Predicting response to neoadjuvant chemotherapy for colorectal liver metastasis using deep learning on prechemotherapy cross-sectional imaging.

BACKGROUND AND OBJECTIVES: Deep learning models (DLMs) are applied across domains of health sciences to generate meaningful predictions. DLMs make use of neural networks to generate predictions from discrete data inputs. This study employs DLM on prechemotherapy cross-sectional imaging to predict patients' response to neoadjuvant chemotherapy. METHODS: Adult patients with colorectal liver metastasis who underwent surgery after neoadjuvant chemotherapy were included. A DLM was trained on computed tomography images using attention-based multiple-instance learning. A logistic regression model incorporating clinical parameters of the Fong clinical risk score was used for comparison. Both model performances were benchmarked against the Response Evaluation Criteria in Solid Tumors criteria. A receiver operating curve was created and resulting area under the curve (AUC) was determined. RESULTS: Ninety-five patients were included, with 33,619 images available for study inclusion. Ninety-five percent of patients underwent 5-fluorouracil-based chemotherapy with oxaliplatin and/or irinotecan. Sixty percent of the patients were categorized as chemotherapy responders (30% reduction in tumor diameter). The DLM had an AUC of 0.77. The AUC for the clinical model was 0.41. CONCLUSIONS: Image-based DLM for prediction of response to neoadjuvant chemotherapy in patients with colorectal cancer liver metastases was superior to a clinical-based model. These results demonstrate potential to identify nonresponders to chemotherapy and guide select patients toward earlier curative resection.

CKLF instigates a "cold" microenvironment to promote MYCN-mediated tumor aggressiveness.

Solid tumors, especially those with aberrant MYCN activation, often harbor an immunosuppressive microenvironment to fuel malignant growth and trigger treatment resistance. Despite this knowledge, there are no effective strategies to tackle this problem. We found that chemokine-like factor (CKLF) is highly expressed by various solid tumor cells and transcriptionally up-regulated by MYCN. Using the MYCN-driven high-risk neuroblastoma as a model system, we demonstrated that as early as the premalignant stage, tumor cells secrete CKLF to attract CCR4-expressing CD4+ cells, inducing immunosuppression and tumor aggression. Genetic depletion of CD4+ T regulatory cells abolishes the immunorestrictive and protumorigenic effects of CKLF. Our work supports that disrupting CKLF-mediated cross-talk between tumor and CD4+ suppressor cells represents a promising immunotherapeutic approach to battling MYCN-driven tumors.

Preoperative intervention for smoking cessation: A systematic review.

BACKGROUND: Smoking is associated with increased postoperative complications. Pre-surgical smoking cessation remains a challenge. Our aim was to summarize pre-hospital smoking cessation interventions and impact on smoking cessation rates. METHODS: Independent review of English language articles identified from systematic searches of MEDLINE, PubMed, PsycInfo, Embase, Web of Science, and Cumulative Index to Nursing & Allied Health Literature databases from 1998 to 2019 was performed (PROSPERO registration number CRD42021247927). Studies of adult patients enrolled in a pre-hospital smoking cessation intervention were included. Studies with historical controls or only self-reported outcomes were excluded. RESULTS: Nine articles including 1762 patients were identified. Exhaled CO was used to confirm cessation. Six studies reported smoking status day of surgery. Interventions included NRT, hand-held technology, e-cigarettes, decision aids/counseling and medications. Four studies demonstrated a difference in smoking cessation rates. Ethics and study appraisal were assessed using ROB2. CONCLUSIONS: Based on the variability of interventions, settings, and outcomes, best practice for successful pre-hospital smoking cessation in surgery clinics would benefit from ongoing investigation.

Dual-wavelength volumetric stereolithography of multilevel microfluidic devices.

