Antibodies against the erythroferrone N-terminal domain prevent hepcidin suppression and ameliorate murine thalassemia.

Erythroferrone (ERFE) is produced by erythroblasts in response to erythropoietin (EPO) and acts in the liver to prevent hepcidin stimulation by BMP6. Hepcidin suppression allows for the mobilization of iron to the bone marrow for the production of red blood cells. Aberrantly high circulating ERFE in conditions of stress erythropoiesis, such as in patients with ß-thalassemia, promotes the tissue iron accumulation that substantially contributes to morbidity in these patients. Here we developed antibodies against ERFE to prevent hepcidin suppression and to correct the iron loading phenotype in a mouse model of ß-thalassemia [Hbb(th3/+) mice] and used these antibodies as tools to further characterize ERFE's mechanism of action. We show that ERFE binds to BMP6 with nanomolar affinity and binds BMP2 and BMP4 with somewhat weaker affinities. We found that BMP6 binds the N-terminal domain of ERFE, and a polypeptide derived from the N terminus of ERFE was sufficient to cause hepcidin suppression in Huh7 hepatoma cells and in wild-type mice. Anti-ERFE antibodies targeting the N-terminal domain prevented hepcidin suppression in ERFE-treated Huh7 cells and in EPO-treated mice. Finally, we observed a decrease in splenomegaly and serum and liver iron in anti-ERFE-treated Hbb(th3/+) mice, accompanied by an increase in red blood cells and hemoglobin and a decrease in reticulocyte counts. In summary, we show that ERFE binds BMP6 directly and with high affinity, and that antibodies targeting the N-terminal domain of ERFE that prevent ERFE-BMP6 interactions constitute a potential therapeutic tool for iron loading anemias.

Erythroferrone inhibits the induction of hepcidin by BMP6.

Decreased hepcidin mobilizes iron, which facilitates erythropoiesis, but excess iron is pathogenic in ß-thalassemia. Erythropoietin (EPO) enhances erythroferrone (ERFE) synthesis by erythroblasts, and ERFE suppresses hepatic hepcidin production through an unknown mechanism. The BMP/SMAD pathway in the liver is critical for hepcidin control, and we show that EPO suppressed hepcidin and other BMP target genes in vivo in a partially ERFE-dependent manner. Furthermore, recombinant ERFE suppressed the hepatic BMP/SMAD pathway independently of changes in serum and liver iron. In vitro, ERFE decreased SMAD1, SMAD5, and SMAD8 phosphorylation and inhibited expression of BMP target genes. ERFE specifically abrogated the induction of hepcidin by BMP5, BMP6, and BMP7 but had little or no effect on hepcidin induction by BMP2, BMP4, BMP9, or activin B. A neutralizing anti-ERFE antibody prevented ERFE from inhibiting hepcidin induction by BMP5, BMP6, and BMP7. Cell-free homogeneous time-resolved fluorescence assays showed that BMP5, BMP6, and BMP7 competed with anti-ERFE for binding to ERFE. We conclude that ERFE suppresses hepcidin by inhibiting hepatic BMP/SMAD signaling via preferentially impairing an evolutionarily closely related BMP subgroup of BMP5, BMP6, and BMP7. ERFE can act as a natural ligand trap generated by stimulated erythropoiesis to regulate the availability of iron.

Characterization of binding mode of action of a blocking anti-platelet-derived growth factor (PDGF)-B monoclonal antibody, MOR8457, reveals conformational flexibility and avidity needed for PDGF-BB to bind PDGF receptor-ß.

Platelet derived growth factor-BB (PDGF-BB) is an important mitogen and cell survival factor during development. PDGF-BB binds PDGF receptor-ß (PDGFRß) to trigger receptor dimerization and tyrosine kinase activation. We present the pharmacological and biophysical characterization of a blocking PDGF-BB monoclonal antibody, MOR8457, and contrast this to PDGFRß. MOR8457 binds to PDGF-BB with high affinity and selectivity, and prevents PDGF-BB induced cell proliferation competitively and with high potency. The structural characterization of the MOR8457-PDGF-BB complex indicates that MOR8457 binds with a 2:1 stoichiometry, but that binding of a single MOR8457 moiety is sufficient to prevent binding to PDGFRß. Comparison of the MOR8457-PDGF-BB structure with that of the PDGFRß-PDGF-BB complex suggested the potential reason for this was a substantial bending and twisting of PDGF-BB in the MOR8457 structure, relative to the structures of PDGF-BB alone, bound to a PDGF-BB aptamer or PDGFRß, which makes it nonpermissive for PDGFRß binding. These biochemical and structural data offer insights into the permissive structure of PDGF-BB needed for agonism as well as strategies for developing specific PDGF ligand antagonists.

