Intestinal Epithelial Wnt Signaling Mediates Acetylcholine-Triggered Host Defense against Infection.

Regulated antimicrobial peptide expression in the intestinal epithelium is key to defense against infection and to microbiota homeostasis. Understanding the mechanisms that regulate such expression is necessary for understanding immune homeostasis and inflammatory disease and for developing safe and effective therapies. We used Caenorhabditis elegans in a preclinical approach to discover mechanisms of antimicrobial gene expression control in the intestinal epithelium. We found an unexpected role for the cholinergic nervous system. Infection-induced acetylcholine release from neurons stimulated muscarinic signaling in the epithelium, driving downstream induction of Wnt expression in the same tissue. Wnt induction activated the epithelial canonical Wnt pathway, resulting in the expression of C-type lectin and lysozyme genes that enhanced host defense. Furthermore, the muscarinic and Wnt pathways are linked by conserved transcription factors. These results reveal a tight connection between the nervous system and the intestinal epithelium, with important implications for host defense, immune homeostasis, and cancer.

Clinicopathologic update of calcium oxalate in breast: A 15-year retrospective review.

Mammary malignancies are radiologically detected by presence of masses, architectural distortions or microcalcifications. Unlike calcium hydroxyapatite, calcium oxalate (CaOx) deposits have been almost exclusively associated with benign mammary processes. The etiology and mechanism of mammary CaOx deposition remains poorly understood, and the original studies elucidating its histopathologic correlation are dated several decades ago. We reviewed radiopathologic findings of breast biopsies and excisions to re-examine the clinicopathologic significance of CaOx deposits and to ascertain potential radiologic characteristics for their identification. Fifty patients from 2004 to 2019 with reported "calcium oxalate" were retrospectively reviewed. CaOx was invariably detected with histopathologic changes of nonproliferative ducts/cysts (90%, 45 of 50), and less commonly, ducts/cysts with usual ductal hyperplasia (10%, 5 of 50). CaOx was missed on one biopsy with a subsequent excision showing apocrine cyst with CaOx. Despite the benign pathological findings, mammographic findings corresponding to CaOx ranged from benign to highly suspicious with 20% categorized as benign (round or punctuate), 22% as intermediate amorphous, 14% as suspicious (coarse/heterogeneous), and 18% as highly suspicious/pleomorphic, respectively. Lobular carcinoma in situ (LCIS) was present in separate fields from CaOx containing benign ducts in two cases which were radiologically characterized as "grouped heterogeneous" and "localized linear." On imaging, more than half of the cases (52.5%) had a corresponding BI-RADS score of 4 and the calcifications were associated with variable distributions and appearances. In conclusion, this is one of the largest studies of CaOx in breast with radiology and pathology correlation. The radiologic appearances of CaOx are nonspecific from benign to highly suspicious. Identification of CaOx on the biopsy is reassuring for a benign diagnosis. Incidental atypical lesions can occur that are often not directly associated with CaOx. CaOx may be overlooked on pathologic evaluation which results in unnecessary surgery. Our findings support close radiologic-pathologic correlation for clinical decision-making pertaining to breast calcifications.

Intestinal alkaline phosphatase decreases intraperitoneal adhesion formation.