Microfluidic devices are typically fabricated in an expensive, multistep process (e.g., photolithography, etching, and bonding). Additive manufacturing (AM) has emerged as a revolutionary technology for simple and inexpensive fabrication of monolithic structures-enabling microfluidic designs that are challenging, if not impossible, to make with existing fabrication techniques. Here, we introduce volumetric stereolithography (vSLA), an AM method in which polymerization is constrained to specific heights within a resin vat, allowing layer-by-layer fabrication without a moving platform. vSLA uses an existing dual-wavelength chemistry that polymerizes under blue light (λ = 458 nm) and inhibits polymerization under UV light (λ = 365 nm). We apply vSLA to fabricate microfluidic channels with different spatial and vertical geometries in less than 10 min. Channel heights ranged from 400 µm to 1 mm and could be controlled with an optical dose, which is a function of blue and UV light intensities and exposure time. Oxygen in the resin was found to significantly increase the amount of dose required for curing (i.e., polymerization to a gelled state), and we recommend that an inert vSLA system is used for rapid and reproducible microfluidic fabrication. Furthermore, we recommend polymerizing far beyond the gel point to form more rigid structures that are less susceptible to damage during post-processing, which can be done by simultaneously increasing the blue and UV light absorbance of the resin with light intensities. We believe that vSLA can simplify the fabrication of complex multilevel microfluidic devices, extending microfluidic innovation and availability to a broader community.

Integrated Workflow for the Label-Free Isolation and Genomic Analysis of Single Circulating Tumor Cells in Pancreatic Cancer.

As pancreatic cancer is the third deadliest cancer in the U.S., the ability to study genetic alterations is necessary to provide further insight into potentially targetable regions for cancer treatment. Circulating tumor cells (CTCs) represent an especially aggressive subset of cancer cells, capable of causing metastasis and progressing the disease. Here, we present the Labyrinth-DEPArray pipeline for the isolation and analysis of single CTCs. Established cell lines, patient-derived CTC cell lines and freshly isolated CTCs were recovered and sequenced to reveal single-cell copy number variations (CNVs). The resulting CNV profiles of established cell lines showed concordance with previously reported data and highlight several gains and losses of cancer-related genes such as FGFR3 and GNAS. The novel sequencing of patient-derived CTC cell lines showed gains in chromosome 8q, 10q and 17q across both CTC cell lines. The pipeline was used to process and isolate single cells from a metastatic pancreatic cancer patient revealing a gain of chromosome 1q and a loss of chromosome 5q. Overall, the Labyrinth-DEPArray pipeline offers a validated workflow combining the benefits of antigen-free CTC isolation with single cell genomic analysis.

Developing an Online Program for Self-Management of Fatigue, Pain, and Urgency in Inflammatory Bowel Disease: Patients' Needs and Wants.

BACKGROUND: Inflammatory bowel disease (IBD) is a lifelong relapsing-remitting condition, characterized by troublesome symptoms including fatigue, pain, and bowel urgency. These symptoms can persist even in clinical remission and have a debilitating impact on social, work-related and intimate domains of life. Symptom self-management can be challenging for some patients, who could potentially benefit from an online self-management tool. AIMS: We aimed to understand patients' symptom self-management strategies and preferred design for a future online symptom self-management intervention. METHODS: Using exploratory qualitative methods, we conducted focus group and individual interviews with 40 people with IBD recruited from UK clinics and from community-dwelling members of the Crohn's and Colitis UK charity; data were collected using a digital audio recorder, and transcribed and anonymized by a third party (professional) transcriber. We used framework analysis for focus group data and thematic analysis for interview data. RESULTS: The data provided three core themes: ways of coping; intervention functionality; and intervention content. Participants attempt to manage all three symptoms simultaneously, recognizing the combined influence of factors such as food, drink, stress, and exercise on all symptoms. They wanted an accessible online intervention functioning across several platforms, with symptom and medication management, and activity-tracking features. CONCLUSIONS: Patients reported numerous ways of self-managing symptoms of fatigue, pain, and urgency/incontinence related to IBD and expressed their needs for content, design, and functionality of the proposed intervention. Based on this and existing intervention development literature, the IBD-BOOST online self-management intervention has now been developed and is undergoing testing.

