Establishment and Evaluation of a Mouse Model of Allergic Rhinitis

[Objectives]To explore a new method for induction of allergic rhinitis in mice,and compare and evaluate it with common modeling methods.[Methods]36 mice were randomly divided into the control group,blank group and experimental group,and there were 12 mice in each group.The mice in the control group were conventionally induced.That is,the mice were first injected intraperitoneally with the mixture composed of OVA 50μg,[Al(OH)3]5 mg and 1ml of normal saline once every other day,and then since the 15 th d,20μL of 5%OVA solution was dropped into each nasal cavity once a day,which lasted for 7 d.The blank group was treated with the same amount of normal saline according to the control group,and received intraperitoneal injection and bilateral nasal drip respectively.In the experimental group,mice were first given intraperitoneal injection of the mixture composed of ovalbumin(OVA)75μg,aluminum hydroxide gel[Al(OH)3]8 mg and normal saline 1.5 mL for basic sensitization.On the 26 th d,20μL of 3%OVA solution was dropped into each nasal cavity once a day,which lasted for 10 d.The number of sneezes,the number of nose scratching,the amount of nasal discharge,and the activity of mice in each group were observed,and the behavior of allergic reaction was scored.Meanwhile,the number of eosinophils in the nasal discharge of mice and the IgE content in serum were measured.[Results]The score of nasal stimulation symptoms,the number of eosinophils and serum IgE level of mice in the control group and the experimental group were higher than those in the blank group(P<0.05),and there was no statistical significance between the two groups in the three indicators(P>0.05).[Conclusions]The modeling method was more suitable for the development of allergic rhinitis patients condition,and reduced the probability of death of mice due to modeling,and simplified the experimental operation.

Designing and generating a mouse model:frequently asked questions

Genetically engineered mouse(GEM)models are commonly used in biomedical research.Generating GEMs involve complex set of experimental procedures requiring sophisticated equipment and highly skilled technical staff.Because of these reasons,most research institutes set up centralized core facilities where custom GEMs are created for research groups.Researchers,on the other hand,when they begin thinking about generating GEMs for their research,several questions arise in their minds.For example,what type of model(s)would be best useful for my research,how do I design them,what are the latest technologies and tools available for developing my model(s),and finally how to breed GEMs in my research.As there are several considerations and options in mouse designs,and as it is an expensive and time-consuming endeavor,careful planning upfront can ensure the highest chance of success.In this article,we provide brief answers to several frequently asked questions that arise when researchers begin thinking about generating mouse model(s)for their work.

Lipopolysaccharide mouse models for Parkinson's disease research:a critical appraisal

Parkinson's disease,the most common movement disorder,has a strong neuroinflammatory aspect.This is evident by increased pro-inflammatory cytokines in the serum,and the presence of activated microglial cells,and inflammatory cytokines in the substantia nigra of post-mortem brains as well as cerebrospinal fluid of Parkinson's disease patients.The central and peripheral neuroinflammatory aspects of Parkinson's disease can be investigated in vivo via administration of the inflammagen lipopolysaccharide,a component of the cell wall of gram-negative bacteria.In this mini-review,we will critically evaluate different routes of lipopolysaccharide administration(including intranasal systemic and ste reotasic),their relevance to clinical Parkinson's disease as well as the recent findings in lipopolysaccharide mouse models.We will also share our own expe riences with systemic and intrastriatal lipopolysaccharide models in C57BL/6 mice and will discuss the usefulness of lipopolysaccharide mouse models for future research in the field.

Role of cancer stem cell ecosystem on breast cancer metastasis and related mouse models

Breast cancer metastasis is responsible for most breast cancer-related deaths and is influenced by many factors within the tumor ecosystem,including tumor cells and microenvironment.Breast cancer stem cells(BCSCs)constitute a small population of cancer cells with unique characteristics,including their capacity for self-renewal and differentiation.Studies have shown that BCSCs not only drive tumorigenesis but also play a crucial role in promoting metastasis in breast cancer.The tumor microenvironment(TME),composed of stromal cells,immune cells,blood vessel cells,fibroblasts,and microbes in proximity to cancer cells,is increasingly recognized for its crosstalk with BCSCs and role in BCSC survival,growth,and dissemination,thereby influencing metastatic ability.Hence,a thorough understanding of BCSCs and the TME is critical for unraveling the mechanisms underlying breast cancer metastasis.In this review,we summarize current knowledge on the roles of BCSCs and the TME in breast cancer metastasis,as well as the underlying regulatory mechanisms.Furthermore,we provide an overview of relevant mouse models used to study breast cancer metastasis,as well as treatment strategies and clinical trials addressing BCSC-TME interactions during metastasis.Overall,this study provides valuable insights for the development of effective therapeutic strategies to reduce breast cancer metastasis.

