VISTA promotes the metabolism and differentiation of myeloid-derived suppressor cells by STAT3 and polyamine-dependent mechanisms.

Myeloid-derived suppressor cells (MDSCs) impair antitumor immune responses. Identifying regulatory circuits during MDSC development may bring new opportunities for therapeutic interventions. We report that the V-domain suppressor of T cell activation (VISTA) functions as a key enabler of MDSC differentiation. VISTA deficiency reduced STAT3 activation and STAT3-dependent production of polyamines, which causally impaired mitochondrial respiration and MDSC expansion. In both mixed bone marrow (BM) chimera mice and myeloid-specific VISTA conditional knockout mice, VISTA deficiency significantly reduced tumor-associated MDSCs but expanded monocyte-derived dendritic cells (DCs) and enhanced T cell-mediated tumor control. Correlated expression of VISTA and arginase-1 (ARG1), a key enzyme supporting polyamine biosynthesis, was observed in multiple human cancer types. In human endometrial cancer, co-expression of VISTA and ARG1 on tumor-associated myeloid cells is associated with poor survival. Taken together, these findings unveil the VISTA/polyamine axis as a central regulator of MDSC differentiation and warrant therapeutically targeting this axis for cancer immunotherapy.

Cardiac expression of microRNA-7 is associated with adverse cardiac remodeling.

Although microRNA-7 (miRNA-7) is known to regulate proliferation of cancer cells by targeting Epidermal growth factor receptor (EGFR/ERBB) family, less is known about its role in cardiac physiology. Transgenic (Tg) mouse with cardiomyocyte-specific overexpression of miRNA-7 was generated to determine its role in cardiac physiology and pathology. Echocardiography on the miRNA-7 Tg mice showed cardiac dilation instead of age-associated physiological cardiac hypertrophy observed in non-Tg control mice. Subjecting miRNA-7 Tg mice to transverse aortic constriction (TAC) resulted in cardiac dilation associated with increased fibrosis bypassing the adaptive cardiac hypertrophic response to TAC. miRNA-7 expression in cardiomyocytes resulted in significant loss of ERBB2 expression with no changes in ERBB1 (EGFR). Cardiac proteomics in the miRNA-7 Tg mice showed significant reduction in mitochondrial membrane structural proteins compared to NTg reflecting role of miRNA-7 beyond the regulation of EGFR/ERRB in mediating cardiac dilation. Consistently, electron microscopy showed that miRNA-7 Tg hearts had disorganized rounded mitochondria that was associated with mitochondrial dysfunction. These findings show that expression of miRNA-7 in the cardiomyocytes results in cardiac dilation instead of adaptive hypertrophic response during aging or to TAC providing insights on yet to be understood role of miRNA-7 in cardiac function.

Androgen regulation of pulmonary AR, TMPRSS2 and ACE2 with implications for sex-discordant COVID-19 outcomes.

The sex discordance in COVID-19 outcomes has been widely recognized, with males generally faring worse than females and a potential link to sex steroids. A plausible mechanism is androgen-induced expression of TMPRSS2 and/or ACE2 in pulmonary tissues that may increase susceptibility or severity in males. This hypothesis is the subject of several clinical trials of anti-androgen therapies around the world. Here, we investigated the sex-associated TMPRSS2 and ACE2 expression in human and mouse lungs and interrogated the possibility of pharmacologic modification of their expression with anti-androgens. We found no evidence for increased TMPRSS2 expression in the lungs of males compared to females in humans or mice. Furthermore, in male mice, treatment with the androgen receptor antagonist enzalutamide did not decrease pulmonary TMPRSS2. On the other hand, ACE2 and AR expression was sexually dimorphic and higher in males than females. ACE2 was moderately suppressible with enzalutamide administration. Our work suggests that sex differences in COVID-19 outcomes attributable to viral entry are independent of TMPRSS2. Modest changes in ACE2 could account for some of the sex discordance.

Screening of Polymer-Based Drug Delivery Vehicles Targeting Folate Receptors in Triple-Negative Breast Cancer.

