Invest Clin 63(1): 81 - 91, 2022 https://doi.org/10.54817/IC.v63n1a07
Corresponding Author: Shibiao Chen, Department of Anesthesiology, the First Affiliated Hospital of Nanchang
University, Nanchang 330006, China. Tel.: 86-0791-88692578. Email: sbiao_ch0211@126.com
Clinical significance of methyl-CpG binding
protein 2 in postherpetic neuralgia:
an observational study.
Zhijian Wang1, Wei Shen1, Mengye Zhu1, Mu Xu1, Mizhen Qiu1, Daying Zhang1
and Shibiao Chen2
1Department of Pain, the First Affiliated Hospital of Nanchang University, Nanchang,
China.
2Department of Anesthesiology, the First Affiliated Hospital of Nanchang University,
Nanchang, China.
Key words: MECP2; postherpetic neuralgia; inflammatory factors; quality of life.
Abstract. The present study was aimed to investigate the clinical signifi-
cance of methyl-CpG binding protein 2 (MECP2) in patients with postherpetic
neuralgia (PHN). This prospective case control study enrolled 319 cases of PHN
patients from April 2017~December 2019. The patients’ sleep quality and qual-
ity of life were evaluated using the Pittsburgh sleep quality score and the SF-
36 scale, respectively. The serum levels of MECP2, CRP, IL-6 and TNF-α were
tested using enzyme linked immunosorbent assay (ELISA). The pain condition
of the patients was evaluated using the visual analogue scale (VAS). The lev-
els of MECP2 were significantly increased in PHN patients compared with the
patients without PHN. Serum MECP2 levels were the highest in patients with
severe pain, and were the lowest in patients with mild pain. Similarly, the fre-
quency of severe pain in patients with low expression of MECP2 was significant-
ly lower than the patients with higher MECP2 expression. Besides, serum levels
of inflammatory factors CRP, IL-6 and TNF-α were markedly increased in PHN
patients, which were also increased with the increase of the severity of pain.
CRP, IL-6 and TNF-α were positively correlated with serum levels of MECP2 in
PHN patients. Before the study, patients with lower MECP2 levels showed a sig-
nificantly higher SF-36 score and lower Pittsburgh and VAS scores than patients
with higher levels of MECP2. However, after one month, no significant differ-
ence was found between the patients. ROC curve showed MECP2 had the po-
tential as a diagnostic biomarker for PHN. In conclusion, higher serum MECP2
levels are associated with a more severe pain condition and increased release of
inflammatory factors.
82 Wang et al.
Investigación Clínica 63(1): 2022
Importancia clínica de la proteína 2 de unión a metil-CpG
(MECP2) en la neuralgia posherpética: un estudio observacional.
Invest Clin 2022; 63 (1): 81 – 91
Palabras clave: MECP2; neuralgia posherpética; factores inflamatorios; calidad de vida.
Resumen. El objetivo de este estudio fue investigar la importancia clínica
de la MECP2 en pacientes con neuralgia posherpética (NPH). Este estudio ob-
servacional prospectivo incluyó 319 pacientes con NPH entre abril de 2017 y
diciembre de 2019. La calidad del sueño y la calidad de vida de los pacientes se
evaluaron con la escala de calidad del sueño de Pittsburgh y la escala SF - 36,
respectivamente. Los niveles séricos de MECP2, PCR, IL-6 y TNF-α fueron de-
terminados por ELISA. Se utilizó la escala visual analógica (EVA) para evaluar la
intensidad del dolor. Los niveles de MECP2 en pacientes con NPH aumentaron
significativamente en comparación con los pacientes sin NPH. El nivel sérico de
MECP2 fue más alto en pacientes con dolor grave y el más bajo en pacientes con
dolor leve. Además, la incidencia de dolor grave en pacientes con baja expresión
de MECP2 fue significativamente menor que en pacientes con alta expresión
de MECP2. Además, los niveles séricos de PCR, IL-6 y TNF-α aumentaron sig-
nificativamente en pacientes con NPH, y se incrementaron con el aumento del
grado de dolor. Los niveles séricos de PCR, IL-6 y TNF-α en pacientes con NPH
se correlacionaron positivamente con los niveles séricos de MECP2. Antes del
estudio, los pacientes con niveles más bajos de MECP2 tenían puntuaciones
significativamente más altas de SF - 36, y puntuaciones más bajas de Pittsburgh
y EVA que los pacientes con niveles más altos de MECP2. Sin embargo, no se
encontraron diferencias significativas entre los pacientes un mes después. Las
curvas ROC mostraron que la MECP2 podría ser un biomarcador de diagnóstico
para la NPH. En general, los niveles séricos más altos de la MECP2 se asociaron
con condiciones de dolor más graves y un aumento de la liberación de factores
inflamatorios.
