Stem Cell-based therapies for COVID-19-related acute respiratory distress syndrome.

As the number of confirmed cases and resulting death toll of the COVID-19 pandemic continue to increase around the globe - especially with the emergence of new mutations of the SARS-CoV-2 virus in addition to the known alpha, beta, gamma, delta and omicron variants - tremendous efforts continue to be dedicated to the development of interventive therapeutics to mitigate infective symptoms or post-viral sequelae in individuals for which vaccines are not accessible, viable or effective in the prevention of illness. Many of these investigations aim to target the associated acute respiratory distress syndrome, or ARDS, which induces damage to lung epithelia and other physiologic systems and is associated with progression in severe cases. Recently, stem cell-based therapies have demonstrated preliminary efficacy against ARDS based on a number of preclinical and preliminary human safety studies, and based on promising outcomes are now being evaluated in phase II clinical trials for ARDS. A number of candidate stem cell therapies have been found to exhibit low immunogenicity, coupled with inherent tropism to injury sites. In recent studies, these have demonstrated the ability to modulate suppression of pro-inflammatory cytokine signals such as those characterizing COVID-19-associated ARDS. Present translational studies are aiming to optimize the safety, efficacy and delivery to fully validate stem cell-based strategies targeting COVID-19 associated ARDS for viable clinical application.

TJP1 Contributes to Tumor Progression through Supporting Cell-Cell Aggregation and Communicating with Tumor Microenvironment in Leiomyosarcoma.

Leiomyosarcoma (LMS) is a mesenchymal malignancy with a complex karyotype. Despite accumulated evidence, the factors contributing to the development of LMS are unclear. Here, we investigated the role of tight-junction protein 1 (TJP1), a membrane-associated intercellular barrier protein during the development of LMS and the tumor microenvironment. We orthotopically transplanted SK-LMS-1 cells and their derivatives in terms of TJP1 expression by intramuscular injection, such as SK-LMS-1 Sh-Control cells and SK-LMS-1 Sh-TJP1. We observed robust tumor growth in mice transplanted with LMS cell lines expressing TJP1 while no tumor mass was found in mice transplanted with SK-LMS-1 Sh-TJP1 cells with silenced TJP1 expression. Tissues from mice were stained and further analyzed to clarify the effects of TJP1 expression on tumor development and the tumor microenvironment. To identify the TJP1-dependent factors important in the development of LMS, genes with altered expression were selected in SK-LMS-1 cells such as cyclinD1, CSF1 and so on. The top 10% of highly expressed genes in LMS tissues were obtained from public databases. Further analysis revealed two clusters related to cell proliferation and the tumor microenvironment. Furthermore, integrated analyses of the gene expression networks revealed correlations among TJP1, CSF1 and CTLA4 at the mRNA level, suggesting a possible role for TJP1 in the immune environment. Taken together, these results imply that TJP1 contributes to the development of sarcoma by proliferation through modulating cell-cell aggregation and communication through cytokines in the tumor microenvironment and might be a beneficial therapeutic target.

Anti-Tumor Effects of Sodium Meta-Arsenite in Glioblastoma Cells with Higher Akt Activities.

Glioblastoma is a type of aggressive brain tumor that grows very fast and evades surrounding normal brain, lead to treatment failure. Glioblastomas are associated with Akt activation due to somatic alterations in PI3 kinase/Akt pathway and/or PTEN tumor suppressor. Sodium meta-arsenite, KML001 is an orally bioavailable, water-soluble, and trivalent arsenical and it shows antitumoral effects in several solid tumor cells via inhibiting oncogenic signaling, including Akt and MAPK. Here, we evaluated the effect of sodium meta-arsenite, KML001, on the growth of human glioblastoma cell lines with different PTEN expression status and Akt activation, including PTEN-deficient cells (U87-MG and U251) and PTEN-positive cells (LN229). The growth-inhibitory effect of KML001 was stronger in U87-MG and U251 cells, which exhibited higher Akt activity than LN229 cells. KML001 deactivated Akt and decreased its protein levels via proteasomal degradation in U87-MG cells. KML001 upregulated mutant PTEN levels via inhibition of its proteasomal degradation. KML001 inhibited cell growth more effectively in active Akt-overexpressing LN229 cells than in mock-expressing LN229 cells. Consistent with these results, KML001 sensitized PTEN-deficient cells more strongly to growth inhibition than it did PTEN-positive cells in prostate and breast cancer cell lines. Finally, we illustrated in vivo anti-tumor effects of KML001 using an intracranial xenograft mouse model. These results suggest that KML001 could be an effective chemotherapeutic drug for the treatment of glioblastoma cancer patients with higher Akt activity and PTEN loss.

