Deletion of the WD40 domain of ATG16L1 exacerbates acute pancreatitis, abolishes LAP-like non-canonical autophagy and slows trypsin degradation.

The WD40 domain (WDD) of ATG16L1 plays a pivotal role in non-canonical autophagy. This study examined the role of recently identified LAP-like non-canonical autophagy (LNCA) in acute pancreatitis. LNCA involves rapid single-membrane LC3 conjugation to endocytic vacuoles in pancreatic acinar cells. The rationale for this study was the previously observed presence of trypsin in the organelles undergoing LNCA; aberrant trypsin formation is an important factor in pancreatitis development. Here we report that the deletion of WDD (attained in ATG16L1[E230] mice) eliminated LNCA, aggravated caerulein-induced acute pancreatitis and suppressed the fast trypsin degradation observed in both a rapid caerulein-induced disease model and in caerulein-treated isolated pancreatic acinar cells. These experiments indicate that LNCA is a WDD-dependent mechanism and suggest that it plays not an activating but a protective role in acute pancreatitis. Furthermore, palmitoleic acid, another inducer of experimental acute pancreatitis, strongly inhibited LNCA, suggesting a novel mechanism of pancreatic lipotoxicity.Abbreviation: AMY: amylase; AP: acute pancreatitis; CASM: conjugation of Atg8 to single membranes; CCK: cholecystokinin; FAEE model: fatty acid and ethanol model; IL6: interleukin 6; LA: linoleic acid; LAP: LC3-associated phagocytosis; LMPO: lung myeloperoxidase; LNCA: LAP-like non-canonical autophagy; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MPO: myeloperoxidase; PMPO: pancreatic myeloperoxidase; POA: palmitoleic acid; WDD: WD40 domain; WT: wild type.

Longitudinal Assessment of Bone Mineral Density in Women Living With and Without HIV Across Reproductive Phases.

BACKGROUND: Women living with HIV commonly experience low areal bone mineral density (BMD), but whether this is affected by low ovarian hormonal states (prolonged amenorrhea or menopause) is unknown. We compared rates of BMD loss between women living with HIV and HIV-negative control women and investigated its association with low ovarian hormonal states. SETTING: Women living with HIV were enrolled from Vancouver Canada and controls from 9 Canadian sites. METHODS: This longitudinal analysis included age-matched women living with HIV in the Children and Women: AntiRetrovirals and Markers of Aging cohort and controls in the population-based Canadian Multicentre Osteoporosis Study. Rate of change/year in BMD at the total hip and lumbar spine (L1-L4) between 3 and 5 years was compared between groups, adjusting for sociodemographic and clinical variables. RESULTS: Ninety-two women living with HIV (median [interquartile range] age: 49.5 [41.6-54.1] years and body mass index: 24.1 [20.7-30.8] kg/m 2 ) and 278 controls (age: 49.0 [43.0-55.0] years and body mass index: 25.8 [22.9-30.6] kg/m 2 ) were included. Total hip BMD loss was associated with HIV (ß: -0.003 [95% CI: -0.006 to -0.0001] g/cm 2 /yr), menopause (ß: -0.007 [-0.01 to -0.005] g/cm 2 /yr), and smoking (ß: -0.003 [-0.006 to -0.0002] g/cm 2 /yr); BMD gain was linked with higher body mass index (ß: 0.0002 [0.0007-0.0004] g/cm 2 /yr). Menopause was associated with losing L1-L4 BMD (ß: -0.01 [-0.01 to -0.006] g/cm 2 /yr). Amenorrhea was not associated with BMD loss. CONCLUSIONS: HIV and menopause negatively influenced total hip BMD. These data suggest women living with HIV require hip BMD monitoring as they age.

Absence of the primary cilia formation gene Talpid3 impairs muscle stem cell function.

Skeletal muscle stem cells (MuSC) are crucial for tissue homoeostasis and repair after injury. Following activation, they proliferate to generate differentiating myoblasts. A proportion of cells self-renew, re-enter the MuSC niche under the basal lamina outside the myofiber and become quiescent. Quiescent MuSC have a primary cilium, which is disassembled upon cell cycle entry. Ex vivo experiments suggest cilia are important for MuSC self-renewal, however, their requirement for muscle regeneration in vivo remains poorly understood. Talpid3 (TA3) is essential for primary cilia formation and Hedgehog (Hh) signalling. Here we use tamoxifen-inducible conditional deletion of TA3 in MuSC (iSC-KO) and show that regeneration is impaired in response to cytotoxic injury. Depletion of MuSC after regeneration suggests impaired self-renewal, also consistent with an exacerbated phenotype in TA3iSC-KO mice after repeat injury. Single cell transcriptomics of MuSC progeny isolated from myofibers identifies components of several signalling pathways, which are deregulated in absence of TA3, including Hh and Wnt. Pharmacological activation of Wnt restores muscle regeneration, while purmorphamine, an activator of the Smoothened (Smo) co-receptor in the Hh pathway, has no effect. Together, our data show that TA3 and primary cilia are important for MuSC self-renewal and pharmacological treatment can efficiently restore muscle regeneration.

