Int Urogynecol J DOI 10.1007/s00192-014-2451-5
ORIGINAL ARTICLE
A pilot study of urine cytokines in ketamine-associated lower urinary tract symptoms Rachel Y. K. Cheung & Jacqueline H. S. Lee & Symphorosa S. C. Chan & Dawn W. T. Liu & K. W. Choy
Received: 21 January 2014 / Accepted: 9 June 2014 # The International Urogynecological Association 2014
Abstract Introduction and hypothesis The aim of this study was to investigate urine cytokine and chemokine levels in symptomatic ketamine abusers compared with age-matched controls. Methods Midstream urine specimens were collected in a prospective study of 23 ketamine abusers and 27 controls who had never used ketamine. Their basic demographic and urinary symptoms were compared. The urine was analyzed by a multiplex panel screen for 19 cytokines/chemokines: EGF, GM-CSF, GRO, IL-1Ra, IL-5, IL-6, IL-7, IL-8, IL-10, IL12p40, IL-12p70, IP-10, MCP-1, MIP-1b, sCD40L, sIL-2Ra, VEGF, MCP-4, and TARC using Luminex™ xMAP® technology. Protein concentration values were normalized to urine creatinine concentrations. Results Mean age of the control group was 21.1±4.3 years (n=27) and of the ketamine group was 20.6±3.7 years (n= 23). All participants were women. The urine cytokine analysis showed a significant elevation in EGF levels in the ketamine group with lower urinary tract symptoms (LUTS) compared with the control group (p 2 years or had stopped < 3 months were comparable with middle-aged women with detrusor overactivity [6, 7]. The pathophysiology of these ketamine-associated urinary symptoms is not clear. LUTS associated with ketamine use overlap with those of overactive bladder (OAB) syndrome [6, 8]. Recent studies have reported the presence of inflammatory biomarker cytokines in urine samples of patients with OAB syndrome [9]. We hypothesized that LUTS in ketamine users may be associated with bladder inflammation. We compared cytokine and chemokine levels in urine samples of ketamine abusers with LUTS and age-matched controls to explore whether there is a relationship between inflammatory markers and the severity of LUTS.
Int Urogynecol J
Materials and methods
Results
The protocol for this research project was approved by the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee Clinical Research Ethics Committee (CUHK-NTEC CRE 2009.453). Adolescents referred to our gynecology clinic with ketamine-abuse-associated urinary problems were invited to participate in the study between December 2009 and April 2010. Aged-matched adolescents who were referred to our clinic with gynecological problems and had no history of ketamine abuse or urinary symptoms were recruited as controls. Consent was obtained before the examination, and concomitant parent or guardian consent was obtained before the examination if the patient was < 16 years. Urinary symptoms were assessed using a validated questionnaire: the Chinese version of Urogenital Distress Inventory Short Form (UDI-6) [10]. A total of 50 midstream urine samples were collected from 23 ketamine abusers and 27 control adolescents who had never abused ketamine. All urine samples had bacteriological investigations, including culture. Cytokines and chemokines were also measured. Urine samples were centrifuged at 3,000 rpm for 10 min immediately after collection. Aliquots of the centrifuged samples were stored at −80 °C pending cytokine/chemokine analysis. A total of 19 cytokines/chemokines, including epidermal growth factor (EGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), growth-regulated peptide alpha (GRO), interleukin-1 receptor alpha (IL)-1Ra, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p40, IL-12p70, interferon gamma-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1b, soluble cluster of differentiation 40 ligand (sCD40L), sIL-2Ra, vascular endothelial growth factor (VEGF), monocyte chemoattractant protein (MCP)-4, and thymus and activation-regulated chemokine (TARC) were tested for in each urine sample using a commercially available human cytokine/chemokine magnetic bead panel (Millipore, Billerica, MA, USA). Cytokine/ chemokine targets in urine samples were captured by specific-antibody-coated, fluorescent-coded magnetic beads and levels were quantified by automated analyzer (Luminex™ 200 System). Cytokine/chemokine levels were normalized to urinary creatinine levels (R&D Systems, Minneapolis, MN, USA). Statistical analysis was performed using the Statistical Package for the Social Sciences (IBM Statistics 20; SPSS Inc, Chicago IL, US). Descriptive statistics were used for age, UDI-6 score, and biomarker calculation. Mann– Whitney U test was used for nonparametric comparison between groups. Pearson’s correlation was used for the association between urine EGF level and UDI-6 score, duration of ketamine use, and duration of cessation of ketamine use.