Comparison of immune responses and intestinal flora in epicutaneously sensitized BALB/c or C57BL/6 mouse models of food allergy

Cutaneous exposure to food allergens through a disrupted skin barrier is recognized as an important cause of food allergy,and the cutaneous sensitized mouse model has been established to investigate relevant allergic disorders.However,the role of different genetic backgrounds of mice on immune responses to food allergens upon epicutaneous sensitization is largely unknown.In this study,two strains of mice,i.e.,the BALB/c and C57BL/6 mice,were epicutaneously sensitized with ovalbumin on atopic dermatitis(AD)-like skin lesions,followed by intragastric challenge to induce IgE-mediated food allergy.Allergic outcomes were measured as clinical signs,specific antibodies and cytokines,and immune cell subpopulations,as well as changes in intestinal barrier function and gut microbiota.Results showed that both strains of mice exhibited typical food-allergic symptoms with a Th2-skewed response.The C57BL/6 mice,rather than the BALB/c mice,were fitter for establishing an epicutaneously sensitized model of food allergy since a stronger Th2-biased response and severer disruptions in the intestinal barrier and gut homeostasis were observed.This study provides knowledge for selecting an appropriate mouse model to study food-allergic responses associated with AD-like skin lesions and highlights the role of genetic variations in the immune mechanism underlying pathogenesis of food allergy.

Effects of Polygala fallax Hemsl Water Extract on a Mouse Model of Gastric Motility Disorders

[Objectives]To explore the effects of Polygona fallax Hemsl water extract on gastrointestinal motility in normal mice and gastric motility disorder model mice and approximate mechanism.[Methods]Using normal mice and mice with gastric motility disorders(modeled with atropine),the effects of different mass concentration groups of P.fallax Hemsl water extract(0.125,0.250,0.500 g/mL)and domperidone groups on gastric residual rate,small intestine propulsion rate,serum motilin(MLT),vasoactive intestinal peptide(VIP),and tissue morphology were studied.[Results]There was a highly significant difference(P<0.01)in the small intestine propulsion rate of liquid in normal mice among the different concentration groups of P.fallax Hemsl water extract compared to the blank group.The small intestine propulsion rate and gastric residue rate of semi-solid paste were statistically significant compared to the blank group(P<0.05).Among them,there was a highly significant difference between the high concentration group(67.75%±7.65%,46.5%±10.62%)and the medium concentration group(60.90%±5.87%,59.27%±7.82%)(P<0.01).There was statistical significance in normal mouse serum MLT content in the high concentration group(P<0.05).There was no effect on serum VIP levels in normal mice;no effect on the morphology of stomach and intestinal tissues of normal mice.The small intestine propulsion rate and gastric residue rate of liquid and semi-solid paste in mice with gastric motility disorders were statistically significant compared to the atropine group,with extremely significant differences(P<0.01).[Conclusions]P.fallax Hemsl water extract has a promoting effect on gastrointestinal motility.One of the specific mechanisms by which P.fallax Hemsl promotes gastrointestinal motility in normal mice may be related to the content of MLT in mouse serum.The mechanism of action in atropine induced gastric paresis mice may be related to the reactivation of M receptors,and the action mechanism of P.fallax Hemsl does not change the original histological basis.It can be inferred that P.fallax Hemsl water extract has a synergistic effect on promoting gastrointestinal motility through other mechanisms,but it is not fully understood and further in-depth research is needed.