NSF/αSNAP2-mediated cis-SNARE complex disassembly precedes vesicle fusion in Arabidopsis cytokinesis.

Eukaryotic membrane fusion requires trans-SNARE complexes bridging the gap between adjacent membranes1. Fusion between a transport vesicle and its target membrane transforms the trans- into a cis-SNARE complex. The latter interacts with the hexameric AAA+-ATPase N-ethylmaleimide-sensitive factor (NSF) and its co-factor alpha-soluble NSF attachment protein (αSNAP), forming a 20S complex2,3. ATPase activity disassembles the SNAP receptor (SNARE) complex into Qa-SNARE, which folds back onto itself, and its partners4,5. The fusion of identical membranes has a different sequence of events6. The fusion partners each have cis-SNARE complexes to be broken up by NSF and αSNAP. The Qa-SNARE monomers are then stabilized by interaction with Sec1/Munc18-type regulators (SM proteins) to form trans-SNARE complexes, as shown for the yeast vacuole7. Membrane fusion in Arabidopsis cytokinesis is formally akin to vacuolar fusion8. Membrane vesicles fuse with one another to form the partitioning membrane known as the cell plate. Cis-SNARE complexes of cytokinesis-specific Qa-SNARE KNOLLE and its SNARE partners are assembled at the endoplasmic reticulum and delivered by traffic via the Golgi/trans-Golgi network to the cell division plane9. The SM protein KEULE is required for the formation of trans-SNARE complexes between adjacent membrane vesicles10. Here we identify NSF and its adaptor αSNAP2 as necessary for the disassembly of KNOLLE cis-SNARE complexes, which is a prerequisite for KNOLLE-KEULE interaction in cytokinesis. In addition, we show that NSF is required for other trafficking pathways and interacts with the respective Q-SNAREs. The SNARE complex disassembly machinery is conserved in plants and plays a unique essential role in cytokinesis.

Prevalence, causes, and impact of non-visualized pregnancy losses in a recurrent pregnancy loss population.

STUDY QUESTION: Does the occurrence of non-visualized pregnancy loss (NVPL) affect future reproductive outcomes in patients with recurrent pregnancy loss (RPL)? SUMMARY ANSWER: The number of previous NVPLs is a significant predictor of subsequent live birth in patients with RPL. WHAT IS KNOWN ALREADY: The number of preceding miscarriages is a strong indicator for future reproductive outcomes. However, NVPL particularly has been sparsely addressed in previous literature. STUDY DESIGN, SIZE, DURATION: We performed a retrospective cohort study of 1981 patients attending a specialized recurrent pregnancy loss clinic (RPL) from January 2012 to March 2021. A total of 1859 patients met the inclusion criteria of the study and were included in the analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients with a history of RPL, defined as ≥2 pregnancy losses before 20 weeks gestation, who attended a specialized RPL clinic in a tertiary care center were included. Patients' evaluation included parental karyotyping, antiphospholipid antibodies screening, uterine cavity assessment with hysterosalpingography (HSG) or hysteroscopy, maternal thyroid stimulating hormone (TSH) testing, and serum hemoglobin A1C testing. Other investigations were performed only when indicated such as testing for inherited thrombophilias, serum prolactin, oral glucose tolerance test, and endometrial biopsy. Patients were divided into three groups; patients who experienced NVPLs only (pure NVPLs group), patients with only visualized pregnancy losses (pure VPLs group), and patients with history of both NVPLs and VPLs (mixed group). Statistical analysis was performed using Wilcoxon rank-sum tests for continuous variables and Fisher's exact tests for categorical variables. Significance was detected when P values <0.05. A logistic regression model was used to determine the impact of NVPLs and VPLs numbers on any live birth subsequent to the initial RPL clinic visit. MAIN RESULTS AND THE ROLE OF CHANCE: The prevalence of patients with pure NVPLs, pure VPLs, and mixed losses was 14.7% (274/1859), 31.8% (591/1859), and 53.5% (994/1859), respectively. The prevalence of acquired and congenital uterine anomalies diagnosed by HSG or hysteroscopy was significantly different between pure NVPLs, pure VPLs, and mixed groups (16.8% versus 23.7% versus. 20.7%, respectively P = 0.05). There were no significant differences in the results of other RPL investigations or baseline demographics between the three groups. A logistic regression model controlling for maternal age at the initial RPL clinic visit and the follow-up duration showed that the numbers of NVPLs (odds ratio (OR): 0.77, CI: 0.68-0.88) and VPLs (OR: 0.75, CI: 0.64-0.86) are strong predictors for subsequent live births after the initial RPL clinic visit (P < 0.001). The odds of having a live birth decreased by 23% and 25% with each additional NVPL and VPL, respectively. LIMITATIONS, REASONS FOR CAUTION: This study may be limited by its retrospective design. Some of our data, including home pregnancy tests and obstetric history, are based on patient self-reporting, which could have overstated the true prevalence of NVPLs. Another limitation is the lack of available live birth data for all patients at the time of the analysis. WIDER IMPLICATIONS OF THE FINDINGS: To our knowledge, this is the first study to examine and analyze the reproductive outcomes of patients with pure NVPLs in a substantial cohort of patients with RPL. NVPLs seem to affect future live births the same way as clinical miscarriages, which supports their inclusion in RPL definitions. STUDY FUNDING/COMPETING INTEREST(S): This study was supported in part by Canadian Institute Heath Grant (CIHR): Reference Number/W11-179912 and Women's Health Research Institute (WHRI), Vancouver, BC, Canada. M.A.B: Research grants from Canadian Institute for Health Research (CIHR) and Ferring Pharmaceutical. M.A.B. is on the advisory board for AbbVie and Baxter. TRIAL REGISTRATION NUMBER: N/A.