Influence of Tasking During Vestibular Testing.

Purpose The purpose of this study was to investigate the effectiveness of different types of tasking on the measurement of peak slow phase velocity (SPV) for caloric testing and rotary chair testing. Method This study evaluated the peak SPV response for caloric testing and rotary chair across five conditions. Three verbal, one tactile, and one condition without tasking were used for both caloric testing and rotary chair. The subjects consisted of 20 young adults (age range: 22-33 years, M = 26.65, SD = 3.72; seven male, 13 female) with normal vestibular function and no history of ear surgery or vestibular disorder. Study participation consisted of two visits with 24 hr minimum between each, one for caloric testing and one for rotary chair testing. The test completed at each visit was counterbalanced. Caloric Testing: The caloric irrigations were performed 5 times, with the ears randomized and tasking conditions randomized. Rotary Chair Testing: Rotary chair sinusoidal harmonic acceleration testing was performed 5 times at 0.08 Hz with the tasking conditions randomized. Results Tasking of any kind resulted in significantly larger peak SPV responses when compared to the no tasking condition for rotary chair testing. When comparing each type of tasking, no significant differences were noted. No significant difference was noted when comparing the conditions with tasking to the no tasking condition for caloric testing. Conclusions Clinically, either mental or tactile tasking can be utilized as a method to reduce VOR suppression during rotary chair testing. As no difference was found when comparing different verbal tasks to each other, the type of tasking can be catered to the patient. If verbal tasking cannot be completed, the braiding tactile task is a valid substitution. Caloric results varied widely across subjects and did not reach statistical significance, so conclusions on the need for tasking cannot be drawn.

Inertial focusing of circulating tumor cells in whole blood at high flow rates using the microfluidic CTCKey™ device for CTC enrichment.

Circulating tumor cells (CTCs) are extremely rare cells shed from tumors into the blood stream. These cells can provide valuable information about their tumor of origin and direct treatment decisions to improve patient outcomes. Current technologies isolate CTCs from a limited blood volume and often require pre-processing that leads to CTC loss, making it difficult to isolate enough CTCs to perform in-depth tumor analysis. Many inertial microfluidic devices have been developed to isolate CTCs at high flow rates, but they typically require either blood dilution, pre-processing to remove red blood cells, or a sheath buffer rather than being able to isolate cells directly from whole blood. To decrease the need for pre-processing while increasing CTC yield, we developed an inertial device, the CTCKey™, to focus CTCs in whole blood at high throughput yielding a concentrated product stream enriched for CTCs. The CTCKey™ consists of two sections to create CTC enriched blood that can be further processed using any CTC isolation device to selectively isolate the CTCs. A thorough analysis was performed using the MCF7 breast cancer cell line spiked into bovine serum albumin (BSA) solutions of varying concentrations, as well as whole blood to characterize the focusing patterns of the CTCKey™. At the optimal flow rate of 2.4 mL min-1, the CTCKey™ reduces the CTC containing blood volume by 78%; the CTCs from 1 mL of blood are now in 0.22 mL of blood. The CTCKey's™ ability to concentrate CTCs from a large original blood volume to a smaller, highly concentrated volume enables a much greater blood volume to be interrogated by downstream isolation and characterization methods despite their low volume input limitations.

Unraveling the regulatory role of endoplasmic-reticulum-associated degradation in tumor immunity.

