An autopsy case of gas gangrene, massive intravascular hemolysis, and cytokine storm due to Clostridium perfringens type A infection.

Clostridium perfringens bacteremia is a rare but rapidly fatal condition, especially in patients exhibiting massive intravascular hemolysis (MIH), gas gangrene, and septic shock. Herein, we present an autopsy case of C. perfringens septicemia exhibiting MIH, gas gangrene, and cytokine storm. The patient was an 84-year-old female with a history of biliary reconstruction surgery for congenital biliary dilatation. She developed MIH, elevated inflammatory mediator levels, thrombocytopenia, and coagulopathy. She went into shock within 1 h of the presentation and died within a few hours. Rapid progression was associated with the transformation of liver abscesses into gas-filled abscesses on computed tomography scan, suggesting the rapid outgrowth of gas-producing bacteria. The patient was finally diagnosed with MIH and gas gangrene due to C. perfringens infection based on the presence of this bacterium in the blood and bile. On autopsy, gas gangrene was observed in almost all organs, originating from the bile duct. Polymerase chain reactions targeting C. perfringens toxins identified the isolated bacterium as C. perfringens type A expressing α-toxin (CPA), perfringolysin O (PFO), and collagenase (ColA). Elevated interleukin 6 and tumor necrosis factor-α expression levels were observed in the serum, and such proinflammatory responses were partially mediated by Toll-like receptor 2. This study elucidated the association between the toxin profiles of clinically isolated C. perfringens and the host cytokine responses in the patient.

NOD2-mediated dual negative regulation of inflammatory responses triggered by TLRs in the gastrointestinal tract.

Loss-of-function mutations in nucleotide-binding oligomerization domain 2 (NOD2) constitute the primary risk factors for Crohn's disease. NOD2 is an intracellular sensor for muramyl dipeptide (MDP), a small molecule derived from the peptidoglycan layer of bacterial cell wall. Although NOD2 is involved in host immune responses, much attention has been paid to the involvement of NOD2 in the maintenance of intestinal homeostasis. Despite the fact that the proinflammatory cytokine and chemokine responses induced by NOD2 activation alone are weaker than those induced by toll-like receptors (TLRs), NOD2 plays a crucial role in host defense against invading pathogens and in the regulation of immune responses. Recent studies have highlighted the importance of negative regulatory functions of NOD2 in TLRs-mediated proinflammatory cytokine responses. MDP-mediated activation of NOD2 induces interferon regulatory factor 4 (IRF4) expression, thereby suppressing nuclear factor-κB-dependent colitogenic cytokine responses through the inhibition of Lys(K)63-linked polyubiquitination on receptor-interacting serine/threonine protein kinase 2. MDP-mediated activation of NOD2 also downregulates TLR9-induced type I IFN responses by inhibiting the K63-linked polyubiquitination of TNF receptor-associated factor 3 via deubiquitinating enzyme A (DUBA) expression. Thus, NOD2 exerts dual negative regulation of TLRs-mediated proinflammatory cytokine and type I IFN responses by inducing the expression of IRF4 and DUBA, respectively. In this review, we summarize the molecular mechanisms whereby NOD2 activation suppresses TLRs-mediated proinflammatory and type I IFN responses. In addition, we discuss the clinical relevance of the NOD2-mediated negative regulation of TLRs in inflammatory bowel disease.

Exo-Cleavable Linkers: Enhanced Stability and Therapeutic Efficacy in Antibody-Drug Conjugates.

