Role of inter-alpha-trypsin inhibitor heavy chain 4 and its citrullinated form in experimental arthritis murine models.

Inter-α-trypsin inhibitor heavy chain 4 (ITIH4) is a major protein in serum and reported to be upregulated at the onset of rheumatoid arthritis (RA). Its citrullinated form, cit-ITIH4, is specifically found in the serum and synovial fluid of patients with RA. However, the detailed function of ITIH4 in arthritis remains unknown. The aim of this study was to clarify the role of ITIH4 and cit-ITIH4 using experimental arthritis models. ITIH4 and cit-ITIH4 expression was examined in steady-state mice and two different arthritis models, and their pathological effects were examined in Itih4-deficient mice. In naïve C57BL/6 (WT) mice, ITIH4 was expressed as mRNA in the liver and the lung and was expressed as protein in serum and hepatocytes. In K/BxN serum transferred arthritis (K/BxN-STA) and collagen-induced arthritis (CIA), ITIH4 and cit-ITIH4 in sera were increased before the onset of arthritis, and cit-ITIH4 was further increased at the peak of arthritis. In Itih4-deficient mice, citrullinated proteins in serum and joints, especially 120 kDa protein, were clearly diminished; however, there was no significant difference in arthritis severity between WT and itih-/- mice either in the K/BxN-STA or CIA model. CIA mice also exhibited pulmonary lesions and itih4-/- mice tended to show enhanced inflammatory cell aggregation compared to WT mice. Neutrophils in the lungs of itih4-/- mice were significantly increased compared to WT mice. In summary, ITIH4 itself did not alter the severity of arthritis but may inhibit autoimmune inflammation via suppression of neutrophil recruitment.

Synthesis and Biological Evaluations of Novel Human Parathyroid Hormone 1 Receptor (hPTHR1) Agonists Bearing Bicyclic Aromatic Moiety.

We have previously shown that the small molecule hPTHR1 agonist PCO371 (1) orally and dose-dependently induces PTH-like calcemic and hypophostemic activity in thyroparathyroidectomized rats. Compound 2a, bearing a bicyclic aromatic ring, was identified as a novel hPTHR1 agonist during hit to lead modification. It showed moderate PTHR1 agonistic activity with an EC20 value of 15 µM, and its metabolic stability in human liver microsome (hLM) as well as its solubility in phosphate buffer (PPb) and Fasted state simulated intestinal fluid (FaSSIF) were found to be poor. As results of the initial derivatization of 2a, we identified the indole derivatives as another scaffold. In this article, we report on the structure-activity relationship (SAR), structure-metabolism relationship (SMR), and structure-solubility relationship (SSR) of bicyclic aromatic derivatives, and the in vivo efficacy of 2j.

Successful treatment of nivolumab and ipilimumab triggered type 1 diabetes by using sodium-glucose transporter 2 inhibitor: a case report and systematic review.

Objective: Checkpoint inhibitors (CPIs) can trigger complications related to the autoimmune process such as CPI-triggered diabetes mellitus. The typical treatment for CPI-triggered diabetes is insulin, but a detailed therapeutic method has not yet been established. To prevent severe symptoms and mortality of diabetic ketoacidosis in advanced-stage cancer patients, the establishment of effective treatment of CPI-triggered diabetes, other than insulin therapy, is required. Methods: We present a case of a 76-year-old man with CPI-triggered diabetes who was treated with nivolumab and ipilimumab for lung cancer. We also conducted a systematic review of 48 case reports of type 1 diabetes associated with nivolumab and ipilimumab therapy before June 2023. Results: The patient's hyperglycemia was not sufficiently controlled by insulin therapy, and after the remission of ketoacidosis, the addition of a sodium-glucose transporter (SGLT) 2 inhibitor, dapagliflozin, improved glycemic control. Most of the reported nivolumab/ipilimumab-induced type 1 diabetes was treatable with insulin, but very few cases required additional oral anti-diabetic agents to obtain good glucose control. Conclusion: Although SGLT2 inhibitors have been reported to have adverse effects on ketoacidosis, recent studies indicate that the occurrence of ketoacidosis is relatively rare. Considering the pathological mechanism of CPI-triggered diabetes, SGLT2 inhibitors could be an effective choice if they are administered while carefully monitoring the patient's ketoacidosis.