Anxiety Mouse Model Constructed by Single Intraperitoneal Injection of m-Chlorophenpiperazine

Anxiety disorder is a common mental disorder. It is necessary to establish a rapid, stable and specific anxiety model to provide a theoretical basis for further research on the pathogenesis of anxiety and drug development. A single intraperitoneal injection of m-chlorophenylpipera-zine (mCPP) (1, 2, 4 mg/kg) was given to male ICR mice to establish an anxiety model, and the effects of mCPP on anxiety behavior, pain, athletic ability, passive avoidance response ability and depressive behavior of male ICR mice were evaluated. A single intraperitoneal injection of mCPP shortened the time in open arms and decreased the percentage of time in open arms of mice in the elevated plus-maze test. mCPP also shortened center zone distance and reduced the number of entries to the central zone in the open field test. Moreover, mCPP reduced head-dip counts and increased the head-dip latency of mice in the hole-board test. After being administrated with a single intraperitoneal injection of mCPP for 24h, the mice showed no significant difference in the entry into the light side and the percentage of time in the light side of the light-dark box test. A single intraperitoneal injection of mCPP had no effects on tail flick latency, rotating time, number of errors and the step-down latency, the immobility time of mice in the tail-flick test, rotarod test, step-down test and TST respectively. In conclusion, we established a rapid and stable anxiety mouse model by single intraperitoneal injection of mCPP.

Establishment of a chronic biliary disease mouse model with cholecystoduodenal anastomosis for intestinal microbiome preservation

BACKGROUND Chronic biliary disease,including cholangitis and cholecystitis,is attributed to ascending infection by intestinal bacteria.Development of a mouse model for bile duct inflammation is imperative for the advancement of novel therapeutic approaches.Current models fail to replicate the harmful bacterial influx to the biliary tract observed in humans and spread of inflammation to the liver.Therefore,we aimed to establish an animal model of biliary disease that faithfully replicates the mechanisms of human diseases.AIM To establish a cholecystoduodenal anastomosis model capable of mimicking the mechanisms of ascending infection and inflammation observed in human biliary diseases.METHODS We established a mouse biliary disease model by directly connecting the gallbladder and duodenum,enabling ascending infection into the biliary tract without traversing the sphincter of Oddi.RESULTS In the cholecystoduodenal anastomosis mouse model,we observed impaired epithelial structure,wall thickening,and macrophage recruitment in the gallbladder.Despite the absence of postoperative antibiotics,we detected no changes in serum proinflammatory cytokine levels,indicating no systemic inflammation.Moreover,patency between the gallbladder and duodenum was confirmed via common bile duct ligation.Injection of patient-derived pathogenic bacteria into bile duct-ligated mice led to ascending infection,which significantly increased proinflammatory cytokine mRNA expression in the liver,duodenum,and ileum.These results indicate that our mouse model exhibited a direct connection between the gallbladder and duodenum,leading to ascending infection and closely mimicking the clinical features of biliary diseases observed in humans.CONCLUSION The cholecystoduodenal anastomosis mouse model is an effective chronic biliary disease model with significant relevance in the development of microbiome-based therapies for the prevention and treatment of biliary disease.

A novel mouse model of calcific aortic valve stenosis

Background:Calcific aortic valve stenosis(CAVS)is one of the most challenging heart diseases in clinical with rapidly increasing prevalence.However,study of the mecha-nism and treatment of CAVS is hampered by the lack of suitable,robust and efficient models that develop hemodynamically significant stenosis and typical calcium deposi-tion.Here,we aim to establish a mouse model to mimic the development and features of CAVS.Methods:The model was established via aortic valve wire injury(AVWI)combined with vitamin D subcutaneous injected in wild type C57/BL6 mice.Serial transthoracic echocardiography was applied to evaluate aortic jet peak velocity and mean gradi-ent.Histopathological specimens were collected and examined in respect of valve thickening,calcium deposition,collagen accumulation,osteogenic differentiation and inflammation.Results:Serial transthoracic echocardiography revealed that aortic jet peak velocity and mean gradient increased from 7 days post model establishment in a time depend-ent manner and tended to be stable at 28 days.Compared with the sham group,sim-ple AVWI or the vitamin D group,the hybrid model group showed typical pathological features of CAVS,including hemodynamic alterations,increased aortic valve thicken-ing,calcium deposition,collagen accumulation at 28 days.In addition,osteogenic dif-ferentiation,fibrosis and inflammation,which play critical roles in the development of CAVS,were observed in the hybrid model.Conclusions:We established a novel mouse model of CAVS that could be induced efficiently,robustly and economically,and without genetic intervention.It provides a fast track to explore the underlying mechanisms of CAVS and to identify more effec-tive pharmacological targets.