Antibody-drug conjugates (ADCs) combine cytotoxic payloads with monoclonal antibodies through chemical linkers. Finding linkers that both enhance circulatory stability and enable effective tumor payload release remains a challenge. The conventional valine-citrulline (Val-Cit) linker is associated with several inherent drawbacks, including hydrophobicity-induced aggregation, a limited drug-antibody ratio (DAR), and premature payload release. This study introduces an exolinker approach, repositioning the cleavable peptide linker at the exo position of the p-aminobenzylcarbamate moiety, as an advancement over conventional linear linkers. This design, which incorporates hydrophilic glutamic acid, addresses the limitations of the Val-Cit platform and improves the ADC in vivo profiles. In vitro and in vivo evaluations showed that exolinker ADCs reduced premature payload release, increased drug-to-antibody ratios, and avoided significant aggregation, even with hydrophobic payloads. Furthermore, the payload remained stably attached to the ADC even in the presence of enzymes like carboxylesterases and human neutrophil elastase, indicating the potential for a favorable safety profile.

A positive cytokine/chemokine feedback loop establishes plasmacytoid DC-driven autoimmune pancreatitis in IgG4-related disease.

The pathogenesis of the murine model of autoimmune pancreatitis associated with IgG4-related disease (AIP/IgG4-RD) induced by administration of polyinosinic-polycytidylic acid (poly[I:C]) is incompletely understood. While it is known that murine and human AIP/IgG4-RD is driven by plasmacytoid dendritic cells (pDCs) producing IFN-α, the origin of these cells and their relation to effector T cells is not known. Here, we show that murine AIP was initiated by TLR3-bearing conventional DCs in the uninflamed pancreas whose activation by the TLR3 ligand poly(I:C) caused IFN-α, CXCL9, and CXCL10 secretion. This, in turn, induced pancreatic recruitment of CXCR3+ T cells and these T cells, via their secretion of CCL25, facilitated migration of pDCs bearing CCR9 into the pancreas. This established a feedback loop anchored by the now dominant pDC production of IFN-α and the continued CXCR3+ T cell facilitation of pDC migration. Remarkably, the interaction between CXCR3+ T cells and pDCs also existed at the functional level since this interaction enhanced the production of CCL25 and IFN-α by CXCR3+ T cells and pDCs, respectively. Evidence presented here that a similar disease mechanism was present in human AIP/IgG4-RD creates new avenues of disease treatment.

Microbe-associated molecular patterns derived from fungi and bacteria promote IgG4 antibody production in patients with type 1 autoimmune pancreatitis.

Enhanced IgG4 antibody (Ab) response is a prominent feature of type 1 autoimmune pancreatitis (AIP). Innate immune responses associated with IgG4 Ab production are poorly defined. We have previously reported that peripheral blood mononuclear cells (PBMCs) isolated from patients with type 1 AIP produce large amounts of IgG4 Abs upon stimulation with bacterial cell wall components. In addition, we showed that activation of plasmacytoid dendritic cells producing interferon (IFN)-α, interleukin (IL)-33, and B cell-activating factor (BAFF) upon sensing intestinal bacteria mediates the development of experimental AIP. In this study, we attempted to clarify the role of innate immunity against fungi in inducing enhanced IgG4 Ab responses in type 1 AIP. PBMCs isolated from healthy controls and patients with type 1 AIP were stimulated with a broad range of bacterial and fungal cell wall components. The concentrations of IgG1, IgG4, and cytokines were measured using enzyme-linked immunosorbent assays. Cell wall components derived from bacteria and fungi induced IgG1 and IgG4 Ab production in patients with type 1 AIP. Various types of microbe-associated molecular pattern motifs enhanced IgG4 Ab production in patients with type 1 AIP compared with the limited motifs in healthy controls. The enhanced IgG1 and IgG4 Ab production that followed in response to bacterial and fungal cell wall components was parallel to that of IFN-α, IFN-γ, IL-10, IL-33, and BAFF. In conclusion, cell wall components derived from fungi as well as bacteria promote IgG4 Ab responses in patients with type 1 AIP.

Early detection of pancreatic cancer by comprehensive serum miRNA sequencing with automated machine learning.