NQO1-Knockout Mice Are Highly Sensitive to Clostridium Difficile Toxin A-Induced Enteritis.

Clostridium difficile toxin A causes acute gut inflammation in animals and humans. It is known to downregulate the tight junctions between colonic epithelial cells, allowing luminal contents to access body tissues and trigger acute immune responses. However, it is not yet known whether this loss of the barrier function is a critical factor in the progression of toxin A-induced pseudomembranous colitis. We previously showed that NADH:quinone oxidoreductase 1 (NQO1) KO (knockout) mice spontaneously display weak gut inflammation and a marked loss of colonic epithelial tight junctions. Moreover, NQO1 KO mice exhibited highly increased inflammatory responses compared with NQO1 WT (wild-type) control mice when subjected to DSS-induced experimental colitis. Here, we tested whether toxin A could also trigger more severe inflammatory responses in NQO1 KO mice compared with NQO1 WT mice. Indeed, our results show that C. difficile toxin A-mediated enteritis is significantly enhanced in NQO1 KO mice compared with NQO1 WT mice. The levels of fluid secretion, villus disruption, and epithelial cell apoptosis were also higher in toxin A-treated NQO1 KO mice compared with WT mice. The previous and present results collectively show that NQO1 is involved in the formation of tight junctions in the small intestine, and that defects in NQO1 enhance C. difficile toxin A-induced acute inflammatory responses, presumably via the loss of epithelial cell tight junctions.

Potassium Acetate Blocks Clostridium difficile Toxin A-Induced Microtubule Disassembly by Directly Inhibiting Histone Deacetylase 6, Thereby Ameliorating Inflammatory Responses in the Gut.

Clostridium difficile toxin A is known to cause deacetylation of tubulin proteins, which blocks microtubule formation and triggers barrier dysfunction in the gut. Based on our previous finding that the Clostridium difficile toxin A-dependent activation of histone deacetylase 6 (HDAC-6) is responsible for tubulin deacetylation and subsequent microtubule disassembly, we herein examined the possible effect of potassium acetate (PA; whose acetyl group prevents the binding of tubulin to HDAC-6) as a competitive/false substrate. Our results revealed that PA inhibited toxin A-induced deacetylation of tubulin and recovered toxin A-induced microtubule disassembly. In addition, PA treatment significantly decreased the production of IL-6 (a marker of inflamed tissue) in the toxin A-induced mouse enteritis model. An in vitro HDAC assay revealed that PA directly inhibited HDAC-6-mediated tubulin deacetylation, indicating that PA acted as a false substrate for HDAC-6. These results collectively indicate that PA treatment inhibits HDAC-6, thereby reducing the cytotoxicity and inflammatory responses caused by C. difficile toxin A.

Antimicrobial Peptide, Lumbricusin, Ameliorates Motor Dysfunction and Dopaminergic Neurodegeneration in a Mouse Model of Parkinson's Disease.

We recently reported that the antimicrobial peptide Lumbricusin (NH2-RNRRWCIDQQA), isolated from the earthworm, increases cell proliferation in neuroblastoma SH-SY5Y cells. Here, we investigated whether Lumbricusin has neurotropic activity in mouse neural stem cells (MNSCs) and a protective effect in a mouse model of Parkinson's disease (PD). In MNSCs isolated from mouse brains, Lumbricusin treatment significantly increased cell proliferation (up to 12%) and reduced the protein expression of p27(Kip1) through proteasomal protein degradation but not transcriptional regulation. Lumbricusin inhibited the 6-OHDA-induced apoptosis of MNSCs, and also showed neuroprotective effects in a mouse PD model, ameliorating the motor impairments seen in the pole, elevated body swing, and rotation tests. These results suggest that the Lumbricusin-induced promotion of neural cell proliferation via p27(Kip1) degradation has a protective effect in an experimental PD model. Thus, the antimicrobial peptide Lumbricusin could possibly be developed as a potential therapeutic agent for the treatment of PD.

Neurotropic and neuroprotective activities of the earthworm peptide Lumbricusin.

