Host immunomodulatory lipids created by symbionts from dietary amino acids.

Small molecules derived from symbiotic microbiota critically contribute to intestinal immune maturation and regulation1. However, little is known about the molecular mechanisms that control immune development in the host-microbiota environment. Here, using a targeted lipidomic analysis and synthetic approach, we carried out a multifaceted investigation of immunomodulatory α-galactosylceramides from the human symbiont Bacteroides fragilis (BfaGCs). The characteristic terminal branching of BfaGCs is the result of incorporation of branched-chain amino acids taken up in the host gut by B. fragilis. A B. fragilis knockout strain that cannot metabolize branched-chain amino acids showed reduced branching in BfaGCs, and mice monocolonized with this mutant strain had impaired colonic natural killer T (NKT) cell regulation, implying structure-specific immunomodulatory activity. The sphinganine chain branching of BfaGCs is a critical determinant of NKT cell activation, which induces specific immunomodulatory gene expression signatures and effector functions. Co-crystal structure and affinity analyses of CD1d-BfaGC-NKT cell receptor complexes confirmed the interaction of BfaGCs as CD1d-restricted ligands. We present a structural and molecular-level paradigm of immunomodulatory control by interactions of endobiotic metabolites with diet, microbiota and the immune system.

Therapeutic effect of intraperitoneal dexamethasone on noise-induced permanent threshold shift in mice model.

The purpose of the study was to which investigate whether dexamethasone, which has anti-inflammatory and immune response suppression roles, could treat noise-induced hearing loss caused by damage to hair cells in the cochlea. The experiment used 8-week-old CBA mice exposed to white noise at an intensity of 110 dB SPL for 2 h, with hearing loss confirmed by the auditory brainstem response test. Dexamethasone was administered by intraperitoneal injection for 5 days, and the therapeutic effect was investigated for 3 weeks. The experimental groups were 3 mg/kg of dexamethasone (3 mpk) and 10 mg/kg of dexamethasone (10 mpk), and the control group was a saline-administered group. The results showed that compared to the control group, the hearing threshold value was recovered by 10 dB SPL compared to the saline group from the 14th day in the 3 mpk group. In the 10 mpk group, thresholds were recovered from the 7th day compared to the saline group. This difference was similar at 4 kHz, and in the case of the 10 mpk group, the threshold was recovered by 20 dB SPL compared to the saline group. The study also confirmed the restoration of nerve cell activity and showed a recovery effect of about 20 µV in the amplitude value change in the 10 mpk group. In conclusion, the study suggests that dexamethasone has a therapeutic effect for noise-induced hearing loss by increasing the activity of nerve cells and showing a recovery effect from hair cells damaged by noise.

SH2 Domains Serve as Lipid-Binding Modules for pTyr-Signaling Proteins.

The Src-homology 2 (SH2) domain is a protein interaction domain that directs myriad phosphotyrosine (pY)-signaling pathways. Genome-wide screening of human SH2 domains reveals that ∼90% of SH2 domains bind plasma membrane lipids and many have high phosphoinositide specificity. They bind lipids using surface cationic patches separate from pY-binding pockets, thus binding lipids and the pY motif independently. The patches form grooves for specific lipid headgroup recognition or flat surfaces for non-specific membrane binding and both types of interaction are important for cellular function and regulation of SH2 domain-containing proteins. Cellular studies with ZAP70 showed that multiple lipids bind its C-terminal SH2 domain in a spatiotemporally specific manner and thereby exert exquisite spatiotemporal control over its protein binding and signaling activities in T cells. Collectively, this study reveals how lipids control SH2 domain-mediated cellular protein-protein interaction networks and suggest a new strategy for therapeutic modulation of pY-signaling pathways.

Synergistic Dual Transition Metal Catalysis.