BACKGROUND: Pancreatic cancer is often diagnosed at advanced stages, and early-stage diagnosis of pancreatic cancer is difficult because of nonspecific symptoms and lack of available biomarkers. METHODS: We performed comprehensive serum miRNA sequencing of 212 pancreatic cancer patient samples from 14 hospitals and 213 non-cancerous healthy control samples. We randomly classified the pancreatic cancer and control samples into two cohorts: a training cohort (N = 185) and a validation cohort (N = 240). We created ensemble models that combined automated machine learning with 100 highly expressed miRNAs and their combination with CA19-9 and validated the performance of the models in the independent validation cohort. RESULTS: The diagnostic model with the combination of the 100 highly expressed miRNAs and CA19-9 could discriminate pancreatic cancer from non-cancer healthy control with high accuracy (area under the curve (AUC), 0.99; sensitivity, 90%; specificity, 98%). We validated high diagnostic accuracy in an independent asymptomatic early-stage (stage 0-I) pancreatic cancer cohort (AUC:0.97; sensitivity, 67%; specificity, 98%). CONCLUSIONS: We demonstrate that the 100 highly expressed miRNAs and their combination with CA19-9 could be biomarkers for the specific and early detection of pancreatic cancer.

Transmesenteric internal hernia: an unexpected adverse event induced by colonoscopy.

Transmesenteric internal hernia is an uncommon cause of small bowel obstruction that occurs when small bowel loops protrude through a mesenteric defect into the abdominal cavity. Herein, we present an unexpected case of colonoscopy-induced transmesenteric internal hernia. An 81-year-old male patient presenting with intermittent hematochezia and constipation had undergone a laparoscopic left nephrectomy for ureteral cancer. A colonoscopy was performed to identify the etiology of his symptoms. He complained of severe abdominal pain 2 h after the examination despite uneventful endoscopic procedures, including cold snare polypectomy. Contrast-enhanced computed tomography revealed a strangulated small bowel obstruction with a closed-loop formation outside the descending colon. The small bowel loop was incarcerated into the left retroperitoneal space. Emergency laparotomy detected small bowel loops that prolapsed into the nephrectomy pedicle via a descending mesenteric defect, developed during the laparoscopic left nephrectomy. The incarcerated small bowel was detached from the hernia and returned to its normal position, and the mesenteric defect was closed. He demonstrated an uneventful postoperative course, with no internal hernia recurrence after discharge. This case indicates the risk of transmesenteric internal hernia through inadvertently created mesenteric defects should be borne in mind, especially when performing colonoscopies in patients who underwent laparoscopic nephrectomies.

Concurrent occurrence of ulcerative duodenitis and ulcerative colitis displaying unique responses to golimumab and ustekinumab.

Recent studies have reported the occurrence of upper gastrointestinal (UGI) inflammation in patients with ulcerative colitis (UC). However, whether UC-associated UGI and colorectal lesions share pathogenic cytokine profiles and responses to biologics remains unknown. Herein, we report a case of concurrent UC and ulcerative duodenitis (UD) that displayed unique responses to biologic treatment. Although treatment with prednisolone (PSL) failed to induce remission in both disorders, golimumab (GLM) and ustekinumab (UST) were effective against UD and UC, respectively, and remission of both disorders was achieved using UST. Immunofluorescence analyses revealed that numbers of immune cells expressing TNF-α were comparable in both duodenal and rectal mucosa before the treatment. GLM or UST treatment markedly decreased numbers of TNF-α-expressing duodenal immune cells, suggesting the presence of correlation between TNF-α expression and disease activity of UD. In contrast, TNF-α expression was not parallel to disease activity of UC because GLM or PSL failed to induce remission despite a marked reduction in TNF-α expression. Responsiveness to GLM or UST together with immunofluorescence studies suggests that TNF-α and IL-12/23p40 are pathogenic cytokines causing UD and UC, respectively, in the present case.

Reciprocal regulation of protein arginine deiminase 2 and 4 expression in the colonic mucosa of ulcerative colitis.