Phosphodiesterase 11A in brain is enriched in ventral hippocampus and deletion causes psychiatric disease-related phenotypes.

Phosphodiesterase 11A (PDE11A) is the most recently identified family of phosphodiesterases (PDEs), the only known enzymes to break down cyclic nucleotides. The tissue expression profile of this dual specificity PDE is controversial, and little is understood of its biological function, particularly in the brain. We seek here to determine if PDE11A is expressed in the brain and to understand its function, using PDE11A(-/-) knockout (KO) mice. We show that PDE11A mRNA and protein are largely restricted to hippocampus CA1, subiculum, and the amygdalohippocampal area, with a two- to threefold enrichment in the ventral vs. dorsal hippocampus, equal distribution between cytosolic and membrane fractions, and increasing levels of protein expression from postnatal day 7 through adulthood. Interestingly, PDE11A KO mice show subtle psychiatric-disease-related deficits, including hyperactivity in an open field, increased sensitivity to the glutamate N-methyl-D-aspartate receptor antagonist MK-801, as well as deficits in social behaviors (social odor recognition memory and social avoidance). In addition, PDE11A KO mice show enlarged lateral ventricles and increased activity in CA1 (as per increased Arc mRNA), phenotypes associated with psychiatric disease. The increased sensitivity to MK-801 exhibited by PDE11A KO mice may be explained by the biochemical dysregulation observed around the glutamate alpha-amino-3-hydroxy-5-methyl-4-isozazolepropionic (AMPA) receptor, including decreased levels of phosphorylated-GluR1 at Ser845 and the prototypical transmembrane AMPA-receptor-associated proteins stargazin (gamma2) and gamma8. Together, our data provide convincing evidence that PDE11A expression is restricted in the brain but plays a significant role in regulating brain function.

Clinical and Histopathologic Features of Myocarditis in Multisystem Inflammatory Syndrome (Adult)-Associated COVID-19.

BACKGROUND: Multisystem inflammatory syndrome (MIS) associated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is a life-threatening condition first described in children (MIS-C). It is characterized by a hyperinflammatory state that involves the cardiovascular, gastrointestinal, dermatologic, and neurologic systems without severe respiratory system involvement. Myocarditis is one of the cardiovascular presentations of MIS that might be complicated with cardiogenic shock. There are few case reports describing SARS-CoV-2-related MIS in adults (MIS-A). CASE SUMMARY: Three cases of healthy young adults diagnosed with severe acute respiratory syndrome-CoV-2 related (MIS-A). The main presentation was cardiogenic shock secondary to histologically proven myocarditis, which resolved rapidly after initiation of medical therapy including anti-inflammatory and immunosuppressive drugs. All the cases, however, required mechanical circulatory support (MCS) as a bridge to recovery. CONCLUSIONS: It appears reasonable to treat the patient with fulminant myocarditis in SARS-CoV-2-associated MIS-A with high-dose corticosteroid "pulse" therapy in order to suppress the inflammatory response and MCS to correct initial metabolic derangement and reestablish/maintain vital organ perfusion. Addition of IV immunoglobulin and other immunomodulators should be assessed in a case-by-case basis especially considering the associated cost resource allocation.

Awake Venovenous Extracorporeal Membrane Oxygenation for Coronavirus Disease 2019 Acute Respiratory Failure.

Implantation of venovenous extracorporeal membrane oxygenation as an alternative to invasive mechanical ventilation, an "awake approach," may facilitate a lung- and diaphragm-protective ventilatory strategies without the associated harms of endotracheal intubation, positive pressure ventilation, and continuous sedation. This report presents the characteristics and outcomes of the patients treated with the awake venovenous extracorporeal membrane oxygenation approach. DESIGN: Retrospective case series. SETTING: Monocenter study. PATIENTS: Severe acute respiratory syndrome coronavirus 2 patients with acute respiratory failure treated with venovenous extracorporeal membrane oxygenation instead of invasive mechanical ventilation from March 2020 to March 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Physiologic and laboratory data were collected at admission to the ICU, prior to and after venovenous extracorporeal membrane oxygenation implantation, and at decannulation. Seven patients were treated with venovenous extracorporeal membrane oxygenation instead of invasive mechanical ventilation due to hypoxemia with a median Pao2/Fio2 ratio at implantation of 76 (interquartile range, 59-92). Four patients in the awake group subsequently required invasive mechanical ventilation, and only one patient (14.3%) died. There were no significant complications attributed venovenous extracorporeal membrane oxygenation. CONCLUSIONS: This report demonstrates that in a selected group of patients, an "awake" venovenous extracorporeal membrane oxygenation approach is feasible and may result in favorable outcomes.