Vitamin D intakes among women living with and without HIV in Canada.

BACKGROUND: Patterns of vitamin D intake are relatively unexplored among women living with HIV, despite its importance for women's health. We compared vitamin D dietary and supplement intakes in women with HIV and population-based national controls and investigated barriers to intake. METHODS: In this case-control study, women with HIV in the Children and Women: AntiRetrovirals and Markers of Aging (CARMA) cohort were matched with Canadian Multicentre Osteoporosis Study (CaMos) controls. Participants were queried for vitamin D in dairy consumption, supplementation/dosage, and sociodemographic variables. We assessed barriers to supplementation and factors associated with dietary intake by regression modelling. RESULTS: Ninety-five women living with HIV were age-matched to 284 controls. Women with HIV had lower income and bone mineral density and were more likely to smoke, take multiple medications and be non-white. Vitamin D dietary intake was lower in women living with HIV versus controls [0.76 vs. 1.79 µg/day; adjusted odds ratio (aOR) for greater than or equal to median intake 0.29 (0.12-0.61), p = 0.002], but any supplementation was higher [62.2% vs. 44.7%; aOR = 3.44 (95% CI: 1.16-11.00), p = 0.03]. Total vitamin D intake was similar between groups. Smoking was associated with no supplementation; non-white ethnicity and low income were related to lower dietary intake. CONCLUSIONS: Women living with HIV showed lower dietary vitamin D intake but higher supplementation rates, suggesting that care providers are promoting supplementation. Women living with HIV who smoke, have low incomes and are non-white may particularly benefit from targeted efforts to improve vitamin D intake.

Control of infection by LC3-associated phagocytosis, CASM, and detection of raised vacuolar pH by the V-ATPase-ATG16L1 axis.

The delivery of pathogens to lysosomes for degradation provides an important defense against infection. Degradation is enhanced when LC3 is conjugated to endosomes and phagosomes containing pathogens to facilitate fusion with lysosomes. In phagocytic cells, TLR signaling and Rubicon activate LC3-associated phagocytosis (LAP) where stabilization of the NADPH oxidase leads to sustained ROS production and raised vacuolar pH. Raised pH triggers the assembly of the vacuolar ATPase on the vacuole membrane where it binds ATG16L1 to recruit the core LC3 conjugation complex (ATG16L1:ATG5-12). This V-ATPase-ATG16L1 axis is also activated in nonphagocytic cells to conjugate LC3 to endosomes containing extracellular microbes. Pathogens provide additional signals for recruitment of LC3 when they raise vacuolar pH with pore-forming toxins and proteins, phospholipases, or specialized secretion systems. Many microbes secrete virulence factors to inhibit ROS production and/or the V-ATPase-ATG16L1 axis to slow LC3 recruitment and avoid degradation in lysosomes.

Autophagy, Acute Pancreatitis and the Metamorphoses of a Trypsinogen-Activating Organelle.