Received: 11-08-2021 Accepted: 30-10-2021
INTRODUCTION
Postherpetic neuralgia (PHN) is a com-
mon complication after an acute episode of
herpes zoster, with an estimated incidence
of 5~20% in herpes zoster patients, espe-
cially in elderly patients 1-3. Studies report
that PHN can last for months to years, se-
riously affecting people’s quality of life 4.
There are many risk factors to influence the
incidence of PHN 5. Generally, the PHN is
thought to be due to the immune/inflamma-
tory response by the reactivation and migra-
tion of varicella zoster virus 6,7. Since pain
is the most common symptom of PHN, both
inflammation and pain related factors are of
great significance in PHN investigation.
Methyl-CpG binding protein 2 (MECP2),
a kind of protein that can bind methylated
DNA, is thought to play important roles in
nervous system diseases like seizure 8, and is
also associated with pain 9. It is found that the
deficiency of MECP2 in forebrain excitatory
neurons could lead to cortical hyperexcita-
tion and seizures 10. However, overexpression
of MECP2 resulted in higher susceptibility
MECP2 in postherpetic neuralgia 83
Vol. 63(1): 81 - 91, 2022
toward seizures 11. Furthermore, MECP2 is
found to be elevated in several pain and in-
flammation conditions 12, 13. Generally, an
increased MECP2 level is accompanied with
nerve injury, like dorsal root ganglia injury
and increased pain sensitivity 14. However, up
to now, there is no study focusing on the role
of MECP2 in PHN.
In the present study, we performed a
prospective observational research to inves-
tigate the clinical significance of MECP2 in
PHN patients. This study might provide a
new research target and biomarker for PHN.
MATERIAL AND METHODS
Patients
This prospective observational study en-
rolled 319 patients with and without posther-
petic neuropathy from April 2017~December
2019. The diagnosis of herpes zoster was es-
tablished according to the Chinese Consen-
sus of Herpes Zoster 15. The diagnosis of PHN
was determined according to the Chinese ex-
pert consensus on diagnosis and treatment of
postherpetic neuralgia 16. Briefly, the herpes
zoster diagnostic criteria were defined as pa-
tients with irregular erythema occurred in a
certain nerve distribution area, followed by
a majority or cluster of millet to mung bean
sized herpes, which quickly turned into blis-
ters and was accompanied by neuralgia. The
diagnostic criteria of PHN were defined as af-
ter the skin lesions of herpes zoster subsided,
the patient developed local pain, pruritus and
paresthesia for more than one month. The
inclusion criteria were: 1) all patients were
diagnosed as PHN according to the above
criteria and didn’t receive any treatment be-
fore; 2) the patients showed abnormal pain
and touch feeling distributed by innervation
area and sometimes showed skin pigmenta-
tion; 3) the pain types were as sharp pain or
persistent burning pain, or tight bundle pain;
and 4) patients showed other discomfort on
lesion position after nerve injury, including
itching, tight feeling and ant feeling. The fol-
lowing patients were excluded: 1) patients
with severe inflammation diseases, such as
pneumonia; 2) patients with fractures or
other severe system diseases like myocardial
infarction or stroke within three months be-
fore the study; 3) patients with other neu-
ralgia like intercostal neuralgia, cephalalgia
nervosa, post-stroke neuralgia, etc. All pa-
tients received routine strategy therapy in-
cluding anti-pain treatment like treatment
with pregabalin (150 mg×2/d for 14 d) or
carbamazepine (100 mg/d for 14 d), and the
grade of pain was recorded by the patients in
awake state. Additionally, serum samples and
medical records were collected from the 319
herpes zoster patients whose skin lesions of
herpes zoster subsided without PHN. The in-
clusion of herpes zoster patients without PHN
was according to the above diagnostic criteria
of herpes zoster as well as the above inclu-
sion criteria. All participants signed a written
informed consent. The ethic approval was ob-
tained from the Ethic Committee of the First
Affiliated Hospital of Nanchang University
and a written informed consent was obtained
from all patients.
Measurement of MECP2 and inflammatory
factors
Blood samples of all PHN patients were
collected at the day they came to the out-
patient department. The samples were col-
lected in tubes without anticoagulant and
were centrifuged at 12000 g for 20 min.