Establishment of a humanized ST6GAL1 mouse model for influenza research

Background:This study aimed to construct and characterize a humanized influenza mouse model expressing hST6GAL1.Methods:Humanized fragments,consisting of the endothelial cell-specific K18 promoter,human ST6GAL1-encoding gene,and luciferase gene,were microinjected into the fertilized eggs of mice.The manipulated embryos were transferred into the oviducts of pseudopregnant female mice.The offspring were identified using PCR.Mice exhibiting elevated expression of the hST6GAL1 gene were selectively bred for propagation,and in vivo analysis was performed for screening.Expression of the humanized gene was tested by performing immunohistochemical(IHC)analysis.Hematologic and biochemical analyses using the whole blood and serum of humanized hST6GAL1 mice were performed.Results:Successful integration of the human ST6GAL1 gene into the mouse genome led to the overexpression of human SiaT ST6GAL1.Seven mice were identified as carrying copies of the humanized gene,and the in vivo analysis indicated that hST6GAL1gene expression in positive mice mirrored influenza virus infection characteristics.The IHC results revealed that hST6GAL1 was expressed in the lungs of humanized mice.Moreover,the hematologic and biochemical parameters of the positive mice were within the normal range.Conclusion:A humanized influenza mouse model expressing the hST6GAL1 gene was successfully established and characterized.

Establishment of an orthotopic pancreatic cancer mouse model: Cells suspended and injected in Matrigel

AIM: To establish an orthotopic mouse model of pancreatic cancer that mimics the pathological features of exocrine pancreatic adenocarcinoma.

Effect of Shuanghuanglian Oral Solution on Liver Function in a Mouse Model of Non-alcoholic Steatohepatitis

[Objectives]To observe the effect of Shuanghuanglian oral solution on liver function in BABL/cJ mice in non-alcoholic steatohepatitis(NASH)model.[Methods]The BABL/cJ mice were randomly divided into three groups:a control group,a model group,and an experimental group.The experimental group was administered with 10%Shuanghuanglian oral solution at a dose of 0.1 mL/(10 g·d),while the control group and experimental group received an equivalent dosage of normal saline.All three groups were treated for a period of 28 d.The liver function of the mice in each group was examined after the treatment.[Results]The body mass,liver index,triacylglycerol(TG),total cholesterol(TC),aspartate aminotransferase(AST),and alanine aminotransferase(ALT)levels were all significantly reduced compared to the model group(P<0.05).[Conclusions]Shuanghuanglian oral solution has a beneficial effect on liver function in BABL/cJ mice.

Mouse models of epithelial ovarian cancer for preclinical studies

Epithelial ovarian cancer(EOC) is the leading cause of gynecological cancer-related mortality in the developed world. EOC is a heterogeneous disease represented by several histological and molecular subtypes. Therefore, exploration of relevant preclinical animal models that consider the heterogenic nature of EOC is of great importance for the development of novel therapeutic strategies that can be translated clinically to combat this devastating disease. In this review, we discuss recent progress in the development of preclinical mouse models for EOC study as well as their advantages and limitations.

Establishment of a Mouse Thrombocytopenia Model Induced by Cyclophosphamide

An experiment was conducted to compare the effects of two mouse thrombocytopenia models induced by cyclophosphamide at two different administration routes to determine a proper cyclophosphamide administration route that could cause stable thrombocytopenia. A suitable drug dosage that could induce thrombocytopenia in mouse efficiently with the definite administration route was then investigated. BALB/c mice were randomly divided into Normal, Model A and Model B groups. To Model A, 200 mg/kg of cyclophosphamide was given by vena caudalis injection as first dose and 30 mg/kg as maintenance dose by intraperitoneal injection at the following 6 days. To Model B, 150 mg/kg of cyclophosphamide was given by subcutaneous injection once a day for consecutive 3 days. All groups were under investigation for 15 days. The result suggested that a decrease in the number of blood platelets of Model B at the 7th day were significantly than that of Normal. Other platelet related indices like platelet distribution width, mean platelet volume and platelet-large cell ratio of Model B increased significantly in comparison with those of Normal group. The platelets count was reduced but fluctuated greatly, and more than half of the mice died in Model A. Therefore, subcutaneous injection of cyclophosphamide for 3 days was used for the cyclophosphamide dosage test. BALB/c mice were randomly divided into Normal, cyclophosphamide low dose （100 mg/kg）, medium dose （120 mg/kg） and high dose （140 mg/kg） groups. All groups were under investigation for 11 days. Though all 3 dosages successfully initiated thrombocytopenia as the platelets number dropped at the 7th day, the low dose was considered to be a suitable one that was of high efficacy and low toxicity. Thus, BALB/c mice challenged by subcutaneous injection of cyclophosphamide 100 mg/kg per day for 3 consecutive day is one simple, feasible and stable mouse thrombocytopenia model that could be used for pharmacodynamic test of the drugs which are supposed to have platelets increasing effect.

