Sex Differences in Adult Incarceration After Pediatric Traumatic Brain Injury

Pediatric traumatic brain injury (pTBI) is a major risk factor associated with adulthood incarceration. Most research into the link between pTBI and adulthood incarceration has focused on incarcerated males, who comprise the vast majority of incarcerated adults, particularly in industrialized nations. In this review, we sought to identify sex-related differences in the incidence and pathophysiology of pTBI and subsequent risk of adulthood incarceration. A scoping review was undertaken using PubMed, Scopus, Ovid, and the Cochrane Library. Articles analyzing sex-related differences in pTBI and adult incarceration rates, studies conducted on an incarcerated population, and cohort studies, cross-sectional studies, clinical trials, systematic reviews, or meta-analyses were included in this review. Of the 85 unique results, 25 articles met our inclusion criteria. Male children are 1.5 times more likely to suffer a TBI than females; however, the prevalence of incarcerated adults with a history of pTBI is ∼35-45% for both sexes. Neurophysiologically, female sex hormones are implicated in neuroprotective roles, mitigating central nervous system (CNS) damage post-TBI, although this role may be more complex, given that injury severity and sequelae have been correlated with male sex whereas increased mortality has been correlated with female sex. Further investigation into the relationship between estrogen and subsequent clinical measurements of CNS function is needed to develop interventions that may alleviate the pathophysiological consequences of pTBI.

A qualitative analysis of patient and caregiver experiences with myelomeningocele through online discussion boards

PURPOSE

Patients and caregivers impacted by myelomeningocele (MMC) use online discussion board forums to create community and share information and concerns about this complex medical condition. We aim to identify the primary concerns expressed on these forums with the goal of understanding gaps in care that may merit investment of resources to improve care received by this population.

METHODS

Anonymous posts from online MMC discussion boards were compiled using internet search engines. Posts were then analyzed using an adaptation of the Grounded Theory Method, a three-step system involving open, axial, and selective coding of the data by two independent researchers to identify common themes.

RESULTS

Analysis of 400 posts written primarily by parents (n = 342, 85.5%) and patients (n = 45, 11.25%) yielded three overarching themes: questions surrounding quality of life, a lack of support for mothers of children with MMC, and confusion with a complex healthcare system. Many posts revealed concerns about management and well-being with MMC, including posts discussing symptoms and related conditions (n = 299, 75.75%), treatments (n = 259, 65.75%), and emotional aspects of MMC (n = 146, 36.5%). Additionally, families, especially mothers, felt a lack of support in their roles as caregivers. Finally, in 118 posts (29.5%), patients and families expressed frustration with navigating a complex healthcare system and finding specialists whose opinions they trusted.

CONCLUSIONS

MMC is a complex medical condition that impacts patients and families in unique ways. Analysis of online discussion board posts identified key themes to be addressed in order to improve the healthcare experiences of those impacted by MMC.

Patient and caregiver perceptions of Chiari malformation: a qualitative analysis of online discussion boards

OBJECTIVE

Patients and their caregivers utilize online discussion board forums as a means to seek and exchange information about their or a loved one's condition. It is important for providers to be aware of such concerns and experiences. The goal of this study was to identify the primary concerns expressed on these discussion boards regarding Chiari malformation type I (CM) and to help guide clinicians in understanding patient challenges in the treatment of CM.

METHODS

The authors performed thematic analysis of anonymous online discussion board posts as identified through internet search engines. They then adopted a previously developed grounded theory method that utilizes a three-tiered coding and grouping process of posts based on commonly discovered content themes.

RESULTS

Analysis of 400 discussion board posts identified four distinct themes raised by CM patients and their caregivers: the path to diagnosis, symptoms experienced, surgical intervention, and high emotional burden. Although each individual experience was unique, the path toward a CM diagnosis was expressed as a journey involving multiple physicians, alternative diagnoses, and feelings of dismissal from providers. The most common reported symptoms included dizziness, headaches, neck and back pain, sensory issues, weakness and paresthesias of the extremities, speech issues, and general fatigue. Additionally, there was an overall sense of uncertainty from patients seeking advice regarding surgical intervention, with users expressing diverse sentiments that included both positive and negative outcomes regarding surgical treatment. Lastly, a wide range of emotions was expressed related to a CM diagnosis, including concern, worry, anxiety, depression, stress, fear, and frustration.