Recent studies have highlighted the importance of autophagy and particularly non-canonical autophagy in the development and progression of acute pancreatitis (a frequent disease with considerable morbidity and significant mortality). An important early event in the development of acute pancreatitis is the intrapancreatic activation of trypsinogen, (i.e., formation of trypsin) leading to the autodigestion of the organ. Another prominent phenomenon associated with the initiation of this disease is vacuolisation and specifically the formation of giant endocytic vacuoles in pancreatic acinar cells. These organelles develop in acinar cells exposed to several inducers of acute pancreatitis (including taurolithocholic acid and high concentrations of secretagogues cholecystokinin and acetylcholine). Notably, early trypsinogen activation occurs in the endocytic vacuoles. These trypsinogen-activating organelles undergo activation, long-distance trafficking, and non-canonical autophagy. In this review, we will discuss the role of autophagy in acute pancreatitis and particularly focus on the recently discovered LAP-like non-canonical autophagy (LNCA) of endocytic vacuoles.

Temporal trends in thyroid-stimulating hormone and live birth rate in subclinical hypothyroid patients in a recurrent pregnancy loss population.

OBJECTIVES: The purpose of this study was to explore if thyroperoxidase antibody positivity impacts thyroid stimulating hormone levels during pregnancies following the index visit and how live birth rate is impacted when treated subclinical hypothyroidism is treated with levothyroxine or not. STUDY DESIGN: A retrospective chart review of 1443 recurrent pregnancy loss patients from BC Women's Hospital recurrent pregnancy loss clinic was conducted. Thyroid stimulating hormone in pregnancies after the index visit across thyroperoxidase antibody status was analyzed using mixed-effects linear regression. Live birth rate in patients with subclinical hypothyroidism (thyroid stimulating hormone 2.5-10 mIU/L) with levothyroxine treatment was compared to those without relative to euthyroid patients using logistic regression. RESULTS AND CONCLUSIONS: There was no significant difference in patient demographics including age, body mass index, or number of previous live births or pregnancy losses between groups. The distribution of recurrent pregnancy loss causes between groups revealed no difference in proportion of patients with anti-phospholipid antibody syndrome, hereditary thrombophilia, hyperprolactinemia, or anatomic causes. There was no significant change in thyroid stimulating hormone across thyroperoxidase antibody or treatment status (p = 0.24) for up to four subsequent pregnancies. An increased live birth rate in subclinical hypothyroidism when treated with levothyroxine relative to untreated (OR = 2.25, p < 0.001) was seen. Thyroid stimulating hormone values do not change over time following the index visit for up to 4 subsequent pregnancies irrespective of the thyroxperoxidase antibody status. An increase in live birth rate was found in patients with borderline subclinical hypothyroidism when treated with levothyroxine.

Enhancing knowledge, skills, and comfort in providing anesthesia assistance during obstetric general anesthesia for operating room nurses: a prospective observational study.

BACKGROUND: Due to a nationwide shortage of anesthesia assistants, operating room nurses are often recruited to assist with the induction of obstetric general anesthesia (GA). We developed and administered a training program and hypothesized there would be significant improvements in knowledge and skills in anesthesia assistance during obstetric GA by operating room nurses following training with adequate retention at six months. METHODS: Following informed consent, all operating room nurses at our institution were invited to participate in the study. Baseline knowledge of participants was assessed using a 14-item multiple choice questionnaire (MCQ), and skills were assessed using a 12-item checklist scored by direct observation during simulated induction of GA. Next, a 20-min didactic lecture followed by a ten-minute hands-on skills station were delivered. Knowledge and skills were immediately reassessed after training, and again at six weeks and six months. The primary outcomes of this study were adequate knowledge and skills retention at six months, defined as achieving ≥ 80% in MCQ and ≥ 80% in skills checklist scores and analyzed using longitudinal mixed-effects linear regression. RESULTS: A total of 34 nurses completed the study at six months. The mean MCQ score at baseline was 8.9 (95% confidence interval [CI], 8.5 to 9.4) out of 14. The mean skills checklist score was 5.5 (95% CI, 4.9 to 6.1) out of 12. The mean comfort scores for assisting elective and emergency Cesarean deliveries were 3.6 (95% CI, 3.2 to 3.9) and 3.1 (95% CI, 2.7 to 3.5) out of 5, respectively. There was a significant difference in the mean MCQ and skills checklist scores across the different study periods (overall P value < 0.001). Post hoc pairwise tests suggested that, compared with baseline, there were significantly higher mean MCQ scores at all time points after the training program at six weeks (11.9; 95% CI, 11.4 to 12.4; P < 0.001) and at six months (12.0; 95% CI, 11.5 to 12.4; P < 0.001). DISCUSSION: The knowledge and skills of operating room nurses in providing anesthesia assistance during obstetric GA at our institution were low at baseline. Following a single 30-min in-house, anesthesiologist-led, structured training program, scores in both dimensions significantly improved. Although knowledge improvements were adequately retained for up to six months, skills improvements decayed rapidly, suggesting that sessions should be repeated at six-week intervals, at least initially.