Allogeneic Hematopoietic Stem Cell Transplant Infusion During Venovenous Extracorporeal Membrane Oxygenation Support.

Management of hematopoietic stem cell transplant complicated by respiratory failure has been facilitated by the use of extracorporeal membrane oxygenation as a bridge to curative chemotherapeutic options. This is the first report of hematopoietic stem cell transplantation on extracorporeal membrane oxygenation in the adult population. CASE SUMMARY: A 28-year-old woman diagnosed with idiopathic aplastic anemia complicated by acute respiratory distress syndrome secondary to pneumonia required venovenous extracorporeal membrane oxygenation to supplement oxygenation and ventilation. She received hematopoietic stem cell transplantation while she was on extracorporeal membrane oxygenation support. MAIN RESULTS AND CONCLUSION: Delivery of the stem cell through extracorporeal membrane oxygenation circuit was successful in the described patient. There was no sequestered stem cell in extracorporeal membrane oxygenation circuit, and she was found to have 90% donor chimerism suggesting successful engraftment. This report showed that infusion of stem cell through extracorporeal membrane oxygenation circuit is safe and feasible, and our results suggest that successful engraftment is possible.

Discovery of benzisoxazoles as potent inhibitors of chaperone heat shock protein 90.

Heat shock protein 90 (Hsp90) is a molecular chaperone that is responsible for activating many signaling proteins and is a promising target in tumor biology. We have identified small-molecule benzisoxazole derivatives as Hsp90 inhibitors. Crystallographic studies show that these compounds bind in the ATP binding pocket interacting with the Asp93. Structure based optimization led to the identification of potent analogues, such as 13, with good biochemical profiles.

Structure-based optimization of protein tyrosine phosphatase 1B inhibitors: from the active site to the second phosphotyrosine binding site.

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of the insulin and leptin receptor pathways and thus an attractive therapeutic target for diabetes and obesity. Starting with a high micromolar lead compound, structure-based optimization of novel PTP1B inhibitors by extension of the molecule from the enzyme active site into the second phosphotyrosine binding site is described. Medicinal chemistry, guided by X-ray complex structure and molecular modeling, has yielded low nanomolar PTP1B inhibitors in an efficient manner. Compounds from this chemical series were found to be actively transported into hepatocytes. This active uptake into target tissues could be one of the possible avenues to overcome the poor membrane permeability of PTP1B inhibitors.

Thyroid autoimmunity and thyroid hormone reference intervals in apparently healthy Chinese adults.

BACKGROUND: Thyroid disorders are common, often go unrecognized, and when left untreated, can have serious public health implications. Dietary and ethnic differences are known to influence thyroid function. However, comparatively few studies have examined the prevalence of autoimmune thyroid disease (AITD) and thyroid function test (TFT) reference intervals in non-Western populations. METHODS: Sera were collected from 486 apparently healthy Chinese adults. Participants were classified as healthy based on physician review of metabolic testing and patient history. TFT (TSH, Free T4, Total T4, Free T3, Total T3, and T-Uptake), thyroid peroxidase autoantibodies (TPO-Ab), and thyroglobulin autoantibodies (Tg-Ab) were measured for all participants. RESULTS: TPO-Ab and Tg-Ab were found in 12.1% and 10.3% of participants, with higher prevalence found in women. Reference intervals were calculated for all TFT. Gender associated differences in mean values were noted for Total T4, Free T3, Total T3, and T-Uptake, but not for TSH and Free T4. CONCLUSIONS: Laboratory evidence of AITD is common in otherwise healthy Chinese adults. Women are significantly more likely to be positive for TPO-Ab and Tg-Ab, which is of particular concern for women of reproductive age. Reference values specific for the Chinese population were established for thyroid function tests in individuals without AITD.

Piperazine sulfonamides as potent, selective, and orally available 11beta-hydroxysteroid dehydrogenase type 1 inhibitors with efficacy in the rat cortisone-induced hyperinsulinemia model.

