Impact of COVID-19 pandemic on interhospital transfer of patients with major trauma in Korea: a retrospective cohort study.

BACKGROUND: Interhospital transfer (IHT) is necessary for providing ultimate care in the current emergency care system, particularly for patients with severe trauma. However, studies on IHT during the pandemic were limited. Furthermore, evidence on the effects of the coronavirus disease 2019 (COVID-19) pandemic on IHT among patients with major trauma was lacking. METHOD: This retrospective cohort study was conducted in an urban trauma center (TC) of a tertiary academic affiliated hospital in Daegu, Korea. The COVID-19 period was defined as from February 1, 2020 to January 31, 2021, whereas the pre-COVID-19 period was defined as the same duration of preceding span. Clinical data collected in each period were compared. We hypothesized that the COVID-19 pandemic negatively impacted IHT. RESULTS: A total of 2,100 individual patients were included for analysis. During the pandemic, the total number of IHTs decreased from 1,317 to 783 (- 40.5%). Patients were younger (median age, 63 [45-77] vs. 61[44-74] years, p = 0.038), and occupational injury was significantly higher during the pandemic (11.6% vs. 15.7%, p = 0.025). The trauma team activation (TTA) ratio was higher during the pandemic both on major trauma (57.3% vs. 69.6%, p = 0.006) and the total patient cohort (22.2% vs. 30.5%, p < 0.001). In the COVID-19 period, duration from incidence to the TC was longer (218 [158-480] vs. 263[180-674] minutes, p = 0.021), and secondary transfer was lower (2.5% vs. 0.0%, p = 0.025). CONCLUSION: We observed that the total number of IHTs to the TC was reduced during the COVID-19 pandemic. Overall, TTA was more frequent, particularly among patients with major trauma. Patients with severe injury experienced longer duration from incident to the TC and lesser secondary transfer from the TC during the COVID-19 pandemic.

Plasma Cell Differentiation, Antibody Quality, and Initial Germinal Center B Cell Population Depend on Glucose Influx Rate.

Serum Ab concentrations, selection for higher affinity BCRs, and generation of higher Ab affinities are important elements of immune response optimization and functions of germinal center (GC) reactions. B cell proliferation requires nutrients to support the anabolism inherent in clonal expansion. Glucose usage by mouse GC B cells has been reported to contribute little to their energy needs, with questions raised as to whether glucose uptake or glycolysis increases in GC B cells compared with their naive precursors. Indeed, metabolism can be highly flexible, such that supply shortage along one pathway may be compensated by increased flux on others. We now show that reduction of the glucose transporter GLUT1 in mice after establishment of a preimmune B cell repertoire, even after initiation of the GC B cell gene expression program, decreased initial GC B cell population numbers, affinity maturation, and plasma cell outputs. Glucose oxidation was heightened in GC B cells, but this hexose flowed more into the pentose phosphate pathway, whose activity was important in controlling reactive oxygen species (ROS) and Ab-secreting cell production. In modeling how glucose usage by B cells promotes the Ab response, the control of ROS appeared insufficient. Surprisingly, the combination of galactose, which mitigated ROS, with provision of mannose, an efficient precursor to glycosylation, supported robust production of and normal Ab secretion by Ab-secreting cells under glucose-free conditions. Collectively, the findings indicate that GCs depend on normal glucose influx, especially in plasma cell production, but reveal an unexpected metabolic flexibility in hexose requirements.

Plasma cell differentiation, antibody quality, and initial germinal center B cell population depend on glucose influx rate.