Synergistic catalysis, a type of plural catalysis which utilizes at least two different catalysts to enable a reaction between two separately activated substrates, has unlocked a plethora of previously unattainable transformations and novel chemical reactivity. Despite the appreciable utility of synergistic catalysis, specific examples involving two transition metals have been limited, as ensuring a judicious choice of reaction parameters to prevent deactivation of catalysts, undesirable monocatalytic event(s) leading to side products, or premature termination and other potentially troublesome outcomes present a formidable challenge. Excluding those driven by photocatalytic mechanisms, this review will highlight the reported examples of reactions that make use of two simultaneous catalytic cycles driven by two transition metal catalysts.

Catalyst-controlled divergent transformations of N-sulfonyl-1,2,3-triazoles into isoquinolin-3-ones and 2-aminoindanones.

Novel catalyst-controlled divergent intramolecular reactions of N-sulfonyl-1,2,3-triazoles with tethered-allylic alcohol have been developed. In the presence of the Pd(0) catalyst alone, 1-vinylated 1,4-dihydroisoquinolin-3-ones were formed, whereas 3-vinylated 2-aminoindanones were accessed under tandem, one-pot, Rh(ii)/Pd(0) dual catalytic conditions. Based on deuterium-labelling experiments and isolation of the intermediate, a plausible reaction mechanism has been proposed.

Clinical outcomes of otogenic skull base osteomyelitis.

PURPOSE: Skull base osteomyelitis (SBO) is an uncommon and a potentially life-threatening condition if not promptly recognized and properly treated. The aim of our study was to present a 32-case series of patients diagnosed with SBO at a single center. METHODS: In this retrospective study, we reviewed the data of patients diagnosed with otogenic SBO between January 2011 and January 2020. 32 patients were enrolled in the study. SBO diagnosis was based on a combination of symptoms and physical examination, bone scan, brain magnetic resonance imaging, and pathologic examination findings. The following clinical data were collected during the follow-up period: types of antibiotics used, duration of antibiotic treatment, C-reactive protein level, presence of disease control, duration from the onset of symptoms to diagnosis, and patient survival. RESULTS: The mean follow-up period was 11 (1-110) months. The mean duration of antibiotic treatment was 115 (19-223) days. The mean C-reactive protein levels at the time of diagnosis and at the endpoint of follow-up were 3.05 (0.56-18.31) and 0.21 (0.03-33.61) mg/dL, respectively (P < 0.001). Disease control rate was 34.9% at 1-year and 83.7% at 5-year follow-up. Patient survival rate was 90.6% at 1- and 3-year follow-ups. At the endpoint of follow-up, three patients died. The mean durations from the onset of symptoms to diagnosis were 50 (5-360) and 90 (30-480) days in patients with the controlled disease and in those with the uncontrolled disease, respectively, at the endpoint of follow-up (P = 0.043). CONCLUSION: Comprehensive assessment and aggressive treatment of patients exhibiting symptoms suggestive of SBO would help in the rapid diagnosis of otogenic SBO, resulting in an improvement in prognosis.

Red cell distribution width is associated with hearing impairment in chronic kidney disease population: a retrospective cross-sectional study.

PURPOSE: Previous studies have shown that inflammatory markers are associated with hearing impairment in participants with inflammatory diseases. Therefore, screening for inflammatory status may have value in predicting the risk of hearing loss (HL) in participants with underlying inflammation. Therefore, red cell distribution width (RDW), an indirect indicator of inflammatory status, was used. The aim of the present study was to evaluate the clinical association between RDW and hearing impairment in a Korean population with chronic kidney disease (CKD). METHODS: In this cross sectional study, a total of 461 participants with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 were included. Participants were divided into three tertiles based on their RDW values. The threshold values at 0.5, 1, and 2 kHz were averaged to obtain the Low/Mid-Freq, and the values at 3, 4, and 6 kHz were averaged to obtain the High-Freq. The average hearing threshold (AHT) was calculated as the pure-tone average of the thresholds at 0.5, 1, 2, and 3 kHz. HL was defined as an AHT of > 40 dB. RESULTS: The numbers of participants in the Low, Middle, and High tertiles were 172, 154, and 135, respectively. The AUROCs of RDW and hs-CRP for HL were 0.644 and 0.522, respectively. In the multivariate analysis, the Low/Mid-Freq, High-Freq, and AHT values were lowest in the participants in the Low tertile compared with those in the Middle or High tertiles Multivariate logistic regression analyses showed that participants in the High tertile exhibited 2.32- and 1.78-fold higher odds for HL compared to those of the Low and Middle tertiles, respectively. There were positive associations between RDW and AHT values. CONCLUSION: High RDW was associated with increased odds of hearing impairment in the Korean population with CKD.

