3 research outputs found
pH-Responsive Micelle Sequestrant Polymers Inhibit Fat Absorption
Current antiobesity therapeutics
are associated with side effects
and/or poor long-term patient compliance, necessitating development
of more efficacious and safer alternatives. Herein, we designed and
engineered a new class of orally acting pharmaceutical agents, or
micelle sequestrant polymers (MSPs), that could respond to the pH
change in the gastrointestinal (GI) tract and potentially sequester
lipid micelles; inhibiting lipid absorption through a pH-triggered
flocculation process. These MSPs, derived from poly(2-(diisopropylamino)ethyl
methacrylate) and poly(2-(dibutylamino)ethyl methacrylate), were soluble
in acidic media, but they transitioned to become insoluble around
pH 7.2 and 6.1, respectively. MSPs showed substantial bile acid and
triglyceride sequestration capacity with fast pH response tested <i>in vitro</i>. <i>In vivo</i> study showed that orally
dosed MSPs significantly enhanced fecal elimination of triglycerides
and bile acids. Several MSPs increased fecal elimination of triglycerides
by 9–10 times compared with that of the control. In contrast,
fecal concentration of bile acids, but not triglycerides, was increased
by cholestyramine or Welchol. Importantly, fecal elimination of bile
acids and triglycerides was unaltered by addition of control dietary
fibers. MSPs may serve as a novel approach to weight loss that inhibits
excess caloric intake by preventing absorption of excess dietary triglycerides
Nonabsorbable Iron Binding Polymers Prevent Dietary Iron Absorption for the Treatment of Iron Overload
Chronic iron overload
is a serious condition that develops as a
consequence of long-term accumulation of iron, eventually overwhelming
iron storage systems and causing oxidative stress and subsequent organ
damage. Current pharmaceuticals used to treat iron overload typically
suffer from toxicities leading to relatively high rates of adverse
events. To address this need, we designed a new class of nonabsorbable
iron binding polymers (IBPs) that bind and sequester iron within the
gastrointestinal (GI) tract. IBPs were synthesized by cross-linking
polyallylamine containing various amounts of conjugated 2,3-dihydroxybenzoic
acid (DHBA). In vitro studies indicated that IBPs possessed high affinity,
substantial binding capacity, and excellent selectivity toward iron.
Moreover, in vivo studies demonstrated that IBPs showed no signs of
side effects in mice and increased fecal iron excretion when compared
to a similar dose of cross-linked polyallylamine. IBPs are a novel,
nonabsorbed oral therapeutic agent that may ultimately prevent iron
absorption as a safe alternative to iron chelation therapies for patients
with hemochromatosis or other iron overload diseases
Molecular Dynamics of Multivalent Soluble Antigen Arrays Support a Two-Signal Co-delivery Mechanism in the Treatment of Experimental Autoimmune Encephalomyelitis
Many
current therapies for autoimmune diseases such as multiple
sclerosis (MS) result in global immunosuppression, rendering insufficient
efficacy with increased risk of adverse side effects. Multivalent
soluble antigen arrays, nanomaterials presenting both autoantigen
and secondary inhibitory signals on a flexible polymer backbone, are
hypothesized to shift the immune response toward selective autoantigenic
tolerance to repress autoimmune disease. Two-signal co-delivery of
both autoantigen and secondary signal were deemed necessary for therapeutic
efficacy against experimental autoimmune encephalomyelitis, a murine
model of MS. Dynamic light scattering and in silico molecular dynamics
simulations complemented these studies to illuminate the role of two-signal
co-delivery in determining therapeutic potential. Physicochemical
characteristics such as particle size and molecular affinity for intermolecular
interactions and chain entanglement likely facilitated cotransport
of two signals to produce efficacy. These findings elucidate potential
mechanisms whereby soluble antigen arrays enact their therapeutic
effect and help to guide the development of future multivalent antigen-specific
immunotherapies