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Pityriasis rubra pilaris (PRP) is a rare inflammatory skin disease with a poorly understood pathogenesis. Through a molecularly driven precision medicine approach and an extensive mechanistic pathway analysis in PRP skin samples, compared to psoriasis, atopic dermatitis, healed PRP, and healthy controls, we identified IL-1ß as a key mediator, orchestrating an NF-κB-mediated IL-1ß-CCL20 axis, including activation of CARD14 and NOD2. Treatment of three patients with the IL-1 antagonists anakinra and canakinumab resulted in rapid clinical improvement and reversal of the PRP-associated molecular signature with a 50% improvement in skin lesions after 2 to 3 weeks. This transcriptional signature was consistent with in vitro stimulation of keratinocytes with IL-1ß. With the central role of IL-1ß underscoring its potential as a therapeutic target, our findings propose a redefinition of PRP as an autoinflammatory keratinization disorder. Further clinical trials are needed to validate the efficacy of IL-1ß antagonists in PRP.
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Anticorpos Monoclonais Humanizados , Proteína Antagonista do Receptor de Interleucina 1 , Interleucina-1beta , Queratinócitos , Pitiríase Rubra Pilar , Humanos , Pitiríase Rubra Pilar/tratamento farmacológico , Pitiríase Rubra Pilar/patologia , Pitiríase Rubra Pilar/genética , Interleucina-1beta/metabolismo , Interleucina-1beta/antagonistas & inibidores , Proteína Antagonista do Receptor de Interleucina 1/uso terapêutico , Queratinócitos/metabolismo , Queratinócitos/efeitos dos fármacos , Queratinócitos/patologia , Anticorpos Monoclonais Humanizados/uso terapêutico , Anticorpos Monoclonais Humanizados/farmacologia , Masculino , NF-kappa B/metabolismo , Proteína Adaptadora de Sinalização NOD2/metabolismo , Proteína Adaptadora de Sinalização NOD2/genética , Proteína Adaptadora de Sinalização NOD2/antagonistas & inibidores , Feminino , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Proteínas Adaptadoras de Sinalização CARD/genética , Pele/patologia , Pele/metabolismo , Pele/efeitos dos fármacos , Interleucina-1/antagonistas & inibidores , Interleucina-1/metabolismo , Interleucina-1/genética , Pessoa de Meia-Idade , Guanilato Ciclase/metabolismo , Guanilato Ciclase/antagonistas & inibidores , Guanilato Ciclase/genética , Adulto , Transdução de Sinais/efeitos dos fármacos , Proteínas de MembranaRESUMO
BACKGROUND: The maxillary sinus is a pyramid-shaped cavity with varying shapes, sizes, and capacities. Its dimensions grow gradually and develop until early adulthood. Anatomical knowledge of the maxillary sinus is essential to understanding sinonasal disorders, planning surgical procedures and preventing complications. Awareness of the sinus's proximity to critical structures helps avoid injuries during surgery. The European, Korean, and Sri Lankan population study parameters show varying results and do not necessarily apply to the Indian population. The standard morphometric data of the maxillary sinus is scanty in the Indian population. The study aimed to determine the volume and morphometry of the maxillary sinus along with gender differences in the Eastern population of the Indian. MATERIALS AND METHODS: A retrospective cross-sectional study was conducted using cone beam computed tomography data of maxillary sinuses of 100 normal individuals. The data were analysed after the three-dimensional reconstruction of digital imaging and communications in medicine (DICOM) images with the help of DICOM to print and Geomagic freeform software in the Anatomy department. The different linear morphometric variables and volume of the maxillary sinus were studied. SPSS version 27.0. was utilised for statistical analyses. RESULTS: The mean values of Antero-posterior diameter, Transverse diameter, Craniocaudal diameters, the height of ostium from the floor and volume of the maxillary sinus in males on the right side are 36.61 mm, 20.7 mm, 40.31 mm, 26.02 mm and 16055.24 mm³ and on the left side are 37.17 mm, 20.17 mm, 40.73 mm, 26.91 mm and 15712.66 mm³ whereas in females the values on the right side are 38.10 mm, 21.56 mm, 38.96 mm, 25.81 mm and 14687.78 mm³ and on left side are 38.23 mm, 21.53 mm, 38.48 mm, 25.28 mm and 14203.13 mm3 respectively. The side-to-side parameter differences were non-significant within the male and female groups, respectively. The females had significantly (p < 0.05) larger transverse diameters than males in both the right and left maxillary sinuses. The males tend to have a slightly larger mean craniocaudal diameter than females, but the difference was found statistically significant (p < 0.05) only in the left maxillary sinus. The gender differentiation based on the measured parameters of bilateral maxillary sinus accuracy rate was 89.4% in males and 61.8% in females. CONCLUSIONS: These parameters serve as a standard or reference point, allowing radiologists and surgeons to compare individual patient scans to population averages and aid in better clinical outcomes. The mean values of different parameters of the maxillary sinus may be utilised to differentiate various suspected sinus pathologies, which is helpful for functional endoscopic sinus surgery. Gender differentiation can be done more accurately by forensic experts using Maxillary sinus transverse diameter bilaterally, followed by craniocaudal diameter of the left side sinus for predicting the gender of an unknown maxilla.
