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Uncircumcised Men Have Greater HIV Risk A new study conducted by
Chicago researchers shows that internal mucosal layers of foreskin are more
susceptible to HIV infection than cervical tissue or the external layers of
foreskin, which explains why uncircumcised men seem to be at much higher risk
for HIV acquisition than men who are circumcised. Previously, numerous studies
reported that uncircumcised men have higher rates of HIV infection and are at a
twofold to eightfold increased risk of becoming infected with HIV compared to
circumcised men. However, why circumcision plays a protective role against
acquisition of HIV has been unknown.
A study published in the September issue of the American Journal of Pathology
by researchers at Rush-Presbyterian-St. Luke's Medical Center, Children's
Memorial Hospital and the University of Illinois at Chicago School of Public
Health points to the biological mechanisms underlying this protective effect.
The researchers examined foreskin tissue obtained from eight children and six
adults who were undergoing circumcision for other reasons. Those tissues were
compared with cervical tissue, which served as controls. The analysis showed
that foreskin mucosa (cells underneath the surface) contain high concentrations
of the cells targeted by HIV. The foreskin tissue contained higher densities of
CD4 T cells, macropahges and Langerhans' Cells (LC) in adults than in children
or in cervical tissue. The highest proportion of these HIV target cells were
found in men with a history of infection, which is consistent with studies
finding that men with sexually transmitted infections are more susceptible to
HIV.
According to Alan Landay, PhD, department of Immunology/Microbiology and at
Rush-Presbyterian-St. Luke's Medical Center, the higher the concentration of HIV
target cells, the more susceptible the tissue is to HIV. This proved to be the
case. When the authors introduced HIV to the tissue in culture, the cells in the
foreskin tissues were infiltrated with HIV rapidly and at much greater intensity
than the cervical tissue.
According to the first author, Bruce Patterson, M.D, viral pathologist in the
division of Infectious Diseases at Children's Memorial Hospital, there are
logical, but as yet unproven theories explaining how HIV infection occurs in the
circumcised penis. "Infection may occur through the urethral mucosa or through
disruptions of the penile shaft epithelia caused by genital ulcer disease or
trauma," he said. In uncircumcised men, Patterson said that the thin keratin
layer they found on the inner compared to the outer mucosal surface predisposed
the foreskin to infection.
The authors mention that a limitation of the study is that they were unable
to obtain tissue from circumcised penises for comparison.
However, the study's senior author, Robert Bailey, PhD, MPH, from the
Division of Epidemiology, School of Public Health at the University of Illinois
at Chicago, is conducting a study in east Africa that will address this issue.
Bailey and his collaborators have begun a randomized controlled trial to compare
HIV acquisition in 1,400 African males age 18-24 who will be circumcised with
1,400 in the same city who are not circumcised.
Bailey's team will take two years to recruit all the young men and will
follow each group for two years, providing them with HIV prevention counseling
and free medical treatment. After four years of study, they will be able to
determine if circumcision reduced the men's chances of becoming HIV infected.
Landay said that the implications of this foreskin tissue evaluation and the
positive association between uncircumcisized individuals and HIV acquisition
indicate that strong consideration should be given to integrating male
circumcision information and services with other HIV preventive methods. |
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