Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset, progressive neurodegenerative disorder with no known cure. Cu/Zn-superoxide dismutase (SOD1) was the first identified protein associated with familial ALS (fALS). Recently, TAR DNA-binding protein 43 (TDP-43) has been found to be a principal component of ubiquitinated cytoplasmic inclusions in neurons and glia in ALS. However, it remains unclear whether these ALS-linked proteins partly have a shared pathogenesis. Here, we determine the association between mutant SOD1 and the modification of TDP-43 and the relationship of pathologic TDP-43 to neuronal cytotoxicity in SOD1 ALS. In this work, using animal model, human tissue, and cell models, we provide the evidence that the association between the TDP-43 modification and the pathogenesis of SOD1 fALS. We demonstrated an age-dependent increase in TDP-43 C-terminal fragments and phosphorylation in motor neurons and glia of SOD1 mice and SOD1G85S ALS patient. Cytoplasmic TDP-43 was also observed in iPSC-derived motor neurons from SOD1G17S ALS patient. Moreover, we observed that mutant SOD1 interacts with TDP-43 in co-immunoprecipitation assays with G93A hSOD1-transfected cell lines. Mutant SOD1 overexpression led to an increase in TDP-43 modification in the detergent-insoluble fraction in the spinal cord of SOD1 mice and fALS patient. Additionally, we showed cellular apoptosis in response to the interaction of mutant SOD1 and fragment forms of TDP-43. These findings suggest that mutant SOD1 could affect the solubility/insolubility of TDP-43 through physical interactions and the resulting pathological modifications of TDP-43 may be involved in motor neuron death in SOD1 fALS.
Background: The objective of this study was to evaluate the efficacy and safety of repeated low-dose rituximab treatment guided by monitoring circulating CD19+ B cells in patients with refractory myasthenia gravis (MG). Methods: Patients with refractory MG who had received rituximab treatment at two teaching hospitals between September 2013 and January 2017 were reviewed retrospectively. The treatment protocol consisted of an induction treatment with low-dose rituximab (375 mg/m2 twice with a 2-week interval), followed by retreatment (375 mg/m2 once). Retreatment was based on either circulating CD19+ B-cell repopulation or clinical relapse. Outcome measures included the MG Foundation of America (MGFA) clinical classification and postintervention status, prednisolone dose, CD19+ B-cell counts, clinical relapse, and adverse effects. Results: Of 17 patients, 11 (65%) achieved the primary endpoint, defined as the minimal manifestation or better status with prednisolone ⩽5 mg/day, after median 7.6 months (range, 2–17 months) following rituximab treatment. Over a median follow up of 24 months (range, 7–49 months), a total of 30 retreatments were undertaken due to clinical relapse without B-cell repopulation ( n = 6), on the basis of B-cell repopulation alone ( n = 16) and both ( n = 8). B-cell recovery appeared to be in parallel with clinical relapse on the group level, although the individual-level association appeared to be modest, with B-cell repopulation observed only at 57% (8/14) of clinical relapses. Conclusions: The repeated low-dose rituximab treatment based on the assessment of circulating B-cell depletion could be a cost-effective therapeutic option for refractory MG. Further studies are needed to verify the potentially better cost-effectiveness of low-dose rituximab, and to identify biomarkers that help optimize treatment in MG patients.
Microgels
of biopolymers such as alginate are widely used to encapsulate
cells and other biological payloads. Alginate is an attractive material
for cell encapsulation because it is nontoxic and convenient: spherical
alginate gels are easily created by contacting aqueous droplets of
sodium alginate with divalent cations such as Ca2+. Alginate
chains in the gel become cross-linked by Ca2+ cations into
a 3-D network. When alginate gels are placed in a buffer, however,
the Ca2+ cross-links are eliminated by exchange with Na+, thereby weakening and degrading the gels. With time, encapsulated
cells are released into the external solution. Here, we describe a
simple solution to the above problem, which involves forming alginate
gels enveloped by a thin shell of a covalently cross-linked
gel. The shell is formed via free-radical polymerization
using conventional monomers such as acrylamide (AAm) or acrylate derivatives,
including polyethylene glycol diacrylate (PEGDA). The entire process
is performed in a single step at room temperature (or 37 °C)
under mild, aqueous conditions. It involves combining the alginate
solution with a radical initiator, which is then introduced as droplets
into a reservoir containing Ca2+ and monomers. Within minutes
of either simple incubation or exposure to ultraviolet (UV) light,
the droplets are converted into alginate–polymer microcapsules
with a core of alginate and a shell of the polymer (AAm or PEGDA).
The microcapsules are mechanically more robust than conventional alginate/Ca2+ microgels, and while the latter swell and degrade when placed
in buffers or in chelators like sodium citrate, the former remain
stable under all conditions. We encapsulate both bacteria and mammalian
cells in these microcapsules and find that the cells remain viable
and functional over time. Lastly, a variation of the synthesis technique
is shown to generate multilayered microcapsules with
a liquid core surrounded by concentric layers of alginate and AAm
gels. We anticipate that the approaches presented here will find application
in a variety of areas including cell therapies, artificial cells,
drug delivery, and tissue engineering.
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