Dose Dependent Effect of Sulfamethoxazole on Inhibiting KATP Channel of Mouse Pancreatic ß Cell.

Sulfamethoxazole (SMX) is widely used as an antibiotic in the clinical application with side effects of hypoglycemia. This is because SMX contains the sulfonamide structure, which closes ATP-sensitive potassium (KATP) channels and induces insulin secretion. However, there are no detail reports that measure the effective dose that can close KATP channels and induce insulin secretion. In this study, whole-cell patch clamp recording was utilized to measure the effect of SMX on KATP channel activity on pancreatic ß cells. Also, the static incubation assay with mice islets was assessed to measure the insulin secretion capacity of SMX. SMX was shown to inhibit the KATP channel in pancreatic ß cell membrane and induce insulin secretion in relatively high concentration. The half maximal inhibitory concentration (IC50) for KATP channel activity of SMX was .46 ± .08 mM. It was also shown that a near IC50 concentration of SMX (.5 mM) was able to nearly fully block the KATP channel when simultaneously applied with low concentration sulfonylurea, tolbutamide (.01 mM). Our present data provide important information for the clinical use of SMX to treat infection in diabetic patients using sulfonylureas.

Effect of fenofibrate and selective PPARα modulator (SPPARMα), pemafibrate on KATP channel activity and insulin secretion.

OBJECTIVE: Insulin secretion is regulated by ATP-sensitive potassium (KATP) channels in pancreatic beta-cells. Peroxisome proliferator-activated receptors (PPAR) α ligands are clinically used to treat dyslipidemia. A PPARα ligand, fenofibrate, and PPARγ ligands troglitazone and 15-deoxy-∆12,14-prostaglandin J2 are known to close KATP channels and induce insulin secretion. The recently developed PPARα ligand, pemafibrate, became a new entry for treating dyslipidemia. Because pemafibrate is reported to improve glucose intolerance in mice treated with a high fat diet and a novel selective PPARα modulator, it may affect KATP channels or insulin secretion. RESULTS: The effect of fenofibrate (100 µM) and pemafibrate (100 µM) on insulin secretion from MIN6 cells was measured by using batch incubation for 10 and 60 min in low (2 mM) and high (10 mM) glucose conditions. The application of fenofibrate for 10 min significantly increased insulin secretion in low glucose conditions. Pemafibrate failed to increase insulin secretion in all of the conditions experimented in this study. The KATP channel activity was measured by using whole-cell patch clamp technique. Although fenofibrate (100 µM) reduced the KATP channel current, the same concentration of pemafibrate had no effect. Both fenofibrate and pemafibrate had no effect on insulin mRNA expression.

Class B1 GPCR activation by an intracellular agonist.

G protein-coupled receptors (GPCRs) generally accommodate specific ligands in the orthosteric-binding pockets. Ligand binding triggers a receptor allosteric conformational change that leads to the activation of intracellular transducers, G proteins and ß-arrestins. Because these signals often induce adverse effects, the selective activation mechanism for each transducer must be elucidated. Thus, many orthosteric-biased agonists have been developed, and intracellular-biased agonists have recently attracted broad interest. These agonists bind within the receptor intracellular cavity and preferentially tune the specific signalling pathway over other signalling pathways, without allosteric rearrangement of the receptor from the extracellular side1-3. However, only antagonist-bound structures are currently available1,4-6, and there is no evidence to support that biased agonist binding occurs within the intracellular cavity. This limits the comprehension of intracellular-biased agonism and potential drug development. Here we report the cryogenic electron microscopy structure of a complex of Gs and the human parathyroid hormone type 1 receptor (PTH1R) bound to a PTH1R agonist, PCO371. PCO371 binds within an intracellular pocket of PTH1R and directly interacts with Gs. The PCO371-binding mode rearranges the intracellular region towards the active conformation without extracellularly induced allosteric signal propagation. PCO371 stabilizes the significantly outward-bent conformation of transmembrane helix 6, which facilitates binding to G proteins rather than ß-arrestins. Furthermore, PCO371 binds within the highly conserved intracellular pocket, activating 7 out of the 15 class B1 GPCRs. Our study identifies a new and conserved intracellular agonist-binding pocket and provides evidence of a biased signalling mechanism that targets the receptor-transducer interface.