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Systemic lupus erythematosus (SLE) is a complex autoimmune disorder impacting various organs, notably prevalent in women of reproductive age. This review explores the involvement of a disintegrin and metalloproteinases (ADAMs) in SLE pathogenesis. Despite advancements in understanding SLE through genome and transcriptome studies, the role of ADAMs in post-translational regulations remains insufficiently explored. ADAMs, transmembrane proteins with diverse functions, impact cell adhesion, migration, and inflammation by shedding cell surface proteins, growth factors, and receptors. Notably, ADAM9 is implicated in Th17 cell differentiation, which is crucial in SLE pathology. ADAM10 and ADAM17 play pivotal roles in T-cell biology, influencing immune cell development and differentiation. Elevated soluble ADAM substrates in SLE patients serve as potential biomarkers correlating with disease activity. Targeting ADAMs or their substrates offers promising therapeutic avenues for SLE management and treatment enhancement.
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Desintegrinas , Lúpus Eritematoso Sistêmico , Humanos , Feminino , Desintegrinas/metabolismo , Proteína ADAM10/metabolismo , Inflamação , Diferenciação Celular , Proteínas de Membrana , Proteínas ADAMRESUMO
OBJECTIVE: To investigate the role of calcium/calmodulin-dependent protein kinase IV (CaMK4) in the development of joint injury in a mouse model of arthritis and patients with RA. METHODS: Camk4-deficient, Camk4flox/floxLck-Cre, and mice treated with CaMK4 inhibitor KN-93 or KN-93 encapsulated in nanoparticles tagged with CD4 or CD8 antibodies were subjected to collagen-induced arthritis (CIA). Inflammatory cytokine levels, humoral immune response, synovitis, and T-cell activation were recorded. CAMK4 gene expression was measured in CD4+ T cells from healthy participants and patients with active RA. Micro-CT and histology were used to assess joint pathology. CD4+ and CD14+ cells in patients with RA were subjected to Th17 or osteoclast differentiation, respectively. RESULTS: CaMK4-deficient mice subjected to CIA displayed improved clinical scores and decreased numbers of Th17 cells. KN-93 treatment significantly reduced joint destruction by decreasing the production of inflammatory cytokines. Furthermore, Camk4flox/floxLck-Cre mice and mice treated with KN93-loaded CD4 antibody-tagged nanoparticles developed fewer Th17 cells and less severe arthritis. CaMK4 inhibition mitigated IL-17 production by CD4+ cells in patients with RA. The number of in vitro differentiated osteoclasts from CD14+ cells in patients with RA was significantly decreased with CaMK4 inhibitors. CONCLUSION: Using global and CD4-cell-targeted pharmacologic approaches and conditionally deficient mice, we demonstrate that CaMK4 is important in the development of arthritis. Using ex vivo cell cultures from patients with RA, CaMK4 is important for both Th17 generation and osteoclastogenesis. We propose that CaMK4 inhibition represents a new approach to control the development of arthritis.
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Artrite Experimental , Osteogênese , Animais , Camundongos , Proteína Quinase Tipo 4 Dependente de Cálcio-Calmodulina/metabolismo , Cálcio/uso terapêutico , Células Th17 , Citocinas/metabolismo , Artrite Experimental/metabolismo , Diferenciação CelularRESUMO
Infection is one of the major causes of mortality in patients with systemic lupus erythematosus (SLE). We previously found that CD38, an ectoenzyme that regulates the production of NAD+, is up-regulated in CD8+ T cells of SLE patients and correlates with the risk of infection. Here, we report that CD38 reduces CD8+ T cell function by negatively affecting mitochondrial fitness through the inhibition of multiple steps of mitophagy, a process that is critical for mitochondria quality control. Using a murine lupus model, we found that administration of a CD38 inhibitor in a CD8+ T cell-targeted manner reinvigorated their effector function, reversed the defects in autophagy and mitochondria, and improved viral clearance. We conclude that CD38 represents a target to mitigate infection rates in people with SLE.