PURPOSE: To compare cellular uptake and cytotoxicity of fluorescein (FL)-labeled polyethylene glycols (PEGs) carrying 2 folate groups (targeted delivery vehicles [TDVs]) to non-PEGylated molecules with 1 or 2 folate groups. MATERIALS AND METHODS: Three PEGylated TDVs and 2 non-PEGylated folic acid (FA)-fluorescein (FL) conjugates (FA-FL and FA-FL-FA) were synthesized. Two triple-negative breast cancer cell lines (MDA-MB-231and MDA-MB-468) were cultured to 70% confluency and incubated for 2 h in a folate-depleted medium. Folate receptor (FR) expression was confirmed by immunocytochemistry. Cellular uptake and cytotoxicity of compounds were measured by flow cytometry. Intracellular localization was confirmed using confocal microscopy. RESULTS: MDA-MB-231 demonstrated 40% more FR staining than MD-MB-468. Intracellular localization of the 2 non-PEGylated molecules (FA-FL and FA-FL-FA) and the 3 PEGylated TDVs was confirmed with confocal microscopy. Cellular uptake was independent of concentration for FA-FL, but there was 26.8% more cytotoxicity at 30 µg/mL compared with no treatment (P ≤ .05). Uptake was > 90% for FA-FL-FA at 10 µg/mL and 30 µg/mL without significant cytotoxicity (P ≤ .005). Cellular uptake was > 80% for all TDVs. The molecule containing monodispersed PEG with Mn = 1,000 g/mol had the highest uptake in both cell lines without cytotoxicity. Maximum toxicity was demonstrated by the molecule containing PEG2,000 only at the highest dose of 30 µg/mL (8.66% ± 3.94% cytotoxicity; cut-off was 20%). CONCLUSIONS: The molecule containing monodispersed PEG with Mn = 1,000 g/mol and 2 FA targeting groups demonstrated better targetability and cellular uptake as a TDV.

Sex, androgens and regulation of pulmonary AR, TMPRSS2 and ACE2.

The sex discordance in COVID-19 outcomes has been widely recognized, with males generally faring worse than females and a potential link to sex steroids. A plausible mechanism is androgen-induced expression of TMPRSS2 and/or ACE2 in pulmonary tissues that may increase susceptibility or severity in males. This hypothesis is the subject of several clinical trials of anti-androgen therapies around the world. Here, we investigated the sex-associated TMPRSS2 and ACE2 expression in human and mouse lungs and interrogated the possibility of pharmacologic modification of their expression with anti-androgens. We found no evidence for increased TMPRSS2 expression in the lungs of males compared to females in humans or mice. Furthermore, in male mice, treatment with the androgen receptor antagonist enzalutamide did not decrease pulmonary TMPRSS2. On the other hand, ACE2 and AR expression was sexually dimorphic and higher in males than females. ACE2 was moderately suppressible with enzalutamide therapy. Our work suggests that sex differences in COVID-19 outcomes attributable to viral entry are independent of TMPRSS2. Modest changes in ACE2 could account for some of the sex discordance.

Role of Myeloma-Derived MIF in Myeloma Cell Adhesion to Bone Marrow and Chemotherapy Response.

BACKGROUND: Multiple myeloma (MM) remains an incurable cancer characterized by accumulation of malignant plasma cells in the bone marrow (BM). The mechanism underlying MM homing to BM is poorly elucidated. METHODS: The clinical significance of migration inhibitory factor (MIF) expression was examined by analyzing six independent gene expression profile databases of primary MM cells using the Student's t test and Kaplan-Meier test. Enzyme-linked immunosorbent assay was used to examine MIF expression. In vivo bioluminescent imaging was used to determine MM cell localization and treatment efficacy in human MM xenograft mouse models, with three to four mice per group. MM cell attachment to BM stromal cells (BMSCs) was monitored by cell adhesion assay. MIF regulation of the expression of adhesion molecules was determined by chromatin immunoprecipitation (ChIP) assay. Statistical tests were two-sided. RESULTS: High levels of MIF were detected in MM BM (MIF level in BM plasma: healthy = 10.72 ± 5.788 ng/mL, n = 5; MM = 1811 ± 248.7 ng/mL, n = 10; P < .001) and associated with poor survival of patients (Kaplan-Meier test for MM OS: 87 MIF(high) patients, 86 MIF(low) patients, P = .02). Knocking down MIF impaired MM cell adhesion to BMSCs in vitro and led to formation of extramedullary tumors in SCID mice. MIF acted through surface receptor CXCR4 and adaptor COPS5 to regulate the expression of adhesion molecules ALCAM, ITGAV, and ITGB5 on MM cells. More importantly, MIF-deficient MM cells were sensitive to chemotherapy in vitro when cocultured with BMSCs and in vivo. MIF inhibitor 4-IPP sensitized MM cells to chemotherapy. CONCLUSIONS: MIF is an important player and a novel therapeutic target in MM. Inhibiting MIF activity will sensitize MM cells to chemotherapy.

The cytoplasmic domain of neuropilin-1 regulates focal adhesion turnover.