The serum levels of MECP2, CRP, IL-6 and
TNF-α were tested using commercially avail-
able enzyme linked immunosorbent assay
(ELISA) kits according to the manufactur-
er’s instructions. The kits used were MECP2
(MYBioSource, cat. No. MBS2515729),
CRP (BOSTER Bio, cat. No. EK1316), IL-6
(BOSTER Bio, cat. No. EK0410) and TNF-α
(BOSTER Bio, cat. No. EK0525).
Data collection
The pain condition of patients was evalu-
ated at the time of diagnosis using the visual
analogue scale (VAS). The severity of the pain
condition of PHN patients were defined as: mild
84 Wang et al.
Investigación Clínica 63(1): 2022
VAS 1~3, moderate VAS 4~6, or severe VAS
7~10. Patient’s demographic data including
age, sex, BMI, complications, and clinical char-
acteristics including disease course, rash types
and sites of skin involvement, were collected.
The patients’ sleep quality and quality of life
were evaluated using the Pittsburgh sleep qual-
ity score and the SF-36 scale before the study
and after one month of treatment, respectively.
Statistical analysis
All data distributed normally were ex-
pressed by means ± SD. The distribution
of the data was analyzed by Kolmogorov-
Smirnov method. Comparison between the
two groups was conducted by t test and com-
parison among three or more groups was
performed using one-way analysis of variance
(ANOVA) followed by Tukey post hoc test.
Rates were compared by Chi square test.
ROC curve was used for diagnostic value
of MECP2 in PHN patients. All calculation
was performed using SPSS 18.0 (SPSS Inc.,
Chicago, USA) and GraphPad 6.0 (GraphPad
Software, San Diego, CA, USA).
RESULTS
MECP2 was upregulated in PHN patients
The basic clinical characteristics of all pa-
tients are listed in Table 1. There were no sig-
nificant differences in age, sex, BMI and com-
plications between the PHN patients and the
controls. The mean VAS score of all PHN pa-
tients was 3.38±2.26. Serum levels of MECP2
were determined in PHN patients and the her-
pes zoster patients without PHN. It was found
that the levels of MECP2 were significantly in-
creased in PHN patients when compared with
the non-PHN patients (P<0.05, Fig. 1).
Table 1
Basic characteristics of all participants.
Variables PHN, n=319 non-PHN, n=319 P value
Age, y 58.32±8.71 58.71±8.88 0.571
Sex, male (%) 179 (56.11) 170 (53.29) 0.689
BMI, kg/m225.33±3.81 25.34±3.79 0.985
Complications, n (%) 0.848
Diabetes 33 (10.34) 38 (11.91)
Hypertension 56 (17.55) 47 (14.73)
Current smoker 112 (35.11) 108 (33.86)
Disease course (PHN), Mon 4.40±1.12 -
Sites of skin involvement, n (%) 0.908
Lumbosacral nerve area 154 (48.28) 161 (50.47)
Intercostal nerve area 61 (19.12) 52 (16.30)
Trigeminal nerve area 43 (13.48) 37 (11.60)
Brachial plexus area 25 (7.84) 30 (9.40)
Perineal nerve area
VAS score 3.38±2.26 -
Distribution of VAS score, n (%)
Mild 152 (47.65) -
Moderate 98 (30.72) -
Severe 69 (21.63) -
MECP2 in postherpetic neuralgia 85
Vol. 63(1): 81 - 91, 2022
MECP2 was positively correlated with pain
severity of PHN patients
Then, levels of MECP2 were detected in
PHN patients with different pain severities.
As shown in Fig. 2, serum MECP2 levels were
the highest in patients with severe pain, and
were the lowest in patients with mild pain,
and the difference was significant between
the groups (P<0.05). The patients were then
further divided into high MECP2 expression
group and low MECP2 expression group ac-
cording to the mean serum levels in PHN pa-
tients (45.83 ng/mL). It was found that the
frequency of severe pain in patients with low
expression of MECP2 was significantly lower
than the patients with higher MECP2 expres-
sion (P<0.05, Table 2). Notably, patients
with mild pain were found to be markedly de-
creased in patients with higher MECP2 than
patients with higher MECP2 (P<0.05).
Relationship between MECP2 and
inflammatory factors in PHN patients
To further investigate the role of
MECP2 in PHN, the serum levels of inflam-
matory factors CRP, IL-6 and TNF-α were de-
termined. It was found all these factors were
markedly increased in PHN patients com-
pared with the no-PHN patients (P<0.05,
Fig. 3), and serum levels of CRP, IL-6 and
TNF-α increased with the severity of pain in
PHN patients (P<0.05), except for the differ-
ence of TNF-α between severe and moderate
pain. The Pearson’s correlation test showed
that CRP, IL-6 and TNF-α were positively cor-
related with serum levels of MECP2 in PHN
patients (P<0.05, Table 3).