Antibody secretion into sera, selection for higher affinity BCR, and the generation of higher Ab affinities are important elements of immune response optimization, and a core function of germinal center reactions. B cell proliferation requires nutrients to support the anabolism inherent in clonal expansion. Glucose usage by GC B cells has been reported to contribute little to their energy needs, with questions raised as to whether or not glucose uptake or glycolysis increases in GC B cells compared to their naïve precursors. Indeed, metabolism can be highly flexible, such that supply shortage along one pathway may be compensated by increased flux on others. We now show that elimination of the glucose transporter GLUT1 after establishment of a pre-immune B cell repertoire, even after initiation of the GC B cell gene expression program, decreased initial GC B cell population numbers, affinity maturation, and PC outputs. Glucose oxidation was heightened in GC B cells, but this hexose flowed more into the pentose phosphate pathway (PPP), whose activity was important in controlling reactive oxygen (ROS) and ASC production. In modeling how glucose usage by B cells promotes the Ab response, the control of ROS appeared insufficient. Surprisingly, the combination of galactose, which mitigated ROS, with provision of mannose - an efficient precursor to glycosylation - supported robust production of and normal Ab secretion by ASC under glucose-free conditions. Collectively, the findings indicate that GC depend on normal glucose influx, especially in PC production, but reveal an unexpected metabolic flexibility in hexose requirements. KEY POINTS: Glucose influx is critical for GC homeostasis, affinity maturation and the generation of Ab-secreting cells.Plasma cell development uses the Pentose Phosphate Pathway, and hexose sugars maintain redox homeostasis.PCs can develop and achieve robust Ab secretion in the absence of glucose using a combination of hexose alternatives.

Poly(ADP-ribose) polymerase 9 mediates early protection against Mycobacterium tuberculosis infection by regulating type I IFN production.

The ADP ribosyltransferases (PARPs 1-17) regulate diverse cellular processes, including DNA damage repair. PARPs are classified on the basis of their ability to catalyze poly-ADP-ribosylation (PARylation) or mono-ADP-ribosylation (MARylation). Although PARP9 mRNA expression is significantly increased in progressive tuberculosis (TB) in humans, its participation in host immunity to TB is unknown. Here, we show that PARP9 mRNA encoding the MARylating PARP9 enzyme was upregulated during TB in humans and mice and provide evidence of a critical modulatory role for PARP9 in DNA damage, cyclic GMP-AMP synthase (cGAS) expression, and type I IFN production during TB. Thus, Parp9-deficient mice were susceptible to Mycobacterium tuberculosis infection and exhibited increased TB disease, cGAS and 2'3'-cyclic GMP-AMP (cGAMP) expression, and type I IFN production, along with upregulation of complement and coagulation pathways. Enhanced M. tuberculosis susceptibility is type I IFN dependent, as blockade of IFN α receptor (IFNAR) signaling reversed the enhanced susceptibility of Parp9-/- mice. Thus, in sharp contrast to PARP9 enhancement of type I IFN production in viral infections, this member of the MAR family plays a protective role by limiting type I IFN responses during TB.

Laparoscopic repair of colonoscopy-induced adult Bochdalek hernia: Case report.

INTRODUCTION: Bochdalek hernias are congenital diaphragmatic malformations caused by a failure to close the pleuroperitoneal cavity in the posterolateral area. Bochdalek hernias are very rare in adult, with congenital diaphragmatic defects being even rarer. PRESENTATION OF CASE: A 35-year-old man presented to our emergency room with epigastric pain after colonoscopy. The patient had no history of trauma. Plain chest X-ray revealed bowel gas patterns and haziness in the left lower lung field. Abdominal computed tomography revealed a left diaphragmatic defect in the posterolateral area, with herniation of the omentum and colon. The patient successfully underwent laparoscopic herniorrhaphy. DISCUSSION: The diaphragm comprises fibrous tissue and muscle. Therefore, direct damage by a colonoscope is almost impossible. Normal chest X-ray as a part of a health screening was performed 9 days prior to admission, and the size of the diaphragmatic defect could be covered by the spleen; therefore, the patient was considered hernia-free for over 30 years. CONCLUSION: We report a rare case of delayed Bochdalek hernia that may have been induced by the difficult insertion of a colonoscopy. Although rare, this disorder should be recognized, examined and treated appropriately to avoid complications.

Conservative treatment of blunt traumatic right renal venous pseudoaneurysm: A case report.