All participants in both groups were women. Mean age of the control group was 21.1±4.3 years (n=27) and was similar to the ketamine group: 20.6±3.7 years (n=23) ; p=0.35) Mean duration of ketamine use was 55.6 (39.2) months; mean duration since cessation was 7.9 (10.1) months. All users took ketamine by inhalation. No urine sample showed bacterial growth. All participants in the ketamine group were tested for serum renal function, including serum creatinine and urea levels; results were all within normal range. UDI-6 scores are shown in Table 1. There were no urinary symptoms reported in controls. Mean urinary EGF level in the ketamine and control groups was 28,184.3±10,970.1 pg/mg and 18,058.7 ± 11,642.1 pg/mg of creatinine, respectively. Cytokine/ chemokine analysis showed a significant elevation in EGF levels in the ketamine group compared with the control group (p=0.002) (Fig. 1). IL1-Ra, IL-8, MCP-1, sCD40L, and sIL2Ra levels were not statistically different from control values (Table 2), and the levels of the remaining 13 proteins were below detection limits. When evaluating the association between the EGF level in the ketamine group and symptoms score in UDI-6, there was no significant relationship between EGF level and symptoms severity (r=−0.148, p=0.427). The duration of ketamine use (r=−0.097, p=0.607) and of ketamine use cessation (r= 0.243, p=0.187) were also not associated with EGF level.
Discussion Ketamine-related LUTS is a relatively new clinical entity, with patients usually presenting with irritative urinary symptoms. Patients reported increased voiding frequency and reduced functional bladder capacity, which significantly impaired QoL, even after ceasing to use ketamine [11]. These symptoms were very similar to those reported in patients with OAB syndrome or interstitial cystitis [8]. Several pathophysiological mechanisms, including epithelial dysfunction, mastcell activation, and neurogenic inflammation have been proposed to explain symptoms. Different factors including Table 1 The Urogenital Distress Inventory Short Form (UDI)-6 score of ketamine users Variables
Ketamine group (n=23)
Irritative subscale Stress subscale Obstructive/discomfort subscale Total Score
29.6 (18.3) 12.0 (15.8) 29.3 (23.4) 70.7 (49.2)
*No participant in the control group had urinary symptoms and all had zero scores in all subscales
Int Urogynecol J Fig. 1 Mean urinary epidermal growth factor (EGF) level (expressed as pg/mg creatinine) in age-matched controls and ketamine group
bladder epithelial dysfunction with urinary absolute leakage, mast-cell degranulation with vasoactive response and mediators, substance P release, and activation or sensitization of mechanoreceptors or chemoreceptors, have been postulated as contributing to progressive bladder injury [12]. Emerging evidence also suggest there is a change in cytokine/ chemokine profile among OAB or ketamine users. Tyagi et al. reported a significant elevation of cytokines (IL-10, IL12p) and chemokines (MIP-1) in urine samples of OAB patients when compared with controls [13]. Ghoniem et al. found a subset of cytokines to be exclusively expressed in OAB patients [9]. Bladder biopsy from a ketamine user showed various inflammatory changes [14–16]. However, the relationship between urine cytokines and ketamine abuse has not been reported. This study was conducted to examine and study the relationship with urinary symptoms severity. EGF was the only cytokine shown to be significantly elevated in symptomatic ketamine users; the other 18 cytokines/chemokines were not. EGF is a tissueremodeling biomarker that predicts disease progression in many renal conditions [17, 18]. It is also related to treatment outcomes in painful bladder syndrome and interstitial cystitis [19]. Bladder biopsies of ketamineinduced cystitis reveal chronic inflammatory changes similar to those encountered in interstitial cystitis [11], resulting in a thin epithelium with neutrophilic and lymphoplasma cell infiltration of the bladder mucosa [20] and/ or a mononuclear inflammatory cell infiltrate in submucosal tissue [21, 22]. Some patients with serious bladder lesions show no surface epithelium, but only smooth muscle, collagen, and adipose tissue [23]. It has been shown that bladder epithelial cells express EGF [19, 24]. In painful bladder syndrome or interstitial