Neutrophils express protein arginine deiminase 2 and PAD4, both of which mediate the citrullination of target proteins to induce production of neutrophil extracellular traps. Although PAD-dependent NETs trigger inflammatory bowel disease, the mechanisms governing the expression of PAD2 and PAD4 are poorly understood. In this study, we tried to clarify expression mechanisms of PAD2 and PAD4 in the colonic mucosa of patients with ulcerative colitis and Crohn's disease. Administration of Cl-amidine, a pan PAD-inhibitor, attenuated the development of dextran sodium sulfate-induced colitis, the effects of which were accompanied by reduced IL-6 and TNF-α production by colonic lamina propria mononuclear cells upon exposure to Toll-like receptor ligands. The mRNA expression of colonic PAD2 and PAD4 was negatively and positively correlated with disease activity and pro-inflammatory cytokine responses in patients with UC, respectively. Reciprocal regulation of PAD2 and PAD4 mRNA expression was observed in the colonic mucosa of UC patients, but not in those of CD patients. PAD4 mRNA expression was correlated with disease activity and pro-inflammatory cytokine responses in patients with CD. Collectively, these data suggest that reciprocal regulation of PAD2 and PAD4 expression is associated with disease activity in UC patients.

Necrotizing Fasciitis of the Serratus Anterior in a Patient Treated With Infliximab and Prednisolone for Ulcerative Colitis and Rheumatoid Arthritis.

Necrotizing fasciitis (NF) is a rapidly progressive bacterial infection with high mortality. Invasive group A Streptococcus (GAS) infection is the leading cause of NF. Our understanding regarding clinicopathological features and pathogenesis of invasive GAS infection is expanding as the incidence of NF in healthy individuals increases. However, clinicopathological features of NF in the presence of autoimmune diseases have been poorly defined. We experienced NF in a patient treated with infliximab and prednisolone for ulcerative colitis and rheumatoid arthritis. Herein, we present time kinetics findings of clinical symptoms and laboratory data of GAS-associated NF in the presence of immunosuppressant-treated immune disorders.

Pharmacological inhibition of HPK1 synergizes with PD-L1 blockade to provoke antitumor immunity against tumors with low antigenicity.

Immune checkpoint inhibitors have significantly transformed the landscape of cancer therapy. Nevertheless, while these inhibitors are highly effective for certain patient groups, many do not benefit due to primary or acquired resistance. Specifically, these treatments often lack sufficient therapeutic efficacy against cancers with low antigenicity. Thus, the development of an effective strategy to overcome cancers with low antigenicity is imperative for advancing next-generation cancer immunotherapy. Here, we show that small molecule inhibitor of hematopoietic progenitor kinase 1 (HPK1) combined with programmed cell death ligand 1 (PD-L1) blockade can enhance T-cell response to tumor with low antigenicity. We found that treatment of OT-1 splenocytes with HPK1 inhibitor enhanced the activation of signaling molecules downstream of T-cell receptor provoked by low-affinity-antigen stimulation. Using an in vivo OT-1 T-cell transfer model, we demonstrated that combining the HPK1 inhibitor with the anti-PD-L1 antibody significantly suppressed the growth of tumors expressing low-affinity altered peptide ligand of chicken ovalbumin, while anti-PD-L1 antibody monotherapy was ineffective. Our findings offer crucial insights into the potential for overcoming tumors with low antigenicity by combining conventional immune checkpoint inhibitors with HPK1 inhibitor.

Influence of oligonucleotides structures for separation of diastereomers by capillary electrophoresis method using polyvinylpyrrolidone 1,300,000.