CONCLUSIONS

CM is a frequent imaging diagnosis identified in patients presenting with a wide range of symptoms, and as a result this leads to a diverse set of patient experiences. Analysis of CM patient and caregiver discussion boards revealed key themes that clinicians may address when counseling for CM.

Helmet Therapy for the Management of Deformational Plagiocephaly in Pediatric Patients with Shunted Hydrocephalus

OBJECTIVE

To evaluate the safety and efficacy of helmet therapy for deformational plagiocephaly in patients with shunted hydrocephalus.

DESIGN

Retrospective chart review.

SETTING

Institutional, tertiary-care hospital.

PATIENTS

All patients at St. Louis Children's Hospital between 2014 and 2021 with shunted hydrocephalus who underwent helmet therapy for deformational plagiocephaly.

INTERVENTIONS

Helmet therapy.

MAIN OUTCOME MEASURES

Cranial vault asymmetry (CVA), cranial vault asymmetry index (CVAI), and cephalic index (CI) were measured before and after completion of helmet therapy.

RESULTS

There were 37 patients with shunted hydrocephalus and documented deformational plagiocephaly. Twelve were managed with helmet therapy. Average age at helmeting initiation and time between shunt placement and helmeting initiation was 5.8 and 4.6 months, respectively. Average CVA, CVAI, and CI at helmeting initiation and termination was 11.6, 7.98, and 85.2, and 6.95, 4.49, and 83.7, respectively. Average duration of helmeting was 3.7 months. CVA and CVAI were significantly lower after helmeting (P = .0028 and .0021) and 11/12 patients had overall improvement in plagiocephaly.

CONCLUSIONS

Helmet therapy appears to be a safe and efficacious management strategy for deformational plagiocephaly in patients with shunted hydrocephalus. Despite the occasional need for additional fittings and surveillance beyond the normal schedule, in all cases appropriately fitting helmets were achieved and no major adverse events occurred. This cohort represents a proof of principle for the safety and efficacy of helmet therapy in patients with shunted hydrocephalus. Further work in larger prospective cohorts is needed to confirm these initial findings.

Postnatal meningeal CSF transport is primarily mediated by the arachnoid and pia maters and is not altered after intraventricular hemorrhage-posthemorrhagic hydrocephalus

BACKGROUND

CSF has long been accepted to circulate throughout the subarachnoid space, which lies between the arachnoid and pia maters of the meninges. How the CSF interacts with the cellular components of the developing postnatal meninges including the dura, arachnoid, and pia of both the meninges at the surface of the brain and the intracranial meninges, prior to its eventual efflux from the cranium and spine, is less understood. Here, we characterize small and large CSF solute distribution patterns along the intracranial and surface meninges in neonatal rodents and compare our findings to meningeal CSF solute distribution in a rodent model of intraventricular hemorrhage-posthemorrhagic hydrocephalus. We also examine CSF solute interactions with the tela choroidea and its pial invaginations into the choroid plexuses of the lateral, third, and fourth ventricles.

METHODS

1.9-nm gold nanoparticles, 15-nm gold nanoparticles, or 3 kDa Red Dextran Tetramethylrhodamine constituted in aCSF were infused into the right lateral ventricle of P7 rats to track CSF circulation. 10 min post-1.9-nm gold nanoparticle and Red Dextran Tetramethylrhodamine injection and 4 h post-15-nm gold nanoparticle injection, animals were sacrificed and brains harvested for histologic analysis to identify CSF tracer localization in the cranial and spine meninges and choroid plexus. Spinal dura and leptomeninges (arachnoid and pia) wholemounts were also evaluated.