Effect of a Novel Trivalent Vaccine Formulation against Acute Lung Injury Caused by Pseudomonas aeruginosa.

An effective vaccine against Pseudomonas aeruginosa would benefit people susceptible to severe infection. Vaccination targeting V antigen (PcrV) of the P. aeruginosa type III secretion system is a potential prophylactic strategy for reducing P. aeruginosa-induced acute lung injury and acute mortality. We created a recombinant protein (designated POmT) comprising three antigens: full-length PcrV (PcrV#1-#294), the outer membrane domain (#190-342) of OprF (OprF#190-#342), and a non-catalytic mutant of the carboxyl domain (#406-613) of exotoxin A (mToxA#406-#613(E553Δ)). In the combination of PcrV and OprF, mToxA, the efficacy of POmT was compared with that of single-antigen vaccines, two-antigen mixed vaccines, and a three-antigen mixed vaccine in a murine model of P. aeruginosa pneumonia. As a result, the 24 h-survival rates were 79%, 78%, 21%, 7%, and 36% in the POmT, PcrV, OprF, mTox, and alum-alone groups, respectively. Significant improvement in acute lung injury and reduction in acute mortality within 24 h after infection was observed in the POmT and PcrV groups than in the other groups. Overall, the POmT vaccine exhibited efficacy comparable to that of the PcrV vaccine. The future goal is to prove the efficacy of the POmT vaccine against various P. aeruginosa strains.

Mesenchymal stem cell-derived exosomes for treatment of sepsis.

Introduction: The pathogenesis of sepsis is an imbalance between pro-inflammatory and anti-inflammatory responses. At the onset of sepsis, the lungs are severely affected, and the injury progresses to acute respiratory distress syndrome (ARDS), with a mortality rate of up to 40%. Currently, there is no effective treatment for sepsis. Cellular therapies using mesenchymal stem cells (MSCs) have been initiated in clinical trials for both ARDS and sepsis based on a wealth of pre-clinical data. However, there remains concern that MSCs may pose a tumor risk when administered to patients. Recent pre-clinical studies have demonstrated the beneficial effects of MSC-derived extracellular vesicles (EVs) for the treatment of acute lung injury (ALI) and sepsis. Methods: After recovery of initial surgical preparation, pneumonia/sepsis was induced in 14 adult female sheep by the instillation of Pseudomonas aeruginosa (~1.0×1011 CFU) into the lungs by bronchoscope under anesthesia and analgesia. After the injury, sheep were mechanically ventilated and continuously monitored for 24 h in a conscious state in an ICU setting. After the injury, sheep were randomly allocated into two groups: Control, septic sheep treated with vehicle, n=7; and Treatment, septic sheep treated with MSC-EVs, n=7. MSC-EVs infusions (4ml) were given intravenously one hour after the injury. Results: The infusion of MSCs-EVs was well tolerated without adverse events. PaO2/FiO2 ratio in the treatment group tended to be higher than the control from 6 to 21 h after the lung injury, with no significant differences between the groups. No significant differences were found between the two groups in other pulmonary functions. Although vasopressor requirement in the treatment group tended to be lower than in the control, the net fluid balance was similarly increased in both groups as the severity of sepsis progressed. The variables reflecting microvascular hyperpermeability were comparable in both groups. Conclusion: We have previously demonstrated the beneficial effects of bone marrow-derived MSCs (10×106 cells/kg) in the same model of sepsis. However, despite some improvement in pulmonary gas exchange, the present study demonstrated that EVs isolated from the same amount of bone marrow-derived MSCs failed to attenuate the severity of multiorgan dysfunctions.