INTRODUCTION: Venous pseudoaneurysm is uncommon in blunt trauma patients, and renal venous pseudoaneurysm is especially rare, even though renal trauma occurs in approximately 8-10 % of abdominal trauma cases. There is controversy regarding the modality of treatment between surgery, conservative care, and radiologic intervention to manage renal venous pseudoaneurysms. We would like to share our experience treating blunt trauma patients having renal venous pseudoaneurysm with conservative care. PRESENTATION OF CASE: A 53-year-old female patient was transferred to our trauma center following a pedestrian accident. Contrast-enhanced abdominal computed tomography (CT) showed right renal injury (grade II) with partial infarction (approximately 30-40 %) and peri-renal hematoma confined to Gerota's fascia without extravasation, a 3 cm sized right renal venous pseudoaneurysm, and a liver laceration (grade III) with a small amount of perihepatic hemoperitoneum. Since her vital signs were stable, with no decrease in the hemoglobin level in the short-term follow-up laboratory test, we decided to treat the patient conservatively in the trauma intensive care unit without angioembolization or surgery. The patient was discharged on the 14th day after OR/IF surgery for a right distal tibiofibular fracture. On a CT scan performed 1 month after discharge, a peri-renal hematoma was no longer observed, and the renal venous pseudoaneurysm had nearly improved. DISCUSSION: Patients with renal arterial injury with unstable vital signs require surgery or angioembolization. Even if vital signs are stable, arterial pseudoaneurysms are more likely to rupture; therefore, surgery or angioembolization is required. In contrast, venous pseudoaneurysms can be managed conservatively compared to intervention or surgery in vitally stable patients because they have a lower possibility of rupture due to relatively low pressure. CONCLUSION: Renal venous pseudoaneurysms are very rare. Surgery, conservative care, and radiologic intervention should be considered depending on the patient's condition. Because venous blood flow is slower than arterial blood flow, renal venous pseudoaneurysm can be treated with conservative care if there are no injuries requiring further management and if the patient's vital signs are stable.

Selective Pharmaceutical Inhibition of PARP14 Mitigates Allergen-Induced IgE and Mucus Overproduction in a Mouse Model of Pulmonary Allergic Response.

The type 2 cytokines IL-4 and IL-13, which share use of an IL-4 receptor α-chain and its nuclear induction of the transcription factor STAT6, are crucial in elicitation and maintenance of allergic conditions including asthma. STAT6 binds poly(ADP-ribose) polymerase (PARP)14, an ADP-ribosyl monotransferase. Elimination of PARP14 by gene targeting led to attenuation of OVA-specific allergic lung inflammation. However, PARP14 has multiple functional domains apart from the portion that catalyzes ADP-ribosylation, and it is not clear whether inhibition of the catalytic function has any biological consequence. Using BALB/c mice sensitized to the allergen Alternaria alternata, we show that peroral administration of RBN012759, a highly selective inhibitor of ADP-ribosylation by PARP14 with negligible impact on other members of the PARP gene family, achieved biologically active plasma concentrations and altered several responses to the Ag. Specifically, the pharmaceutical compound decreased mucus after allergen challenge, blunted the induced increases in circulating IgE, and prevented suppression of IgG2a. We conclude that PARP14 catalytic activity can contribute to pathogenesis in allergic or atopic processes and propose that other biological endpoints dependent on ADP-ribosylation by PARP14 can be targeted using selective inhibition.

Risk factors of trauma-induced thrombotic microangiopathy-like syndrome: A retrospective analysis.

Patients with trauma may develop thrombocytopenia. We encountered cases wherein patients experienced symptoms resembling thrombotic microangiopathies (TMAs) following severe trauma. As the condition of these patients did not meet the diagnostic criteria of thrombotic thrombocytopenic purpura and there was no mention of trauma among the several causes of TMAs, it was termed as "trauma-induced thrombotic microangiopathy-like syndrome" (t-TMAS). In this study, we aimed to analyze the risk factors that may affect the incidence of t-TMAS in patients with severe trauma. This retrospective study was conducted in the trauma intensive care unit at the Kyungpook National University Hospital between January 2018 and December 2019. The medical records of 1164 of the 1392 enrolled participants were analyzed. To assess the risk factors of t-TMAS, we analyzed age, sex, mechanism of trauma, abbreviated injury scale (AIS) score, injury severity score (ISS), hematological examination, and red blood cell volume transfused in 24 hours. Among the 1164 patients, 20 (1.7%) were diagnosed with t-TMAS. The univariate analysis revealed higher age, ISS, and myoglobin, lactate, creatine kinase-myocardial band (on admission), creatine phosphokinase, lactate dehydrogenase (LDH), and lactate (day 2) levels in the t-TMAS group than in the non-t-TMAS group. The red blood cell volume transfused in 24 hours was higher in the t-TMAS group than in the non-t-TMAS group. t-TMAS was more common in patients with injuries in the chest, abdomen, and pelvis (AIS score ≥3) than in those with head injuries (AIS score ≥3) alone. The higher the sum of AIS scores of the chest, abdomen, and pelvis injuries, the higher the incidence of t-TMAS. Multivariate analysis revealed age, ISS, and LDH level (day 2) to be independent predictors of t-TMAS. Trauma surgeons should consider the possibility of t-TMAS if thrombocytopenia persists without any evidence of bleeding, particularly among older patients with multiple severe torso injuries who have high LDH levels on day 2. Early diagnosis and treatment of t-TMAS could improve patients' prognosis.

