In the most recent edition of the New England Journal of Medicine
(NEJM), a letter from Dr. Faustman written in response to a letter to
the NEJM from Douglas Melton in July 2006 was published. The text of
both these letters is included at the end of this message for
reference.

I was hoping someone could respond with a better explanation than we
have received so far. While Dr. Faustman's response addresses most
of the elements Mr. Melton's letter raised, I did find one citation
troubling, mainly because Dr. Faustman has never completely explained
why she and her team believes that the use of bacille Calmette-Guérin
(BCG) will have the desired effect of arresting the autoimmune
attack. She has written and stated that earlier trials (the one
cited was published in 2005) occurred before they knew exactly how
BCG worked, but I'm afraid that explanation still does not clarify
what will be different about how they are using this drug, or why
they are convinced it will have the same effect as Freund's adjuvant
had in the NOD mouse. Will they be doing something different in
terms of dosage, frequency of dosing, etc.?

The quote I am referring to from Mr. Melton's letter is as follows
(the full article follows):

(Unfortunately, controlled studies have shown that neither the
complete Freund's adjuvant nor the bacille Calmette-Guérin adjuvant
appears to have this effect in humans.8)

Citation:
8. Huppmann M, Baumgarten A, Ziegler A, Bonifacio E. Neonatal bacille
Calmette-Guerin vaccination and type 1 diabetes. Diabetes Care
2005;28:1204-6.

There may certainly be convincing evidence to support the reason they
believe that BCG will accomplish this, but I'd like for the Faustman
lab to explain in more detail why they believe it will do so!!

Regards!

Reversal of Type 1 Diabetes in Mice
[Correspondence]
Faustman, Denise L.

Harvard Medical School, Boston, MA 02115

To the Editor: Dr. Melton (July 6 issue) [1] misrepresents my study
on the reversal of type 1 diabetes in mice and its implications for
new treatment strategies in humans. [2] As in a previous study, [3]
my colleagues and I discovered that an immune therapy triggered a
permanent reversal of end-stage type 1 diabetes in mice. The
treatment involved two components: injecting the mice with an immune
adjuvant (to induce the production of tumor necrosis factor, which
destroys autoreactive T cells) and injecting splenocytes from a donor
mouse.

Dr. Melton writes that we ascribed the reversal of type 1 diabetes in
a mouse model solely to the transplantation of spleen cells and that
we claimed to have identified a stem cell among the donor splenocytes
that contributed to regrowth of the islets in the recipient. It is
true that we observed adult stem cells and that these cells can
contribute, in part, to the regrowth of the islets. However, Dr.
Melton does not acknowledge that we also observed regeneration of
pancreatic islets and complete reversal of type 1 diabetes without
the introduction of any live donor splenocytes. [2] Infusion of live
splenic cells hastened the development of permanent normoglycemia in
the mice but did not enhance the rate of cure. We did not claim that
the regenerative process required a stem cell, and we did not rule
out other mechanisms, such as regrowth or rescue of host islets. Our
research simply found regeneration of the pancreas once the
autoimmune process was removed.

Instead of cheering the fact that our laboratory's immunomodulatory
approach was replicated successfully by three recent studies, [4-6]
Dr. Melton places emphasis on the failure of these cited studies to
identify a splenocyte contribution to the observed regeneration of
the pancreas. It is possible that methodologic differences between
our protocol and theirs precluded finding a contribution of splenic
stem cells to pancreatic regeneration in these studies. But since
then, the optional splenic contribution has been replicated. [7]

From a clinical perspective, the existence of an adult stem cell in
the spleen seems to be beside the point. Many studies have since
shown that the regenerative process in the pancreas is likely to be
intact and that targeted immune intervention may unleash the
spontaneous regeneration of the pancreas. It seems reasonable to test
the hypothesis that for end-stage diabetes, an immune intervention
that destroys autoreactive T cells in the mouse can also work in the
clinic.

Dr. Faustman reports owning stock in General Electric, Pfizer,
Microsoft, IBM, Keel, and Johnson & Johnson, all of which have
research programs or products involving stem cells. Dr. Faustman's
employer, Massachusetts General Hospital, owns patent applications on
the nuclear factor-(kappa)B-tumor necrosis factor pathway for the
treatment of autoimmunity. Should the hospital receive income from
those applications, Dr. Faustman or her laboratory could receive
income.

Denise L. Faustman, M.D., Ph.D.

Harvard Medical School, Boston, MA 02115

REFERENCES

1. Melton DA. Reversal of type 1 diabetes in mice. N Engl J Med
2006;355:89-90.

2. Kodama S, Kuhtreiber W, Fujimura S, Dale EA, Faustman DL. Islet
regeneration during the reversal of autoimmune diabetes in NOD mice.
Science 2003;302:1223-7.

3. Ryu S, Kodama S, Ryu K, Schoenfeld DA, Faustman DL. Reversal of
established autoimmune diabetes by restoration of endogenous beta
cell function. J Clin Invest 2001;108:63-72.

4. Nishio J, Gaglia JL, Turvey SE, Campbell C, Benoist C, Mathis D.
Islet recovery and reversal of murine type 1 diabetes in the absence
of any infused spleen cell contribution. Science 2006;311:1775-8.

5. Suri A, Calderon B, Esparza TJ, Frederick K, Bittner P, Unanue ER.
Immunological reversal of autoimmune diabetes without hematopoietic
replacement of beta cells. Science 2006;311:1778-80.

6. Chong AS, Shen J, Tao J, et al. Reversal of diabetes in non-obese
diabetic mice without spleen cell-derived beta cell regeneration.
Science 2006;311:1774-5.

7. Faustman DL, Tran SD, Kodama S, et al. Comment on papers by Chong
et al., Nishio et al., and Suri et al. on diabetes reversal in NOD
mice. Science 2006;314:1243.