Effect of climatic environment on immunological features of rheumatoid arthritis.

The aim of this study was to clarify the effect of climatic environment on the immunological features of rheumatoid arthritis (RA). Blood samples were collected from patients with RA and healthy controls (HCs), matched by age and sex, living in two locations, Tsukuba and Karuizawa, which differ in their altitude and average air temperature and atmospheric pressure. Analysis of peripheral blood mononuclear cells (PBMCs) revealed that the proportion of T and B cell subpopulations in HCs and RA patients were significantly different between two sites. Inverse probability weighting adjustment with propensity scores was used to control for potential confounding factors. The results revealed that, in comparison with RA patients in Tsukuba, those in Karuizawa showed a significant increase in cTh1, cTfh1, and Tph cells, and significant decrease in cTh17, cTh17.1, and CD8+ Treg in T cell subpopulations, and a significant increase in DNB, DN1, DN2, and class-switched memory B cells, and a significant decrease in unswitched memory B, naïve B cells, and ABCs in B cell subpopulations. Our results suggest the possibility that climatic environment might have an effect on immune cell proportion and function, and be related to the pathogenic mechanism of RA.

Biological properties of Staphylococcus virus ΦSA012 for phage therapy.

Staphylococcus virus ΦSA012 has a wide host range and efficient lytic activity. Here, we assessed the biological stability of ΦSA012 against temperature, freeze-thawing, and pH to clinically apply the phage. In addition, inoculation of ΦSA012 through i.p. and i.v. injections into mice revealed that phages were reached the limit of detection in serum and accumulated notably spleens without inflammation at 48 h post-inoculation. Furthermore, inoculation of ΦSA012 through s.c. injections in mice significantly induced IgG, which possesses neutralizing activity against ΦSA012 and other Staphylococcus viruses, ΦSA039 and ΦMR003, but not Pseudomonas viruses ΦS12-3 and ΦR18 or Escherichia viruses T1, T4, and T7 in vitro. Immunoelectron microscopic analysis showed that purified anti-phage IgG recognizes the long-tail fiber of staphylococcus viruses. Although S. aureus inoculation resulted in a 25% survival rate in a mouse i.p. model, ΦSA012 inoculation (i.p.) improved the survival rate to 75%; however, the survival rate of ΦSA012-immunized mice decreased to less than non-immunized mice with phage i.v. injection at a MOI of 100. These results indicated that ΦSA012 possesses promise for use against staphylococcal infections but we should carefully address the appropriate dose and periods of phage administration. Our findings facilitate understandings of staphylococcus viruses for phage therapy.

Relationship between mortality and molecular epidemiology of methicillin-resistant Staphylococcus aureus bacteremia.

Staphylococcus aureus is the primary cause of bacteremia, and methicillin-resistant S. aureus bacteremia is associated with a high mortality rate. Methicillin-resistant S. aureus clones are widespread worldwide, and molecular epidemiological studies are important. Therefore, this study aimed to determine the characteristics of patients who died due to methicillin-resistant S. aureus bacteremia and microbiological characteristics of methicillin-resistant S. aureus strains in a tertiary teaching hospital. This single-center, retrospective study included patients with methicillin-resistant S. aureus isolated from blood bacterial culture performed at Kyoto Prefectural University of Medicine Hospital, from October 2016 to May 2019. The data analyzed included patient background, clinical strain characteristics, and molecular epidemiology. Of 41 patients with methicillin-resistant S. aureus bacteremia (median age, 60 [28-70] years; 24 (59%) were men), and 7 (17%) died due to methicillin-resistant S. aureus bacteremia. The median age of those who died in the methicillin-resistant S. aureus bacteremia group was predominantly higher than that of those in the alive group (p = 0.03). The most common cause of methicillin-resistant S. aureus bacteremia was endovascular devices, which occurred in 20 (49%), 18 (53%), and 2 (29%) patients in the total, alive, and died groups, respectively. Bacteriological characteristics showed that type IV Staphylococcal Cassette Chromosome mec genotype was most frequently detected in the total (n = 34 [83%]), alive (n = 29 [85%]), and died (n = 5 [71%]) groups. In the molecular cluster analysis, CC8, ST8, staphylococcal Cassette Chromosome mec type IV, and community-acquired-methicillin-resistant S. aureus formed the largest groups. The diversity of methicillin-resistant S. aureus clones is evident, and it is possible that clones with new virulence factors may still emerge. In the future, it will be crucial to monitor the epidemiological trends of methicillin-resistant S. aureus to respond quickly to changes in pathogenic and clonal factors, to clarify the gene expression network by identifying old and new virulence factors.

