MAP Research
Johne's Disease Connection
The microorganism, mycobacterium avium subspecies paratuberculosis,
has been established in the veterinary literature to be the cause for Johne's
disease, a disease causing colitis in cattle, sheep, and subhuman primate
species. This disease resembles, clinically, Crohn’s disease in humans
and acts very much the same. Studies in England and in Wales
have shown the presence of mycobacterium paratuberculosis in milk and water
supplies. It is known that infected cows secrete this bacteria in
milk and hence, milk borne infection appears to be theoretically possible.
Crohn's Recognized
Crohn's disease was first recognized by a Glasgow surgeon, named Dalziel
in 1913, when he first recognized that this disease was different than
intestinal tuberculosis; however, similar to paratuberculosis in cows.
At that time, he postulated a possible mycobacterial cause; however, failed
to prove this connection, in that this organism could not be demonstrated
microscopically or cultured. In 1932, Dr. Crohn and Dr. Ginzberg felt that
this disease was not due to a mycobacterial origin since these Crohn’s
patients were not found to have this bacteria visible microscopically and
by culture technique. An important milestone in the research of mycobacterium
occurred in 1985, when a genetic code (the IS900 insertion sequence) that
is unique for mycobacterium paratuberculosis was found in both the bacillary
and spheroplast forms of this microorganism. A technique known as
polymerase chain reaction (PCR technique) makes it possible to detect minute
numbers of this mycobacterium paratuberculosis against other DNA signals
present in the human body. This sequence is very specific for this
species of mycobacterium since there are many other known species that
can cause disease (tuberculosis, avium, intracellulare, etc.). A number
of studies have now confirmed the identification of mycobacterium in serum
responses (antibody response), as well as in tissue studies (PCR studies),
confirming the presence of this bacteria in patients with Crohn’s disease
as compared with non-inflammatory bowel disease patients. The studies to
date have shown this microorganism to be present in higher numbers percentage-wise
in Crohn’s disease patients.
Associated with CD
Consequently, the paratuberculosis problem not only includes the challenge
of linking this bacteria to a specific disease, but also, the possibility
that this mycobacterium paratuberculosis
has
been carried to human populations in certain foods and, in some areas,
via the water supply. Most of us have been exposed to these bacteria and
because of our immune systems ability to fight this bacteria, a transient
intestinal infection will occur (short-lived diarrhea) and there will be
no after effects. However, in those people genetically susceptible to inflammatory
bowel disease (patients with a genetic predisposition, i.e. family history,
or other risk factors such as immunosuppressed states), this infection
can cause a disease, causing inflammation of the bowel and subsequent immune
response, which is characteristic in patients with Crohn’s disease. The
factors making one predisposed to this microorganism are, to date, undefined
and recent genetic studies suggest a defect in chromosome 12 or chromosome
16 in patients susceptible to Crohn’s disease. Because of this association
of mycobacterium paratuberculosis and the response to its pathogenicity,
recurrent spells of exacerbation and remission, so characteristic of this
disease, can occur. It is felt that in the early phase of this disease,
clinical improvement can be achieved by killing the bacterium. There has
been one clinical trial of patients with Crohn’s disease treated with a
combined antibiotic therapy consisting of two antibiotics showing a 93.5
percent response rate in Crohn’s disease patients treated with a two-drug,
long-term antibiotic therapy directed at mycobacterium paratuberculosis.
These patients showed a substantial improvement in symptoms and “remission
of their disease” with no other therapy. It appears that a small
proportion of patients with Crohn’s disease required long term therapy
to “maintain” their diseases. Most achieve remission on several months
of treatment.
Investigations
It is hoped that the future investigation will search for mycobacterium
paratuberculosis in Crohn’s patients by newer technologies, as we have
relied heretofore on genetic probes (PCR), culture techniques (often times
negative), or older antibody testing. Newer techniques will involve looking
within tissue specimens of patients with Crohn’s disease for the spheroplast,
which is the cell wall-less form of this bacteria, and a special technique
using gold tagging which will ultimately allow for the identification of
this particular bacterium in patients with Crohn’s to be compared with
controlled populations of non-inflammatory bowel disease patients Ultimately,
the identification of this bacteria by multiple modalities will prove the
association and lead to further trials of treatment of Crohn’s disease
patients with antibiotics. Since mycobacterium paratuberculosis is
often resistant to conventional antibiotics, newer forms of treatment will
need to be studied to pursue more effective treatments. It is hoped
that natural compounds from plants will prove to be effective and nontoxic
in eradicating this bacteria. The combined ability to detect this
bacteria by a non-invasive and sensitive and specific technique in the
genetically predisposed patients will allow for eradication of the bacteria
at an early stage and ultimately prevention of the disease known as Crohn’s
disease.
Ultimately, Crohn’s disease, which in the United States costs between
1 and 1.2 billion dollars per year, will someday not only be treatable,
but preventable.