In the field of oligonucleotides drug discovery, phosphorothioate (PS) modification has been recognized as an effective tool to overcome the nuclease digestion, and generates 2n of possible diastereomers, where n equals the number of PS linkages. However, it is also well known that differences in drug efficacy and toxicity are caused by differences in stereochemistry of oligonucleotides. Therefore, the development of a high-resolution analytical method that enables stereo discrimination of oligonucleotides is desired. Under this circumstance, capillary electrophoresis (CE) using polyvinylpyrrolidone (PVP) is considered as one of the useful tools for the separation analysis of diastereomers. In this study, we evaluated the several oligonucleotides with the structural diversities in order to understand the separation mechanism of the diastereomers by CE. Especially, five kinds of 2'-moieties were deeply examined by CE with PVP 1,300,000 polymer solution. We found that different trend of the peak shapes and the peak resolution were observed among these oligonucleotides. For example, the better peak resolution was observed in 6 mer PS3-DNA compared to the rigid structure of 6 mer PS3-LNA. As for this reason, the computational simulation revealed that difference of accessible surface area caused by the steric structure of thiophosphate in each oligonucleotide is one of the key attributes to explain the separation of the diastereomers. In addition, we achieved the separation of sixteen peak tops of the diastereomers in 6 mer PS4-DNA, and the complete separation of fifteen diastereomers in 6 mer PS4-RNA. These knowledge for the separation of the diastereomers by CE will be expected to the quality control of the oligonucleotide drugs.

Role of leucine-rich repeat kinase 2 in severe acute pancreatitis.

Introduction: Intrapancreatic activation of trypsinogen caused by alcohol or high-fat intake and the subsequent autodigestion of the pancreas tissues by trypsin are indispensable events in the development of acute pancreatitis. In addition to this trypsin-centered paradigm, recent studies provide evidence that innate immune responses triggered by translocation of intestinal bacteria to the pancreas due to intestinal barrier dysfunction underlie the immunopathogenesis of acute pancreatitis. Although severe acute pancreatitis is often associated with pancreatic colonization by fungi, the molecular mechanisms linking fungus-induced immune responses to the development of severe acute pancreatitis are poorly understood. Leucine-rich repeat kinase 2 (LRRK2) is a multifunctional protein that mediates innate immune responses to fungi and bacteria. Mutations in Lrrk2 is a risk factor for Parkinson's disease and Crohn's disease, both of which are driven by innate immune responses to gut organisms. Discussion: In this Minireview article, we discuss how activation of LRRK2 by the recognition of fungi induces severe acute pancreatitis.

Crosstalk between NOD2 and TLR2 suppresses the development of TLR2-mediated experimental colitis.

Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular sensor for muramyl dipeptide (MDP), a degradation product of bacterial cell wall peptidoglycan (PGN). PGN stimulates cell-surface Toll-like receptor 2 (TLR2) independently of NOD2, indicating the presence of crosstalk between extracellular TLR2 and intracellular NOD2 upon exposure to PGN. NOD2-deficient mice were sensitive, while TLR2-deficient mice were resistant to experimental colitis induced by intrarectal administration of PGN. Severe colitis in NOD2-deficient mice was accompanied by increased expression of nuclear factor-kappa B-dependent cytokines and decreased expression of autophagy-related 16-like 1 (ATG16L1). MDP activation of NOD2 enhanced autophagy mediated by TLR2 in human dendritic cells. mRNA expression of TLR2 tended to be higher in the colonic mucosa of patients with active ulcerative colitis compared to that of those in remission. Induction of remission was associated with increased mRNA expression of ATG16L1 in both ulcerative colitis and Crohn's disease patients. Conversely, mRNA expression of receptor-interacting serine/threonine-protein kinase 2 was higher in the inflammatory colonic mucosa of patients with active disease than in the non-inflamed mucosa of patients in remission, in both ulcerative colitis and Crohn's disease. These findings highlight the role of NOD2-TLR2 crosstalk in the immunopathogenesis of colitis.

Cytokine and chemokine profiles in ulcerative colitis relapse after coronavirus disease 2019 vaccination.