cystitis, EGF may be needed for re-epithelialization, and elevated EGF concentration may be a response to epithelial damage [25]. The finding of elevated EGF level in ketamine users indicates a similar tissue repairing or fibrosis attributed to their symptoms. Increased urine EGF levels in the ketamine group may be the result of kidney or bladder damage. As ketamine users more often experience urine storage problems, such as urinary frequency and urgency, we hypothesize there may be more epithelial damage and remodeling in the bladder, similar to patients with painful bladder syndrome or interstitial cystitis. It is known that ketamine-related cystitis increases suburothelial inflammation and increases urothelial cell apoptosis. One proposed mechanism involves the direct toxic effect of ketamine and its metabolites on bladder interstitial cells, which is believed to lead to inflammation, submucosal edema, and fibrosis of the detrusor muscles. This direct and indirect
Table 2 Mean urinary cytokine/chemokine level in ketamine and control groups Cytokine/chemokine (pg/mg creatinine)a
Controls
Ketamine
P value
IL-1Ra IL-8 MCP-1 sCD40L sIL-2Ra
348.8±396.2 24.2±27.6 224.7±213.8 115.0±111.1 154.2±85.7
321.6±211.4 30.0±48.2 243.1±125.3 81.2±84.3 151.5±60.5
0.36 0.59 0.25 0.58 0.87
The remaining 13 proteins were below the detection limits (see text for abbreviation) a
See text for definitions
Int Urogynecol J
effect of ketamine and its metabolites may cause an autoimmune reaction against the bladder urothelium, resulting in cell apoptosis. Although EGF level was not associated with symptom severity in this study, it may be associated with epithelial damage and the remodeling process. EGF signaling is needed to activate proliferation and inhibition of unexpected cell death/apoptosis [26]. Therefore, EGF level may help predict the recovery and prognosis of LUTS symptoms. As this is a cohort study with EGF measurement at a single time point, future longitudinal study is needed to observe the relationship of EGF level with disease progression. In this study, 15 of the 23 (65.2 %) ketamine users abused ketamine for > 3 years, and 14 of them (60.9 %) of them had stopped using ketamine for < 6 months. All urine samples were sent for bacterial culture to exclude urinary tract infection (UTI). This was done because UTI is reported to induce higher levels of chemokines in the urine [27]. All urine samples were collected in the first consultation before patients were started on any treatment. Urinary symptoms were assessed by an appropriate, validated QoL questionnaire. Scores from this questionnaire reflect symptomatology reliably [10]. This finding of > 50 % higher urine EGF level in the ketamine group may imply a long recovering period for the damaged bladder epithelium. Besides, the nonsignificant difference and even undetectable levels of the other chemokines and cytokines, including Interleukins, may reflect the reduced inflammatory condition after ketamine cessation. There is very limited information from previous studies regarding urine cytokines in either active or exketamine users for reference. This study was limited by small sample size. Urinary cytokine level may be confounded by other medications the patients were taking. However, both study and control group participants were relatively young and with good past health. They were age matched, and urine cytokine levels had normalized with their urine creatinine levels. We found no association between cytokine level and duration of keratin use or cessation, and this may be affected by various ketamine dosages and purity. It is difficult to quantify accurately the amount of ketamine used or the duration of abuse. In addition, polydrug consumption, with potential impact of EGF levels, cannot be ruled out. In conclusion, EGF was the only elevated marker in urine samples of ketamine users, which may represent the bladder epithelial remodeling process. We should further investigate its level at different time points during the recovering process and review the association of EGF level with associated LUTS disease progress and treatment response. Acknowledgments This study was supported in part by Beat Drugs Fund (MD10835) from the Government of the Hong Kong Special Administrative Region. Conflicts of interest None.