RéSUMé: CONTEXTE: En raison d'une pénurie nationale d'assistants en anesthésie, le personnel infirmier de la salle d'opération est souvent sollicité pour aider à l'induction de l'anesthésie générale (AG) obstétricale. Nous avons élaboré et administré un programme de formation et émis l'hypothèse qu'il y aurait des améliorations significatives dans les connaissances et les compétences en matière d'assistance en anesthésie pendant l'anesthésie générale obstétricale par les infirmières de salle d'opération après avoir suivi une formation, avec une rétention adéquate à six mois. MéTHODE: Après avoir obtenu le consentement éclairé, tout le personnel infirmier de salle d'opération de notre établissement a été invité à participer à l'étude. Les connaissances de base des participants ont été évaluées à l'aide d'un questionnaire à choix multiples (QCM) à 14 éléments, et les compétences ont été évaluées à l'aide d'une liste de contrôle de 12 éléments notée par observation directe lors d'une simulation d'induction d'anesthésie générale. Par la suite, un cours didactique de 20 minutes suivi d'une station de compétences pratiques de dix minutes a été donné. Les connaissances et les compétences ont été réévaluées immédiatement après la formation, puis de nouveau à six semaines et six mois. Les critères d'évaluation principaux de cette étude étaient la rétention adéquate des connaissances et des compétences à six mois, définie comme l'atteinte de ≥ 80 % dans les scores du QCM et ≥ 80 % dans les scores de la liste de contrôle des compétences et analysée à l'aide d'une régression linéaire longitudinale à effets mixtes. RéSULTATS: Au total, 34 infirmières ont terminé l'étude à six mois. Au début de l'étude, le score moyen au QCM était de 8,9 (intervalle de confiance [IC] à 95 %, 8,5 à 9,4) sur 14. Le score moyen sur la liste de contrôle des compétences était de 5,5 (IC 95 %, 4,9 à 6,1) sur 12. Les scores moyens d'aisance dans l'assistance pour un accouchement par césarienne programmé et d'urgence étaient de 3,6 (IC 95 %, 3,2 à 3,9) et 3,1 (IC 95 %, 2,7 à 3,5) sur 5, respectivement. Une différence significative a été observée dans les scores moyens au QCM et sur la liste de contrôle des compétences entre les différentes périodes d'étude (valeur globale P < 0,001). Les tests appariés post-hoc ont suggéré que, par rapport aux connaissances évaluées au début de l'étude, les scores moyens au QCM étaient significativement plus élevés à tous les moments après le programme de formation, à six semaines (11,9; IC 95 %, 11,4 à 12,4; P < 0,001) et à six mois (12,0; IC 95 %, 11,5 à 12,4; P < 0,001). DISCUSSION: Les connaissances et les compétences du personnel infirmier de salle d'opération dans la prestation d'une assistance en anesthésie pendant l'AG obstétricale dans notre établissement étaient faibles au commencement de notre étude. Après un seul programme de formation structuré de 30 minutes à l'interne, dirigé par un anesthésiologiste, les scores dans les deux dimensions se sont considérablement améliorés. Bien que les améliorations des connaissances aient été retenues de manière adéquate jusqu'à six mois, les améliorations des compétences se sont rapidement détériorées, ce qui suggère que les séances devraient être répétées à des intervalles de six semaines, au moins au début.

Brief Report: Undertreated Midlife Symptoms for Women Living With HIV Linked to Lack of Menopause Discussions With Care Providers.