A Case-Control Study on the Changes in Natural Killer Cell Activity following Administration of Polyvalent Mechanical Bacterial Lysate in Korean Adults with Recurrent Respiratory Tract Infection.

Polyvalent mechanical bacterial lysate (PMBL) is used for the treatment and prevention of recurrent respiratory tract infections. Although PMBL is an immunostimulant, it remains unknown whether treatment with PMBL influences natural killer cell activity (NKA). Hence, this case-control study compared the changes in IFN-γ levels (surrogate index for NKA) following PMBL treatment or time passing between the PMBL-treated group and controls. The treatment group included adults who had a PMBL prescription for three months against recurrent respiratory tract infection from an outpatient clinic, while the control group had healthy adults visiting the health promotion center for periodic health check-ups. The control group (N = 506) showed no change in IFN-γ levels, while the treatment group (N = 301) showed a significant increase in mean from 462.8 to 749.3 pg/mL after PMBL treatment. In the subgroup with IFN-γ <500 pg/mL, IFN-γ levels significantly increased in both groups. However, the change in the treatment group (287 ± 822 pg/mL) was greater than that in the control group (58 ± 809 pg/mL), and the interaction between the visit and case/control was significant (p = 0.030) in a generalized estimating equation model. In conclusion, NKA increased in the subjects with recurrent respiratory tract infections with PMBL treatment.

Cross-Sectional and Time-Dependent Analyses on Inflammatory Markers following Natural Killer Cell Activity.

The function of natural killer (NK) cells in inflammation has not been explored enough in large-scale population studies. The cross-sectional and time-dependent relationship between NK cell activity (NKA) and inflammatory markers was examined. METHODS: A total of 7031 subjects were involved in the cross-sectional analyses. Non-linear relationship between NKA and inflammatory indices was analyzed using generalized additive models. The time-dependent changes were analyzed in 1005 subjects with repeated measurement in 3-6 months. The changes in inflammatory markers were analyzed based on the changes in NKA. RESULTS: As NKA reduces to a very low level, the white blood cell (WBC) and neutrophil counts increase sharply, and the lymphocyte count exhibits a slow decline. With increasing NKA larger than about 500 pg/mL, WBC and neutrophil-lymphocyte ratio (NLR) reduces in a mild slope. Among the subjects with repeated measurements, the follow-up NKA was increased with advancing baseline NKA levels. The subjects with a reduction in NKA indicated increment in WBC count, neutrophil count, and NLR, and decrease in lymphocyte count. CONCLUSIONS: Very low levels of NKA suggest a high inflammatory immune response. The changes in NKA may interact with the balance between neutrophils and lymphocytes.

Supplying the trip to antibody production-nutrients, signaling, and the programming of cellular metabolism in the mature B lineage.

The COVID pandemic has refreshed and expanded recognition of the vital role that sustained antibody (Ab) secretion plays in our immune defenses against microbes and of the importance of vaccines that elicit Ab protection against infection. With this backdrop, it is especially timely to review aspects of the molecular programming that govern how the cells that secrete Abs arise, persist, and meet the challenge of secreting vast amounts of these glycoproteins. Whereas plasmablasts and plasma cells (PCs) are the primary sources of secreted Abs, the process leading to the existence of these cell types starts with naive B lymphocytes that proliferate and differentiate toward several potential fates. At each step, cells reside in specific microenvironments in which they not only receive signals from cytokines and other cell surface receptors but also draw on the interstitium for nutrients. Nutrients in turn influence flux through intermediary metabolism and sensor enzymes that regulate gene transcription, translation, and metabolism. This review will focus on nutrient supply and how sensor mechanisms influence distinct cellular stages that lead to PCs and their adaptations as factories dedicated to Ab secretion. Salient findings of this group and others, sometimes exhibiting differences, will be summarized with regard to the journey to a distinctive metabolic program in PCs.