During malignant transformation and cancer progression, tumor cells face both intrinsic and extrinsic stress, endoplasmic reticulum (ER) stress in particular. To survive and proliferate, tumor cells use multiple stress response pathways to mitigate ER stress, promoting disease aggression and treatment resistance. Among the stress response pathways is ER-associated degradation (ERAD), which consists of multiple components and steps working together to ensure protein quality and quantity. In addition to its established role in stress responses and tumor cell survival, ERAD has recently been shown to regulate tumor immunity. Here we summarize current knowledge on how ERAD promotes protein degradation, regulates immune cell development and function, participates in antigen presentation, exerts paradoxical roles on tumorigenesis and immunity, and thus impacts current cancer therapy. Collectively, ERAD is a critical protein homeostasis pathway intertwined with cancer development and tumor immunity. Of particular importance is the need to further unveil ERAD's enigmatic roles in tumor immunity to develop effective targeted and combination therapy for successful treatment of cancer.

Chemical and Microstructural Characterization of pH and [Ca2+] Dependent Sol-Gel Transitions in Mucin Biopolymer.

Mucus is responsible for controlling transport and barrier function in biological systems, and its properties can be significantly affected by compositional and environmental changes. In this study, the impacts of pH and CaCl2 were examined on the solution-to-gel transition of mucin, the primary structural component of mucus. Microscale structural changes were correlated with macroscale viscoelastic behavior as a function of pH and calcium addition using rheology, dynamic light scattering, zeta potential, surface tension, and FTIR spectroscopic characterization. Mucin solutions transitioned from solution to gel behavior between pH 4-5 and correspondingly displayed a more than ten-fold increase in viscoelastic moduli. Addition of CaCl2 increased the sol-gel transition pH value to ca. 6, with a twofold increase in loss moduli at low frequencies and ten-fold increase in storage modulus. Changing the ionic conditions-specifically [H+] and [Ca2+] -modulated the sol-gel transition pH, isoelectric point, and viscoelastic properties due to reversible conformational changes with mucin forming a network structure via  non-covalent cross-links between mucin chains.

The Clinical Significance of the Failure to Perceive Vertigo in the Postcaloric Period Despite a Robust Caloric Response.

Purpose The purpose of this project was to explore the association between the perception of motion during caloric testing and two tasks associated with central vestibular processing: postural stability and visuospatial memory. Method This was a prospective study of 25 patients who were found to have nonvestibular etiologies of their symptoms and normal vestibular function test results and who underwent caloric testing with a mean maximum slow phase eye velocity for each irrigation of 15° or greater. Following each caloric irrigation, patients were asked whether they had any sensation of movement. Patients were grouped based on the presence or absence of motion during the caloric exam (motion perception vs. absent perception). Postural stability was assessed using computerized dynamic posturography, and visuospatial memory was assessed using a memory match card game application. Results There were no significant differences between groups on any measures of peripheral vestibular function. However, the Absent Perception Group showed greater postural instability during Condition 5 of posturography and performed significantly worse on a task of visuospatial working memory. Both age and absence of motion perception predicted abnormal performance on measures of postural stability and visuospatial working memory. Conclusions There appears to be clinical implications to a lack of motion perception during the caloric exam in patients with an otherwise normal peripheral vestibular system. Based on the current findings, we are unable to determine whether differences in postural stability and visuospatial memory were due to age or a central vestibular processing deficit.

Revisional Surgery in Patients with Recurrent Dysphagia after Heller Myotomy.

BACKGROUND: Recurrent/persistent symptoms of achalasia occur in 10-20% of individuals after Heller myotomy. The causes and treatment outcomes are ambiguous. Our aim is to assess the causes and outcomes of a multidisciplinary approach to this patient population. METHODS: All patients undergoing revisional operations after a Heller myotomy were reviewed retrospectively. DATA COLLECTED: demographics, date of initial Heller myotomy, preoperative evaluation, etiology of recurrent symptoms, date of revisional operation, and surgical outcomes. RESULTS: A total of 34 patients underwent 37 revisional operations. Operations were tailored based on preoperative multidisciplinary evaluation. Causes of symptoms: periesophageal/perihiatal fibrosis 11 (27%), obstructing fundoplication 11 (27%), incomplete myotomy 8 (20%), progression of disease 9 (22%), and epiphrenic diverticulum 1 (2%). Operations performed: reversal/no creation of fundoplication with or without re-do myotomy 22 (59%), revision/creation of fundoplication with or without myotomy 6 (16%), and esophagectomy 9 (24%). Ten patients in the 37 operations (27%) developed postoperative complications. Of 33 patients for 36 operations with follow-up, 25 patient-operations (69%) resulted in resolution or improved dysphagia. Although there was variation in symptomatic improvement by cause and operation type, none reached statistical significance. CONCLUSION: There are several causes of dysphagia after Heller myotomy and a thoughtful evaluation is required. Complication rates are higher than first-time operations. Symptomatic improvement occurs in the majority of cases, but a significant minority will have persistent dysphagia. Although an individualized approach to dysphagia after Heller myotomy may improve symptoms and passage of food, the perception of dysphagia may persist in patients.