Surface translocation of Kir2.1 channel induces IL-1ß secretion in microglia.

One of the major properties of microglia is to secrete cytokines as a reaction to stress such as lipopolysaccharide (LPS) application. The mechanism of cytokine secretion from the microglia upon stress through the inflammasome-mediated release process is well studied, and the voltage-gated Kv1.3 channel is known to play an important role in this process. Most previous studies investigated long-term inflammasome-mediated cytokine release (at least over 4 h) and there are only a few studies on the acute reaction (within minutes order) of the microglia to stress and its cytokine secretion capacity. In this study, we found that LPS induced an increase in Kir2.1 current within 15 min after administration but had no effect on voltage-dependent outward currents. Moreover, cytological and western blot analysis revealed that the increase in the Kir2.1 channel current after LPS administration was induced by the translocation of Kir2.1 from the cytoplasm to the cell surface. From an experiment using the inhibitor and trafficking mutation of Kir2.1, an increase in Kir2.1 was found to contribute to the secretion of the inflammatory cytokine, IL-1ß. Although the physiological significance of this acute IL-1ß secretion remains unclear, our present data imply that Kir2.1 translocation functions as a regulator of IL-1ß secretion, and therefore becomes a potential target to control cytokine release from microglia.

Role of extracellular vesicles in severe pneumonia and sepsis.

INTRODUCTION: Extracellular vesicles (EV) released constitutively or following external stimuli from structural and immune cells are now recognized as important mediators of cell-to-cell communication. They are involved in the pathogenesis of pneumonia and sepsis, leading causes of acute respiratory distress syndrome (ARDS) where mortality rates remain up to 40%. Multiple investigators have demonstrated that one of the underlying mechanisms of the effects of EVs is through the transfer of EV content to host cells, resulting in apoptosis, inflammation, and permeability in target organs. AREAS COVERED: The current review focuses on preclinical research examining the role of EVs released into the plasma and injured alveolus during pneumonia and sepsis. EXPERT OPINION: Inflammation is associated with elevated levels of circulating EVs that are released by activated structural and immune cells and can have significant proinflammatory, procoagulant, and pro-permeability effects in critically ill patients with pneumonia and/or sepsis. However, clinical translation of the use of EVs as biomarkers or potential therapeutic targets may be limited by current methodologies used to identify and quantify EVs accurately (whether from host cells or infecting organisms) and lack of understanding of the role of EVs in the reparative phase during recovery from pneumonia and/or sepsis.

Preoperative Left Ventricular Energy Loss in the Operating Theater Reflects Subjective Symptoms in Chronic Aortic Regurgitation.