Association between MECP2 and quality
of life of PHN patients
The Pittsburgh sleep quality score and
the SF-36 scale, as well as the VAS score were
then evaluated before the study and after
one month of treatment. It was found that
before study, patients with lower MECP2 lev-
els showed significantly higher SF-36 score
and lower Pittsburgh and VAS scores than
patients with higher MECP2 (P<0.05, Table
4). However, after one month, no significant
differences were found between the patients.
Diagnostic value of MECP2 in PHN
Finally, we determined the diagnostic
value of MECP2 for PHN in herpes zoster
Serum MECP2 (ng/ml)
PHN
non-PHN
0
10
20
30
40
***
Fig. 1. Serum levels of MECP2 in PHN patients and the non-PHN.
86 Wang et al.
Investigación Clínica 63(1): 2022
patients. It was found that MECP2 has the
potential as a biomarker for PHN diagnosis,
with a ROC curve ACU, cutoff value 33.56
ng/mL, sensitivity 70.5%, specificity 65.5%
(Fig. 4).
DISCUSSION
Postherpetic neuralgia is a common
complication after treatment of herpes zos-
ter and may decrease the patients’ quality
of life. Since the prevention of PHN is an ef-
fective method to reduce the patients’ pain
after herpes zoster, biomarkers for diagnosis
and prediction of PHN are also important.
In the present study, we demonstrated that
serum MECP2 was up-regulated in PHN pa-
tients and higher MECP2 was associated with
a more severe pain condition, higher levels
of inflammatory factors, and lower quality of
life before treatment.
Rzeszotarska have reported that MECP2
is a factor associated with both inflammatory
factors and pain 12. Generally, most studies
found that increased MECP2 is associated
with increased pain sensitivity and increased
pro-inflammatory factors. It was found in
the mouse chronic pain model, that MECP2
was increased in S1 glutamate (GluS1) neu-
rons and increased MECP2 was associated
with increased neuronal activity and knock-
down of MECP2 diminished the offspring
pain sensitization, which was increased by
overexpressing MECP2. In 2,4,6-trinitroben-
zenesulfonic acid-induced- pelvic inflamma-
tion pain in a rat model, MECP2 was also
Serum MECP2 (ng/ml)
M ild
Moderate
Severe
0
50
100
150
***
***
Fig. 2. Serum levels of MECP2 in patients with different pain severity.
Table 2
Pain severity in PHN patients with different expression of MECP2.
Variables Low MECP2, n=173 High MECP2, n=146 P value
VAS distribution, n (%) <0.0001
Mild 113 (65.32) 39 (26.71)
Moderate 43 (24.86) 55 (37.67)
Severe 17 (9.83) 52 (35.62)
MECP2 in postherpetic neuralgia 87
Vol. 63(1): 81 - 91, 2022
found to be overexpressed in neurons and
the increased MECP2 was accompanied with
increased cAMP response element-binding
protein 13. In chronic constriction injury,
global DNA methylation and MeCP2 expres-
sion were both increased in the rats’ spinal
cord, which could be decreased by intrathe-
cal 5-azacytidine 17. Besides, the deficiency of
MECP2 resulted in an increase in neutrophil
infiltration and anti-inflammatory factor
IL-10, as well as decreased level of TNF-α 18.
The inhibition of MECP2 was also found to
alleviate inflammation, while overexpression
of MECP2 promoted inflammation response
in different kinds of cells 19-21. However, sev-
eral studies also found positive results, dem-
onstrating overexpression of MECP2 led to
decreased acute mechanical pain, thermal
pain in acute pain transduction and over-
expression improved neuropathic pain 22. In
Rett syndrome, mutation and duplication of
MECP2 both induce decreased pain sensitiv-
ity 9. Besides, MECP2 deficiency might also
exacerbate neuroinflammatory setting and
autoreactive response during an autoim-
mune challenge 23. In the present study, we
observed that serum MECP2 was up-regulat-
ed in PHN patients and was associated with
Fig. 3. Serum levels of CRP, IL-6 and TNF-α in non-PHN patients and PHN patients with different pain severity.
Table 3
Correlation between MECP2 and inflammatory
factors in PHN patients.
Factors Pearson’ correlation P value
CRP 0.495 <0.001
IL-6 0.471 <0.001
TNF-α0.354 <0.001