Human androgen deficiency： insights gained from androgen receptor knockout mouse models

The mechanism of androgen action is complex. Recently, significant advances have been made into our understanding of how androgens act via the androgen receptor （AR） through the use of genetically modified mouse models. A number of global and tissue-specific AR knockout （ARKO） models have been generated using the Cre-loxP system which allows tissue- and/or cell-specific deletion. These ARKO models have examined a number of sites of androgen action including the cardiovascular system, the immune and hemopoetic system, bone, muscle, adipose tissue, the prostate and the brain. This review focuses on the insights that have been gained into human androgen deficiency through the use of ARKO mouse models at each of these sites of action, and highlights the strengths and limitations of these Cre-loxP mouse models that should be considered to ensure accurate interpretation of the phenotype.

Role of FGF/FGFR signaling in skeletal development and homeostasis: learning from mouse models

Fibroblast growth factor （FGF）/fibroblast growth factor receptor （FGFR） signaling plays essential roles in bone development and diseases. Missense mutations in FGFs and FGFRs in humans can cause various congenital bone diseases, including chondrodysplasia syndromes, craniosynostosis syndromes and syndromes with dysregulated phosphate metabolism. FGF/FGFR signaling is also an important pathway involved in the maintenance of adult bone homeostasis. Multiple kinds of mouse models, mimicking human skeleton diseases caused by missense mutations in FGFs and FGFRs, have been established by knock-m/out and transgenic technologies. These genetically modified mice provide good models for studying the role of FGF/FGFR signaling in skeleton development and homeostasis. In this review, we summarize the mouse models of FGF signaling-related skeleton diseases and recent progresses regarding the molecular mechanisms, underlying the role of FGFs/FGFRs in the regulation of bone development and homeostasis. This review also provides a perspective view on future works to explore the roles of FGF signaling in skeletal development and homeostasis.

Human liver chimeric mouse model based on diphtheria toxin-induced liver injury

AIM To establish an inducible liver injury mouse model and transplant human hepatocytes to obtain liverhumanized mice.METHODS We crossed three mouse strains,including albumin(Alb)-cre transgenic mice,inducible diphtheria toxin receptor(DTR) transgenic mice and severe combined immune deficient(SCID)-beige mice,to create Alb-cre/DTR/SCID-beige(ADSB) mice,which coincidentally harbor Alb-cre and DTR transgenes and are immunodeficient. As the Cre expression is driven by the liver-specific promoter Alb(encoding ALB),the DTR stop signal flanked by two lox P sites can be deleted in the ADSB mice,resulting in DTR expression in the liver. ADSB mice aged 8-10 wk were injected intraperitoneally(i.p.) with diphtheria toxin(DT) and liver damage was assessed by serum alanine aminotransferase(ALT) level. Two days later,mouse livers were sampled for histological analysis,and human hepatocytes were transplanted into the livers on the same day. A human ALB enzyme-linked immunosorbent assay was performed 7,14,21 and 28 d after transplantation. Human CD68 immunohistochemistry was performed 30 and 90 d after transplantation.RESULTS We crossed Alb-cre with DTR and SCID-beige mice to obtain ADSB mice. These mice were found to have liver damage 4 d after i.p. injection of 2.5 ng/g bodyweight DT. Bodyweight began to decrease on day 2,increased on day 7,and was lowest on day 4(range,10.5%-13.4%). Serum ALT activity began to increase on day 2 and reached a peak value of 289.7 ± 16.2 IU/m L on day 4,then returned to background values on day 7. After transplantation of human liver cells,peripheral blood human ALB level was 1580 ± 454.8 ng/m L(range,750.2-3064.9 ng/m L) after 28 d and Kupffer cells were present in the liver at 30 d in ADSB mice.CONCLUSION Human hepatocytes were successfully repopulated in the livers of ADSB mice. The inducible mouse model of humanized liver in ADSB mice may have functional applications,such as hepatocyte transplantation,hepatic regeneration and drug metabolism.