References 1. Central Registry of Drug Abuse, Narcotics Division, Security Bureau, HKSAR Government. HKSAR Narcotics Division website: http:// www.nd.gov.hk/en/report/ptf/56th/chapter2.pdf. Accessed 11 Jan 2014 2. Curran HV, Morgan C (2000) Cognitive, dissociative and psychotogenic effects of ketamine in recreationsla users on the night of drug use and 3 days later. Addiction 95:575–590 3. Weiner AL, Vieira L, McKay CA et al (2000) Ketamine abusers presenting to the emergency department: a case series. J Emerg Med 18:447–451 4. Pal R, Balt S, Erowid E et al (2013) Ketamine is associated with lower urinary tract signs and symptoms. Drug Alcohol Depend 32: 189–194 5. Middlela S, Pearce I (2011) Ketamine-induced vesicopath: a literature review. Int J Clin Pract 65:27–30 6. Cheung RY, Chan SS, Lee JH et al (2011) Urinary symptoms and impaired quality of life in female ketamine users: persistence after cessation of use. Hong Kong Med J 17:267–273 7. Cheung RY, Chan S, Yiu AK et al (2012) Quality of life in women with urinary incontinence is impaired and comparable to women with chronic diseases. Hong Kong Med J 18:214–220 8. Daan NM, Scheweitzer KJ, van der Vaart CH (2012) Assocaitions between subjective overactive bladder symptoms and objective parameters on bladder dairy and filling cystometry. Int Urogynecol J 23: 1619–1624 9. Ghoniem G, Faruqui N, Elmissiry M et al (2011) Differential profile analysis of urinary cytokines in patients with overactive bladder. Int Urogynecol J 22:953–961 10. Chan SS, Choy KW, Lee BP et al (2010) Chinese validation of urogenital distress inventory and incontinence impact questionnaire short form. Int Urogynecol J 21:807–812 11. Shahani R, Streutker C, Dickson B et al (2007) Ketamine associated ulcerative cystitis: a new clinical entity. Urology 69:810–812 12. Nazif, Techiman JM, Gebhart GF (2007) Neural upregulation in interstitial cystitis. Urology 69:24–33 13. Tyagi P, Barclay D, Zamora R et al (2010) Urine cytokines suggest an inflammatory response in the overactive bladder: a pilot study. Int Urol Nephrol 42:629–635 14. Chiew YW, Yang CS (2009) Disabling frequent urination in a young adult. Ketamine-associated ulcerative cystitis. Kidney Int 76:123–124 15. Tsai JH, Tsai KB, Jang MY (2008) Ulcerative cystitis associated with ketamine. Am J Addict 17:453 16. Colebynders B, Van Erps P (2008) Cystitis due to the use of ketamine as a recreational drug: a case report. J Med Case Rep 2:219 17. Stangou M, Papagianni A, Bantis C et al (2012) Detection of multiple cytokines in the urine of patients with focal necrotizing glomerulonephritis may predict short and long term outcome of renal function. Cytokine 57:120–126 18. Kwon O, Ahn K, Zhang B et al (2010) Simultaneous monitoring of multiple urinary cytokines may predict renal and patient outcome in ischemic AKI. Ren Fail 32:699–708 19. Sairanen J, Hotakainen K, Tammela TL et al (2008) Urinary epidermal growth factor and interleukin-6 levels in patients with painful bladder syndrome/interstitial cystitis treated with cyclosporing or pentosan polysulfate sodium. Urology 71:630–633 20. Chen CH, Lee MH, Chen YC et al (2011) Ketamine-snorting associated cystitis. J Formos Med Assoc 110:787–791 21. Tsai TH, Cha TL, Lin CM et al (2009) Ketamine-assocaited bladder dysfunction. Int J Urol 16:826–829 22. Yeung LY, Rudd JA, Lam WP et al (2009) Mice are prone to kidney pathology after prolonged ketamine addiction. Toxicol Lett 191:275–278 23. Storr TM, Quibell R (2009) Can ketamine prescribed for pain cause damage to the urinary tract? Palliat Med 23:670–672
Int Urogynecol J 24. Keay S, Zhang CO, Shoenfelt JL et al (2003) Decreased in vitro proliferation of bladder epithelial cells from patients with interstitial cystitis. Urology 61:1278–1284 25. Keay S, Zhang CO, Kagen DI et al (1997) Concentration of specific epithelial growth factors in the urine of interstitial cystitis patients and controls. J Urol 158:1983–1988
26. Lee CL, Jiang YH, Kuo HC (2013) Increased apoptosis and suburothelial inflammation in patients with ketamine-related cystitis: a comparison with non-ulcerative interstitial cystitis and controls. BJU Int 112:1156–1162 27. Otto G, Burdick M, Strieter R et al (2005) Chemokine response to febrile urinary tract infection. Kidney Int 68:62–70
ORIGINAL ARTICLE
A pilot study of urine cytokines in ketamine-associated lower urinary tract symptoms Rachel Y. K. Cheung & Jacqueline H. S. Lee & Symphorosa S. C. Chan & Dawn W. T. Liu & K. W. Choy