BACKGROUND: Damage to the peritoneum initiates an inflammatory response leading to the formation of adhesions, which subsequently cause significant morbidity in some patients. Intestinal alkaline phosphatase (IAP) is a gut enzyme capable of detoxifying various inflammatory mediators such as lipopolysaccharide, lipoteichoic acid, CpG DNA, and adenosine triphosphate. In this study, we aimed to examine the anti-inflammatory effects of IAP on postoperative adhesions in mice. METHODS: C57BL/6 mice were subjected to a midline laparotomy and then six musculoperitoneal buttons (MPBs) were created by pinching and ligating the peritoneum and underlying muscle. The buttons were half-excised and E-cauterized, and then cecal abrasion was performed. Five hundred microliters of vehicle with IAP 5000 U or vehicle alone were applied over the peritoneal cavity. In some experiments, the mice were euthanized on the first and second postoperative day (POD), and cytokines analysis was done on the MPB, peritoneal tissue, and peritoneal fluid. In separate experiments, the mice were sacrificed on the 21st POD, and adhesion to each button was scored based on type and tenacity. RESULTS: IAP group mice had significantly lower adhesion scores compared with controls (21.5 ± 1.7 versus 13.2 ± 1.3; P = 0.0014, n = 15). MPB from IAP group mice had significantly lower interleukin-1ß and tumor necrosis factor-α protein level compared to control mice (105.66 ± 4.5 versus 69.8 ± 4.8 versus pg/mg, P = 0.0001; 45.25 ± 2.8 pg/mg versus 24.88 ± 4.1 pg/mg; P = 0.0007, n = 10). IAP treatment significantly decreased interleukin-1ß and tumor necrosis factor-α mRNA expression in MPB in the first POD (1.14 ± 0.25 versus 0.33 ± 0.07; P = 0.0068; 1.33 ± 0.31 versus 0.33 ± 0.08; P = 0.0064, n = 10). CONCLUSIONS: Application of IAP during laparotomy could represent a novel approach to prevent postoperative adhesions.

Left Ventricular Septal Avulsion in the Setting of Blunt Cardiac Injury.

A 23-year-old man sustained blunt cardiac injury after a motor vehicle collision resulting in left ventricular septal avulsion, ruptured chordae tendineae, and moderate to severe tricuspid regurgitation that necessitated operative intervention. The patient underwent successful resection of a prolapsed avulsed septal wall segment and concomitant tricuspid valve repair.

A NOVEL NOX/PHOX-CD38-NAADP-TFEB AXIS IMPORTANT FOR MACROPHAGE ACTIVATION DURING BACTERIAL PHAGOCYTOSIS.

Macrophage activation in the presence of bacterial cells and molecules entails complex programs of gene expression. How such triggers elicit specific gene expression programs is incompletely understood. We previously discovered that TFEB (transcription factor EB) is a key contributor to macrophage activation during bacterial phagocytosis. However, the mechanism linking phagocytosis of bacterial cells to TFEB activation and downstream pro-inflammatory cytokine induction remained unknown. We found that macrophages lacking both TFEB and TFE3 (transcription factor E3) were unable to mount a pro-inflammatory phenotype in response to bacterial infection. The NOX/PHOX (NADPH oxidase)-dependent oxidative burst was required for nuclear translocation of TFEB during phagocytosis of Gram-positive or -negative bacteria, and reactive oxygen species (ROS) were sufficient to trigger TFEB activation in a CD38- and NAADP (nicotinic acid adenine dinucleotide phosphate)-dependent manner. Consistent with the Ca2+-releasing activity of NAADP, intracellular Ca2+ chelation and PPP3/calcineurin inhibition prevented TFEB activation by phagocytosis and ROS (reactive oxygen species), impairing the induction of pro-inflammatory cytokines such as IL6 and TNF/TNFα. Therefore, here we describe a previously unknown pathway that links phagocytosis with macrophage pro-inflammatory polarization via TFEB and related transcription factor TFE3. These findings reveal that activation of TFEB and TFE3 is a key regulatory event for the activation of macrophages, and have important implications for infections, inflammation, cancer, obesity, and atherosclerosis.

Targeting the gut to prevent sepsis from a cutaneous burn.

Severe burn injury induces gut barrier dysfunction and subsequently a profound systemic inflammatory response. In the present study, we examined the role of the small intestinal brush border enzyme, intestinal alkaline phosphatase (IAP), in preserving gut barrier function and preventing systemic inflammation after burn wound infection in mice. Mice were subjected to a 30% total body surface area dorsal burn with or without intradermal injection of Pseudomonas aeruginosa. Mice were gavaged with 2000 units of IAP or vehicle at 3 and 12 hours after the insult. We found that both endogenously produced and exogenously supplemented IAP significantly reduced gut barrier damage, decreased bacterial translocation to the systemic organs, attenuated systemic inflammation, and improved survival in this burn wound infection model. IAP attenuated liver inflammation and reduced the proinflammatory characteristics of portal serum. Furthermore, we found that intestinal luminal contents of burn wound-infected mice negatively impacted the intestinal epithelial integrity compared with luminal contents of control mice and that IAP supplementation preserved monolayer integrity. These results indicate that oral IAP therapy may represent an approach to preserving gut barrier function, blocking proinflammatory triggers from entering the portal system, preventing gut-induced systemic inflammation, and improving survival after severe burn injuries.

