1666 | Miscellaneous
The Value of Neutrophil Elastase in Diagno-
sis of Type III Prostatitis
Jun Zhu, Changhai Yang, Zhichun Dong, Liming Li
Corresponding Author:
Changhai Yang, MD
Department of Urology, Tianjin Medi-
cal University General Hospital, 154
Anshan Road, Heping District, Tianjin
300052, China.
Tel: +86 22 6553 9807
Fax: +86 22 6553 9807
E-mail: ychanghai@yahoo.com
Received August 2013
Accepted April 2014
Department of Urology, Tianjin
Medical University General
Hospital, 154 Anshan Road,
Heping District, Tianjin 300052,
China.
MISCELLANEOUS
Purpose: To explore the value and significance of neutrophil elastase (NE) in diagnosis of
type III prostatitis.
Materials and Methods: The prospective study recruited 123 patients diagnosed with type III
prostatitis (IIIA, 36 cases; IIIB, 87 cases) and 84 healthy controls, between April 2008 and July
2012. NE concentrations in expressed prostatic secretions (EPS), EPS routine examination,
bacterial culture and The National Institute of Health Chronic Prostatitis Symptom Index (NIH-
CPSI) score were detected in all the subjects. Difference of NE, CPSI score, and withe blood
cell (WBC) count between 2 or more than 2 groups and relationships between NE concentra-
tions and WBC count were all analyzed.
Results: There was significant difference in levels of NE (P < .05) between IIIA and IIIB
groups, and obviously positive correlation between the level of NE and number of leukocyte
in type IIIA prostatitis group was observed (P < .05). The values of CPSI score between IIIA
and IIIB groups was statistically significant (P = .037). The levels of leukocyte mount, NE
and CPSI were statistically significant between IIIA and the control group (P < .05). NE con-
centration and CPSI score were statistically significant between IIIB and control group (P <
.05), while the numbers of leukocyte was not statistically significant (P = .360).
Conclusion: The level of NE in EPS is a significant indicator in diagnosis of type IIIA and
IIIB prostatitis.
Keywords: prostatitis; classification; diagnosis chronic disease; leukocyte elastase; chem-
istry.
1667Vol. 11 | No. 03 | May - June 2014 |U R O LO G Y J O U R N A L
The value of NE in Diagnosis of Type III Prostatitis | Zhu et al
INTRODUCTION
Prostatitis is an inflammation of the prostate and chronic prostatitis is the most common urologic disease in men less than 50 years old, accounting
for approximately 8-25% of the urology outpatients.(1,2) In
the US, over 2 million patient-visits per year are a result of
prostatitis.(3) Data has shown that about 50% of men suffer
from prostatitis in a period of their lifetime.(4) It is not only
brought kinds of discomfort to the patients, but also took
significant harm to their mental health(5-8) and caused huge
economic burden on public health.(9-12) Due to the complex-
ity of its etiology and various symptoms, clinical diagnosis
of the cause and therapy has been lack of effective programs
and methods and the therapy effect is usually unsatisfactory.
According to The National Institute of Health (NIH) clas-
sification method in 1995, type III prostatitis (chronic non-
bacterial prostatitis) is the most common disease, account-
ing for approximately 95% of the urology outpatients.(13) It
is also divided into two subtypes IIIA and IIIB according to
whether there are white blood cells (WBCs) in expressed
prostatic secretions (EPS). More evidences revealed that
the therapy and treatment were significantly different be-
tween two subtypes of type III prostatitis.(14,15) However, in
clinical treatment, IIIA and IIIB of chronic prostatitis has
similar clinical symptoms and it is difficult and not effective
to distinguish them by WBC count only.(16,17) Researchers
tried to find other factors, in addition to leukocytes, which
could effectively differentiate IIIA and IIIB prostatitis, for
chronic prostatitis caused the prostate secretory abnormal-
ity on prostate secretory functions.(18-21)
In this study, we detected concentrations of the neutrophil
elastase (NE) in EPS among IIIA, IIIB prostatitis patients
and normal control group and compared the difference of NE
concentrations in EPS among type IIIA, IIIB chronic prosta-
titis patients and normal control group to attempt to provide
a reliable measure for distinguishing and diagnosing the type
III chronic prostatitis.
MATERIALS AND METHODS
An observational prospective design was applied in this
study. A total of 123 patients diagnosed with type III prosta-
titis were recruited to participate in the study between April
2008 and July 2012. The exclusion criteria were the pres-
ence of cancer of the genitourinary tract; active urinary stone
disease or herpes of the genitourinary system; perirectal in-
flammatory disorders; inflammatory bowel disease; a history
of pelvic radiation or systemic chemotherapy; a history of
intravesical chemotherapy; urethral stricture 12 French (F) or
smaller; neurologic disease or disorder affecting the bladder;
and prostate surgery within the past 3 months. The inclusion
criteria were, patients between 18 to 50 years old to reduce
the effect of age factor, the course of the disease lasted for a
period of at least three months, patients receiving no antibi-
otic treatment for any reason for the last 4 weeks, patients
whose prostatic fluid having no bacterial growth and patients
having symptoms of discomfort or pain in the pelvic region.