Lipids Regulate Lck Protein Activity through Their Interactions with the Lck Src Homology 2 Domain.

Lymphocyte-specific protein-tyrosine kinase (Lck) plays an essential role in T cell receptor (TCR) signaling and T cell development, but its activation mechanism is not fully understood. To explore the possibility that plasma membrane (PM) lipids control TCR signaling activities of Lck, we measured the membrane binding properties of its regulatory Src homology 2 (SH2) and Src homology 3 domains. The Lck SH2 domain binds anionic PM lipids with high affinity but with low specificity. Electrostatic potential calculation, NMR analysis, and mutational studies identified the lipid-binding site of the Lck SH2 domain that includes surface-exposed basic, aromatic, and hydrophobic residues but not the phospho-Tyr binding pocket. Mutation of lipid binding residues greatly reduced the interaction of Lck with the ζ chain in the activated TCR signaling complex and its overall TCR signaling activities. These results suggest that PM lipids, including phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate, modulate interaction of Lck with its binding partners in the TCR signaling complex and its TCR signaling activities in a spatiotemporally specific manner via its SH2 domain.

Association between sarcopenia and hearing thresholds in postmenopausal women.

Background: Given the association between metabolic disturbance and sarcopenia, sarcopenia may be intrinsically associated with the prevalence of HL. However, few studies describe the association between sarcopenia and HL. The aim of this study was to evaluate the clinical association between sarcopenia and HL in postmenopausal Korean women. Patients and Methods: A total of 4,038 women were ultimately included in this study. All participants were postmenopausal. Participants were divided into two groups based on criteria from the Foundation for the National Institute of Health Sarcopenia Project: a normal group (sarcopenia index ≥ 0.512) and a sarcopenia group (sarcopenia index < 0.512). Low-frequency (Low-Freq), mid-frequency (Mid-Freq), and high-frequency (High-Freq) values were obtained. The average hearing threshold (AHT) was calculated as the pure tone average at the 4 frequencies of 0.5 kHz, 1 kHz, 2 kHz, and 3 kHz. Mild HL was as an AHT of 24 to 40 dB; moderate-to-profound HL was defined as an AHT of 40 dB or greater. Results: Of the 4,038 participants, 272 (6.7%) were allocated to the sarcopenia group, leaving 3,766 (93.3%) in the normal group. The groups differed significantly in terms of having hypertension (775 [20.6%] vs. 108 [39.7%]; P < 0.001) or metabolic syndrome (817 [21.7%] vs. 110 [40.4%]; P < 0.001) in the normal and sarcopenia groups, respectively. Visceral fat area (cm3) in the normal and sarcopenia groups was 99.0 ± 21.9 cm3 and 117.0 ± 21.8 cm3 , respectively (P < 0.001). The hsCRP level was higher in the sarcopenia group than in the normal group. For univariate and multivariate analyses, all 4 hearing thresholds were higher in the sarcopenia group than in the normal group. In addition, linear regression analyses showed Low-Freq, Mid-Freq, and High-Freq to be inversely correlated with the sarcopenia index. The unadjusted OR for mild HL was 2.692 (95% CI, 1.963-3.692; P < 0.001) in the sarcopenia group relative to the normal group, with an adjusted OR of 1.584 (95% CI, 1.131-2.217; P = 0.007). The unadjusted OR for moderate-to-profound HL in the sarcopenia group relative to the normal group was 6.246 (95% CI, 4.530-8.612; P < 0.001); the adjusted OR was 2.667 (95% CI, 1.866-3.812; P < 0.001). Conclusion: Sarcopenia may be associated with HL. It may be beneficial to perform screening audiometry in patients with sarcopenia.