Over-Generalizing About GC (Hypoxia): Pitfalls of Limiting Breadth of Experimental Systems and Analyses in Framing Informatics Conclusions.

Accumulating evidence suggests that many immune responses are influenced by local nutrient concentrations in addition to the programming of intermediary metabolism within immune cells. Humoral immunity and germinal centers (GC) are settings in which these factors are under active investigation. Hypoxia is an example of how a particular nutrient is distributed in lymphoid follicles during an antibody response, and how oxygen sensors may impact the qualities of antibody output after immunization. Using exclusively a bio-informatic analysis of mRNA levels in GC and other B cells, recent work challenged the concept that there is any hypoxia or that it has any influence. To explore this proposition, we performed new analyses of published genomics data, explored potential sources of disparity, and elucidated aspects of the apparently conflicting conclusions. Specifically, replicability and variance among data sets derived from different naïve as well as GC B cells were considered. The results highlight broader issues that merit consideration, especially at a time of heightened focus on scientific reports in the realm of immunity and antibody responses. Based on these analyses, a standard is proposed under which the relationship of new data sets should be compared to prior "fingerprints" of cell types and reported transparently to referees and readers. In light of independent evidence of diversity within and among GC elicited by protein immunization, avoidance of overly broad conclusions about germinal centers in general when experimental systems are subject to substantial constraints imposed by technical features also is warranted.

Synchronous gallbladder metastasis of renal cell carcinoma presenting as a gallbladder polyp: A case report.

RATIONALE: Gallbladder polyps are common in the general population, but gallbladder metastasis of renal cell carcinoma (RCC) is very rare. In a patient with RCC diagnosed with a small gallbladder polyp that does not meet the traditional size criteria, the surgeon faces a dilemma of whether cholecystectomy should be performed given the possibility of metastasis. PATIENT CONCERNS: A 55-year-old man who had received a left nephrectomy for RCC presented with a gallbladder polyp that was noted at the time of the nephrectomy. Imaging showed the maximum diameter of the polyp had increased from 5 mm to 24 mm in the 40 months after the initial diagnosis. DIAGNOSIS: Pathological and immunohistology findings confirmed the gallbladder polyp as a metastasis of clear-cell RCC. INTERVENTIONS: : We performed a laparoscopic cholecystectomy. OUTCOMES: Even though the synchronous solitary gallbladder metastasis was left untreated and a cholecystectomy was not performed over the 40 months, no metastasis occurred in other sites. The patient is free from disease 10 months after the cholecystectomy. LESSONS: Solitary gallbladder metastasis of RCC may have more favorable outcomes than typical metastases. Although gallbladder metastasis of RCC occur rarely, it can occur, and any changes in gallbladder polyps in RCC patients should be managed under a strong suspicion of metastasis.

Selective glutamine metabolism inhibition in tumor cells improves antitumor T lymphocyte activity in triple-negative breast cancer.

Rapidly proliferating tumor and immune cells need metabolic programs that support energy and biomass production. The amino acid glutamine is consumed by effector T cells and glutamine-addicted triple-negative breast cancer (TNBC) cells, suggesting that a metabolic competition for glutamine may exist within the tumor microenvironment, potentially serving as a therapeutic intervention strategy. Here, we report that there is an inverse correlation between glutamine metabolic genes and markers of T cell-mediated cytotoxicity in human basal-like breast cancer (BLBC) patient data sets, with increased glutamine metabolism and decreased T cell cytotoxicity associated with poor survival. We found that tumor cell-specific loss of glutaminase (GLS), a key enzyme for glutamine metabolism, improved antitumor T cell activation in both a spontaneous mouse TNBC model and orthotopic grafts. The glutamine transporter inhibitor V-9302 selectively blocked glutamine uptake by TNBC cells but not CD8+ T cells, driving synthesis of glutathione, a major cellular antioxidant, to improve CD8+ T cell effector function. We propose a "glutamine steal" scenario, in which cancer cells deprive tumor-infiltrating lymphocytes of needed glutamine, thus impairing antitumor immune responses. Therefore, tumor-selective targeting of glutamine metabolism may be a promising therapeutic strategy in TNBC.