Though the vascular endothelial growth factor coreceptor neuropilin-1 (Nrp1) plays a critical role in vascular development, its precise function is not fully understood. We identified a group of novel binding partners of the cytoplasmic domain of Nrp1 that includes the focal adhesion regulator, Filamin A (FlnA). Endothelial cells (ECs) expressing a Nrp1 mutant devoid of the cytoplasmic domain (nrp1(cyto)(Δ/Δ)) migrated significantly slower in response to VEGF relative to the cells expressing wild-type Nrp1 (nrp1(+/+) cells). The rate of FA turnover in VEGF-treated nrp1(cyto)(Δ/Δ) ECs was an order of magnitude lower in comparison to nrp1(+/+) ECs, thus accounting for the slower migration rate of the nrp1(cyto)(Δ/Δ) ECs.

Increased levels of survivin, via association with heat shock protein 90, in mucosal T cells from patients with Crohn's disease.

BACKGROUND & AIMS: Defective apoptosis of lamina propria T cells (LPTs) is involved in the pathogenesis of Crohn's disease. Survivin, a member of the inhibitors of apoptosis family, prevents cell death and regulates cell division. Survivin has been studied extensively in cancer, but little is known about its role in Crohn's disease. METHODS: LPTs were isolated from mucosal samples of patients with Crohn's disease or ulcerative colitis and healthy individuals (controls). LPTs were activated with interleukin-2 or via CD3, CD2, and CD28 signaling, and cultured at 42°C to induce heat shock. Survivin expression was assessed by immunohistochemistry, confocal microscopy, and immunoblotting; survivin levels were reduced by RNA interference. Cell viability, apoptosis, and proliferation were measured by trypan blue exclusion, annexin-V/7-Aminoactinomycin D staining, and uptake of [3]thymidine, respectively. RESULTS: LPTs from patients with Crohn's disease had higher levels of survivin than LPTs from patients with ulcerative colitis or controls. RNA knockdown of survivin in LPTs inhibited their proliferation and promoted apoptosis. Levels of survivin were low in LPTs from patients with ulcerative colitis and controls as a result of ubiquitin-mediated proteasome degradation. In LPTs from patients with Crohn's disease, survivin bound to the heat shock protein (HSP)90, and therefore was resistant to proteasome degradation. Incubating LPTs with 17-N-allylamino-17-demethoxygeldanamycin, an inhibitor of HSP90, reduced levels of survivin and induced apoptosis. CONCLUSIONS: Levels of survivin are increased in LPTs from patients with Crohn's disease (compared with ulcerative colitis and controls) because survivin interacts with HSP90 and prevents proteasome degradation. This allows LPTs to avoid apoptosis. Strategies to restore apoptosis to these cells might be developed to treat patients with Crohn's disease.

Rab13-dependent trafficking of RhoA is required for directional migration and angiogenesis.

Angiogenesis requires concomitant remodeling of cell junctions and migration, as exemplified by recent observations of extensive endothelial cell movement along growing blood vessels. We report that a protein complex that regulates cell junctions is required for VEGF-driven directional migration and for angiogenesis in vivo. The complex consists of RhoA and Syx, a RhoA guanine exchange factor cross-linked by the Crumbs polarity protein Mupp1 to angiomotin, a phosphatidylinositol-binding protein. The Syx-associated complex translocates to the leading edge of migrating cells by membrane trafficking that requires the tight junction recycling GTPase Rab13. In turn, Rab13 associates with Grb2, targeting Syx and RhoA to Tyr(1175)-phosphorylated VEGFR2 at the leading edge. Rab13 knockdown in zebrafish impeded sprouting of intersegmental vessels and diminished the directionality of their tip cells. These results indicate that endothelial cell mobility in sprouting vessels is facilitated by shuttling the same protein complex from disassembling junctions to the leading edges of cells.

Proteins of the Plasmodium falciparum two transmembrane Maurer's cleft protein family, PfMC-2TM, and the 130 kDa Maurer's cleft protein define different domains of the infected erythrocyte intramembranous network.

Plasmodium falciparum Maurer's clefts participate in the transport of macromolecules within the cytoplasm, including the transport of virulence proteins to the erythrocyte membrane surface. We identified a family of genes PfMC-2TM encoding transmembrane proteins located within the intramembranous network of the infected erythrocyte using monoclonal antibody SP1C1. The distribution of the PfMC-2TM protein family within domains of the network was investigated by colocalization and confocal microscopy studies using monoclonal antibody SP1C1 specific for PFMC-2TM and monoclonal antibody SP1A6 specific for the130 kDa Maurer's cleft protein. Peptide-specific antibodies were prepared against six peptides from different domains of PfMC-2TM and used with the Mabs, as well as known antibodies specific to Maurer's clefts proteins (ring-expressed protein and membrane-associated histidine-rich protein 1), the erythrocyte membrane protein 1 (PfEMP-1), and serine-rich antigen in colocalization studies. We show that PfMC-2TM is located in the Maurer's clefts throughout the intracellular blood stage, and immunoelectron microscopy shows domains of PfMC-2TM localized in the parasitophorous vacuole and parasitophorous vacuole membrane. The distribution of the 130 kDa Maurer's cleft protein changes from within the parasite to the clefts during intracellular development as the parasite matures from young trophozoite to segmented schizont.