UNC93B1 is essential for the plasma membrane localization and signaling of Toll-like receptor 5.

The proper trafficking and localization of Toll-like receptors (TLRs) are important for specific ligand recognition and efficient signal transduction. The TLRs sensing bacterial membrane components are expressed on the cell surface and recruit signaling adaptors to the plasma membrane upon stimulation. On the contrary, the nucleotide-sensing TLRs are mostly found inside cells and signal from the endolysosomes in an acidic pH-dependent manner. Trafficking of the nucleotide-sensing TLRs from the endoplasmic reticulum to the endolysosomes strictly depends on UNC93B1, and their signaling is completely abolished in the 3d mutant mice bearing the H412R mutation of UNC93B1. In contrast, UNC93B1 was considered to have no role for the cell surface-localized TLRs and signaling via TLR1, TLR2, TLR4, and TLR6 is normal in the 3d mice. Unexpectedly, we discovered that TLR5, a cell surface receptor for bacterial protein flagellin, also requires UNC93B1 for plasma membrane localization and signaling. TLR5 physically interacts with UNC93B1, and the cells from the 3d or UNC93B1-deficient mice not only lack TLR5 at the plasma membrane but also fail to secret cytokines and to up-regulate costimulatory molecules upon flagellin stimulation, demonstrating the essential role of UNC93B1 in TLR5 signaling. Our study reveals that the role of UNC93B1 is not limited to the TLRs signaling from the endolysosomes and compels the further probing of the mechanisms underlying the UNC93B1-assisted differential targeting of TLRs.

Pd-Catalyzed Aminocarbonylation of the Blaise Reaction Intermediate: One-Pot Synthesis of (Z)-3-Methyleneisoindolin-1-ones from Nitriles.

A highly efficient method for the one-pot synthesis of stereocontrolled (Z)-3-methyleneisoindolin-1-ones was developed starting from 2-bromoarylnitriles via tandem sequential reaction with a Reformatsky reagent (Blaise reaction), followed by Pd-catalyzed intramolecular aminocarbonylation with carbon monoxide at 1 atm pressure. It has been found that the conformational flexibility of the bisphophine ligand is of great importance to the success of this tandem aminocarbonylation reaction.

Synthesis of α-methylene-δ-oxo-γ-amino esters via Rh(ii)-catalyzed coupling of 1-sulfonyl-1,2,3-triazoles with Morita-Baylis-Hillman adducts.

A rhodium(ii)-catalyzed coupling of 1-sulfonyl-1,2,3-triazoles, prepared from 1-alkynes and sulfonyl azides, with Morita-Baylis-Hillman (MBH) adducts afforded highly functionalized α-methylene-δ-oxo-γ-amino esters in excellent yields with broad functional group tolerance. This transformation can also be successfully accomplished as a multicomponent all-in-one-pot reaction of 1-alkynes, sulfonyl azides and MBH adducts in the presence of Cu(i) and Rh(ii) catalysts.

Acidic amino acid residues in the juxtamembrane region of the nucleotide-sensing TLRs are important for UNC93B1 binding and signaling.

TLRs are divided into two groups based on their subcellular localization patterns. TLR1, 2, 4, 5, and 6 are expressed on the cell surface, whereas the nucleotide-sensing TLRs, such as TLR3, 7, 8, and 9 stay mainly inside cells. The polytopic membrane protein UNC93B1 physically interacts with the nucleotide-sensing TLRs and delivers them from the endoplasmic reticulum to endolysosomes, where the TLRs recognize their ligands and initiate signaling. In cells with nonfunctional UNC93B1, the nucleic acid-sensing TLRs fail to exit the endoplasmic reticulum and consequently do not signal. However, the detailed molecular mechanisms that underlie the UNC93B1-mediated TLR trafficking remain to be clarified. All nucleotide-sensing TLRs contain acidic amino acid residues in the juxtamembrane region between the leucine-rich repeat domain and the transmembrane segment. We show that the D812 and E813 residues of TLR9 and the D699 and E704 residues of TLR3 help to determine the interaction of these TLRs with UNC93B1. Mutation of the acidic residues in TLR3 and TLR9 prevents UNC93B1 binding, as well as impairs TLR trafficking and renders the mutant receptors incapable of transmitting signals. Therefore, the acidic residues in the juxtamembrane region of the nucleotide-sensing TLRs have important functional roles.