RESULTS

There was significantly less CSF tracer distribution in the dura compared to the arachnoid and pia maters in neonatal rodents. Both small and large CSF tracers were transported intracranially to the arachnoid and pia mater of the perimesencephalic cisterns and tela choroidea, but not the falx cerebri. CSF tracers followed a similar distribution pattern in the spinal meninges. In the choroid plexus, there was large CSF tracer distribution in the apical surface of epithelial cells, and small CSF tracer along the basolateral surface. There were no significant differences in tracer intensity in the intracranial meninges of control vs. intraventricular hemorrhage-posthemorrhagic hydrocephalus (PHH) rodents, indicating preserved meningeal transport in the setting of PHH.

CONCLUSIONS

Differential CSF tracer handling by the meninges suggests that there are distinct roles for CSF handling between the arachnoid-pia and dura maters in the developing brain. Similarly, differences in apical vs. luminal choroid plexus CSF handling may provide insight into particle-size dependent CSF transport at the CSF-choroid plexus border.

SH2 domain protein E and ABL signaling regulate blood vessel size

Blood vessels in different vascular beds vary in size, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vessel size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow, eventually leading to the DA collapse. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA size in she mutants correlated with an increased endothelial expression of claudin 5a (cldn5a), which encodes a protein enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates vessel and lumen size during vascular tubulogenesis.

Elucidating the Morphogenic and Signaling Roles of Defined Growth Factors Controlling Human Endothelial Cell Lumen Formation Versus Sprouting Behavior

Five growth factors [ie, insulin, fibroblast growth factor-2 (FGF-2), stem cell factor, IL-3, and stromal-derived factor 1α] in combination are necessary for human endothelial cells (ECs) to undergo tube morphogenesis, a process requiring both lumen formation and sprouting behavior. This study investigated why these factors are required by subdividing the factors into 4 separate groups: insulin-only, insulin and FGF-2, no FGF-2 (all factors but without FGF-2), and all factors. The study found that the insulin-only condition failed to support EC morphogenesis or survival, the insulin and FGF-2 condition supported primarily EC lumen formation, and the no FGF-2 condition supported EC sprouting behavior. By comparison, the all-factors condition more strongly stimulated both EC lumen formation and sprouting behavior, and signaling analysis revealed prolonged stimulation of multiple promorphogenic signals coupled with inhibition of proregressive signals. Pharmacologic inhibition of Jak kinases more selectively blocked EC sprouting behavior, whereas inhibition of Raf, phosphatidylinositol 3-kinase, and Akt kinases showed selective blockade of lumen formation. Inhibition of Src family kinases and Notch led to increased sprouting coupled to decreased lumen formation, whereas inhibition of Pak, Mek, and mammalian target of rapamycin kinases blocked both sprouting and lumen formation. These findings reveal novel downstream biological and signaling activities of defined factors that are required for the assembly of human EC-lined capillary tube networks.

Meningeal CSF transport is primarily mediated by the arachnoid and pia maters during development

Background

The recent characterization of the glymphatic system and meningeal lymphatics has re-emphasized the role of the meninges in facilitating CSF transport and clearance. Here, we characterize small and large CSF solute distribution patterns along the intracranial and surface meninges in neonatal rodents and compare our findings to a rodent model of intraventricular hemorrhage-posthemorrhagic hydrocephalus. We also examine CSF interactions with the tela choroidea and its pial invaginations into the choroid plexuses of the lateral, third, and fourth ventricles.

Methods

1.9-nm gold nanoparticles, 15-nm gold nanoparticles, or 3 kDa Red Dextran Tetramethylrhodamine constituted in aCSF were infused into the right lateral ventricle of P7 rats to track CSF circulation. 10 minutes post-1.9-nm gold nanoparticle and Red Dextran Tetramethylrhodamine injection and 4 hours post-15-nm gold nanoparticle injection, animals were sacrificed and brains harvested for histologic analysis to identify CSF tracer localization in the cranial and spine meninges and choroid plexus. Spinal dura and leptomeninges (arachnoid and pia) wholemounts were also performed.

Results

There was significantly less CSF tracer distribution in the dura compared to the arachnoid and pia maters in neonatal rodents. Both small and large CSF tracers were transported intracranially to the arachnoid and pia mater of the perimesencephalic cisterns and tela choroidea, but not the dura mater of the falx cerebri. CSF tracers followed a similar distribution pattern in the spinal meninges. In the choroid plexus, there was large CSF tracer distribution in the apical surface of epithelial cells, and small CSF tracer along the basolateral surface. There were no significant differences in tracer intensity in the intracranial meninges of control vs. intraventricular hemorrhage-posthemorrhagic hydrocephalus (PHH) rodents, indicating preserved meningeal transport in the setting of PHH.