Received: 21 January 2014 / Accepted: 9 June 2014 # The International Urogynecological Association 2014
Abstract Introduction and hypothesis The aim of this study was to investigate urine cytokine and chemokine levels in symptomatic ketamine abusers compared with age-matched controls. Methods Midstream urine specimens were collected in a prospective study of 23 ketamine abusers and 27 controls who had never used ketamine. Their basic demographic and urinary symptoms were compared. The urine was analyzed by a multiplex panel screen for 19 cytokines/chemokines: EGF, GM-CSF, GRO, IL-1Ra, IL-5, IL-6, IL-7, IL-8, IL-10, IL12p40, IL-12p70, IP-10, MCP-1, MIP-1b, sCD40L, sIL-2Ra, VEGF, MCP-4, and TARC using Luminex™ xMAP® technology. Protein concentration values were normalized to urine creatinine concentrations. Results Mean age of the control group was 21.1±4.3 years (n=27) and of the ketamine group was 20.6±3.7 years (n= 23). All participants were women. The urine cytokine analysis showed a significant elevation in EGF levels in the ketamine group with lower urinary tract symptoms (LUTS) compared with the control group (p 2 years or had stopped < 3 months were comparable with middle-aged women with detrusor overactivity [6, 7]. The pathophysiology of these ketamine-associated urinary symptoms is not clear. LUTS associated with ketamine use overlap with those of overactive bladder (OAB) syndrome [6, 8]. Recent studies have reported the presence of inflammatory biomarker cytokines in urine samples of patients with OAB syndrome [9]. We hypothesized that LUTS in ketamine users may be associated with bladder inflammation. We compared cytokine and chemokine levels in urine samples of ketamine abusers with LUTS and age-matched controls to explore whether there is a relationship between inflammatory markers and the severity of LUTS.
Int Urogynecol J
Materials and methods
Results
The protocol for this research project was approved by the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee Clinical Research Ethics Committee (CUHK-NTEC CRE 2009.453). Adolescents referred to our gynecology clinic with ketamine-abuse-associated urinary problems were invited to participate in the study between December 2009 and April 2010. Aged-matched adolescents who were referred to our clinic with gynecological problems and had no history of ketamine abuse or urinary symptoms were recruited as controls. Consent was obtained before the examination, and concomitant parent or guardian consent was obtained before the examination if the patient was < 16 years. Urinary symptoms were assessed using a validated questionnaire: the Chinese version of Urogenital Distress Inventory Short Form (UDI-6) [10]. A total of 50 midstream urine samples were collected from 23 ketamine abusers and 27 control adolescents who had never abused ketamine. All urine samples had bacteriological investigations, including culture. Cytokines and chemokines were also measured. Urine samples were centrifuged at 3,000 rpm for 10 min immediately after collection. Aliquots of the centrifuged samples were stored at −80 °C pending cytokine/chemokine analysis. A total of 19 cytokines/chemokines, including epidermal growth factor (EGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), growth-regulated peptide alpha (GRO), interleukin-1 receptor alpha (IL)-1Ra, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p40, IL-12p70, interferon gamma-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1b, soluble cluster of differentiation 40 ligand (sCD40L), sIL-2Ra, vascular endothelial growth factor (VEGF), monocyte chemoattractant protein (MCP)-4, and thymus and activation-regulated chemokine (TARC) were tested for in each urine sample using a commercially available human cytokine/chemokine magnetic bead panel (Millipore, Billerica, MA, USA). Cytokine/ chemokine targets in urine samples were captured by specific-antibody-coated, fluorescent-coded magnetic beads and levels were quantified by automated analyzer (Luminex™ 200 System). Cytokine/chemokine levels were normalized to urinary creatinine levels (R&D Systems, Minneapolis, MN, USA). Statistical analysis was performed using the Statistical Package for the Social Sciences (IBM Statistics 20; SPSS Inc, Chicago IL, US). Descriptive statistics were used for age, UDI-6 score, and biomarker calculation. Mann– Whitney U test was used for nonparametric comparison between groups. Pearson’s correlation was used for the association between urine EGF level and UDI-6 score, duration of ketamine use, and duration of cessation of ketamine use.