Targeting bacterial quorum sensing shows promise in improving intestinal barrier function following burn­site infection.

Burn­site infections, commonly due to Pseudomonas aeruginosa, have been associated with deranged intestinal integrity, allowing bacteria and their products to translocate from the gut to the circulatory system. The P. aeruginosa quorum sensing (QS) transcription factor MvfR (PqsR) controls the expression of numerous virulence factors, and the synthesis of several toxic products. However, the role of QS in intestinal integrity alterations, to the best of our knowledge, has not been previously investigated. Using a proven anti­MvfR, anti­virulence agent, the in vivo results of the present study revealed that inhibition of MvfR function significantly decreased Fluorescein Isothiocyanate­Dextran (FITC­Dextran) flow from the intestine to the systemic circulation, diminished bacterial translocation from the intestine to mesenteric lymph nodes (MLNs), and improved tight junction integrity in thermally injured and infected mice. In addition, the MvfR antagonist administration alleviates the intestinal inflammation, as demonstrated by reduced ileal TNF­α and fecal lipocalin­2 concentrations. In addition, it is associated with lower levels of circulating endotoxin and decreased P. aeruginosa dissemination from the burn wound to the ileum. Collectively, these results hold great promise that the inhibition of this QS system mitigates gut hyperpermeability by attenuating the derangement of morphological and immune aspects of the intestinal barrier, suggesting that MvfR function is crucial in the deterioration of intestinal integrity following P. aeruginosa burn­site infection. Therefore, an anti­virulence approach targeting MvfR, could potentially offer a novel therapeutic approach against multi­drug resistant P. aeruginosa infections following thermal injuries. Since this approach is targeting virulence pathways that are non­essential for growth or viability, our strategy is hypothesized to minimize the development of bacterial resistance, and preserve the beneficial enteric microbes, while improving intestinal integrity that is deranged as a result of burn and infection.

Transcription factor TFEB cell-autonomously modulates susceptibility to intestinal epithelial cell injury in vivo.

Understanding the transcription factors that modulate epithelial resistance to injury is necessary for understanding intestinal homeostasis and injury repair processes. Recently, transcription factor EB (TFEB) was implicated in expression of autophagy and host defense genes in nematodes and mammalian cells. However, the in vivo roles of TFEB in the mammalian intestinal epithelium were not known. Here, we used mice with a conditional deletion of Tfeb in the intestinal epithelium (Tfeb ΔIEC) to examine its importance in defense against injury. Unperturbed Tfeb ΔIEC mice exhibited grossly normal intestinal epithelia, except for a defect in Paneth cell granules. Tfeb ΔIEC mice exhibited lower levels of lipoprotein ApoA1 expression, which is downregulated in Crohn's disease patients and causally linked to colitis susceptibility. Upon environmental epithelial injury using dextran sodium sulfate (DSS), Tfeb ΔIEC mice exhibited exaggerated colitis. Thus, our study reveals that TFEB is critical for resistance to intestinal epithelial cell injury, potentially mediated by APOA1.

An Evolutionarily Conserved PLC-PKD-TFEB Pathway for Host Defense.

The mechanisms that tightly control the transcription of host defense genes have not been fully elucidated. We previously identified TFEB as a transcription factor important for host defense, but the mechanisms that regulate TFEB during infection remained unknown. Here, we used C. elegans to discover a pathway that activates TFEB during infection. Gene dkf-1, which encodes a homolog of protein kinase D (PKD), was required for TFEB activation in nematodes infected with Staphylococcus aureus. Conversely, pharmacological activation of PKD was sufficient to activate TFEB. Furthermore, phospholipase C (PLC) gene plc-1 was also required for TFEB activation, downstream of Gαq homolog egl-30 and upstream of dkf-1. Using reverse and chemical genetics, we discovered a similar PLC-PKD-TFEB axis in Salmonella-infected mouse macrophages. In addition, PKCα was required in macrophages. These observations reveal a previously unknown host defense signaling pathway, which has been conserved across one billion years of evolution.