Conclusions

Differential CSF tracer handling by the leptomeninges suggests that there are distinct roles for CSF handling between the arachnoid-pia and dura maters in the developing brain. Similarly, differences in apical vs. luminal choroid plexus CSF handling may provide insight into particle-size dependent CSF transport at the CSF-choroid plexus border.

SH2 domain protein E (SHE) and ABL signaling regulate blood vessel size

Blood vessels in different vascular beds vary in lumen diameter, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vascular lumen size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA lumen, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA lumen in she mutants correlated with an increased endothelial expression of claudin 5a and 5b (cldn5a / cldn5b), which encode proteins enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA lumen size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates lumen size during vascular tubulogenesis.

Gold nanoparticle-enhanced X-ray microtomography of the rodent reveals region-specific cerebrospinal fluid circulation in the brain

Cerebrospinal fluid (CSF) is essential for the development and function of the central nervous system (CNS). However, the brain and its interstitium have largely been thought of as a single entity through which CSF circulates, and it is not known whether specific cell populations within the CNS preferentially interact with the CSF. Here, we develop a technique for CSF tracking, gold nanoparticle-enhanced X-ray microtomography, to achieve micrometer-scale resolution visualization of CSF circulation patterns during development. Using this method and subsequent histological analysis in rodents, we identify previously uncharacterized CSF pathways from the subarachnoid space (particularly the basal cisterns) that mediate CSF-parenchymal interactions involving 24 functional-anatomic cell groupings in the brain and spinal cord. CSF distribution to these areas is largely restricted to early development and is altered in posthemorrhagic hydrocephalus. Our study also presents particle size-dependent CSF circulation patterns through the CNS including interaction between neurons and small CSF tracers, but not large CSF tracers. These findings have implications for understanding the biological basis of normal brain development and the pathogenesis of a broad range of disease states, including hydrocephalus.

Shared Objective Mentorship via Virtual Research and Education Initiatives for Medical Students and Residents in Neurosurgery: A Systematic Review and Methodological Discussion of the Neurosurgery Education and Research Virtual Group Experience

OBJECTIVE

Virtual mentorship and research programs are becoming increasingly popular to facilitate education and career development for students and residents. We review virtual research initiatives for early trainees in neurosurgery and describe our effort to expand access to resources and shared objective mentorship (SOM) via the novel Neurosurgery Education and Research Virtual Group (NERVE).

METHODS

A systematic review of neurosurgical programming delivered via a virtual platform was conducted using PubMed, Embase, and Scopus databases. Identified articles were screened. Those meeting prespecified inclusion criteria were reviewed in full and examined for relevant data. Data analysis was performed using Microsoft Excel, and means and standard deviations were calculated. Descriptive analysis of NERVE characteristics was also performed.

RESULTS

Of the 2438 identified articles, 10 were included. The most common (70%) implementation style was a webinar-based lecture series. The least common (10%) was a longitudinal curricular interest group. Of the total NERVE cohort, 90% were first generation medical students and 82% attended institutions without home programs. Survey results indicated 73.8% had contributed to at least 2 research projects throughout the year.

CONCLUSIONS

There is a scarcity of virtual neurosurgical resources which facilitate SOM opportunities for trainees. In our systematic review, NERVE is the only multi-institutional virtual initiative aimed at increasing access to neurosurgical education and research opportunities for the purpose of SOM among early trainees from disadvantaged backgrounds. This highlights the group's niche and potential impact on increasing diversity in neurosurgery, improving trainees' career development, and facilitating future resident research productivity.

Surgical management of petrous apex cholesteatomas in the pediatric population: A systematic review

Background:

Cholesteatomas are growths of squamous epithelium that can form inside the middle ear and mastoid cavity and damage nearby structures causing hearing loss when located at the petrous apex. The primary goal of petrous apex cholesteatoma resection is gross total removal with tympanoplasty and canal-wall up or canal-wall down tympanomastoidectomy. At present, there is no definitive surgical approach supported by greater than level 4 evidence in the literature to date.