All participants in both groups were women. Mean age of the control group was 21.1±4.3 years (n=27) and was similar to the ketamine group: 20.6±3.7 years (n=23) ; p=0.35) Mean duration of ketamine use was 55.6 (39.2) months; mean duration since cessation was 7.9 (10.1) months. All users took ketamine by inhalation. No urine sample showed bacterial growth. All participants in the ketamine group were tested for serum renal function, including serum creatinine and urea levels; results were all within normal range. UDI-6 scores are shown in Table 1. There were no urinary symptoms reported in controls. Mean urinary EGF level in the ketamine and control groups was 28,184.3±10,970.1 pg/mg and 18,058.7 ± 11,642.1 pg/mg of creatinine, respectively. Cytokine/ chemokine analysis showed a significant elevation in EGF levels in the ketamine group compared with the control group (p=0.002) (Fig. 1). IL1-Ra, IL-8, MCP-1, sCD40L, and sIL2Ra levels were not statistically different from control values (Table 2), and the levels of the remaining 13 proteins were below detection limits. When evaluating the association between the EGF level in the ketamine group and symptoms score in UDI-6, there was no significant relationship between EGF level and symptoms severity (r=−0.148, p=0.427). The duration of ketamine use (r=−0.097, p=0.607) and of ketamine use cessation (r= 0.243, p=0.187) were also not associated with EGF level.
Discussion Ketamine-related LUTS is a relatively new clinical entity, with patients usually presenting with irritative urinary symptoms. Patients reported increased voiding frequency and reduced functional bladder capacity, which significantly impaired QoL, even after ceasing to use ketamine [11]. These symptoms were very similar to those reported in patients with OAB syndrome or interstitial cystitis [8]. Several pathophysiological mechanisms, including epithelial dysfunction, mastcell activation, and neurogenic inflammation have been proposed to explain symptoms. Different factors including Table 1 The Urogenital Distress Inventory Short Form (UDI)-6 score of ketamine users Variables
Ketamine group (n=23)
Irritative subscale Stress subscale Obstructive/discomfort subscale Total Score
29.6 (18.3) 12.0 (15.8) 29.3 (23.4) 70.7 (49.2)
*No participant in the control group had urinary symptoms and all had zero scores in all subscales
Int Urogynecol J Fig. 1 Mean urinary epidermal growth factor (EGF) level (expressed as pg/mg creatinine) in age-matched controls and ketamine group
bladder epithelial dysfunction with urinary absolute leakage, mast-cell degranulation with vasoactive response and mediators, substance P release, and activation or sensitization of mechanoreceptors or chemoreceptors, have been postulated as contributing to progressive bladder injury [12]. Emerging evidence also suggest there is a change in cytokine/ chemokine profile among OAB or ketamine users. Tyagi et al. reported a significant elevation of cytokines (IL-10, IL12p) and chemokines (MIP-1) in urine samples of OAB patients when compared with controls [13]. Ghoniem et al. found a subset of cytokines to be exclusively expressed in OAB patients [9]. Bladder biopsy from a ketamine user showed various inflammatory changes [14–16]. However, the relationship between urine cytokines and ketamine abuse has not been reported. This study was conducted to examine and study the relationship with urinary symptoms severity. EGF was the only cytokine shown to be significantly elevated in symptomatic ketamine users; the other 18 cytokines/chemokines were not. EGF is a tissueremodeling biomarker that predicts disease progression in many renal conditions [17, 18]. It is also related to treatment outcomes in painful bladder syndrome and interstitial cystitis [19]. Bladder biopsies of ketamineinduced cystitis reveal chronic inflammatory changes similar to those encountered in interstitial cystitis [11], resulting in a thin epithelium with neutrophilic and lymphoplasma cell infiltration of the bladder mucosa [20] and/ or a mononuclear inflammatory cell infiltrate in submucosal tissue [21, 22]. Some patients with serious bladder lesions show no surface epithelium, but only smooth muscle, collagen, and adipose tissue [23]. It has been shown that bladder epithelial cells express EGF [19, 24]. In painful bladder syndrome or interstitial