Angiotensin II and its receptor subtypes in the human retina.

PURPOSE: To quantify and evaluate the distribution of angiotensin II (Ang II) and its receptors in the human retina. METHODS: Donor eyes were obtained within 12 hours postmortem and classified as hypertensive or normotensive and diabetic or nondiabetic, based on the donors' medical histories. Ang II in retina and vitreous was quantified by RIA. Ang II receptors were characterized and quantified by competitive membrane-binding assays. Ang II, its heptapeptide metabolite Ang-(1-7), and AT1 and AT2 receptors were localized by immunohistochemistry and confocal imaging. RESULTS: Levels of Ang II in the retina were significantly higher than in vitreous (P < 0.05). Ang II in the diabetic retina had a higher median compared with that in the nondiabetic retina. Ang II and Ang-(1-7) colocalized in retinal Müller cells. The retina had the highest levels of Ang II receptors that were significantly higher than the optic nerve, retinal pigment epithelium-choroid complex, and ciliary body-iris complex (P < 0.05). AT1 receptors were more abundant than AT2 receptors in the retina. Immunoreactivity for AT1 was detected in Müller cells and on blood vessels. AT2 receptors were localized throughout the Müller cells and nuclei of ganglion cells and neurons in the inner nuclear layer. CONCLUSIONS: In the human retina, identification of Ang II and its bioactive metabolite Ang-(1-7) in Müller cells suggests that these glial cells are able to produce and process Ang II. Ang receptors were localized in the blood vessels and neural cells. Local Ang II signaling may thus allow for autoregulation of neurovascular activity. Such an autonomous system could modulate the onset and severity of retinovascular disease.

Vitamin D enhances ALA-induced protoporphyrin IX production and photodynamic cell death in 3-D organotypic cultures of keratinocytes.

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) is based upon the intracellular synthesis of protoporphyrin IX (PpIX), which absorbs light and targets metabolically active cells. We tested the hypothesis that levels of PpIX within keratinocytes might be increased by vitamin D (Vit D), a differentiation-promoting hormone. Vit D promoted terminal differentiation in monolayer cultures of rat epidermal keratinocytes (REKs), but high PpIX signals were found only in stratifying islands. To simulate a normal epidermis, REKs were grown in organotypic cultures. The presence of Vit D (10(-10) M for 4 days) led to heightened expression of terminal differentiation markers (stratum corneum, K10, and loricrin). PpIX levels, at 4 hours after addition of ALA (1 mM), were significantly increased in the Vit D-preconditioned cultures by confocal fluorescence microscopy and semiquantitative image analysis. Maximal PpIX induction was seen at (Vit D) 10(-12)-10(-10) M. Phototoxic cell killing after exposure to 635 nm light was significantly higher in Vit D-preconditioned cultures. No differences in apoptotic markers between Vit D and control cultures were seen, suggesting that Vit D augments photodynamic cell death via alternative pathways (e.g., necrosis). In summary, Vit D may be useful as a biological enhancer of ALA-based PDT.

Mice expressing the alpha(1B)-adrenergic receptor induces a synucleinopathy with excessive tyrosine nitration but decreased phosphorylation.

We had previously reported that systemic overexpression of the alpha(1B)-adrenergic receptor (AR) in a transgenic mouse induced a neurodegenerative disease that resembled the parkinsonian-like syndrome called multiple system atrophy (MSA). We now report that our mouse model has cytoplasmic inclusion bodies that colocalize with oligodendrocytes and neurons, are positive for alpha-synuclein and ubiquitin, and therefore may be classified as a synucleinopathy. Alpha-synuclein monomers as well as multimers were present in brain extracts from both normal and transgenic mice. However, similar to human MSA and other synucleinopathies, transgenic mice showed an increase in abnormal aggregated forms of alpha-synuclein, which also increased its nitrated content with age. However, the same extracts displayed decreased phosphorylation of alpha-synuclein. Other traits particular to MSA such as Purkinje cell loss in the cerebellum and degeneration of the intermediolateral cell columns of the spinal cord also exist in our mouse model but differences still exist between them. Interestingly, long-term therapy with the alpha(1)-AR antagonist, terazosin, resulted in protection against the symptomatic as well as the neurodegeneration and alpha-synuclein inclusion body formation, suggesting that signaling of the alpha(1B)-AR is the cause of the pathology. We conclude that overexpression of the alpha(1B)-AR can cause a synucleinopathy similar to other parkinsonian syndromes.