Methods:

A systematic review was conducted utilizing PubMed, Embase, and Scopus databases. Articles were screened and selected to be reviewed in full text. The articles that met inclusion criteria were reviewed for relevant data. Data analysis, means, and standard deviations were calculated using Microsoft Excel.

Results:

After screening, five articles were included in the systematic review. There were a total of eight pediatric patients with nine total cholesteatomas removed. Conductive hearing loss was the most common (77%) presenting symptom. Perforations were noted in seven ears (86%). Recurrence was noted in 50% of patients with an average recurrence rate of 3.5 years (SD = 1.73). Average length of follow-up was 32.6 months (SD = 21.7). Canal-wall up was the most utilized technique (60%) and there were zero noted surgical complications. Five of the seven (71%) patients that experienced hearing loss from perforation noted improved hearing.

Conclusion:

Due to its rarity, diagnostic evaluation and treatment can vary. Further, multi-institutional investigation is necessary to develop population-level management protocols for pediatric patients affected by petrous apex cholesteatomas.

Proinflammatory mediators, TNFα, IFNγ, and thrombin, directly induce lymphatic capillary tube regression

In this work, we sought to investigate the direct effects of proinflammatory mediators on lymphatic endothelial cell (LEC) capillaries and whether they might induce regression. Our laboratory has developed novel in-vitro, serum-free, lymphatic tubulogenesis assay models whereby human LEC tube networks readily form in either three-dimensional collagen or fibrin matrices. These systems were initially conceptualized in the hopes of better understanding the influence of proinflammatory mediators on LEC capillaries. In this work, we have screened and identified proinflammatory mediators that cause regression of LEC tube networks, the most potent of which is TNFα (tumor necrosis factor alpha), followed by IFNγ (interferon gamma) and thrombin. When these mediators were combined, even greater and more rapid lymphatic capillary regression occurred. Surprisingly, IL-1β (interleukin-1 beta), one of the most potent and pathologic cytokines known, had no regressive effect on these tube networks. Finally, we identified new pharmacological drug combinations capable of rescuing LEC capillaries from regression in response to the potent combination of TNFα, IFNγ, and thrombin. We speculate that protecting lymphatic capillaries from regression may be an important step toward mitigating a wide variety of acute and chronic disease states, as lymphatics are believed to clear both proinflammatory cells and mediators from inflamed and damaged tissue beds. Overall, these studies identify key proinflammatory mediators, including TNFα, IFNγ, and thrombin, that induce regression of LEC tube networks, as well as identify potential therapeutic agents to diminish LEC capillary regression responses.

Selective and Marked Blockade of Endothelial Sprouting Behavior Using Paclitaxel and Related Pharmacologic Agents

Whether alterations in the microtubule cytoskeleton affect the ability of endothelial cells (ECs) to sprout and form branching networks of tubes was investigated in this study. Bioassays of human EC tubulogenesis, where both sprouting behavior and lumen formation can be rigorously evaluated, were used to demonstrate that addition of the microtubule-stabilizing drugs, paclitaxel, docetaxel, ixabepilone, and epothilone B, completely interferes with EC tip cells and sprouting behavior, while allowing for EC lumen formation. In bioassays mimicking vasculogenesis using single or aggregated ECs, these drugs induce ring-like lumens from single cells or cyst-like spherical lumens from multicellular aggregates with no evidence of EC sprouting behavior. Remarkably, treatment of these cultures with a low dose of the microtubule-destabilizing drug, vinblastine, led to an identical result, with complete blockade of EC sprouting, but allowing for EC lumen formation. Administration of paclitaxel in vivo markedly interfered with angiogenic sprouting behavior in developing mouse retina, providing corroboration. These findings reveal novel biological activities for pharmacologic agents that are widely utilized in multidrug chemotherapeutic regimens for the treatment of human malignant cancers. Overall, this work demonstrates that manipulation of microtubule stability selectively interferes with the ability of ECs to sprout, a necessary step to initiate and form branched capillary tube networks.

