Acute Necrotizing Encephalopathy Associated with Coronavirus Disease 2019 in an Infant

A 5-week-old infant born at term was diagnosed with acute necrotizing encephalopathy associated with severe acute respiratory syndrome coronavirus 2 as evidenced by clinical presentation, neuroimaging, and cerebrospinal fluid studies. Our patient was treated with high-dose intravenous methylprednisolone, tocilizumab, and intravenous immunoglobulin with significant short-term clinical improvement but long-term sequelae.

COVID-19 in lung transplant recipients: A single center case series from New York City

There are limited data describing COVID-19 in lung transplant recipients. We performed a single center, retrospective case series study of lung transplant patients followed by the Columbia Lung Transplant program who tested positive for SARS-CoV-2 between March 19 and May 19, 2020. Thirty-two lung transplant patients developed mild (16%), moderate (44%), or severe (41%) COVID-19. The median age of patients was 65 years, and the median time from lung transplant was 5.6 years. Symptoms included cough (66%), dyspnea (50%), fever (47%), and gastrointestinal upset (44%). Patients received hydroxychloroquine (84%), azithromycin (75%), augmented steroids (44%), tocilizumab (19%), and remdesivir (9%). Eleven patients (34%) died at a median time of 14 days from admission. Complications during admission included: acute kidney injury (63%), transaminitis (31%), shock (31%), acute respiratory distress syndrome (25%), neurological events (25%), arrhythmias (22%), and venous thromboembolism (9%). Compared to patients with moderate COVID-19, patients with severe COVID-19 had higher peak white blood cell counts (15.8 vs 7 × 10³ /uL, P = .019), C-reactive protein (198 vs. 107 mg/L, P = .010) and D-dimer (8.6 vs. 2.1 ug/mL, P = .004) levels, and lower nadir lymphocyte counts (0.09 vs. 0.4 × 10³ /uL, P = .006). COVID-19 is associated with severe illness and a high mortality rate in lung transplant recipients.

Knockout of the Nogo-B Gene Attenuates Tumor Growth and Metastasis in Hepatocellular Carcinoma

Human hepatocellular carcinoma (HCC) is a malignant cancer. It is a challenge to develop anti-HCC drugs due to HCC's extreme aggressiveness and with the sensitivity of the liver to show severe adverse effects. More importantly, the precise mechanisms causing HCC pathogenicity are not known. Our previous study disclosed Nogo-B as a reticulon 4 (Rtn4) family member. In the present study, we first identified that Nogo-B played a critical role in HCC progression. We found, via in vitro and in vivo assays, that Nogo-B was expressed aberrantly in primary HCC tumor tissues and immortal HCC cells but was relatively scarce in the normal liver tissues or cells. Nogo-B knockout, via the CRISPR-Cas9 technique, resulted in significant suppression of HCC cell proliferation and tumor growth. Next-generation sequencing analysis showed that Nogo-B knockout have effects on interleukin-6 (IL-6) signaling pathway. Furthermore, we observed that IL-6 induced phosphorylation of STAT3 (pSTAT3) in wild-type HCC cells, but Nogo-B knockout could reduce IL-6-induced increase of pSTAT3, supporting that Nogo-B affects HCC tumor progression possibly via regulating the IL-6/STAT3 signaling pathway. In conclusion, Nogo-B is expressed aberrantly in HCCs and plays an oncogenic role. These findings support that Nogo-B may be a novel anti-HCC therapeutic target.

Proteinase-activated receptor-2 mediated inhibition of TNFalpha-stimulated JNK activation - A novel paradigm for G(q/11) linked GPCRs

In this study we examined the potential for PAR(2) and TNFalpha to synergise at the level of MAP kinase signalling in PAR(2) expressing NCTC2544 cells. However, to our surprise we found that activation of PAR(2) by trypsin or the specific activating peptide SLIGKV-OH strongly inhibited both the phosphorylation and activity of JNK. In contrast neither p38 MAP kinase nor ERK activation was affected although TNFalpha stimulated IkappaBalpha loss was partially reversed. The inhibitory effect was not observed in parental cells nor in cells expressing PAR(4), however inhibition was reversed by pre-incubation with the novel PAR(2) antagonist K14585, suggesting that the effect is specific for PAR(2) activation. SLIGKV-OH was found to be more potent in inhibiting TNFalpha-induced JNK activation than in stimulating JNK alone, suggesting agonist-directed signalling. The PKC activator PMA, also mimicked the inhibitory effect of SLIGKV-OH, and the effects of both agents were reversed by pre-treatment with the PKC inhibitor, GF109203X. Furthermore, incubation with the novel G(q/11) inhibitor YM25480 also reversed PAR(2) mediated inhibition. Activation of PAR(2) was found to disrupt TNFR1 binding to RIP and TRADD and this was reversed by both GF109203X and YM25480. A similar mode of inhibition observed in HUVECs through PAR(2) or P2Y2 receptors demonstrates the potential of a novel paradigm for GPCRs linked to G(q/11), in mediating inhibition of TNFalpha-stimulated JNK activation. This has important implications in assessing the role of GPCRs in inflammation and other conditions.