AMPKα1 in B Cells Dampens Primary Antibody Responses yet Promotes Mitochondrial Homeostasis and Persistence of B Cell Memory.

Emerging evidence indicates that metabolic programs regulate B cell activation and Ab responses. However, the metabolic mediators that support the durability of the memory B cell and long-lived plasma cell populations are not fully elucidated. Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionary conserved serine/threonine kinase that integrates cellular energy status and nutrient availability to intracellular signaling and metabolic pathways. In this study, we use genetic mouse models to show that loss of ΑMPKα1 in B cells led to a weakened recall Ab response associated with a decline in the population of memory-phenotype B cells. AMPKα1-deficient memory B lymphocytes exhibited aberrant mitochondrial activity, decreased mitophagy, and increased lipid peroxidation. Moreover, loss of AMPKα1 in B lymphoblasts was associated with decreased mitochondrial spare respiratory capacity. Of note, AMPKα1 in B cells was dispensable for stability of the bone marrow-resident, long-lived plasma cell population, yet absence of this kinase led to increased rates of Ig production and elevated serum Ab concentrations elicited by primary immunization. Collectively, our findings fit a model in which AMPKα1 in B cells supports recall function of the memory B cell compartment by promoting mitochondrial homeostasis and longevity but restrains rates of Ig production.

Selective inhibition of mTORC1 in tumor vessels increases antitumor immunity.

A tumor blood vessel is a key regulator of tissue perfusion, immune cell trafficking, cancer metastasis, and therapeutic responsiveness. mTORC1 is a signaling node downstream of multiple angiogenic factors in the endothelium. However, mTORC1 inhibitors have limited efficacy in most solid tumors, in part due to inhibition of immune function at high doses used in oncology patients and compensatory PI3K signaling triggered by mTORC1 inhibition in tumor cells. Here we show that low-dose RAD001/everolimus, an mTORC1 inhibitor, selectively targets mTORC1 signaling in endothelial cells (ECs) without affecting tumor cells or immune cells, resulting in tumor vessel normalization and increased antitumor immunity. Notably, this phenotype was recapitulated upon targeted inducible gene ablation of the mTORC1 component Raptor in tumor ECs (RaptorECKO). Tumors grown in RaptorECKO mice displayed a robust increase in tumor-infiltrating lymphocytes due to GM-CSF-mediated activation of CD103+ dendritic cells and displayed decreased tumor growth and metastasis. GM-CSF neutralization restored tumor growth and metastasis, as did T cell depletion. Importantly, analyses of human tumor data sets support our animal studies. Collectively, these findings demonstrate that endothelial mTORC1 is an actionable target for tumor vessel normalization, which could be leveraged to enhance antitumor immune therapies.

Discovering New Lipidomic Features Using Cell Type Specific Fluorophore Expression to Provide Spatial and Biological Specificity in a Multimodal Workflow with MALDI Imaging Mass Spectrometry.

Identifying the spatial distributions of biomolecules in tissue is crucial for understanding integrated function. Imaging mass spectrometry (IMS) allows simultaneous mapping of thousands of biosynthetic products such as lipids but has needed a means of identifying specific cell-types or functional states to correlate with molecular localization. We report, here, advances starting from identity marking with a genetically encoded fluorophore. The fluorescence emission data were integrated with IMS data through multimodal image processing with advanced registration techniques and data-driven image fusion. In an unbiased analysis of spleens, this integrated technology enabled identification of ether lipid species preferentially enriched in germinal centers. We propose that this use of genetic marking for microanatomical regions of interest can be paired with molecular information from IMS for any tissue, cell-type, or activity state for which fluorescence is driven by a gene-tracking allele and ultimately with outputs of other means of spatial mapping.

mTORC1 as a cell-intrinsic rheostat that shapes development, preimmune repertoire, and function of B lymphocytes.