New Labyrinth Microfluidic Device Detects Circulating Tumor Cells Expressing Cancer Stem Cell Marker and Circulating Tumor Microemboli in Hepatocellular Carcinoma.

Hepatocellular Carcinoma (HCC) is one of the most lethal cancers with a high mortality and recurrence rate. Circulating tumor cell (CTC) detection offers various opportunities to advance early detection and monitoring of HCC tumors which is crucial for improving patient outcome. We developed and optimized a novel Labyrinth microfluidic device to efficiently isolate CTCs from peripheral blood of HCC patients. CTCs were identified in 88.1% of the HCC patients over different tumor stages. The CTC positivity rate was significantly higher in patients with more advanced HCC stages. In addition, 71.4% of the HCC patients demonstrated CTCs positive for cancer stem cell marker, CD44, suggesting that the major population of CTCs could possess stemness properties to facilitate tumor cell survival and dissemination. Furthermore, 55% of the patients had the presence of circulating tumor microemboli (CTM) which also correlated with advanced HCC stage, indicating the association of CTM with tumor progression. Our results show effective CTC capture from HCC patients, presenting a new method for future noninvasive screening and surveillance strategies. Importantly, the detection of CTCs with stemness markers and CTM provides unique insights into the biology of CTCs and their mechanisms influencing metastasis, recurrence and therapeutic resistance.

Cholinesterase Inhibitory Arisugacins L-Q from a Penicillium sp. Isolate Obtained through a Citizen Science Initiative and Their Activities in a Phenotype-Based Zebrafish Assay.

Phenotype-based screening of a fungal extract library yielded an active sample from a Penicillium sp. isolate that impaired zebrafish motility. Bioassay-guided purification led to the identification of 14 meroterpenoids including six new metabolites, arisugacins L-Q (4, 5, 8, and 12-14), seven known arisugacins (1-3, 6, 7, 9, and 10), and one known terreulactone (11). Their structures were determined using a combination of NMR and HRESIMS data, evidence secured from theoretical and experimental ECD spectra, and the modified Mosher's method. The purified compounds were tested in zebrafish embryos, as well as in vitro for cholinesterase inhibition activities. Compound 12 produced defects in myotome structure (metameric muscle, which is critical for locomotion) in vivo and showed the most potent and selective acetylcholinesterase inhibitory activity with an IC50 of 191 nM in vitro. The phenotype assay was also used to reveal bioactivities for several previously reported arisugacins, which had failed to show activity in prior cell-based and in vitro testing. This study demonstrates that utilization of the zebrafish phenotype assay is an effective approach for the identification of bioactive extracts, is compatible with the bioassay-guided compound purification strategies, and offers a valuable tool for probing complex natural product sources to detect bioactive small molecules with potential therapeutic or other commercial applications.

The Effect of Recording Montage and Tone Burst Duration on Cervical and Ocular Vestibular Evoked Myogenic Potential Latency and Amplitude.