cystitis, EGF may be needed for re-epithelialization, and elevated EGF concentration may be a response to epithelial damage [25]. The finding of elevated EGF level in ketamine users indicates a similar tissue repairing or fibrosis attributed to their symptoms. Increased urine EGF levels in the ketamine group may be the result of kidney or bladder damage. As ketamine users more often experience urine storage problems, such as urinary frequency and urgency, we hypothesize there may be more epithelial damage and remodeling in the bladder, similar to patients with painful bladder syndrome or interstitial cystitis. It is known that ketamine-related cystitis increases suburothelial inflammation and increases urothelial cell apoptosis. One proposed mechanism involves the direct toxic effect of ketamine and its metabolites on bladder interstitial cells, which is believed to lead to inflammation, submucosal edema, and fibrosis of the detrusor muscles. This direct and indirect
Table 2 Mean urinary cytokine/chemokine level in ketamine and control groups Cytokine/chemokine (pg/mg creatinine)a
Controls
Ketamine
P value
IL-1Ra IL-8 MCP-1 sCD40L sIL-2Ra
348.8±396.2 24.2±27.6 224.7±213.8 115.0±111.1 154.2±85.7
321.6±211.4 30.0±48.2 243.1±125.3 81.2±84.3 151.5±60.5
0.36 0.59 0.25 0.58 0.87
The remaining 13 proteins were below the detection limits (see text for abbreviation) a
See text for definitions
Int Urogynecol J
effect of ketamine and its metabolites may cause an autoimmune reaction against the bladder urothelium, resulting in cell apoptosis. Although EGF level was not associated with symptom severity in this study, it may be associated with epithelial damage and the remodeling process. EGF signaling is needed to activate proliferation and inhibition of unexpected cell death/apoptosis [26]. Therefore, EGF level may help predict the recovery and prognosis of LUTS symptoms. As this is a cohort study with EGF measurement at a single time point, future longitudinal study is needed to observe the relationship of EGF level with disease progression. In this study, 15 of the 23 (65.2 %) ketamine users abused ketamine for > 3 years, and 14 of them (60.9 %) of them had stopped using ketamine for < 6 months. All urine samples were sent for bacterial culture to exclude urinary tract infection (UTI). This was done because UTI is reported to induce higher levels of chemokines in the urine [27]. All urine samples were collected in the first consultation before patients were started on any treatment. Urinary symptoms were assessed by an appropriate, validated QoL questionnaire. Scores from this questionnaire reflect symptomatology reliably [10]. This finding of > 50 % higher urine EGF level in the ketamine group may imply a long recovering period for the damaged bladder epithelium. Besides, the nonsignificant difference and even undetectable levels of the other chemokines and cytokines, including Interleukins, may reflect the reduced inflammatory condition after ketamine cessation. There is very limited information from previous studies regarding urine cytokines in either active or exketamine users for reference. This study was limited by small sample size. Urinary cytokine level may be confounded by other medications the patients were taking. However, both study and control group participants were relatively young and with good past health. They were age matched, and urine cytokine levels had normalized with their urine creatinine levels. We found no association between cytokine level and duration of keratin use or cessation, and this may be affected by various ketamine dosages and purity. It is difficult to quantify accurately the amount of ketamine used or the duration of abuse. In addition, polydrug consumption, with potential impact of EGF levels, cannot be ruled out. In conclusion, EGF was the only elevated marker in urine samples of ketamine users, which may represent the bladder epithelial remodeling process. We should further investigate its level at different time points during the recovering process and review the association of EGF level with associated LUTS disease progress and treatment response. Acknowledgments This study was supported in part by Beat Drugs Fund (MD10835) from the Government of the Hong Kong Special Administrative Region. Conflicts of interest None.
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