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is the enzyme that converts cortisone to cortisol. Evidence suggests that selective inhibition of 11beta-HSD1 could treat diabetes and metabolic syndrome. Presented herein are the synthesis, structure-activity relationship, and in vivo evaluation of piperazine sulfonamides as 11beta-HSD1 inhibitors. Through modification of our initial lead 5a, we have identified potent and selective 11beta-HSD1 inhibitors such as 13q and 13u with good pharmacokinetic properties.

beta-Keto sulfones as inhibitors of 11beta-hydroxysteroid dehydrogenase type I and the mechanism of action.

The design, synthesis, and biological evaluation of beta-keto sulfones as 11beta-HSD1 inhibitors and the mechanism of inhibition are described here. This class of compounds is not active against 11beta-HSD2 and therefore may have therapeutic potential for metabolic syndrome and type 2 diabetes.

An enzyme-linked immunosorbent assay to measure insulin receptor dephosphorylation by PTP1B.

Considerable effort exists within drug discovery to develop novel compounds to improve the underlying metabolic defects in type 2 diabetes. One approach is focused on inhibition of the tyrosine phosphatase, PTP1B, an important negative regulator of both insulin and leptin signaling. Historically, tyrosine phosphatase assays have used either small organic phosphates or, alternatively, phosphorylated peptides from the target proteins themselves. In characterizing inhibitors of PTP1B, measuring turnover of small organic phosphates is limited to evaluation of compounds that bind the active site itself. Peptide substrates allow identification of additional subsets of inhibitors (e.g., those that bind the second aryl-phosphate site), but assays of peptide turnover often involve detection steps that then limit full kinetic evaluation of inhibitors. Here we use a polyclonal antibody specific for the phosphorylated insulin receptor to allow much more sensitive detection of peptide phosphorylation. This kinetically robust enzyme-linked immunosorbent assay (ELISA) gives k(cat) and K(m) values for a phosphorylated insulin receptor peptide consistent with values determined by a continuous fluorescence-based assay. Furthermore, IC50 values determined for well-behaved active site inhibitors agree well with values determined for p-nitrophenyl phosphate cleavage. This assay permits full characterization of a larger subset of inhibitors as drug candidates for this promising target.

Probing acid replacements of thiophene PTP1B inhibitors.

The following account describes our systematic effort to replace one of the carboxylate groups of our diacid thiophene PTP1B inhibitors. Active hits were validated using enzymatic assays before pursuing efforts to improve the potency. Only when the C2 carboxylic acid was replaced with another ionizable functional group was reversible and competitive inhibition retained. Use of a tetrazole ring or 1,2,5-thiadiazolidine-3-one-1,1-dioxide as a carboxylate mimetic led to the discovery of two unique starting series that showed improved permeability (PAMPA) and potency of the order of 300nM. The SAR from these efforts underscores some of the major challenges in developing small molecule inhibitors for PTP1B.

Synthesis and biological evaluation of sulfonamidooxazoles and beta-keto sulfones: selective inhibitors of 11beta-hydroxysteroid dehydrogenase type I.

The design, synthesis, and biological evaluation of arylsulfonamidooxazoles as 11beta-HSD1 inhibitors and the serendipitous discovery of beta-keto sulfones as potent 11beta-HSD1 inhibitors are described here. These two classes of compounds are not active against 11beta-HSD2 and therefore may have significant therapeutic potential for metabolic syndrome, type 2 diabetes and related metabolic dysfunctions.

Ertiprotafib improves glycemic control and lowers lipids via multiple mechanisms.

Ertiprotafib belongs to a novel class of insulin sensitizers developed for treatment of type 2 diabetes. In insulin-resistant rodent models, ertiprotafib and a close analog lowered both fasting blood glucose and insulin levels and improved glycemic excursion during an oral glucose tolerance test. In addition, treatment of rodents improved lipid profiles, with significantly lowered triglyceride and free fatty acid levels. These results suggested that this therapeutic activity might involve mechanisms in addition to PTP1b inhibition. In this study, we demonstrate that ertiprotafib activates peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma at concentrations comparable with those of known agonists of these regulators. Furthermore, it is able to drive adipocyte differentiation of C3H10T(1/2) cells, a hallmark of PPARgamma activation. Livers from ertiprotafib-treated animals showed significant induction of acyl-CoA oxidase activity, probably caused by PPARalpha engagement in these animals. We also show that ertiprotafib inhibits PTP1b in vitro with nonclassic kinetics at concentrations above its EC(50) for PPAR agonism. Thus, the complete mechanism of action for ertiprotafib and related compounds in vivo may involve multiple independent mechanisms, including (but not necessarily limited to) PTP1b inhibition and dual PPARalpha/PPARgamma agonism. Ertiprotafib pharmacology and interpretation of clinical results must be seen in light of this complexity.