The diagnosis of patients was consistent with the NIH defini-
tion of the chronic prostatitis/pelvic pain syndrome.(22) Pa-
tients with type III prostatitis were classified as having sub-
type IIIA (36 cases) or IIIB (87 cases). Ejaculated samples
from healthy men showed a good sperm density and progres-
sive motility and morphology (≥ 20%) and were considered
normal ejaculates according to World Health Organization
criteria.(23) Eighty-four normal volunteers who didn’t show
any signs of prostatic diseases were used as controls. They
were recruited from the subjects undergoing complete his-
tory and physical examination. Informed consent was ob-
tained from their parents. Study protocols were approved by
Figure . Correlation analysis of NE and WBC count between IIIA and
B groups. NE concentrations was positively correlated with WBC
count (Spearman's rank correlation coefficient, r = 0.596, P < .05).
Keys: WBC, white blood cell; NE, neutrophil elastase.
1668 |
the Institutional Research Ethics Committee of the General
Hospital of Tianjin Medical University.
A complete history and physical examination were per-
formed, including laboratory analysis, which was micros-
copy and culture of the urine specimen before massage,
and EPS and/or urine specimen after prostatic massage. For
category IIIA the EPS and/or urine specimen after prostatic
massage had to be sterile with no uropathogenic growth, and
there had to be a documented inflammatory pattern on mi-
croscopy of EPS that was greater than 10 WBCs per high
power field (hpf), and/or urine sediment after prostatic mas-
sage that was greater than 5 WBCs per hpf. To be classified as
IIIB, the EPS and/or urine specimen after prostatic massage
had to be sterile with no uropathogen growth, and there had
to be no documented inflammatory pattern on microscopy of
EPS that was less than 10 WBCs per hpf, and/or urine sedi-
ment after prostatic massage that was less than 5 WBCs per
hpf. All patients had a complete medical history, a physical
examination, and a 4-glass urinalysis, WBC counts in EPS,
serum prostate specific antigen (PSA), NIH-CPSI score, and
transrectal ultrasonography, according to Hochreiter and col-
leagues.(24)
Prostatic fluid samples were obtained at the hospital by pro-
static massage, after a period of sexual abstinence of 3-5
days. The samples were collected in a sterile container and
transferred to a cryovial, stored at –20°C. Standard microbial
investigations (e.g., for aerobic and anaerobic bacterial infec-
tions, ureaplasma urealyticum and mycoplasma infections,
chlamydia trachomatis, trichomonas vaginalis and candida
infections) were performed for all prostatic fluid samples.
Some of the fluid was transferred for storage at –80°C until it
was used for the analysis of NE. The remaining fluid on the
glass slide was placed under a coverslip and examined for
WBC count in 5 fields at high power (400 ×). The average
number of WBCs per hpf was recorded.
NE was determined by quantitative sandwich enzyme immu-
noassay [Human PMN Elastase ELISA (enzyme-linked im-
munosorbent assay), Ray Biotech., Inc., Minneapolis, MN,
USA] according to the manufacturer’s instructions. The in-
tensity of the color was measured at 450 nm.
Statistical Analysis
Data were analyzed by using the statistical package for the
social science (SPSS Inc, Chicago, Illinois, USA) version
19.0. Normally distributed continuous data are presented as
means ± standard deviation (SD) and were compared using t
tests. Non-normally distributed continuous data are present-
ed as the median and range, and were compared using the
rank test. Difference among 2 or more than 2 groups were
Miscellaneous
Table 1. Changes in IPSS and uroflowmetry parameters after treatment with tamsulosin.
Characteristics
Patients Controls
IIIA IIIB ---
Number of subjects 36 87 84
Mean age, years 32 30 28.88
Course (months)
3-6 22 52 ------
> 6 14 35
Bacterial infection
Positive 0 0 0
Negative 36 87 84
CPPS symptom 36 87 -----
Associated symptom
LUTS 28 48
Non-LUTS 8 39
CPPS treatment
α-Blockers 28 65
NSAID 25 48
Keys: CPPS, chronic pelvic pain syndrome; NSAID, nonsteroidal anti-inflammatory drug; LUTS, lower urinary tract symptoms.