BACKGROUND: There is currently no subjective, definitive evaluation method for therapeutic indication other than symptoms in aortic regurgitation. Energy loss, a novel parameter of cardiac workload, can be visualized and quantified using echocardiography vector flow mapping. The purpose of the present study was to evaluate whether energy loss in patients with chronic aortic regurgitation can quantify their subjective symptoms more clearly than other conventional metrics. METHODS: We studied 15 patients undergoing elective aortic valve surgery for aortic regurgitation. We divided the patients into symptomatic and asymptomatic groups using their admission records. We analyzed the mean energy loss in one cardiac cycle using transesophageal echocardiography during the preoperative period. The relationships between symptoms, energy loss, and other conventional metrics were statistically analyzed. RESULTS: There were seven and eight patients in the symptomatic and asymptomatic groups, respectively. The mean energy loss of one cardiac cycle was higher in the symptomatic group (121 mW/m [96-184]) than in the asymptomatic group (87 mW/m [80-103]) (p = 0.040), whereas the diastolic diameter was higher in the asymptomatic group (65 mm [59-78]) than in the symptomatic group (57 mm [51-57]) (p = 0.040). There was no significant difference between the symptomatic and asymptomatic groups in terms of other conventional metrics. CONCLUSIONS: An energy loss can quantify patients' subjective symptoms more clearly than other conventional metrics. The small sample size is the primary limitation of our study, further studies assessing larger cohort of patients are warranted to validate our findings.

Efficacy of SGLT2 inhibitors as additional treatment in Japanese type 2 diabetic patients: second or third choice?

OBJECTIVES: Due to the increase of type 2 diabetes (T2D), the number of patients in treatment with multiple anti-diabetic agents is increased. According to the recent recommendation of treatment guidelines, sodium-glucose cotransporter 2 (SGLT2) inhibitors would be used as additional treatment to the currently administered anti-diabetic drugs for poorly controlled T2D patients. Here, we assessed the efficacy of SGLT2 inhibitors added to the current treatment with metformin, dipeptidyl peptidase-4 (DPP4) inhibitors, or both in Japanese T2D patients. RESULTS: Japanese T2D subjects with poor glucose control, who were treated with metformin (n = 10), DPP4 inhibitors (n = 11), or both (n = 28) and who were in need of additional treatment, were recruited. HbA1c levels before and 6 months after addition of SGLT2 inhibitor treatment were used to compare the effectiveness. The HbA1c levels after addition of SGLT2 inhibitors significantly decreased in all groups. The change in HbA1c levels (delta HbA1c) showed no significant difference between the three groups. The present data indicated that addition of SGLT2 inhibitors to metformin and/or DPP4 inhibitors is equally effective in the treatment of Japanese T2D patients.

RORγt+Foxp3+ regulatory T cells in the regulation of autoimmune arthritis.

RORγt+Foxp3+regulatory T (Treg) cells, known as T regulatory 17 cells (Tr17 cells), are a novel subset of Treg cells, which have the potential to regulate the development of experimental autoimmune encephalomyelitis (EAE) thorough a specific repression of T helper 17 (Th17) cell-mediated inflammation. However, the function of Tr17 cells the development of other autoimmune diseases such as autoimmune arthritis remains unclear. Collagen-induced arthritis (CIA) was found to be prolonged in Foxp3creRORγtfl/fl mice, in which Tr17 cells were deleted, compared with Foxp3wtRORγtfl/fl mice. Tr17 cells were significantly increased in ankle joints (AJ) compared with draining lymph nodes after the onset of arthritis. CC chemokine receptor 6 (CCR6) was up-regulated on Tr17 cells compared to RORγt negative Treg cells. CD25, cytotoxic T-lymphocyte antigen 4 (CTLA-4), glucocorticoid-induced TNF-receptor (GITR), and inducible T-cell co-stimulator (ICOS) expression was also up-regulated on Tr17 cells compared to RORγt negative Treg cells. IL-10-producing cells and Blimp-1+ and T-bet+ cells were increased in Tr17 cells compared to RORγt-negative Treg cells. Tr17-enriched Treg cells significantly suppressed proliferation of conventional T cells through IL-10 compared with CCR6-Treg cells. Tr17 cells increased during the clinical course of CIA and accumulated in inflamed joints. Taken together, it appears that Tr17 cells play a crucial role in the regulation of autoimmune arthritis.