Reversal of Type 1 Diabetes in Mice
Douglas A. Melton, Ph.D.

In 2003, the field of diabetes was shaken up by an article published
in Science,1 stating that established autoimmune diabetes in mice
could be permanently reversed with the injection of spleen cells.
Kodama et al. reported that a known immune modulator, complete
Freund's adjuvant, and the temporary transplantation of islets to the
kidney capsule could be coupled with the injection of splenocytes to
cure diabetes in mice. The idea was that the adjuvant modulates the
immune attack and the transplanted islets maintain normal
blood glucose levels long enough for the spleen cells to regenerate
the insulin-producing beta cells. The authors described the approach
as follows:

"Stem cells of the spleen have been demonstrated to home to the
pancreas where they mature into fully functional islet cells
responsible for restoring normoglycemia."2 This article was important
because of its claim that readily available cells, spleen cells,
could be used to produce pancreatic
beta cells.

The report attracted considerable attention because it pointed to new
clinical strategies for treating type 1 diabetes. In addition, the
use of spleen cells avoided the ethical questions surrounding the use
of embryonic stem cells as a
possible route to the production of beta cells. At the same time,
some scientists were skeptical of the claim that spleen cells could
form pancreatic beta cells. To their credit, Kodama et al. provided
detailed protocols so that others could repeat and independently
verify their conclusions.

Recently, the results of three independent efforts to replicate the
experiment were reported, again in Science.3-5 The results were
remarkably consistent: no splenocyte contribution to the islets was
observed, and no evidence was found to support the principal
conclusion of Kodama et al.
All three studies showed, as others had previously,6,7 that diabetes
can be reversed in this mouse model. However, the recovered host beta
cells, rather than spleen cells, were responsible for this reversal.
Each of the three studies supports the conclusion that the adjuvant-
dependent dampening of the autoimmune attack, coupled with the
recovery of residual host islets, underlies the cure in mice.

What does all this mean for possible clinical treatment? It is
noteworthy that in these studies, the progression of autoimmune
diabetes was reversed in control mice receiving the adjuvant.
(Unfortunately, controlled studies have shown that neither the
complete Freund's adjuvant nor the bacille Calmette-
Guérin adjuvant appears to have this effect in humans.8) Although a
mechanistic understanding of the autoimmune reversal in mice due to
the adjuvant is still lacking, the finding emphasizes the importance
of identifying the initiating antigen or antigens and the subsequent
cascade of immune T and B cells responsible for the autoimmune
attack. This approach is the best way to find interventions that
can be effectively designed and applied. The value of this approach
is supported by the promising results of early-stage clinical trials
wherein other modulators of the immune system - for example, the anti-
CD3 antibody9 - are administered during the "honeymoon" period of
type 1 diabetes, when there is still considerable betacell mass.

The three recent studies also illustrate the dramatic response of
beta cells to environmental signals. In each study, the beta cells
recovered from an immune attack and proliferated to restore beta-cell
mass. Beta-cell mass has been shown to increase in several other
circumstances, including pregnancy, obesity, and in some patients,
after gastric bypass surgery. Mice in which the insulin receptor in
the liver cells has been knocked out respond by increasing beta-cell
mass by a factor of 10.10 If we can harness this endogenous capacity
of beta cells to proliferate and can combine this ability with a more
effective blunting of the autoimmune attack in humans, it may well be
possible to devise important new treatments for type 1 diabetes.

No potential conflict of interest relevant to this article was
reported.

From the Harvard Stem Cell Institute, Department of Molecular
and Cellular Biology, Harvard University, Boston.

REFERENCES

1. Kodama S, Kuhtreiber W, Fujimura S, Dale EA, Faustman DL.
Islet regeneration during the reversal of autoimmune diabetes in NOD
mice. Science 2003;302:1223-7.

2. Kodama S, Faustman DL. Routes to regenerating islet cells:
stem cells and other biological therapies for type 1 diabetes.
Pediatr Diabetes 2004;5:Suppl 2:38-44.

3. Chong AS, Shen J, Tao J, et al. Reversal of diabetes in nonobese
diabetic mice without spleen cell-derived beta cell regeneration.
Science 2006;311:1774-5.

4. Nishio J, Gaglia JL, Turvey SE, Campbell C, Benoist C, Mathis D.
Islet recovery and reversal of murine type 1 diabetes in the absence
of any infused spleen cell contribution. Science 2006;311:1775-8.

5. Suri A, Calderon B, Esparza TJ, Frederick K, Bittner P, Unanue ER.
Immunological reversal of autoimmune diabetes without hematopoietic
replacement of beta cells. Science 2006;311:1778-80.

6. Sadelain MW, Qin HY, Lauzon J, Singh B. Prevention of type I
diabetes in NOD mice by adjuvant immunotherapy. Diabetes
1990;39:583-9.

7. Wang T, Singh B, Warnock GL, Rajotte RV. Prevention of
recurrence of IDDM in islet-transplanted diabetic NOD mice by
adjuvant immunotherapy. Diabetes 1992;41:114-7.

8. Huppmann M, Baumgarten A, Ziegler A, Bonifacio E. Neonatal
bacille Calmette-Guerin vaccination and type 1 diabetes.
Diabetes Care 2005;28:1204-6.

9. Herold KC, Hagopian W, Auger JA, et al. Anti-CD3 monoclonal
antibody in new-onset type 1 diabetes mellitus. N Engl J Med
2002;346:1692-8.

10. Kulkarni RN, Jhala US, Winnay JN, Krajewski S, Montminy
M, Kahn CR. PDX-1 haploinsufficiency limits the compensatory
islet hyperplasia that occurs in response to insulin resistance. J
Clin Invest 2004;114:828-36.