Transplacental exposure to baﬁlomycin disrupts pancreatic islet
organogenesis and accelerates diabetes onset in NOD mice
, P.Z. Zimmet
, M.A. Myers
Department of Biochemistry and Molecular Biology, Monash University, Building 13D, Wellington Road, Clayton, Victoria 3800, Australia
International Diabetes Institute, Caulﬁeld, Victoria 3162, Australia
Received 14 October 2003; revised 28 January 2004; accepted 19 February 2004
Baﬁlomycin, a plecomacrolide produced by plant-pathogenic Streptomyces, contaminates tuberous vegetables and has adverse
eﬀects on cells in adult mice. We therefore determined whether dietary baﬁlomycin inﬂuenced the progression of diabetes in the
non-obese diabetic (NOD) mouse model of autoimmune Type 1 diabetes. Parent NOD mice were fed sub-toxic doses of baﬁlomycin
in drinking water from conception until weaning, or various times after birth and blood glucose was monitored in the oﬀspring.
Pancreatic islets in neonatal oﬀspring were examined histologically by quantitative morphometry and islet cell apoptosis was
estimated by TUNEL assay. Exposure in utero to baﬁlomycin but not after birth signiﬁcantly accelerated onset and increased the
frequency of diabetes. In exposed mice, pancreatic islet organogenesis was disrupted, characterized by a striking increase in -cell
mass and a shift in timing of the normal wave of neonatal islet cell apoptosis from 2 weeks to 4 weeks of age. We postulate that
accelerated onset and increased incidence of diabetes later in life result from disruption of the normal turnover of cells in the
neonatal pancreas. Since baﬁlomycin and related plecomacrolides contaminate Streptomyces-infected vegetables, dietary exposure
during pregnancy could be an important and previously unsuspected environmental component of human Type 1 diabetes.
2004 Elsevier Ltd. All rights reserved.
Keywords: Mice; Inbred NOD; Diabetes mellitus; Insulin-dependent; Antibiotics; Macrolide; Prenatal exposure; Delayed eﬀects; Vacuolar
proton-translocating ATPases; Baﬁlomycin
Type 1 diabetes is caused by an interaction between
environmental agents and genetic predisposition that
activates autoimmune mechanisms leading to pro-
gressive loss of pancreatic islet cells [1–3] but expla-
nations are lacking for the increasing worldwide inci-
dence of the disease . While the genetic contribution
to Type 1 diabetes susceptibility is well established, the
relative importance and mode of action of environ-
mental inﬂuences such as viruses, toxins, in utero milieu
and early infant diet remain unclear . A possible
environmental contributor is plecomacrolides in veg-
etables infected by species of the soil bacterium Strepto-
myces, speciﬁcally baﬁlomycins and concanamycins .
These are potent and speciﬁc inhibitors of the evolution-
arily conserved vacuolar proton-translocating ATPase
(vATPase), an enzyme critical for establishing pH
gradients in intracellular organelles . Inhibition of
vATPase activity occurs at nanomolar concentrations
without aﬀecting the activity of the related mitochon-
drial F-ATPase . Species of Streptomyces that infect
plant roots and tubers causing common scab disease in
potatoes  produce baﬁlomycin B1  and concan-
amycins A and C [11,12] and these can be detected in
peel from infected potato tubers . Consequently
there is a ready route for baﬁlomycins and related
plecomacrolides to enter the human diet.
In adult mice injection of baﬁlomycin induces the
formation of small “neogenic” islets and increases pan-
creatic insulin content and we have proposed that these
islet changes may promote autoimmune diabetes
through inappropriate release and immune presentation
of islet autoantigens . Progression to Type 1 diabetes
requires initial engagement of naı¨ve autoreactive T cells
* Corresponding author. Tel.: +61-3-99051435; fax:
E-mail address: Mark.Myers@med.monash.edu.au (M.A. Myers).
Journal of Autoimmunity 22 (2004) 287–296
0896-8411/04/$ - see front matter 2004 Elsevier Ltd. All rights reserved.