Effect of periocular injection of celecoxib and propranolol on ocular level of vascular endothelial growth factor in a diabetic mouse model

AIM： To investigate the effects of periocular injection of propranolol and celecoxib on ocular levels of vascular endothelial growth factor （VEGF） in a diabetic mouse model. METHODS： Forty 4-6wk BALB-C male mice weighing 20-25 g were used. The study groups included： nondiabetic control （group 1）, diabetic control （group 2）, diabetic propranolol （group 3）, and diabetic celecoxib （group 4）. After induction of type 1 diabetes by streptozotocin, propranolol （10 μg） and celecoxib （200 μg dissolved in carboxymethylcellulose 0.5%） were injected periocularly. The ocular level of VEGF was measured in all the study groups using enzyme-linked immuno sorbent assay （ELISA） method. RESULTS： Ocular VEGF level was significantly increased （1.25 fold） in the diabetic control group when compared to the non-diabetic group one week after induction with streptozotocin （P=0.002）. Both periocular propranolol and celecoxib significantly reduced ocular VEGF levels （P=0.047 and P〈0.001, respectively）. The effect was more pronounced with celecoxib, CONCLUSION： The periocular administration of propranolol and celecoxib can significantly reduce ocular VEGF levels in a diabetic mouse model.

Microarray microRNA profiling of urinary exosomes in a 5XFAD mouse model of Alzheimer’s disease

Background:Alzheimer's disease(AD)is an incurable and irreversible neurodegen-erative disease,without a clear pathogenesis.Therefore,identification of candidates before amyloid-βplaque(Aβ)deposition proceeds is of major significance for earlier intervention in AD.Methods:To explore the potential noninvasive earlier biomarkers of AD in a 5XFAD mouse model,microRNAs(miRNAs)from urinary exosomes in 1-month-old pre-Aβaccumulation 5XFAD mice models and their littermate controls were profiled by mi-croarray analysis.The differentially expressed miRNAs were further analyzed via droplet digital PCR(ddPCR).Results:Microarray analysis demonstrated that 48 differentially expressed miRNAs(18 upregulated and 30 downregulated),of which six miRNAs-miR-196b-5p,miR-339-3p,miR-34a-5p,miR-376b-3p,miR-677-5p,and miR-721-were predicted to display gene targets and important signaling pathways closely associated with AD pathogenesis and verified by ddPCR.Conclusions:Urinary exosomal miRNAs showing differences in expression prior to Aβ-plaque deposition were identified.These exosomal miRNAs represent potential noninvasive biomarkers that may be used to prevent AD in clinical applications.

Reduced EGFR signaling enhances cartilage destruction in a mouse osteoarthritis model

Osteoarthritis （OA） is a degenerative joint disease and a major cause of pain and disability in older adults. We have previously identified epidermal growth factor receptor （EGFR） signaling as an important regulator of cartilage matrix degradation during epiphyseal cartilage development. To study its function in OA progression, we performed surgical destabilization of the medial meniscus （DMM） to induce OA in two mouse models with reduced EGFR activity, one with genetic modification （, was/＋ mice） and the other one with pharmacological inhibition （gefitinib treatment）. Histological analyses and scoring at 3 months post-surgery revealed increased cartilage destruction and accelerated OA progression in both mouse models. TUNEL staining demonstrated that EGFR signaling protects chondrocytes from OA-induced apoptosis, which was further confirmed in primary chondrocyte culture. Immunohistochemistry showed increased aggrecan degradation in these mouse models, which coincides with elevated amounts of ADAMTS5 and matrix metalloproteinase 13 （MMP13）, the principle proteinases responsible for aggrecan degradation, in the articular cartilage after DMM surgery. Furthermore, hypoxia-inducible factor 2α （HIF2α）, a critical catabolic transcription factor stimulating MMP13 expression during OA, was also upregulated in mice with reduced EGFR signaling. Taken together, our findings demonstrate a primarily protective role of EGFR during OA progression by regulating chondrocyte survival and cartilage degradation.