Visceral Fat Area Determined Using Bioimpedance Analysis Is Associated with Hearing Loss.

BACKGROUND: Visceral fat area (VFA) using bioimpedance analysis (BIA) as a simple analyzer can be used to assess VFA, which may be associated with HL. The aim of the present study was to evaluate the clinical relevance and usefulness of VFA using BIA as a predictor of HL. PATIENTS AND METHODS: In total, 18,415 patients were recruited into our study. VFAs were measured using multi-frequency BIA. VFAs were normalized by body mass index (BMI). Participants were divided into 3 tertiles based on their VFA/BMI for both sexes. For both ears of each participant, the low-frequency (Low-Freq), mid-frequency (Mid-Freq), and high-frequency (High-Freq) values were obtained calculating the pure tone averages at 0.5 and 1 kHz, 2 and 3 kHz, and 4 and 6 kHz, respectively. The average hearing threshold (AHT) was calculated as the pure tone average at the 4 frequencies (i.e., 0.5, 1, 2, and 3 kHz). HL was defined as AHT >40 dB. RESULTS: The VFA/BMI had the greatest AUROC among VFA, BMI, and VFA/BMI in both sexes in this study. In both univariate and multivariate analyses, VFA/BMI tertiles were associated with all 4 hearing thresholds (i.e., Low-Freq, Mid-Freq, High-Freq, and AHT). The 4 hearing thresholds were positively correlated with VFA/BMI as a continuous variable. The odds ratio for HL increased as the VFA/BMI tertile increased. CONCLUSION: VFA/BMI was associated with hearing impairment in the Asian population. The participants with high VFA/BMI should be closely monitored for hearing impairment.

Identification of pathogenic mechanisms of COCH mutations, abolished cochlin secretion, and intracellular aggregate formation: genotype-phenotype correlations in DFNA9 deafness and vestibular disorder.

Mutations in COCH (coagulation factor C homology) cause autosomal-dominant nonsyndromic hearing loss with variable degrees of clinical onset and vestibular malfunction. We selected eight uncharacterized mutations and performed immunocytochemical and Western blot analyses to track cochlin through the secretory pathway. We then performed a comprehensive analysis of clinical information from DFNA9 patients with all 21 known COCH mutations in conjunction with cellular and molecular findings to identify genotype-phenotype correlations. Our studies revealed that five mutants were not secreted into the media: two von Willebrand factor A (vWFA) domain mutants, which were not transported from the endoplasmic reticulum to Golgi complex and formed high-molecular-weight aggregates in cell lysates, and three LCCL domain mutants, which were detected as intracellular dimeric cochlins. Mutant cochlins that were not secreted and accumulated in cells result in earlier age of onset of hearing defects. In addition, individuals with LCCL domain mutations show accompanying vestibular dysfunction, whereas those with vWFA domain mutations exhibit predominantly hearing loss. This is the first report showing failure of mutant cochlin transport through the secretory pathway, abolishment of cochlin secretion, and formation and retention of dimers and large multimeric intracellular aggregates, and high correlation with earlier onset and progression of hearing loss in individuals with these DFNA9-causing mutations.

Functional mapping of the auditory tract in rodent tinnitus model using manganese-enhanced magnetic resonance imaging.

