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Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis of premature infants and an orphan disease with no specific treatment. Most patients with confirmed NEC develop moderate-severe thrombocytopenia requiring one or more platelet transfusions. Here we used our neonatal murine model of NEC-related thrombocytopenia to investigate mechanisms of platelet depletion associated with this disease [K. Namachivayam, K. MohanKumar, L. Garg, B. A. Torres, A. Maheshwari, Pediatr. Res. 81, 817–824 (2017)]. In this model, enteral administration of immunogen trinitrobenzene sulfonate (TNBS) in 10-d-old mouse pups produces an acute necrotizing ileocolitis resembling human NEC within 24 h, and these mice developed thrombocytopenia at 12 to 15 h. We hypothesized that platelet activation and depletion occur during intestinal injury following exposure to bacterial products translocated across the damaged mucosa. Surprisingly, platelet activation began in our model 3 h after TNBS administration, antedating mucosal injury or endotoxinemia. Platelet activation was triggered by thrombin, which, in turn, was activated by tissue factor released from intestinal macrophages. Compared to adults, neonatal platelets showed enhanced sensitivity to thrombin due to higher expression of several downstream signaling mediators and the deficiency of endogenous thrombin antagonists. The expression of tissue factor in intestinal macrophages was also unique to the neonate. Targeted inhibition of thrombin by a nanomedicine-based approach was protective without increasing interstitial hemorrhages in the inflamed bowel or other organs. In support of these data, we detected increased circulating tissue factor and thrombin-antithrombin complexes in patients with NEC. Our findings show that platelet activation is an important pathophysiological event and a potential therapeutic target in NEC.

Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the underlying mechanisms are unclear. Here we report a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions develop NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema/separation of the lamina propria in the ileocecal region and colon within 12–24 h. The anemic intestine is infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Chelation of RBC degradation products with haptoglobin, absence of TLR4, macrophage depletion, and inhibition of macrophage activation is protective. Intestinal injury worsens with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants., The development of neonatal necrotising enterocolitis has been temporally associated with red blood cell transfusions in retrospective human studies. Here, the authors develop a neonatal mouse model of necrotising enterocolitis in anaemic mice receiving red blood cell transfusion that recapitulates features of the human condition.

Cytokines and growth factors play diverse roles in the uninflamed fetal/neonatal intestinal mucosa and in the development of inflammatory bowel injury during necrotizing enterocolitis (NEC). During gestational development and the early neonatal period, the fetal/premature intestine is exposed to high levels of many "inflammatory" cytokines and growth factors, first via swallowed amniotic fluid in utero and then, after birth, in colostrum and mother's milk. This article reviews the dual, seemingly counter-intuitive roles of cytokines, where these agents play a "trophic" role and promote maturation of the uninflamed mucosa, but can also cause inflammation and promote intestinal injury during NEC.

Background Thrombocytopenia is frequently encountered in infants with necrotizing enterocolitis (NEC). To develop a preclinical model of NEC-related thrombocytopenia, we measured serial platelet counts in 10-day-old (P10) mouse pups with trinitrobenzene sulfonic acid (TNBS)-induced NEC-like injury. We also measured platelet volume indices, immature platelet fraction (IPF), and megakaryocyte number/ploidy in these animals. Methods Platelet counts, platelet volume indices, and IPF were measured in control (N=65) and TNBS-treated pups (N=104) using an automated hematology analyzer. Bone marrow megakaryocyte number, ploidy and CD41 expression were measured by flow cytometry. These findings were confirmed in a small cohort of P3 mice with NEC-like injury. Results Murine pups with TNBS-mediated NEC-like injury developed thrombocytopenia at 15–24h after exposure to TNBS. Intestinal injury was associated with increased platelet volume indices (mean platelet volume, platelet-to-large cell ratio, and platelet distribution width), and IPF, indicating increased thrombopoiesis. These mice also showed increased megakaryocyte number, ploidy, and CD41 expression, indicating increased megakaryocyte differentiation. Conclusions Similar to human NEC, murine NEC-like injury was also associated with decreased platelet counts. There was evidence of increased megakaryocyte differentiation and thrombopoiesis, which favors peripheral consumption of platelets as the likely mechanism of thrombocytopenia in these animals, over decreased platelet production.