Objectives The objectives of this study were (a) to investigate the optimal tone burst duration when recording the cervical vestibular evoked myogenic potential (cVEMP) and the ocular vestibular evoked myogenic potential (oVEMP) and (b) to determine whether monopolar recording influences the latency or amplitude of the cVEMP or the oVEMP. Method Fifteen subjects ( M = 27.7 years, SD = 6.73 years) participated in this study. The participants had no prior history of otological or neurological disease. Both oVEMPs and cVEMPs were recorded at a fixed stimulus level for stimulus durations of 2, 5, 10, and 25 ms. For both cVEMP and oVEMP, responses were obtained using a traditional differential recording montage and a monopolar recording montage. Results The cVEMP and the oVEMP had the greatest amplitude in the 2-ms stimulus condition. There was a statistically significant decrease in amplitude for durations greater than 2 ms. Monopolar and bipolar cVEMP and oVEMP latencies and amplitudes were not significantly different. Conclusion As stimulus duration increased beyond 2 ms, the amplitude of the response decreased for both the cVEMP and the oVEMP. There was no significant change in latency with increasing stimulus duration for either response. These results suggested the optimal stimulus duration for both the oVEMP and cVEMP is 2 ms, and there is no apparent advantage of using a bipolar recording technique.

Impact of Stimulus Polarity on oVEMP Response Using the Belly-Tendon Electrode Montage.

BACKGROUND: One stimulus parameter not well established with respect to the ocular vestibular evoked myogenic potential (oVEMP) is stimulus polarity. Many research studies traditionally record oVEMPs using alternating polarity primarily. PURPOSE: The purpose of this study was to evaluate the effects of stimulus polarity on the oVEMP response under three different conditions (condensation, rarefaction, and alternating) with updated but established recording procedures-the belly-tendon electrode montage. RESEARCH DESIGN: oVEMPs were assessed with changes in stimulus polarity in the seated upright position. STUDY SAMPLE: Thirty otologically normal participants (60 ears) with no history of hearing or balance disorders and normal middle ear function. DATA COLLECTION AND ANALYSIS: Five hundred-hertz air-conducted tone bursts at 95-dB nHL were used to evoke the oVEMP response while recordings were made from the contralateral eye to acoustical stimulation using the belly-tendon electrode montage. Measurements were made using three polarities: alternating, condensation, and rarefaction. Natus Bio-logic AEP hardware and software was used for all data collection and analysis. RESULTS: Condensation stimulus phase provided the largest response amplitude compared with alternating and/or rarefaction. Rarefaction provided the earliest latency among stimulus polarities. CONCLUSIONS: Condensation is a more effective stimulus polarity regarding response amplitude when recording the oVEMP. This study further supports the use of the belly-tendon electrode montage for recording the oVEMP response.

A temporary indwelling intravascular aphaeretic system for in vivo enrichment of circulating tumor cells.

Circulating tumor cells (CTCs) have become an established biomarker for prognosis in patients with various carcinomas. However, current ex vivo CTC isolation technologies rely on small blood volumes from a single venipuncture limiting the number of captured CTCs. This produces statistical variability and inaccurate reflection of tumor cell heterogeneity. Here, we describe an in vivo indwelling intravascular aphaeretic CTC isolation system to continuously collect CTCs directly from a peripheral vein. The system returns the remaining blood products after CTC enrichment, permitting interrogation of larger blood volumes than classic phlebotomy specimens over a prolonged period of time. The system is validated in canine models showing capability to screen 1-2% of the entire blood over 2 h. Our result shows substantial increase in CTC capture, compared with serial blood draws. This technology could potentially be used to analyze large number of CTCs to facilitate translation of analytical information into future clinical decisions.

Cytochrome P450 monooxygenase lipid metabolites are significant second messengers in the resolution of choroidal neovascularization.