1669Vol. 11 | No. 03 | May - June 2014 |U R O LO G Y J O U R N A L
assessed by using t tests, ANOVA or post hoc Dunnett's T3
tests, as required. Correlations of NE, NIH-CPSI score and
WBC count were analyzed by Spearman's rank correlation
coefficient. The P value < .05 was considered statistically
significant.
RESULTS
Patients' Characteristics
A total of 207 participants in Tianjin Medical University
General Hospital were studied. There were 36 cases of type
IIIA prostatitis, 87 cases of type IIIB prostatitis and 84 cases
of normal controls. The general characteristics of the recruit-
ed patients are shown in Table 1.
NE Concentrations Were Elevated in Prostatitis Patients as
Compared with Controls
We summarized the WBC count, NIH-CPSI score and NE
concentrations in prostatitis IIIA, IIIB and control groups, re-
spectively (Table 2). NE concentration in patients with pros-
tatitis IIIA displayed significantly higher as compared with
that of prostatitis IIIB group (median 907.33 ng/mL, in con-
trols vs. 94.92 ng/mL, respectively, P < .05; Table 3).
Association Analysis of NE Levels CPSI Score and WBC
Count
As shown in Table 3 and Figure, the level of NE was posi-
tively correlated with WBC count (Spearman's rank correla-
tion coefficient, r = 0.596, P < .05). Data revealed that there
was significant differences on the values of CPSI between
prostatitis IIIA and prostatitis IIIB (P = .037).
Test data of the experimental and control groups were also
compared by SPSS 19.0. The NE in EPS of patients with
prostatitis IIIA and IIIB was statistically different from that
of control group (all P < .05). The CPSI score of patients with
prostatitis IIIA and IIIB was also statistically different from
that of control group (all P < .05). WBC count in patients
with prostatitis IIIA displayed statistically significant differ-
ence as compared with that of control group (P < .05), but
there was no statistical difference on WBC count between
prostatitis IIIB group and control group (P = .360).
DISCCUSSION
It has been diagnosed as type III prostatitis that patients
showing obvious symptoms of chronic bacterial prostatitis
but microbiological culture results were negative.(25) How-
ever, with the improvement and optimization of culture
methods, we observed the microbial growth in the EPS from
patients that were traditionally diagnosed for type III prosta-
titis. For example, coagulase-negative cocci was difficult to
grow in general medium, however, after obligate culture, it
was demonstrated that coagulase negative cocci existed in
the EPS of about 68% of patients with type III prostatitis,
which was further to be confirmed by microscopic examina-
tion.(26) The traditional culture method had played an impor-
tant role in the diagnosis and treatment of prostatitis, but it
was a time-consuming and laborious process and susceptible
to contaminate, especially, only a small number of microbial
species were able to cultivate.(27,28) Thus, the traditional cul-
ture method played a limited role in the course of recognition
about type III prostatitis related microorganisms.
Elastase is a kind of enzyme that can hydrolyze elastin in
the body and named by the generated sites, such as neutro-
phils elastase (NE), which was present in neutrophils. Under
physiological conditions, NE played an effective protection
in host defense system, and its activity was strictly regulated
by the inhibitors of endogenous protease. In early stage of in-
flammation, WBCs were the first line of defense when patho-
gen invaded into the body. The gathered at the site of inflam-
mation by chemotaxis of kinds of chemokines and NE were
released by neutrophils. NE can escape from the regulation
The value of NE in Diagnosis of Type III Prostatitis | Zhu et al
Table 2. Related data in the test groups and the control group.*
Groups No. WBC count NIH-CPSI score NE
IIIA 36 17.89 ± 6.18 24.50 ± 5.41 907.33 ± 769.70
IIIB 87 4.01 ± 2.21 21.80 ± 5.01 0.119 ± 0.009
Control 84 3.60 ± 2.21 1.72 ± 0.74 0.068 ± 0.015a
Keys: WBC, white blood cells; NIH-CPSI, National Institutes of Health-Chronic Prostatitis Symptom Index; NE, neutrophil elastase (ng/mL).
* Data are expressed as means ± SD.
1670 |
of multiple protease inhibitors at the inflammation site. The
balance was broke out between NE and its endogenous pro-
tease inhibitors and NE maintained the activated state, result-
ing in the damage and dysfunction of the tissues and organs.
Recent studies have found that infectious NE levels in EPS
of prostatitis patients were significantly higher than that in
patients with non-infectious prostatitis, which demonstrated
that NE could distinguish infectious and non-infectious pros-
tatitis to a certain extent.(29) Some researchers reported that
compared with C3, the terminal complement complex and
plasma ceruloplasmin, NE was the best indicator to diagnose
of the acute and chronic urethritis/prostatitis.(30,31)
Simultaneously, NE also can be used as a detected indica-
tor of clinical efficacy. NE concentration rapidly increased
to more than 290 ng/mL from the normal level at the stage
of acute inflammation until the inflammation was cured.
