Interpretation
Since the detection of microorganisms in the bladder of female without
UTI,12 additional confirmatory evidence has clearly
demonstrated the presence of a living bacterial community in the bladder
of both women with and without lower urinary tract
symptoms.2, 8, 13-15 This significant paradigm shift
raises many questions about the role of the female urinary microflora in
lower urinary tract health and disease. In this
cross-section
study, we characterized the differences of urinary microbiomes between
the women with different degrees of OAB symptoms using high throughput
sequencing of the bacterial 16S rRNA gene.
Besides diverse, the most common urotype in both groups wasLactobacillus , and similar results were observed by PRICE in UUI
patients.16 In addition, we found mild group had a
larger proportion of individuals with Lactobacillus -dominant
urine, previous studies found that the UUI cohort exhibited decreasedLactobacillus sequence abundances compared to those for the
control cohort,2 and in the 5mg Antimuscarinic
responder group,Lactobacilluswas the most frequently cultivable urotype,17 in
contrast, women who developed a post-treatment UTI had fewerLactobacillus sequences.6 Lactobacillusis best known for its dominance in vaginal microbiota and it can prevent
vaginitis by maintaining a physiological acidic environment in the
vagina.
It
seems pretty clear thatLactobacillusin the bladder also plays an important regulatory or protective role in
functional lower urinary tract (LUT) disorders.
The
bacterial diversity (number of unique bacterial species) and
richness were increased in the
moderate/severe patients urinary microbiome, in contrast, the evenness,
represents the distribution of microbial species within the sample, was
not statistically different. Although the M group has a smaller sample
size than the M/S group, we further found statistically significant
trends in terms of species diversity and richness by socres of OABSS,
and confirmed that the higher the socres the higher the Observed
species, Chao1, ACE, and Shannon’s index, verifying that the more severe
the symptoms of OAB patients, the higher the diversity and richness of
urine bacteria. This result is in consistent with the finding of
PRICE16, but is inconsistent with the findings of
Karstens
L.5 PRICE et al. used an enhanced culture method
called Expanded Quantitative Urine Culture (EQUC) coupled to MALDI-TOF
mass spectrometry to identify the Chao1, ACE, and Shannon’s Indices were
positively correlated to Urinary Distress Inventory (UDI) subscale
score, which measures the severity of the disease.16But Karstens et al. found that lower microbial diversity was associated
with increased symptom severity in women with UUI.5 We
think this can be explained by the fact that two seemingly opposite
structural changes in the bacterial flora are both destructive to the
normal bacterial flora. Although little is known about the optimal
characteristics of the urinary microbiome, extreme diversity is unlikely
to be a preferred or advantageous biological state. The lowest diversity
may be associated with a lack of beneficial microbes. At the other
extreme, the increase in diversity may reflect the loss of the urinary
flora regulation mechanism, which does not allow a healthy microbial
community. Despite the differences in the composition of the
inter-individual microbiota, individuals in the same group still have
similarities in the urinary microbiota. as shown in the PCoA analysis
that clustered mild group and moderate/severe group separately (Figure
2), indicating the possibility of a common urinary microbiota disorder
associated with the same degree of OAB.
At phylum level, we detected thatActinobacteriaincreased
significantly in the urine of moderate/severe patients, and our previous
research found that compared with asymptomatic patients, OAB patients
have significantly more Actinobacteria in their
urine.8 These findings raise the possibility that
dysbiotic microbial populations may play a role in the pathogenesis of
OAB. At genus level, correlation analysis found that
several
specific bacteria are associated with different OAB sub-symptoms, some
of which have also been reported by other researchers to be associated
with LUTS. There was a positive correlation between abundance
ofPrevotella and the degree of Nighttime frequency. Coincidentally,
in Pearce et al.’s study,2 they found that enrichment
of Prevotella was observed in UUI patients. Emerging studies have
linked the increased abundance of Prevotella species to localized
disease, including periodontitis, bacterial vaginosis, rheumatoid
arthritis, metabolic disorders and low-grade
inflammation.18 Apostolidis A et al. found bladder
biopsies in patients with OAB revealed signs of chronic
inflammation.19 This suggests that the bladder
microbiome may participate in the occurrence and development of LUTS by
causing chronic inflammation. We also detected that the more severe the
symptoms of Nighttime frequency, the higher abundance ofPorphyromona .
In addition, the same trend
ofPorphyromona abundance changes was observed in Shoskes et
al.’study, which revealed that chronic prostatitis/chronic pelvic pain
syndrome (CP/CPPS) patients had over-representation of genusPorphyromona .20All
these indicate that the intriguing possibility that specific microbial
patterns may be linked to specific symptoms, which provides a great
enlightenment for future researches of the urinary microbiome and the
algorithms for the diagnosis and treatment of LUTS..