BACKGROUND: Increasingly, women living with HIV are entering menopause (ie, cessation of menses for ≥1 year) and experiencing midlife symptoms. Menopausal hormone therapy (MHT) is first-line therapy for bothersome hot flashes and early menopause (ie, before age 45 years); however, its use in women living with HIV is poorly described. We conducted a cross-sectional assessment of MHT uptake and barriers to use in this group. SETTING: This study was conducted across 3 Canadian provinces from 2015 to 2017. METHODS: Perimenopausal and postmenopausal women living with HIV (35 years or older) in the Canadian HIV Women's Sexual and Reproductive Health Cohort Study who answered questions related to MHT use were included. Univariable/multivariable logistic regression evaluated factors associated with MHT use, adjusted for age and contraindications. RESULTS: Among 464 women, 47.8% (222 of 464) had a first-line indication for MHT; however, only 11.8% (55 of 464) reported ever using MHT and 5.6% (26 of 464) were current users. Only 44.8% had ever discussed menopause with their care provider despite almost all women having regular HIV care (97.8%). African/Caribbean/Black women had lower unadjusted odds of MHT treatment compared with White women [odds ratio (OR) 0.42 (0.18-0.89); P = 0.034]. Those who had discussed menopause with their care provider had higher odds of treatment [OR 3.13 (1.74-5.86); P < 0.001]. In adjusted analyses, only women having had a menopause discussion remained significantly associated with MHT use [OR 2.97 (1.62-5.61); P < 0.001]. CONCLUSION: Women living with HIV are seldom prescribed MHT despite frequent indication. MHT uptake was associated with care provider-led menopause discussions underscoring the need for care provider education on menopause management within HIV care.

Non-canonical autophagy functions of ATG16L1 in epithelial cells limit lethal infection by influenza A virus.

Influenza A virus (IAV) and SARS-CoV-2 (COVID-19) cause pandemic infections where cytokine storm syndrome and lung inflammation lead to high mortality. Given the high social and economic cost of respiratory viruses, there is an urgent need to understand how the airways defend against virus infection. Here we use mice lacking the WD and linker domains of ATG16L1 to demonstrate that ATG16L1-dependent targeting of LC3 to single-membrane, non-autophagosome compartments - referred to as non-canonical autophagy - protects mice from lethal IAV infection. Mice with systemic loss of non-canonical autophagy are exquisitely sensitive to low-pathogenicity IAV where extensive viral replication throughout the lungs, coupled with cytokine amplification mediated by plasmacytoid dendritic cells, leads to fulminant pneumonia, lung inflammation and high mortality. IAV was controlled within epithelial barriers where non-canonical autophagy reduced IAV fusion with endosomes and activation of interferon signalling. Conditional mouse models and ex vivo analysis showed that protection against IAV infection of lung was independent of phagocytes and other leucocytes. This establishes non-canonical autophagy in airway epithelial cells as a novel innate defence that restricts IAV infection and lethal inflammation at respiratory surfaces.

Noncanonical function of an autophagy protein prevents spontaneous Alzheimer's disease.

Noncanonical functions of autophagy proteins have been implicated in neurodegenerative conditions, including Alzheimer's disease (AD). The WD domain of the autophagy protein Atg16L is dispensable for canonical autophagy but required for its noncanonical functions. Two-year-old mice lacking this domain presented with robust ß-amyloid (Aß) pathology, tau hyperphosphorylation, reactive microgliosis, pervasive neurodegeneration, and severe behavioral and memory deficiencies, consistent with human disease. Mechanistically, we found this WD domain was required for the recycling of Aß receptors in primary microglia. Pharmacologic suppression of neuroinflammation reversed established memory impairment and markers of disease pathology in this novel AD model. Therefore, loss of the Atg16L WD domain drives spontaneous AD in mice, and inhibition of neuroinflammation is a potential therapeutic approach for treating neurodegeneration and memory loss. A decline in expression of ATG16L in the brains of human patients with AD suggests the possibility that a similar mechanism may contribute in human disease.

The Uptake, Trafficking, and Biodistribution of Bacteroides thetaiotaomicron Generated Outer Membrane Vesicles.

Gram-negative bacteria ubiquitously produce and release nano-size, non-replicative outer membrane vesicles (OMVs). In the gastrointestinal (GI-) tract, OMVs generated by members of the intestinal microbiota are believed to contribute to maintaining the intestinal microbial ecosystem and mediating bacteria-host interactions, including the delivery of bacterial effector molecules to host cells to modulate their physiology. Bacterial OMVs have also been found in the bloodstream although their origin and fate are unclear. Here we have investigated the interactions between OMVs produced by the major human gut commensal bacterium, Bacteroides thetaiotaomicron (Bt), with cells of the GI-tract. Using a combination of in vitro culture systems including intestinal epithelial organoids and in vivo imaging we show that intestinal epithelial cells principally acquire Bt OMVs via dynamin-dependent endocytosis followed by intracellular trafficking to LAMP-1 expressing endo-lysosomal vesicles and co-localization with the perinuclear membrane. We observed that Bt OMVs can also transmigrate through epithelial cells via a paracellular route with in vivo imaging demonstrating that within hours of oral administration Bt OMVs can be detected in systemic tissues and in particular, the liver. Our findings raise the intriguing possibility that OMVs may act as a long-distance microbiota-host communication system.