Otherwise, the concentration of NE would maintain a high
level.(32) Decreased NE levels showed that anti-inflammatory
treatments were effective. If NE levels had not declined, the
treatment plan should be redesigned, prompting doctors to
find out the other chronic inflammatory lesions.(11)
In the study, we identified a NE cutoffs (246.4 ng/mL) for
diagnosing type prostatitis patients, which is slightly lower
than the revised cutoff of 280 ng/mL for diagnosing inflam-
matory disease as depicted in the literature. (30) This findings
may be the results that NE secretion is different in various tis-
sues and organs or affected by different individuals or popu-
lations. Besides, we measured the NE concentration in EPS
of patients with type IIIA and IIIB prostatitis. We found that
NE concentrations in EPS of prostatitis IIIA was significantly
higher than that of prostatitis IIIB. NE concentrations in EPS
of patients with type IIIA and IIIB prostatitis were both sig-
nificantly higher than that in the normal control group. These
results indicated that patients with type IIIA and type IIIB
prostatitis were both infected with microorganisms. The in-
fection in patients with type IIIA prostatitis was more seri-
ous than that with type IIIB prostatitis. When tissues were
infectious, NE was released by neutrophils. Thus, we can
make a conclusion that antibiotic treatment may be a pos-
sible method for the type III prostatitis, especially type IIIA
chronic prostatitis. In addition, we compared the correlation
between NE concentration and leukocytes in EPS of patients
and found that NE concentration positively correlated with
leucocyte amount, which indicated that NE can be used as a
meaningful indicator in the diagnosis of type III prostatitis,
and also demonstrated that the levels of NE concentration
were able to reflect the severity of chronic prostatitis.
However, we also observed that higher NE concentration ac-
companied with few leucocyte amount or low CPSI score
which was uncommon, but with some meaning. For example,
the results that high NE concentration accompanied with few
WBCs were observed and it was largely because prostate duct
was blocked that the WBCs at inflammatory sites could not
spread into EPS and were not calculated, but NE could spread
Miscellaneous
Table 3. Difference of related indicators among 2 or more than 2 groups.
Groups IIIA/IIIB IIIA/Control IIIB/Control III (A+B)/Control
MD (I-J) p MD (I-J) p MD (I-J) p t p
WBC count 14.061 < .05 14.591 < .05 0.530 .360 6.438937 < .05
NIH-CPSI score 2.695 .037 23.762 < .05 21.067 < .05 44.99526 < .05
NE 812.4092 < .05 834.7583 < .05 22.34914 .097 5.125425 < .05
Keys: WBC, white blood cells; NIH-CPSI, National Institutes of Health- Chronic Prostatitis Symptom Index; NE, neutrophil elastase; MD, mean differ-
ence.
Table 4. Correlation analysis of WBC count, NIH-CPSI score and NE between IIIA and IIIB groups.
Parameters WBC/NIH-CPSI score WBC/NE NIH-CPSI score/NE
r 0.402 0.596 0.382
P < .05 < .05 < .05
Keys: WBC, white blood cells; NIH-CPSI, National Institutes of Health- Chronic Prostatitis Symptom Index; NE, neutrophil elastase; r, Pearson correlation coefficient.
1671Vol. 11 | No. 03 | May - June 2014 |U R O LO G Y J O U R N A L
The value of NE in Diagnosis of Type III Prostatitis | Zhu et al
into EPS. Currently, the main criteria of prostatitis in clinical
diagnosis were that WBC count was more than 10 in EPS, but
it was not accurate only relying on one diagnostic indicator.
Diagnosis of prostatitis should be a systematic work and all
of the treatment should be checked including the symptoms,
pathological examination (EPS microscopy), physiological
and biochemical test, bacteriological examination, ultrasound
examination and urodynamic examination and etc. All of the
diagnostic treatments should be a comprehensive, objective
and scientific on prostatitis. In conclusion, NE concentration
in EPS of patients can be used as a reference for diagnosis of
type III A and B prostatitis. With the promotion of inspection
techniques, such as protein chip, the detection of NE concen-
tration would be more convenient and may become one of the
diagnostic indicators of type III prostatitis.
CONCLUSION
The limitation of our study is the lack of a large group of
patients which may create the risk of a type II statistical er-
ror, but despite that, the study has shown that the level of NE
in EPS is a significant indicator in diagnosis of type IIIA and
IIIB prostatitis. There was a positive correlation between NE
concentration and the leukocyte mount, which demonstrated
the levels of NE in EPS could reflect the severity of type III
chronic prostatitis.
CONFLICT OF INTEREST
None declared.
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