We have shown previously that enteral administration of 2, 4, 6-trinitrobenzene sulfonic acid in 10-d-old C57BL/6 pups produces an acute necrotizing enterocolitis with histopathological and inflammatory changes similar to human necrotizing enterocolitis (NEC). To determine whether murine neonatal 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-mediated intestinal injury could be used as a NEC model, we compared gene expression profiles of TNBS-mediated intestinal injury and NEC.Whole-genome microarray analysis was performed on proximal colon from control and TNBS-treated pups (n = 8/group). For comparison, we downloaded human microarray data of NEC (n = 5) and surgical control (n = 4) from a public database. Data were analyzed using the software programs Partek Genomics Suite and Ingenuity Pathway Analysis.We detected extensive changes in gene expression in murine TNBS-mediated intestinal injury and human NEC. Using fold-change cut-offs of ±1.5, we identified 4,440 differentially-expressed genes (DEGs) in murine TNBS-mediated injury and 1,377 in NEC. Murine TNBS-mediated injury and NEC produced similar changes in expression of orthologous genes (r = 0.611, P0.001), and also activated nearly-identical biological processes and pathways. Lipopolysaccharide was top predicted upstream regulator in both the murine and human datasets.Murine neonatal TNBS-mediated enterocolitis and human NEC activate nearly-identical biological processes, signaling pathways, and transcriptional networks.

Background Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis of premature infants. Based on our recent findings of increased Smad7 expression in surgically-resected bowel affected by NEC, we hypothesized that NEC macrophages undergo inflammatory activation because increased Smad7 expression renders these cells resistant to normal, gut-specific, transforming growth factor (TGF)-β-mediated suppression of inflammatory pathways. Methods We used surgically-resected human NEC tissue, murine models of NEC-like injury, bone marrow-derived and intestinal macrophages, and RAW264.7 cells. Smad7 and IκB kinase-beta (IKK-β) were measured by quantitative polymerase chain reaction (qPCR), Western blots, and immunohistochemistry. Promoter activation was confirmed in luciferase reporter and chromatin immunoprecipitation assays. Results NEC macrophages showed increased Smad7 expression, particularly in areas with severe tissue damage and high bacterial load. LPS-induced Smad7 expression suppressed TGF-β signaling and augmented NF-κB activation and cytokine production in macrophages. Smad7-mediated NF-κB activated was likely mediated via increased expression of IKK-β, which, further increased Smad7 expression in a feed-forward loop. We show that Smad7 induced IKK-β expression through direct binding to the IKK-β promoter and its transcriptional activation. Conclusions Smad7 expression in NEC macrophages interrupts TGF-β signaling and promotes NF-κB-mediated inflammatory signaling in these cells through increased expression of IKK-β.

Imaging of micro particles in micro-fluidic channels is one of the recent thrust areas in research as it provides more flexibility in setup and analysis compared to conventional microscopy. However, a probe based imaging scheme, with achievable high resolutions incorporating multimodal analysis is one of the challenges researchers have been facing. In this context, this paper illustrates a simple dual modality high resolution flexible probe imaging system for imaging applications in micro/optofluidic channels. The proposed system exhibits axial and lateral resolution of about 16 μm and 3.12 μm respectively. This proposed system also exhibits a modulation transfer function (MTF) of about 38.42 %. The performance of the system is validated by imaging micro particles in a microchannel and obtaining the fluorescent emission spectrum simultaneously.

We have developed a variable focal lengths image fiber based microscope system for biomedical application. The objective lens of the proposed system comprises lens of variable focal lengths and is prepared on micro glass slide by spin coating technique. The position of each lens is aligned in precision along the optical axis of system by employing high resolution xyz stage. The performance of the system is verified by imaging fluorescent microspheres of size ∼ 1μm. The proposed system can be employed in real-time fiber based high resolution imaging for biological specimens.

High-resolution measurement and contouring of objects with micro-scale sizes have been two of the research challenges in many areas, such as nondestructive testing and imaging, imaging of artifacts in MEMS, and lab-on-chip devices, as well as in biomedical imaging. In this context, we use a transillumination incorporated fiber probe imaging system to enable imaging of the targeted object in a single shot. It also enables positioning of the probe system to the region of interest for further fine analysis, thereby reducing the long scanning time faced by conventional approaches. The capability of the developed probe is illustrated using standard USAF resolution chart and fluorescent microspheres as test targets. The probe system has axial and lateral resolutions of about 16 μm and 144 lp/mm, respectively. This proposed probe scheme can potentially be employed as a viable diagnostic imaging methodology.