Over-expression of interleukin-6 enhances cell survival and transformed cell growth in human malignant cholangiocytes

BACKGROUND/AIMS

Over-expression of IL-6 has been implicated in cholangiocarcinoma growth but the cellular mechanisms involved are unknown. Our aims were to assess the mechanisms by which over-expression of IL-6 promotes transformed cell growth in malignant cholangiocytes.

METHODS

Stably transfected cell lines over-expressing IL-6 were derived from malignant human cholangiocytes. Transformed cell growth was assessed by anchorage independent growth in vitro and by xenograft growth in nude mice. Expression of the anti-apoptotic protein Mcl-1 was quantitated by immunoblot analysis and by real-time PCR. Gene silencing was performed using siRNA. Dominant negative upstream kinase activators and isoform-specific constructs were used to evaluate the involvement of p38 MAP kinase signaling pathways.

RESULTS

Over-expression of IL-6 increased xenograft growth, anchorage independent growth and cell survival but did not significantly alter cell proliferation. The basal expression of Mcl-1 was increased in IL-6 over-expressing cells. Selective knockdown of Mcl-1 by siRNA increased gemcitabine-induced cytotoxicity. Moreover, IL-6 increased Mcl-1 mRNA and protein expression via a p38 MAPK dependent mechanism.

CONCLUSIONS

These data demonstrate a major role of survival signaling pathways in mediating the effects of IL-6 over-expression in cholangiocarcinoma growth. Mcl-1 is identified as a mediator of IL-6-induced tumor cell survival and shown to be transcriptionally regulated by IL-6 via a p38 MAPK dependent pathway. We conclude that modulation of IL-6 mediated survival signaling pathways involving the p38 MAPK or downstream targets such as Mcl-1 may prove useful therapeutic strategies for human cholangiocarcinoma.

Identification of the hydrophobic strand in the A-B loop of leptin as major binding site III: implications for large-scale preparation of potent recombinant human and ovine leptin antagonists

Interaction of leptin with its receptors resembles that of interleukin-6 and granulocyte colony-stimulating factor, which interact with their receptors through binding sites I-III. Site III plays a pivotal role in receptors' dimerization or tetramerization and subsequent activation. Leptin's site III also mediates the formation of an active multimeric complex through its interaction with the IGD (immunoglobulin-like domain) of LEPRs (leptin receptors). Using a sensitive hydrophobic cluster analysis of leptin's and LEPR's sequences, we identified hydrophobic stretches in leptin's A-B loop (amino acids 39-42) and in the N-terminal end of LEPR's IGD (amino acids 325-328) that are predicted to participate in site III and to interact with each other in a beta-sheet-like configuration. To verify this hypothesis, we prepared and purified to homogeneity (as verified by SDS/PAGE, gel filtration and reverse-phase chromatography) several alanine muteins of amino acids 39-42 in human and ovine leptins. CD analyses revealed that those mutations hardly affect the secondary structure. All muteins acted as true antagonists, i.e. they bound LEPR with an affinity similar to the wild-type hormone, had no agonistic activity and specifically inhibited leptin action in several leptin-responsive in vitro bioassays. Alanine mutagenesis of LEPR's IGD (amino acids 325-328) drastically reduced its biological but not binding activity, indicating the importance of this region for interaction with leptin's site III. FRET (fluorescence resonance energy transfer) microscopy experiments have documented that the transient FRET signalling occurring upon exposure to leptin results not from binding of the ligand, but from ligand-induced oligomerization of LEPRs mediated by leptin's site III.

Characterization of the survival motor neuron (SMN) promoter provides evidence for complex combinatorial regulation in undifferentiated and differentiated P19 cells

There exist two SMN (survival motor neuron) genes in humans, the result of a 500 kb duplication in chromosome 5q13. Deletions/mutations in the SMN1 gene are responsible for childhood spinal muscular atrophy, an autosomal recessive neurodegenerative disorder. While the SMN1 and SMN2 genes are not functionally equivalent, up-regulation of the SMN2 gene represents an important therapeutic target. Consequently, we exploited in silico, in vitro and in vivo approaches to characterize the core human and mouse promoters in undifferentiated and differentiated P19 cells. Phylogenetic comparison revealed four highly conserved regions that contained a number of cis-elements, only some of which were shown to activate/repress SMN promoter activity. Interestingly, the effect of two Sp1 cis-elements varied depending on the state of P19 cells and was only observed in combination with a neighbouring Ets cis-element. Electrophoretic mobility-shift assay and in vivo DNA footprinting provided evidence for DNA-protein interactions involving Sp, NF-IL6 and Ets cis-elements, whereas transient transfection experiments revealed complex interactions involving these recognition sites. SMN promoter activity was strongly regulated by an NF-IL6 response element and this regulation was potentiated by a downstream Ets element. In vivo results suggested that the NF-IL6 response must function either via a protein-tethered transactivation mechanism or a transcription factor binding an upstream element. Our results provide strong evidence for complex combinatorial regulation and suggest that the composition or state of the basal transcription complex binding to the SMN promoter is different between undifferentiated and differentiated P19 cells.