Age-related macular degeneration (AMD) is the most common cause of blindness for individuals age 50 and above in the developed world. Abnormal growth of choroidal blood vessels, or choroidal neovascularization (CNV), is a hallmark of the neovascular (wet) form of advanced AMD and leads to significant vision loss. A growing body of evidence supports a strong link between neovascular disease and inflammation. Metabolites of long-chain polyunsaturated fatty acids derived from the cytochrome P450 (CYP) monooxygenase pathway serve as vital second messengers that regulate a number of hormones and growth factors involved in inflammation and vascular function. Using transgenic mice with altered CYP lipid biosynthetic pathways in a mouse model of laser-induced CNV, we characterized the role of these lipid metabolites in regulating neovascular disease. We discovered that the CYP-derived lipid metabolites epoxydocosapentaenoic acids (EDPs) and epoxyeicosatetraenoic acids (EEQs) are vital in dampening CNV severity. Specifically, overexpression of the monooxygenase CYP2C8 or genetic ablation or inhibition of the soluble epoxide hydrolase (sEH) enzyme led to increased levels of EDP and EEQ with attenuated CNV development. In contrast, when we promoted the degradation of these CYP-derived metabolites by transgenic overexpression of sEH, the protective effect against CNV was lost. We found that these molecules work in part through their ability to regulate the expression of key leukocyte adhesion molecules, on both leukocytes and endothelial cells, thereby mediating leukocyte recruitment. These results suggest that CYP lipid signaling molecules and their regulators are potential therapeutic targets in neovascular diseases.

The alternative complement pathway aids in vascular regression during the early stages of a murine model of proliferative retinopathy.

Proliferative retinopathic diseases often progress in 2 phases: initial regression of retinal vasculature (phase 1) followed by subsequent neovascularization (NV) (phase 2). The immune system has been shown to aid in vascular pruning in such retinopathies; however, little is known about the role of the alternative complement pathway in the initial vascular regression phase. Using a mouse model of oxygen-induced retinopathy (OIR), we observed that alternative complement pathway-deficient mice (Fb(-/-)) exhibited a mild decrease in vascular loss at postnatal day (P)8 compared with age- and strain-matched controls (P = 0.035). Laser capture microdissection was used to isolate the retinal blood vessels. Expression of the complement inhibitors Cd55 and Cd59 was significantly decreased in blood vessels isolated from hyperoxic retinas compared with those from normoxic control mice. Vegf expression was measured at P8 and found to be significantly lower in OIR mice than in normoxic control mice (P = 0.0048). Further examination of specific Vegf isoform expression revealed a significant decrease in Vegf120 (P = 0.00032) and Vegf188 (P = 0.0092). In conjunction with the major modulating effects of Vegf during early retinal vascular development, our data suggest a modest involvement of the alternative complement pathway in targeting vessels for regression in the initial vaso-obliteration stage of OIR.

Inhibition of the alternative complement pathway preserves photoreceptors after retinal injury.

Degeneration of photoreceptors is a primary cause of vision loss worldwide, making the underlying mechanisms surrounding photoreceptor cell death critical to developing new treatment strategies. Retinal detachment, characterized by the separation of photoreceptors from the underlying retinal pigment epithelium, is a sight-threatening event that can happen in a number of retinal diseases. The detached photoreceptors undergo apoptosis and programmed necrosis. Given that photoreceptors are nondividing cells, their loss leads to irreversible visual impairment even after successful retinal reattachment surgery. To better understand the underlying disease mechanisms, we analyzed innate immune system regulators in the vitreous of human patients with retinal detachment and correlated the results with findings in a mouse model of retinal detachment. We identified the alternative complement pathway as promoting early photoreceptor cell death during retinal detachment. Photoreceptors down-regulate membrane-bound inhibitors of complement, allowing for selective targeting by the alternative complement pathway. When photoreceptors in the detached retina were removed from the primary source of oxygen and nutrients (choroidal vascular bed), the retina became hypoxic, leading to an up-regulation of complement factor B, a key mediator of the alternative pathway. Inhibition of the alternative complement pathway in knockout mice or through pharmacological means ameliorated photoreceptor cell death during retinal detachment. Our current study begins to outline the mechanism by which the alternative complement pathway facilitates photoreceptor cell death in the damaged retina.