Ample evidence indicates that nutrient concentrations in extracellular milieux affect signaling mediated by environmental sensor proteins. For instance, the mechanistic target of rapamycin (mTOR) is reduced during protein malnutrition and is known to be modulated by concentrations of several amino acids when in a multiprotein signaling complex that contains regulatory-associated protein of mTOR. We hypothesized that a partial decrease in mTOR complex 1 (mTORC1) activity intrinsic to B-lineage cells would perturb lymphocyte development or function, or both. We show that a cell-intrinsic decrease in mTORC1 activity impacted developmental progression, antigen receptor repertoire, and function along the B lineage. Thus, preimmune repertoires of B-lineage cells were altered in the marrow and periphery in a genetic model of regulatory-associated protein of mTOR haplo-insufficiency. An additional role for mTORC1 was revealed when a B-cell antigen receptor transgene was found to circumvent the abnormal B-cell development: haploinsufficient B cells were profoundly impaired in responses to antigen in vivo. Collectively, our findings indicate that mTORC1 serves as a rheostat that shapes differentiation along the B lineage, the preimmune repertoire, and antigen-driven selection of mature B cells. The findings also reveal a range in the impact of this nutrient sensor on activity-response relationships for distinct endpoints.-Raybuck, A. L., Lee, K., Cho, S. H., Li, J., Thomas, J. W., Boothby, M. R. mTORC1 as a cell-intrinsic rheostat that shapes development, preimmune repertoire, and function of B lymphocytes.

Accuracy of machine learning for differentiation between optic neuropathies and pseudopapilledema.

BACKGROUND: This study is to evaluate the accuracy of machine learning for differentiation between optic neuropathies, pseudopapilledema (PPE) and normals. METHODS: Two hundred and ninety-five images of optic neuropathies, 295 images of PPE, and 779 control images were used. Pseudopapilledema was defined as follows: cases with elevated optic nerve head and blurred disc margin, with normal visual acuity (> 0.8 Snellen visual acuity), visual field, color vision, and pupillary reflex. The optic neuropathy group included cases of ischemic optic neuropathy (177), optic neuritis (48), diabetic optic neuropathy (17), papilledema (22), and retinal disorders (31). We compared four machine learning classifiers (our model, GoogleNet Inception v3, 19-layer Very Deep Convolution Network from Visual Geometry group (VGG), and 50-layer Deep Residual Learning (ResNet)). Accuracy and area under receiver operating characteristic curve (AUROC) were analyzed. RESULTS: The accuracy of machine learning classifiers ranged from 95.89 to 98.63% (our model: 95.89%, Inception V3: 96.45%, ResNet: 98.63%, and VGG: 96.80%). A high AUROC score was noted in both ResNet and VGG (0.999). CONCLUSIONS: Machine learning techniques can be combined with fundus photography as an effective approach to distinguish between PPE and elevated optic disc associated with optic neuropathies.

Hypoxia-inducible factors in CD4+ T cells promote metabolism, switch cytokine secretion, and T cell help in humoral immunity.

T cell help in humoral immunity includes interactions of B cells with activated extrafollicular CD4+ and follicular T helper (Tfh) cells. Each can promote antibody responses but Tfh cells play critical roles during germinal center (GC) reactions. After restimulation of their antigen receptor (TCR) by B cells, helper T cells act on B cells via CD40 ligand and secreted cytokines that guide Ig class switching. Hypoxia is a normal feature of GC, raising questions about molecular mechanisms governing the relationship between hypoxia response mechanisms and T cell help to antibody responses. Hypoxia-inducible factors (HIF) are prominent among mechanisms that mediate cellular responses to limited oxygen but also are induced by lymphocyte activation. We now show that loss of HIF-1α or of both HIF-1α and HIF-2α in CD4+ T cells compromised essential functions in help during antibody responses. HIF-1α depletion from CD4+ T cells reduced frequencies of antigen-specific GC B cells, Tfh cells, and overall antigen-specific Ab after immunization with sheep red blood cells. Compound deficiency of HIF-1α and HIF-2α led to humoral defects after hapten-carrier immunization. Further, HIF promoted CD40L expression while restraining the FoxP3-positive CD4+ cells in the CXCR5+ follicular regulatory population. Glycolysis increases T helper cytokine expression, and HIF promoted glycolysis in T helper cells via TCR or cytokine stimulation, as well as their production of cytokines that direct antibody class switching. Indeed, IFN-γ elaboration by HIF-deficient in vivo-generated Tfh cells was impaired. Collectively, the results indicate that HIF transcription factors are vital components of the mechanisms of help during humoral responses.