Patients with acute upper gastrointestinal bleeding were assigned to receive endoscopy within 6 hours or between 6 and 24 hours after gastroenterologic consultation. Mortality at 30 days was 8.9% in ...the former group and 6.6% in the latter group; earlier endoscopy did not lower mortality.
SHARPIN, together with RNF31/HOIP and RBCK1/HOIL1, form the linear ubiquitin chain assembly complex (LUBAC) E3 ligase that catalyzes M1-linked polyubiquitination. Mutations in
and
in humans and
in ...mice lead to autoinflammation and immunodeficiency, but the mechanism underlying the immune dysregulation remains unclear. We now show that the phenotype of the
mice is dependent on CYLD, a deubiquitinase previously shown to mediate removal of K63-linked polyubiquitin chains. Dermatitis, disrupted splenic architecture, and loss of Peyer's patches in the
mice were fully reversed in
mice. We observed enhanced association of RIPK1 with the death-signaling Complex II following TNF stimulation in
cells, a finding dependent on CYLD since we observed reversal in
cells. Enhanced RIPK1 recruitment to Complex II in
cells correlated with impaired phosphorylation of CYLD at serine 418, a modification reported to inhibit its enzymatic activity. The dermatitis in the
mice was also ameliorated by the conditional deletion of
using
or
indicating that CYLD-dependent death of myeloid cells is inflammatory. Our studies reveal that under physiological conditions, TNF- and RIPK1-dependent cell death is suppressed by the linear ubiquitin-dependent inhibition of CYLD. The
phenotype illustrates the pathological consequences when CYLD inhibition fails.
Ripoptocide - A Spark for Inflammation Ang, Rosalind L; Chan, Mark; Ting, Adrian T
Frontiers in cell and developmental biology,
08/2019, Letnik:
7
Journal Article
Recenzirano
Odprti dostop
The clinical success of biologics that inhibit TNF (Tumor Necrosis Factor) in inflammatory bowel diseases (IBD), psoriasis and rheumatoid arthritis (RA) has clearly established a pathogenic role for ...this cytokine in these inflammatory disorders. TNF binding to its receptors activates NFκB and MAPK signaling, inducing the expression of downstream pro-inflammatory genes. This is thought to be the primary mechanism by which TNF elicits inflammation. TNF is also a well-known trigger of caspase-dependent apoptosis or caspase-independent necroptosis. Whether cell death has any role in TNF-mediated inflammation has been less clear. Emerging data from animal models now suggest that cellular demise caused by TNF may indeed provoke inflammation. The default response of most cells to TNF stimulation is survival, rather than death, due to the presence of two sequential cell death checkpoints. The early checkpoint is transcription-independent involving the non-degradative ubiquitination of RIPK1 to prevent RIPK1 from becoming a death-signaling molecule. The later checkpoint requires the induction of pro-survival genes by NFκB-mediated transcription. When the early checkpoint is disrupted, RIPK1 initiates cell death and we suggest the term
to describe this manner of death (encompassing both apoptosis and necroptosis). The sensitivity of a cell to ripoptocide is determined by the balance between regulatory molecules that enforce and those that disassemble the early checkpoint. As there is evidence suggesting that ripoptocide is inflammatory, individuals may develop inflammation due to ripoptocide brought about by genetic, epigenetic or post-translational alteration of these checkpoint regulators. For these individuals, drugs that reinforce the early checkpoint and inhibit ripoptocide could be useful in ameliorating inflammation.
Pharmacokinetics of melamine has not been studied in pregnancies despite of the many reports on the effect on renal damage in adult and neonates. In this study, Sprague–Dawley rats have been used as ...a model to study the single-dose effect of melamine administration in late pregnancy and in neonates within 24
h. Melamine concentrations in maternal serum, breast milk, whole foetus, amniotic fluid, neonatal serum and neonatal kidney was measured by liquid chromatography coupled with mass spectrometry. Melamine was detected in all the samples, including foetal rats and amniotic fluid
in utero. Melamine was able to pass through placenta and reach the foetus, and to accumulate in lactating mammary gland and neonatal kidney. Moreover, melamine was eliminated through the placenta of the foetus and the kidneys of the neonates, and later excreted into the amniotic fluid. The study characterised for the first time the distribution of melamine in foetuses and neonates, providing reference for toxicological study of melamine during pregnancy.