Defining an Upstream VEGF (Vascular Endothelial Growth Factor) Priming Signature for Downstream Factor-Induced Endothelial Cell-Pericyte Tube Network Coassembly

OBJECTIVE

In this work, we have sought to define growth factor requirements and the signaling basis for different stages of human vascular morphogenesis and maturation. Approach and Results: Using a serum-free model of endothelial cell (EC) tube morphogenesis in 3-dimensional collagen matrices that depends on a 5 growth factor combination, SCF (stem cell factor), IL (interleukin)-3, SDF (stromal-derived factor)-1α, FGF (fibroblast growth factor)-2, and insulin (factors), we demonstrate that VEGF (vascular endothelial growth factor) pretreatment of ECs for 8 hours (ie, VEGF priming) leads to marked increases in the EC response to the factors which includes; EC tip cells, EC tubulogenesis, pericyte recruitment and proliferation, and basement membrane deposition. VEGF priming requires VEGFR2, and the effect of VEGFR2 is selective to the priming response and does not affect factor-dependent tubulogenesis in the absence of priming. Key molecule and signaling requirements for VEGF priming include RhoA, Rock1 (Rho-kinase), PKCα (protein kinase C α), and PKD2 (protein kinase D2). siRNA suppression or pharmacological blockade of these molecules and signaling pathways interfere with the ability of VEGF to act as an upstream primer of downstream factor-dependent EC tube formation as well as pericyte recruitment. VEGF priming was also associated with the formation of actin stress fibers, activation of focal adhesion components, upregulation of the EC factor receptors, c-Kit, IL-3Rα, and CXCR4 (C-X-C chemokine receptor type 4), and upregulation of EC-derived PDGF (platelet-derived growth factor)-BB, PDGF-DD, and HB-EGF (heparin-binding epidermal growth factor) which collectively affect pericyte recruitment and proliferation.

CONCLUSIONS

Overall, this study defines a signaling signature for a separable upstream VEGF priming step, which can activate ECs to respond to downstream factors that are necessary to form branching tube networks with associated mural cells.

Proinflammatory Mediators, IL (Interleukin)-1β, TNF (Tumor Necrosis Factor) α, and Thrombin Directly Induce Capillary Tube Regression

OBJECTIVE

In this work, we examine the molecular basis for capillary tube regression and identify key proregressive factors, signaling pathways, and pharmacological antagonists of this process. Approach and Results: We demonstrate that the proinflammatory mediators, IL (interleukin)-1β, TNF (tumor necrosis factor) α, and thrombin, singly and in combination, are potent regulators of capillary tube regression in vitro. These proregressive factors, when added to endothelial cell-pericyte cocultures, led to selective loss of endothelial cell-lined tube networks, with retention and proliferation of pericytes despite the marked destruction of adjacent capillary tubes. Moreover, treatment of macrophages with the TLR (toll-like receptor) agonists Pam3CSK4 and lipopolysaccharide generates conditioned media with marked proregressive activity, that is completely blocked by a combination of neutralizing antibodies directed to IL-1β and TNFα but not to other factors. The same combination of blocking antibodies, as well as the anti-inflammatory cytokine IL-10, interfere with macrophage-dependent hyaloid vasculature regression in mice suggesting that proinflammatory cytokine signaling regulates capillary regression in vivo. In addition, we identified a capillary regression signaling signature in endothelial cells downstream of these proregressive agents that is characterized by increased levels of ICAM-1 (intercellular adhesion molecule-1), phospho-p38, and phospho-MLC2 (myosin light chain-2) and decreased levels of phospho-Pak2, acetylated tubulin, phospho-cofilin, and pro-caspase3. Finally, we identified combinations of pharmacological agents (ie, FIST and FISTSB) that markedly rescue the proregressive activities of IL-1β, TNFα, and thrombin, individually and in combination.

CONCLUSIONS

Overall, these new studies demonstrate that the major proinflammatory mediators, IL-1β, TNFα, and thrombin, are key regulators of capillary tube regression-a critical pathological process regulating human disease.