We recently isolated a polypeptide from the earthworm Lumbricus terrestris that is structurally similar to defensin, a well-known antibacterial peptide. An 11-mer antibacterial peptide (NH2-RNRRWCIDQQA), designated Lumbricusin, was synthesized based on the amino acid sequence of the isolated polypeptide. Since we previously reported that CopA3, a dung beetle peptide, enhanced neuronal cell proliferation, we here examined whether Lumbricusin exerted neurotropic and/or neuroprotective effects. Lumbricusin treatment induced a time-dependent increase (∼51%) in the proliferation of human neuroblastoma SH-SY5Y cells. Lumbricusin also significantly inhibited the apoptosis and decreased viability induced by treatment with 6-hydroxy dopamine, a Parkinson's disease-mimicking agent. Immunoblot analyses revealed that Lumbricusin treatment increased ubiquitination of p27(Kip1) protein, a negative regulator of cell-cycle progression, in SH-SY5Y cells, and markedly promoted its degradation. Notably, adenoviral-mediated over-expression of p27(Kip1) significantly blocked the antiapoptotic effect of Lumbricusin in 6-hydroxy dopamine-treated SH-SY5Y cells. These results suggest that promotion of p27(Kip1) degradation may be the main mechanism underlying the neuroprotective and neurotropic effects of Lumbricusin.

Role of NADH: quinone oxidoreductase-1 in the tight junctions of colonic epithelial cells.

NADH:quinone oxidoreductase 1 (NQO1) is known to be involved in the regulation of energy synthesis and metabolism, and the functional studies of NQO1 have largely focused on metabolic disorders. Here, we show for the first time that compared to NQO1-WT mice, NQO1-KO mice exhibited a marked increase of permeability and spontaneous inflammation in the gut. In the DSS-induced colitis model, NQO1-KO mice showed more severe inflammatory responses than NQO1-WT mice. Interestingly, the transcript levels of claudin and occludin, the major tight junction molecules of gut epithelial cells, were significantly decreased in NQO1-KO mice. The colons of NQO1-KO mice also showed high levels of reactive oxygen species (ROS) and histone deacetylase (HDAC) activity, which are known to affect transcriptional regulation. Taken together, these novel findings indicate that NQO1 contributes to the barrier function of gut epithelial cells by regulating the transcription of tight junction molecules.

Insect peptide CopA3-induced protein degradation of p27Kip1 stimulates proliferation and protects neuronal cells from apoptosis.

We recently demonstrated that the antibacterial peptide, CopA3 (a D-type disulfide dimer peptide, LLCIALRKK), inhibits LPS-induced macrophage activation and also has anticancer activity in leukemia cells. Here, we examined whether CopA3 could affect neuronal cell proliferation. We found that CopA3 time-dependently increased cell proliferation by up to 31 ± 2% in human neuroblastoma SH-SY5Y cells, and up to 29 ± 2% in neural stem cells isolated from neonatal mouse brains. In both cell types, CopA3 also significantly inhibited the apoptosis and viability losses caused by 6-hydroxy dopamine (a Parkinson disease-mimicking agent) and okadaic acid (an Alzheimer's disease-mimicking agent). Immunoblotting revealed that the p27Kip1 protein (a negative regulator of cell cycle progression) was markedly degraded in CopA3-treated SH-SY5Y cells. Conversely, an adenovirus expressing p27Kip1 significantly inhibited the antiapoptotic effects of CopA3 against 6-hydroxy dopamine- and okadaic acid-induced apoptosis, and decreased the neurotropic effects of CopA3. These results collectively suggest that CopA3-mediated protein degradation of p27Kip1 may be the main mechanism through which CopA3 exerts neuroprotective and neurotropic effects.

Cytosine deaminase-expressing human neural stem cells inhibit tumor growth in prostate cancer-bearing mice.

Prostate cancer is the most common malignancy among men. Prostate cancer-related deaths are largely attributable to the development of hormone resistance in the tumor. No effective chemotherapy has yet been developed for advanced prostate cancer. It is desirable if a drug can be delivered directly and specifically to prostate cancer cells. Stem cells have selective migration ability toward cancer cells and therapeutic genes can be easily transduced into stem cells. In one form of gene therapy for cancer, the stem cells carry a gene encoding an enzyme that transforms an inert prodrug into a toxic product. Cytosine deaminase (CD) transforms the pro-drug 5-fluorocytosine into highly cytotoxic 5-fluorouracil (5-FU). The migration of the genetically modified stem cells was monitored by molecular magnetic resonance imaging, after labeling the stem cells with fluorescent magnetic nanoparticles (MNPs). Human neural stem cells encoding CD (HB1.F3.CD) were prepared and labeled with MNP. In tumor-bearing C57B mice, systemically transplanted HB1.F3.CD stem cells migrated toward the tumor and in combination with prodrug 5-FC, the volume of tumor implant was significantly reduced. These findings may contribute to development of a new selective chemotherapeutic strategy against prostate cancer.

Clostridium difficile toxin A inhibits erythropoietin receptor-mediated colonocyte focal adhesion through inactivation of Janus Kinase-2.