Crescentic glomerulonephritis in children.

BACKGROUND: To date, there is insufficient knowledge about crescentic glomerulonephritis (cGN), the most frequent immunologic cause of acute kidney injury in children. METHODS: Over a period of 16 years, we retrospectively analyzed kidney biopsy results, the clinical course, and laboratory data in 60 pediatric patients diagnosed with cGN. RESULTS: The underlying diseases were immune complex GN (n = 45/60, 75%), including IgA nephropathy (n = 19/45, 42%), lupus nephritis (n = 10/45, 22%), Henoch-Schoenlein purpura nephritis (n = 7/45, 16%) and post-infectious GN (n = 7/45, 16%), ANCA-associated pauci-immune GN (n = 10/60, 17%), and anti-glomerular basement-membrane GN (n = 1/60, 2%). Patient CKD stages at time of diagnosis and at a median of 362 days (range 237-425) were CKD I: n = 13/n = 29, CKD II: n = 15/n = 9, CKD III: n = 16/n = 7, CKD IV: n = 3/n = 3, CKD V: n = 13/n = 5. Course of cGN was different according to class of cGN, duration of disease from first clinical signs to diagnosis of cGN by biopsy, percentage of crescentic glomeruli, amount of tubular atrophy/interstitial fibrosis and necrosis on renal biopsy, gender, age, nephrotic syndrome, arterial hypertension, dialysis at presentation, and relapse. Forty-eight/60 children were treated with ≥ 5 (methyl-) prednisolone pulses and 53 patients received oral prednis(ol)one in combination with mycophenolate mofetil (n = 20), cyclosporine A (n = 20), and/or cyclophosphamide (n = 6), rituximab (n = 5), azathioprine (n = 2), tacrolimus (n = 1), and plasmapheresis/immunoadsorption (n = 5). CONCLUSIONS: The treatment success of cGN is dependent on early diagnosis and aggressive therapy, as well as on the percentage of crescentic glomeruli on renal biopsy and on the underlying type of cGN. CsA and MMF seem to be effective alternatives to cyclophosphamide.

LAP-like non-canonical autophagy and evolution of endocytic vacuoles in pancreatic acinar cells.

Activation of trypsinogen (formation of trypsin) inside the pancreas is an early pathological event in the development of acute pancreatitis. In our previous studies we identified the activation of trypsinogen within endocytic vacuoles (EVs), cellular organelles that appear in pancreatic acinar cells treated with the inducers of acute pancreatitis. EVs are formed as a result of aberrant compound exocytosis and subsequent internalization of post-exocytic structures. These organelles can be up to 12 µm in diameter and can be actinated (i.e. coated with F-actin). Notably, EVs can undergo intracellular rupture and fusion with the plasma membrane, providing trypsin with access to cytoplasmic and extracellular targets. Unraveling the mechanisms involved in cellular processing of EVs is an interesting cell biological challenge with potential benefits for understanding acute pancreatitis. In this study we have investigated autophagy of EVs and discovered that it involves a non-canonical LC3-conjugation mechanism, reminiscent in its properties to LC3-associated phagocytosis (LAP); in both processes LC3 was recruited to single, outer organellar membranes. Trypsinogen activation peptide was observed in approximately 55% of LC3-coated EVs indicating the relevance of the described process to the early cellular events of acute pancreatitis. We also investigated relationships between actination and non-canonical autophagy of EVs and concluded that these processes represent sequential steps in the evolution of EVs. Our study expands the known roles of LAP and indicates that, in addition to its well-established functions in phagocytosis and macropinocytosis, LAP is also involved in the processing of post-exocytic organelles in exocrine secretory cells. ABBREVIATIONS: AP: acute pancreatitis; CCK: cholecystokinin; CLEM: correlative light and electron microscopy; DPI: diphenyleneiodonium; EV: endocytic vacuole; LAP: LC3-associate phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PACs: pancreatic acinar cells; PFA: paraformaldehyde; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; Res: resveratrol; TAP: trypsinogen activation peptide; TEM: transmission electron microscopy; TLC-S: taurolithocholic acid 3-sulfate; TRD: Dextran Texas Red 3000 MW Neutral; ZGs: zymogen granules.

Integrative analysis of Paneth cell proteomic and transcriptomic data from intestinal organoids reveals functional processes dependent on autophagy.