Coronavirus disease 2019 (COVID-19) vaccines are highly effective; however, vaccine-related adverse events, including autoimmunity, have been reported. Case reports describing relapse or new-onset of ulcerative colitis (UC) after COVID-19 mRNA vaccination are available. However, the molecular mechanisms underlying the development of colonic inflammation associated with COVID-19 mRNA vaccination are poorly understood. Furthermore, it is unclear whether the relapse of UC after COVID-19 vaccination is driven by unique cytokine responses that differ from those of UC not associated with vaccination. mRNAs derived from COVID-19 vaccines are potent inducers of type I IFN response. We encountered three cases of UC relapse after COVID-19 vaccination. mRNA expressions of IFN-α, IFN-ß, IL-1ß, and IL-12/23p40 showed higher tendency in the colonic mucosa of patients with UC associated with vaccination compared with those not associated with vaccination. In contrast, the expressions of C-X-C motif chemokine ligand 9 (CXCL9) and CXCL10 were comparable. Immunofluorescence analyses also showed higher expression of IFN-α in the colonic mucosa of patients with UC associated with COVID-19 vaccination than in those not associated with vaccination. Taken together, these data suggest that the colonic mucosa of patients with UC who relapsed after COVID-19 vaccination was characterized by enhanced type I IFN responses.

Biological Evaluation of Antibody-Drug Conjugates Produced by Tag-Free Lipoate Ligase A Modification.

The concept of tag-free protein modification has attracted considerable interest in chemical biology because of its flexible and straightforward reaction process. In 2021, a groundbreaking approach using lipoate ligase A (LplA) for tag-free enzymatic modification of antibodies was unveiled, demonstrating its potential for the generation of precise antibody conjugates. In this study, to further explore LplA-mediated antibody-drug conjugate (ADC) synthesis, we performed initial biological evaluations of ADCs synthesized using LplA. Using the anti-HER2 antibody trastuzumab, we introduced octanoic acid azide using LplA and subsequently obtained an ADC using click chemistry with the drug DBCO-VC-PAB-MMAE. The bioactivity of the synthesized anti-HER2-ADC was evaluated using HER2-positive SKBR-3 and HER2-negative MCF7 cells. Its toxicity and selectivity were found to be comparable to those of the FDA-approved Kadcyla. In addition, a stability study involving rat and human plasma demonstrated the stability of the LplA-mediated ADC. Additionally, the affinity for the neonatal Fc receptor (FcRn) was retained after conjugation. These preliminary in vitro evaluations suggested that LplA-derived ADCs can have considerable pharmaceutical potential. Our results can set the stage for further in vivo evaluations and safety assessments. We suggest that the integration of tag-free LplA methods into the production of ADCs can offer a novel and promising approach for biopharmaceutical manufacturing.

A Comparison of the Efficacies of OK-432 and Talc Slurry for Pleurodesis in Patients with Prolonged Air Leak after Pulmonary Resection.

PURPOSE: A prolonged air leak (PAL) is one of the common postoperative complications of pulmonary resection. The aim of this study was to evaluate the efficacy and safety of pleurodesis with sterile talc or OK-432 for postoperative air leak. METHODS: Patients with postoperative air leak who received chemical pleurodesis using sterile talc or OK-432 were retrospectively identified from medical records data. For pleurodesis with either agent, prior assessment and approval by the hospital safety department were carried out for each case, in addition to individual consent. RESULTS: Between February 2016 and June 2022, 39 patients had PALs and underwent chemical pleurodesis. Among them, 24 patients received pleurodesis with talc (Talc group) and 15 with OK-432 (OK-432 group). The leak resolved after less than two pleurodesis treatments in 22 patients (91.7%) in the Talc group compared with 14 patients (93.3%) in the OK-432 group. Pleurodesis significantly increased white blood cell counts, C-reactive protein concentration, and body temperature in the OK-432 group compared with that in the Talc group (p <0.001, p = 0.003, and p <0.001, respectively). CONCLUSIONS: Pleurodesis with talc may be an effective treatment option for postoperative air leak. Our findings suggest that talc was as effective as OK-432 and resulted in a milder systemic inflammatory response.