Previously, we demonstrated that the erythropoietin receptor (EpoR) is present on fibroblasts, where it regulates focal contact. Here, we assessed whether this action of EpoR is involved in the reduced cell adhesion observed in colonocytes exposed to Clostridium difficile toxin A. EpoR was present and functionally active in cells of the human colonic epithelial cell line HT29 and epithelial cells of human colon tissues. Toxin A significantly decreased activating phosphorylations of EpoR and its downstream signaling molecules JAK-2 (Janus kinase 2) and STAT5 (signal transducer and activator of transcription 5). In vitro kinase assays confirmed that toxin A inhibited JAK 2 kinase activity. Pharmacological inhibition of JAK2 (with AG490) abrogated activating phosphorylations of EpoR and also decreased focal contacts in association with inactivation of paxillin, an essential focal adhesion molecule. In addition, AG490 treatment significantly decreased expression of occludin (a tight junction molecule) and tight junction levels. Taken together, these data suggest that inhibition of JAK2 by toxin A in colonocytes causes inactivation of EpoR, thereby enhancing the inhibition of focal contact formation and loss of tight junctions known to be associated with the enzymatic activity of toxin A.

The insect peptide CopA3 inhibits lipopolysaccharide-induced macrophage activation.

We recently demonstrated that the insect peptide CopA3 (LLCIALRKK), a disulfide-linked dimeric peptide, exerts antimicrobial and anti-inflammatory activities in a mouse colitis model. Here, we examined whether CopA3 inhibited activation of macrophages by LPS. Exposure of an unseparated mouse peritoneal cell population or isolated peritoneal macrophages to LPS markedly increased secretion of IL-6 and TNF-α; these effects were significantly inhibited by CopA3 treatment. The inhibitory effect of CopA3 was also evident in murine macrophage cell line, RAW 264.7. Western blotting revealed that LPS-induced activation of STAT1 and STAT5 in macrophages was significantly inhibited by CopA3. Inhibition of JAK (STAT1/STAT5 kinase) with AG490 markedly reduced the production of IL-6 and TNF-α in macrophages. Collectively, these observations suggest that CopA3 inhibits macrophage activation by inhibiting activating phosphorylations of the transcription factors, STAT1 and STAT5, and blocking subsequent production of IL-6 and TNF-α and indicate that CopA3 may be useful as an immune-modulating agent.

Proton magnetic resonance spectroscopy of musculoskeletal lesions at 3 T with metabolite quantification.

PURPOSE: To evaluate whether proton MR spectroscopy (MRS) at 3 T with metabolite quantification is helpful for characterizing musculoskeletal lesions and to reveal whether the concentration of choline is correlated with the pathologic degree of malignancy. MATERIAL AND METHODS: Three-tesla MR images and proton MRS data from 27 consecutive patients with surgically proven musculoskeletal lesions were retrospectively analyzed. We analyzed the presence of choline peaks of malignant tumors according to the degree of malignancies, and we compared them with those of benign lesions. The concentrations of choline calculated by means of the linear combination of model spectra were also compared with respect to the degree of malignancy in each group. RESULTS: The proton MRS had an overall sensitivity of 68.4%, specificity of 87.5%, positive predictive value of 92.3%, and negative predictive value of 53.8% for the detection of choline compounds. The positive detection rate for choline compounds in the primary malignancy group (53.8%) was lower than that of the metastasis group (100%). All false-negative results were shown in the Grade 1 primary malignancy group. There was no difference in the concentration of choline compounds with respect to the pathologic degree of differentiation. CONCLUSION: MR spectroscopy at 3 T with metabolite quantification is a helpful method that shows high specificity (87.5%) in characterizing musculoskeletal lesions, even though its sensitivity (68.4%) is relatively low. Grade 1 primary malignancies of bone and soft tissue tumor have a high potential for producing false-negative results.

Possible mechanisms of improved radiation response by cytotoxic RNase, Onconase, on A549 human lung cancer xenografts of nude mice.

The cytotoxic RNase, Onconase (ONC), isolated from amphibian oocytes, was used to study its effect on the radiation response in A549 human NSCLC in vitro and in vivo. In cell culture studies, we found that ONC increased the radiation response by ONC-induced inhibition of O2 consumption (QO2). The occurrence of apoptosis was increased by ONC and was dependent on dosages and time exposure (measured by a Tunnel in situ cell death detection assay). Moreover, ONC inhibited sublethal damage repair (SLDR), confirmed by a split dose experiment. In animal studies, ONC significantly increased the radiation-induced tumor growth delay of A549 tumors in vivo. Using a non-invasive DCE-MRI technology, ONC-induced changes of perfusion were observed in A549 tumors. We concluded that the ONC-induced enhancement in tumor oxygenation was mainly due to the reduction in QO2 rather than an increase in tumor blood flow. This investigation suggests important potential clinical uses of ONC for the treatment of NSCLC cancer patients.