Paneth cells are key epithelial cells that provide an antimicrobial barrier and maintain integrity of the small-intestinal stem cell niche. Paneth cell abnormalities are unfortunately detrimental to gut health and are often associated with digestive pathologies such as Crohn's disease or infections. Similar alterations are observed in individuals with impaired autophagy, a process that recycles cellular components. The direct effect of autophagy impairment on Paneth cells has not been analysed. To investigate this, we generated a mouse model lacking Atg16l1 specifically in intestinal epithelial cells, making these cells impaired in autophagy. Using three-dimensional intestinal organoids enriched for Paneth cells, we compared the proteomic profiles of wild-type and autophagy-impaired organoids. We used an integrated computational approach combining protein-protein interaction networks, autophagy-targeted proteins and functional information to identify the mechanistic link between autophagy impairment and disrupted pathways. Of the 284 altered proteins, 198 (70%) were more abundant in autophagy-impaired organoids, suggesting reduced protein degradation. Interestingly, these differentially abundant proteins comprised 116 proteins (41%) that are predicted targets of the selective autophagy proteins p62, LC3 and ATG16L1. Our integrative analysis revealed autophagy-mediated mechanisms that degrade key proteins in Paneth cell functions, such as exocytosis, apoptosis and DNA damage repair. Transcriptomic profiling of additional organoids confirmed that 90% of the observed changes upon autophagy alteration have effects at the protein level, not on gene expression. We performed further validation experiments showing differential lysozyme secretion, confirming our computationally inferred downregulation of exocytosis. Our observations could explain how protein-level alterations affect Paneth cell homeostatic functions upon autophagy impairment.This article has an associated First Person interview with the joint first authors of the paper.

The ATG5-binding and coiled coil domains of ATG16L1 maintain autophagy and tissue homeostasis in mice independently of the WD domain required for LC3-associated phagocytosis.

Macroautophagy/autophagy delivers damaged proteins and organelles to lysosomes for degradation, and plays important roles in maintaining tissue homeostasis by reducing tissue damage. The translocation of LC3 to the limiting membrane of the phagophore, the precursor to the autophagosome, during autophagy provides a binding site for autophagy cargoes, and facilitates fusion with lysosomes. An autophagy-related pathway called LC3-associated phagocytosis (LAP) targets LC3 to phagosome and endosome membranes during uptake of bacterial and fungal pathogens, and targets LC3 to swollen endosomes containing particulate material or apoptotic cells. We have investigated the roles played by autophagy and LAP in vivo by exploiting the observation that the WD domain of ATG16L1 is required for LAP, but not autophagy. Mice lacking the linker and WD domains, activate autophagy, but are deficient in LAP. The LAP-/- mice survive postnatal starvation, grow at the same rate as littermate controls, and are fertile. The liver, kidney, brain and muscle of these mice maintain levels of autophagy cargoes such as LC3 and SQSTM1/p62 similar to littermate controls, and prevent accumulation of SQSTM1 inclusions and tissue damage associated with loss of autophagy. The results suggest that autophagy maintains tissue homeostasis in mice independently of LC3-associated phagocytosis. Further deletion of glutamate E230 in the coiled-coil domain required for WIPI2 binding produced mice with defective autophagy that survived neonatal starvation. Analysis of brain lysates suggested that interactions between WIPI2 and ATG16L1 were less critical for autophagy in the brain, which may allow a low level of autophagy to overcome neonatal lethality. Abbreviations: CCD: coiled-coil domain; CYBB/NOX2: cytochrome b-245: beta polypeptide; GPT/ALT: glutamic pyruvic transaminase: soluble; LAP: LC3-associated phagocytosis; LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; NOD: nucleotide-binding oligomerization domain; NADPH: nicotinamide adenine dinucleotide phosphate; RUBCN/Rubicon: RUN domain and cysteine-rich domain containing Beclin 1-interacting protein; SLE: systemic lupus erythematosus; SQSTM1/p62: sequestosome 1; TLR: toll-like receptor; TMEM: transmembrane protein; TRIM: tripartite motif-containing protein; UVRAG: UV radiation resistance associated gene; WD: tryptophan-aspartic acid; WIPI: WD 40 repeat domain: phosphoinositide interacting.

[Rapid Progressive Glomerulonephritis in Children]. / Die Rasch Progessive Glomerulonephritis im Kindesalter.

Rapid Progressive Glomerulonephritis (RPGN) is a rare but very severe disease in children that often leads to acute and/or chronic renal failure requiring dialysis therapy. In this review, diagnostic criteria of RPGN including renal biopsy are discussed. An overview on general therapeutic strategies is discussed. Entities/diseases that cause RPGN are then described and special diagnostic and therapeutic features are given.