TNF ligation of TNF receptor 1 (TNFR1) promotes either inflammation and cell survival by (a) inhibiting RIPK1's death-signaling function and activating NF-κB or (b) causing RIPK1 to associate with ...the death-inducing signaling complex to initiate apoptosis or necroptosis. The cellular source of TNF that results in RIPK1-dependent cell death remains unclear. To address this, we employed in vitro systems and murine models of T cell-dependent transplant or tumor rejection in which target cell susceptibility to RIPK1-dependent cell death could be genetically altered. We show that TNF released by T cells is necessary and sufficient to activate RIPK1-dependent cell death in target cells and thereby mediate target cell cytolysis independently of T cell frequency. Activation of the RIPK1-dependent cell death program in target cells by T cell-derived TNF accelerates murine cardiac allograft rejection and synergizes with anti-PD1 administration to destroy checkpoint blockade-resistant murine melanoma. Together, the findings uncover a distinct immunological role for TNF released by cytotoxic effector T cells following cognate interactions with their antigenic targets. Manipulating T cell TNF and/or target cell susceptibility to RIPK1-dependent cell death can be exploited to either mitigate or augment T cell-dependent destruction of allografts and malignancies to improve outcomes.
TANK binding kinase 1 (TBK1) regulates IFN-I, NF-κB, and TNF-induced RIPK1-dependent cell death (RCD). In mice, biallelic loss of TBK1 is embryonically lethal. We discovered four humans, ages 32, 26, ...7, and 8 from three unrelated consanguineous families with homozygous loss-of-function mutations in TBK1. All four patients suffer from chronic and systemic autoinflammation, but not severe viral infections. We demonstrate that TBK1 loss results in hypomorphic but sufficient IFN-I induction via RIG-I/MDA5, while the system retains near intact IL-6 induction through NF-κB. Autoinflammation is driven by TNF-induced RCD as patient-derived fibroblasts experienced higher rates of necroptosis in vitro, and CC3 was elevated in peripheral blood ex vivo. Treatment with anti-TNF dampened the baseline circulating inflammatory profile and ameliorated the clinical condition in vivo. These findings highlight the plasticity of the IFN-I response and underscore a cardinal role for TBK1 in the regulation of RCD.
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•Homozygous LoF TBK1 produces systemic autoinflammation, not overt viral disease.•Expressed but inactive TBK1 inhibits IFN-I induction more than no TBK1.•Autoinflammation is driven by TNF-induced cell death caused by dysregulated RIPK1.•Treatment with anti-TNF resolves clinical disease.
TBK1 signals activation of antiviral defenses and controls TNF-mediated inflammation. Deletion of TBK1 in mice is embryonically lethal. Humans lacking TBK1 expression survive and have adequate antiviral function. Instead, these individuals suffer from inflammatory pathology driven by sensitivity to TNF-induced cell death that can be effectively treated with anti-TNF therapeutics.
Crossing the blood-brain barrier in primates is a major obstacle for gene delivery to the brain. Adeno-associated viruses (AAVs) promise robust, non-invasive gene delivery from the bloodstream to the ...brain. However, unlike in rodents, few neurotropic AAVs efficiently cross the blood-brain barrier in non-human primates. Here we report on AAV.CAP-Mac, an engineered variant identified by screening in adult marmosets and newborn macaques, which has improved delivery efficiency in the brains of multiple non-human primate species: marmoset, rhesus macaque and green monkey. CAP-Mac is neuron biased in infant Old World primates, exhibits broad tropism in adult rhesus macaques and is vasculature biased in adult marmosets. We demonstrate applications of a single, intravenous dose of CAP-Mac to deliver functional GCaMP for ex vivo calcium imaging across multiple brain areas, or a cocktail of fluorescent reporters for Brainbow-like labelling throughout the macaque brain, circumventing the need for germline manipulations in Old World primates. As such, CAP-Mac is shown to have potential for non-invasive systemic gene transfer in the brains of non-human primates.
Frequent gene duplications in the genome incessantly supply new genetic materials for functional innovation presumably driven by positive Darwinian selection. This mechanism in the desaturase gene ...family has been proposed to be important in triggering the pheromonal diversification in insects. With the recent completion of a dozen Drosophila genomes, a genome-wide perspective is possible. In this study, we first identified homologs of desaturase genes in 12 Drosophila species and noted that while gene duplication events are relatively frequent, gene losses are not scarce, especially in the desat1-desat2-desatF clade. By reconciling the gene tree with species phylogeny and the chromosomal synteny of the sequenced Drosophila genomes, at least one gene loss in desat2 and a minimum of six gene gains (resulting in seven desatF homologs, α-η), three gene losses and one relocation in desatF were inferred. Upon branching off the ancestral desat1 lineage, both desat2 and desatF gained novel functions through accelerating protein evolution. The amino acid residues under positive selection located near the catalytic sites and the C-terminal region might be responsible for altered substrate selectivity between closely related species. The association between the expression pattern of desatF-α and the chemical composition of cuticular hydrocarbons implies that the ancestral function of desatF-α is the second desaturation at the four carbons after the first double bond in diene synthesis, and the shift from bisexual to female-specific expression in desatF-α occurred in the ancestral lineage of Drosophila melanogaster subgroup. A relationship between the number of expressed desatF homologs and the diene diversification has also been observed. These results suggest that the molecular diversification of fatty acid desaturases after recurrent gene duplication plays an important role in pheromonal diversity in Drosophila.
Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T cells associated with chronic infection by human T-cell lymphotropic virus type-1 (HTLV-1). ATLL patients with aggressive subtypes ...have dismal outcomes. We demonstrate that ATLL cells co-opt an early checkpoint within the tumor necrosis factor receptor 1 (TNFR1) pathway, resulting in survival advantage. This early checkpoint revolves around an interaction between the deubiquitinase CYLD and its target RIPK1. The status of RIPK1 K63-ubiquitination determines cell fate by creating either a prosurvival signal (ubiquitinated RIPK1) or a death signal (deubiquitinated RIPK1). In primary ATLL samples and in cell line models, an increased baseline level of CYLD phosphorylation was observed. We therefore tested the hypothesis that this modification of CYLD, which has been reported to inhibit its deubiquitinating function, leads to increased RIPK1 ubiquitination and thus provides a prosurvival signal to ATLL cells. CYLD phosphorylation can be pharmacologically reversed by IKK inhibitors, specifically by TBK1/IKKε and IKKβ inhibitors (MRT67307 and TPCA). Both of the IKK sub-families can phosphorylate CYLD, and the combination of MRT67307 and TPCA have a marked effect in reducing CYLD phosphorylation and triggering cell death. ATLL cells overexpressing a kinase-inactive TBK1 (TBK1-K38A) demonstrate lower CYLD phosphorylation and subsequently reduced proliferation. IKK blockade reactivates CYLD, as evidenced by the reduction in RIPK1 ubiquitination, which leads to the association of RIPK1 with the death-inducing signaling complex (DISC) to trigger cell death. In the absence of CYLD, RIPK1 ubiquitination remains elevated following IKK blockade and it does not associate with the DISC. SMAC mimetics can similarly disrupt CYLD phosphorylation and lead to ATLL cell death through reduction of RIPK1 ubiquitination, which is CYLD dependent. These results identify CYLD as a crucial regulator of ATLL survival and point to its role as a potential novel target for pharmacologic modification in this disease.
e22522
Background: Breast cancer is the most common cancer in women worldwide. Both intrinsic and environmental factors contribute to the disparities in breast cancer incidence across different ...regions. In Hong Kong, the incidence has been increasing in the past decades. With over 4700 women diagnosed in 2019, breast cancer is responsible for 27% of all female cancers in Hong Kong. Apart from intrinsic non-modifiable risk factors, some risk factors are modifiable and may reduce cancer risk. Methods: We conducted a case-control study that involved breast cancer patients from the Hong Kong Breast Cancer Registry with matched healthy controls from the community between 2014 and 2017. A standardized written questionnaire was used through face-to-face interviews of all study participants. The questionnaire collected information on participants’ demographics, general health, smoking history and other lifestyle factors including physical activity, self-assessed dietary habits (balanced, vegetarian, meat and dairy-rich diets), self-perceived stress levels (measured with a 4-point Likert scale, and high stress level was defined as having over 50% of the participant’s time with stress being scored 3 or above out of a Likert scale of 4), body mass index, family history, menstrual and reproductive history, and history on the use of oral contraceptives and hormone replacement therapy. Multiple logistic regression was fitted to compare all risk factors. Results: A total of 5,186 breast cancer patients and 5,571 controls were recruited. Modifiable risk factors that were shown to be associated with an increased risk of breast cancer included self-perceived high stress level (adjusted odd ratios aOR = 3.44; 95% CI = 3.13-3.78), meat-rich diet (aOR = 1.77; 95% CI = 1.54-2.04), dairy-rich diet (aOR = 3.33; 95% CI = 2.01-5.52), overweight/obese status (aOR = 1.21; 95% CI = 1.10-1.32), delayed child-bearing (aOR = 2.23; 95% CI = 1.79-2.79), nulliparity (aOR = 1.21; 95% CI = 1.08-1.35) and ever use of oral contraceptives (aOR = 1.34; 95% CI = 1.22-1.47), while exercise (OR = 0.62; 95% CI = 0.56-0.68) and breast-feeding (aOR = 0.76; 95% CI = 0.69-0.83) were associated with reduced risk. Conclusions: In Hong Kong, high stress level, meat- and dairy- rich diet, overweight/obese, reproductive history and use of oral contraceptives were identified to be modifiable risk factors for breast cancer. Adjusting these factors through lifestyle modification may curb the increasing trend of breast cancer incidences in the coming decades.
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