take 6-8 week old male C57BL / 6 mice and anesthetize them with 3% isoflurane; 2) 40 μL (1 mg) of MSU crystal suspension was injected into the right paw of a mouse, and PBS was injected into the left paw as a control at the same time; 3) Eight hours after administration of MSU crystals, tophi-like deposits formed in the foot model; 4) Monitor joint swelling and euthanize the mice.

[0069] C. Experimental Grouping: The above models are randomly divided into the following groups: Group A: Control group (no treatment), marked as Ctrl group in the attached figure; Group B: Uricase treatment group, marked as URI group in the attached diagram; Group C: The group treated with the pharmaceutical composition used in Example 1 for treating tophi, labeled as the DNase group in the attached figure; Group D: The group treated with the pharmaceutical composition used in Example 2 for treating tophi, labeled as DNase+URI group in the attached figure.

[0070] Each group consisted of 27 mice, with 3 mice per day from day 0 to day 8 used for observation of swelling index and final anatomical results.

[0071] D. In vitro experiments: In an in vitro experiment, tophi were prepared by co-incubating high-density human neutrophils with MSU crystals (0.6 mg / million cells) at 37°C for 24 h. After 4 h of Sytox Green staining, a large amount of DNA was found in the tophi. After 2 h of intervention with DNase-I (100 U / ml), the tophi were further investigated.

[0072] The fluorescence degradation intensity of Sytox Green in the Ctrl group and the DNase intervention group was observed using confocal microscopy. The degree of depolymerization of the gross structure of tophi was assessed by visual inspection.

[0073] E. Mouse experiments: ① Six- to eight-week-old male C57BL / 6 mice were selected, and 40 μL of MSU crystals (25 mg / mL) were prepared as a sterile suspension and then injected subcutaneously into the paw of the mice.

[0074] Forty-eight hours after injection, the white tophi-like deposits formed on the paws of mice were dissected, fixed with 4% paraformaldehyde for 10 minutes, dehydrated, cleared, and then embedded in paraffin to prepare 5 μm sections.

[0075] After incubating the sections overnight at 4°C with PBS blocking solution containing 10% fetal bovine serum, they were incubated overnight at 4°C with the primary antibody citrullinated histone H3 (CitH3, 1:100, NB100-57135) and dsDNA (1:100, ab27156).

[0076] After washing three times with PBS, incubate with fluorescently labeled secondary antibody at room temperature for 1 hour.

[0077] Cell nuclei were stained with DAPI and mounted. Images of tophi tissue in mouse paws were acquired using a confocal laser scanning microscope.

[0078] ②After MSU crystals were injected into the sole of the foot, tophi-like deposits formed 8 hours later.

[0079] Mice in each experimental group were injected locally with the corresponding enzyme preparations or drug combinations. In the DNase+URI group, 20 μl of deoxyribonuclease (concentration of 1600 U / mL) and 20 μl of uricase (concentration of 50 U / mL) were injected locally into the paws of mice. Joint swelling was monitored and the mice were euthanized.

[0080] In this invention, during the initial mouse paw modeling process, an equal volume of sterile PBS is injected locally into the paw of the opposite side simultaneously. Then, the thickness of both paws of the mouse is measured at the same time every day. The ratio of the modeled paw to the control paw is the swelling index.

[0081] During the treatment, the skin of the mouse paws was carefully peeled off with surgical scissors to fully expose the tophi deposits underneath. Anatomical images of the paws of mice in each group were taken at the same time every day, and ImageJ was used to semi-quantitatively analyze the changes in deposit volume to assess the treatment effect.

[0082] In mouse experiments, the degradation time of tophi was calculated after three repeated experiments in each intervention group within their respective degradation time window.

[0083] In mouse experiments, after three sets of repeated experiments, the residual tophi in the mouse paw anatomical images during the time window of tophi disappearance were analyzed using ImageJ in the Ctrl group, DNase group, URI group and DNase+URI group.

[0084] Data were analyzed using GraphPad Prism 10.1 and expressed as mean ± SD. Student's t-test was used to compare differences between two groups, and one-way ANOVA was used to compare differences among multiple groups. A p-value < 0.05 was considered statistically significant.

[0085] F. Experimental Results: like Figure 1 As shown, in the in vitro experiments of this invention, the tophi prepared in vitro were stained with DNA and found to contain a large amount of DNA, and nucleases could rapidly degrade the DNA within them.

[0086] like Figure 2 As shown in the in vitro experiments of this invention, the tophi prepared in vitro were treated with nuclease and uricase alone and in combination. In the visual images, the DNase intervention group alone showed a loose tissue structure, but the white crystals did not disappear. The simple URI intervention did not have a visual degradation effect. After DNase combined with URI treatment, the structure of the tophi in vitro completely disappeared.