Animal models of salicylate-induced tinnitus have demonstrated that salicylate modulates neuronal activity in several brain structures leading to neuronal hyperactivity in auditory and non-auditory brain areas. In addition, these animal tinnitus models indicate that tinnitus can be a perceptual consequence of altered spontaneous neural activity along the auditory pathway. Peripheral and/or central effects of salicylate can account for neuronal activity changes in salicylate-induced tinnitus. Because of this ambiguity, an in vivo imaging study would be able to address the peripheral and/or central involvement of salicylate-induced tinnitus. Therefore, in the present study, we developed a novel manganese-enhanced magnetic resonance imaging (MEMRI) method to map the in vivo functional auditory tract in a salicylate-induced tinnitus animal model by administrating manganese through the round window. We found that acute salicylate-induced tinnitus resulted in higher manganese uptake in the cochlea and in the central auditory structures. Furthermore, serial MRI scans demonstrated that the manganese signal increased in an anterograde fashion from the cochlea to the cochlear nucleus. Therefore, our in vivo MEMRI data suggest that acute salicylate-induced tinnitus is associated with higher spontaneous neural activity both in peripheral and central auditory pathways.

From triazoles to imidazolines through the sequential N-H insertion of α-imino rhodium-carbenes into ß-enamino esters/enamine-imine tautomerization/conjugate addition cascade.

A rhodium(II)-catalyzed denitrogenative coupling of N-sulfonyl-1,2,3-triazoles with ambiphilic ß-enamino esters affords 2,5-dihydro-1H-imidazoles (3-imidazolines) with broad functional group tolerance. Mechanistic studies using a deuterium-labeled triazole suggest that the reaction proceeds in a cascade through the N-H insertion of an α-imino rhodium-carbene, followed by enamine-imine tautomerization and conjugate addition. Moreover, the reaction proceeds with high diastereoselectivity for α-substituted ß-enamino esters (R(3) = Me, Ph) to give a single diastereomer.

Hemophagocytic lymphohistiocytosis associated with acute otitis media: A case report.

INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening syndrome for which early recognition and treatment are essential for improving outcomes. HLH is characterized by uncontrolled immune activation leading to fever, cytopenias, hepatosplenomegaly, coagulation abnormalities, and elevated typical markers. This condition can be genetic or secondary, with the latter often triggered by infections. Here, we present a unique case of HLH secondary to acute otitis media (AOM), a common ear infection. PATIENT CONCERNS: We describe a 4-year-old boy who initially presented with a high fever and otalgia, later diagnosed with bilateral AOM. Despite antibiotic treatment, his condition deteriorated. DIAGNOSIS: The patient fulfilled diagnostic criteria for HLH. INTERVENTIONS: Aggressive treatment by using combination therapy with immunoglobulins, intravenous steroids (dexamethasone), cyclosporine, and etoposide was performed. OUTCOMES: After 1 month of treatment, improvement in the otologic symptoms was observed, and hematological findings gradually improved and normalized. LESSIONS: The link between AOM and HLH may be associated with inflammatory responses and immunological mechanisms, highlighting the importance of considering HLH in severe infection cases. This case emphasizes the need for prompt diagnosis and management, especially in secondary HLH scenarios, to improve patient outcomes. It is imperative to be aware of the potential correlation between these 2 conditions, and healthcare professionals should consider the likelihood of HLH.

Fast formation and maturation enhancement of human liver organoids using a liver-organoid-on-a-chip.

Background: Spatial and functional hepatic zonation, established by the heterogeneous tissue along the portal-central axis of the liver, is important for ensuring optimal liver function. Researchers have attempted to develop reliable hepatic models to mimic the liver microenvironment and analyze liver function using hepatocytes cultured in the developed systems. However, mimicking the liver microenvironment in vitro remains a great challenge owing to the lack of perfusable vascular networks in the model systems and the limitation in maintaining hepatocyte function over time. Methods: In this study, we established a microphysiological system that operated under continuous flush medium flow, thereby allowing the supply of nutrients and oxygen to liver organoids and the removal of waste and release of cytokines therefrom, similar to the function of blood vessels. Results: The application of microphysiological system to organoid culture was advantageous for reducing the differentiation time and enhancing the functional maturity of human liver organoid. Conclusion: Hence, our microphysiological culture system might open the possibility of the miniaturized liver model system into a single device to enable more rational in vitro assays of liver response.