Predictive Factors for Pneumomediastinum During Management of Connective Tissue Disease-related Interstitial Lung Disease: A Retrospective Study.

Objective To identify factors associated with pneumomediastinum during management of connective tissue disease (CTD)-related interstitial lung disease (ILD). Methods Patients diagnosed with pneumomediastinum after the initiation of corticosteroid therapy for their CTD-ILD were enrolled. The baseline characteristics of patients who developed pneumomediastinum after the initiation of corticosteroid therapy (n=13, all occurring within 120 days) were compared to those of patients who did not develop pneumomediastinum (n=49). A multivariate logistic regression analysis was performed to identify factors associated with pneumomediastinum. A receiver operating characteristic (ROC) curve analysis was also performed to assess the predictive performance. Results The body mass index (BMI) [odds ratio (OR) (95% confidence interval (CI)) 0.482 (0.272-0.853)] and serum lactate dehydrogenase (LDH) [OR (95% CI) 1.013 (1-1.025)] levels at baseline were identified as independent factors associated with pneumomediastinum after corticosteroid initiation. The optimal cut-off points of the BMI and LDH levels for predicting pneumomediastinum development, as estimated by the Youden index, were 20.2 kg/m2 and 378 U/L, respectively. LDH showed a sensitivity of 61.5% and the highest specificity of 87.8%. Importantly, combining these markers resulted in the highest sensitivity of 100% and a specificity of 71.4%. Conclusion A low BMI and high serum LDH levels at baseline are useful predictive factors for pneumomediastinum development in CTD-ILD patients.

T-bet represses collagen-induced arthritis by suppressing Th17 lineage commitment through inhibition of RORγt expression and function.

T-bet is a key transcription factor for the T helper 1 lineage and its expression level is negatively correlated to inflammation in patients with rheumatoid arthritis (RA). Our previous study using T-bet transgenic mice revealed over-expression of T-bet completely suppressed collagen-induced arthritis (CIA), a murine model of RA, indicating a potential suppressive role of T-bet in the pathogenesis of autoimmune arthritis. Here, we show T-bet-deficiency exacerbated CIA. T-bet in CD4 + T cells, but not in CD11c + dendritic cells, was critical for regulating the production of IL-17A, IL-17F, IL-22, and TNFα from CD4 + T cells. T-bet-deficient CD4 + T cells showed higher RORγt expression and increased IL-17A production in RORγt-positive cells after CII immunization. In addition, T-bet-deficient naïve CD4 + T cells showed accelerated Th17 differentiation in vitro. CIA induced in CD4-Cre T-betfl/fl (cKO) mice was more severe and T-bet-deficient CD4 + T cells in the arthritic joints of cKO mice showed higher RORγt expression and increased IL-17A production. Transcriptome analysis of T-bet-deficient CD4 + T cells revealed that expression levels of Th17-related genes were selectively increased. Our results indicate that T-bet in CD4 + T cells repressed RORγt expression and function resulting in suppression of arthritogenic Th17 cells and CIA.

Co-infection with Legionella and SARS-CoV-2: a case report.

INTRODUCTION: We report a case of COVID-19 with Legionella co-infection that was treated successfully. CASE REPORT: A 73-year-old man presented to the hospital with symptoms of fatigue that continued for the next 5 days. The patient was receiving docetaxel and prednisolone chemotherapy for prostate cancer. Laboratory findings on admission showed positive urine Legionella antigen test and SARS-CoV-2 test. He was administered antiviral and antibacterial agents, and a corticosteroid. Pneumonia exacerbated on day 2 of hospitalization. The patient underwent tracheal intubation and began receiving multidisciplinary care. On day 8 of hospitalization, his oxygenation improved, and the patient was extubated. He discharged on day 27 of hospitalization. CONCLUSIONS: The patient had a favorable outcome with early diagnosis and early treatment of both diseases. Patients with severe COVID-19 disease need to be evaluated for co-infection. Further, early diagnosis and early treatment of the microbial bacteria causing the co-infection are important.