Recent study has shown that ribonuclease 7 (RNase 7)
contributes to defense of the human urinary tract
against bacterial infection. The urinary tract is the
body’s drainage system for removing wastes and extra
water. The system includes two kidneys, two ureters,
a bladder, and a urethra. Despite its proximity to the
anus, the urinary tract is usually sterile—but how it
maintains its sterility is not well understood.
Building on previous research that demonstrated
that RNase 7 is produced in human tissues (free
of microscopic signs of disease or inlammation)
of the bladder, ureters, and a speciic part of the
kidney called the collecting tubule, and is present in
uninfected urine in suficient quantity to kill bacteria,
the same group of investigators has now reported
the initial characterization of the antimicrobial
features of RNase 7 in the human urinary tract during
infection. Signiicantly more RNase 7 was detected
in acutely inlamed kidney tissue compared to either
non-inlamed or chronically inlamed kidney tissue.
Consistent with indings included in the scientists’
earlier study, non-inlamed collecting tubule produced
RNase 7, as did acutely inlamed and chronically
inlamed collecting tubule. However, in contrast to
the non-inlamed condition, the kidney’s proximal
tubules produced RNase 7 in the setting of acute and
chronic inlammation. The urine from children with
bacterial infections contained signiicantly more
RNase 7 compared to urine from uninfected children.
RNase 7 was shown to be a potent, broad-spectrum
antimicrobial agent against different types of bacteria
(scientiically categorized as Gram-positive and Gram-negative),
which are commonly found to cause urinary
tract infections. RNase 7 exerts its antimicrobial
activity by disrupting the bacterial cell membrane—
making perforations such that the bacterium is no
This study adds considerable knowledge to
understanding how the urinary tract maintains sterility.
Future studies that reveal the regulatory machinery
involved in RNase 7 production or detail how this
protein exerts its antimicrobial activity at the molecular
level may help develop new therapeutic approaches to
maintaining the sterility of the human urinary tract.
Spencer JD, Schwaderer AL, Wang H, et al. Ribonuclease 7,
an antimicrobial peptide upregulated during infection,
contributes to microbial defense of the human urinary tract.
Kidney Int 83: 615-625, 2013.