[0087] comprehensive Figure 1 and Figure 2 It can be seen that the nuclease treatment group can significantly destroy the NETs structure, and the DNase+URI group shows a more obvious effect in promoting structural depolymerization, suggesting that nucleases play an important role in the destruction of tophi structure.

[0088] like Figure 3 As shown, the immunofluorescence staining image of the paraffin-embedded sections obtained after dissection of the mouse paw gouty model 48 hours after modeling, followed by fixation in 4% paraformaldehyde, shows the presence of a large number of NETs components with CitH3 core markers, and a large amount of colocalized dsDNA within them.

[0089] like Figure 4 As shown, in the mouse experiment of this invention, the tophi in the Ctrl group mice degraded and disappeared on their own around day 8.

[0090] like Figure 5 As shown, in the mouse experiment of this invention, the tophi in the DNase group of mice disappeared ahead of schedule on day 6.

[0091] like Figure 6 As shown, the semi-quantitative analysis of the tophi area in the degradation window of the Ctrl group in the mouse experiment of this invention indicates that local DNase intervention can promote the degradation of tophi in mice.

[0092] like Figure 7 As shown, the semi-quantitative analysis of the tophi area in the DNase group during the degradation window in the mouse experiment of this invention indicates that local DNase intervention can promote the degradation of tophi in mice.

[0093] like Figure 8 As shown, in mouse experiments of the present invention, the application of uricase alone (URI group) did not promote the regression of tophi.

[0094] like Figure 9As shown, the tophi in mice treated with the drug composition for treating tophi of the present invention (DNase+URI group) resolved prematurely on day 5.

[0095] like Figure 10 As shown, the semi-quantitative analysis of the tophi area in the degradation window of the URI group in the mouse experiment of the present invention indicates that there is no effect on promoting degradation.

[0096] like Figure 11 As shown, the combined treatment of DNase+URI group in the mouse experiment of the present invention semi-quantitatively demonstrated that it can significantly promote the degradation of tophi in the area of ​​tophi within the degradation window.

[0097] It should be noted that, from an animal welfare perspective and based on the results of the Ctrl and DNase groups, mice in the URI group and the drug combination treatment group (DNase+URI group) were not sacrificed or dissected on days 0-2, but were only observed.

[0098] like Figure 12 As shown in the swelling index chart, the DNase+URI group showed the fastest reduction in swelling, outperforming the other groups, followed by the DNase group. The uricase treatment group showed the slowest reduction in swelling, even slower than the Ctrl group.

[0099] like Figure 13 As shown, the DNase group and the DNase combined with URI group of the present invention exhibit a significant effect in accelerating the degradation of tophi.

[0100] comprehensive Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 and Figure 13 It can be seen that, compared with the control group and the single uricase treatment group, the nuclease treatment group can significantly destroy the NETs structure, and the combined treatment group shows a more obvious effect in promoting structural depolymerization, indicating that nucleases play an important role in the destruction of tophi structure.

[0101] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A pharmaceutical composition for treating tophi, characterized by, It includes nuclease and uricase, wherein the nuclease is a deoxyribonuclease, and the nuclease is used to degrade DNA structure.

2. The pharmaceutical composition for treating tophi according to claim 1, wherein The volume ratio of the nuclease to the uricase is (1-2):

1.

3. The pharmaceutical composition for treating tophi according to claim 2, wherein the pharmaceutical composition is administered in an amount of 0.1 to 10 mg / kg. The concentration of the nuclease is 1200 U / mL-1600 U / mL.

4. The pharmaceutical composition for treating gouty tophi as described in claim 2, characterized in that, The concentration of the uricase is 30 U / mL-50 U / mL.

5. The pharmaceutical composition for treating gouty tophi as described in claim 2, characterized in that, The uricase is either PEG-modified uricase or recombinant uricase.

6. The pharmaceutical composition for treating gouty tophi as described in claim 1, 2, 3, 4, or 5, characterized in that, The drug composition is administered via local injection.

7. The pharmaceutical composition for treating gouty tophi as described in claim 1, 2, 3, 4, or 5, characterized in that, It was screened using a mouse MSU crystal induction model.

8. The pharmaceutical composition for treating gouty tophi as described in claim 7, characterized in that, The method for constructing the mouse MSU crystal induction model includes the following steps: 1) Anesthetize male mice aged 6-8 weeks; 2) MSU crystal suspension was injected into the right paw of mice, while PBS was injected into the left paw as a control. 3) After a predetermined time is given, MSU crystals can form tophi-like deposits in the foot model.

9. The pharmaceutical composition for treating gouty tophi as described in claim 8, characterized in that, The method for constructing the mouse MSU crystal induction model also includes step 4), which specifically involves monitoring joint swelling.

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