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Lúpus Eritematoso Sistêmico , Viroses , Animais , Linfócitos T CD8-Positivos/metabolismo , Humanos , Lúpus Eritematoso Sistêmico/metabolismo , Camundongos , Mitocôndrias , Mitofagia , Viroses/metabolismoRESUMO
The complement system is involved in the origin of autoimmunity and systemic lupus erythematosus. Both genetic deficiency of complement components and excessive activation are involved in primary and secondary renal diseases, including lupus nephritis. Among the pathways, the classical pathway has long been accepted as the main pathway of complement activation in systemic lupus erythematosus. However, more recent studies have shown the contribution of factors B and D which implies the involvement of the alternative pathway. While there is evidence on the role of the lectin pathway in systemic lupus erythematosus, it is yet to be demonstrated whether this pathway is protective or harmful in lupus nephritis. Complement is being explored for the development of disease biomarkers and therapeutic targeting. In the current review we discuss the involvement of complement in lupus nephritis.
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Lúpus Eritematoso Sistêmico , Nefrite Lúpica , Ativação do Complemento/fisiologia , Proteínas do Sistema Complemento , Humanos , Lectinas , Nefrite Lúpica/tratamento farmacológicoRESUMO
Acute and chronic kidney failure is common in hospitalized patients with COVID-19, yet the mechanism of injury and predisposing factors remain poorly understood. We investigated the role of complement activation by determining the levels of deposited complement components (C1q, C3, FH, C5b-9) and immunoglobulin along with the expression levels of the injury-associated molecules spleen tyrosine kinase (Syk), mucin-1 (MUC1) and calcium/calmodulin-dependent protein kinase IV (CaMK4) in the kidney tissues of people who succumbed to COVID-19. We report increased deposition of C1q, C3, C5b-9, total immunoglobulin, and high expression levels of Syk, MUC1 and CaMK4 in the kidneys of COVID-19 patients. Our study provides strong rationale for the expansion of trials involving the use of inhibitors of these molecules, in particular C1q, C3, Syk, MUC1 and CaMK4 to treat patients with COVID-19.
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COVID-19/metabolismo , Proteínas do Sistema Complemento/metabolismo , Rim/metabolismo , Mucina-1/metabolismo , SARS-CoV-2 , Quinase Syk/metabolismo , Idoso , Idoso de 80 Anos ou mais , COVID-19/patologia , Proteína Quinase Tipo 4 Dependente de Cálcio-Calmodulina/genética , Proteína Quinase Tipo 4 Dependente de Cálcio-Calmodulina/metabolismo , Proteínas do Sistema Complemento/genética , Evolução Fatal , Feminino , Regulação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Mucina-1/genética , Quinase Syk/genéticaRESUMO
PURPOSE: Correct localization of the sacral hiatus is essential for administering a successful caudal epidural block. The purpose of this study is to create a statistical model of sacral hiatus from dorsal sacral parameters to improve the location of the hiatus and thus, reduce the failure rate. The aim of this investigation was to examine the relationship of sacral hiatus morphology and dimension with sacral curvature. This study further examines the dorsal sacral parameters that could affect the sacral hiatus dimension. METHODS: Adult, human, dry sacra and three-dimensionally reconstructed sacra from computed tomography imaging of normal subjects were included in the study and measured using digital Vernier calipers of 0.01 mm accuracy and Geomagic freeform plus software, respectively. RESULT: The most frequent shape of the sacral hiatus was an inverted V (48%) followed by inverted U shape (32%), an irregular shape (12.3%), an M shape (4.7) and an A shape (2.8%). The data were represented by mean and standard deviation. Sacra with M-shaped hiatus had the lowest hiatal length (14.21 ± 5.44 mm), whereas sacra with an inverted V-shaped hiatus had the highest length (25.41 ± 11.3 mm). The anteroposterior diameter of the sacral hiatus at the base in males and females was found to be 3.46 ± 1.48 mm and 2.79 ± 0.83 mm, respectively (P < 0.001). The distance between the caudal end of the median sacral crest and the apex of the sacral hiatus (7.90 ± 6.74 mm, 4.4 ± 5.86 mm) also revealed sexual dimorphism (P < 0.001). CONCLUSION: The correlations between most of the dorsal sacral parameters and length of the sacral hiatus are significant. The intercornual distance is also moderately correlated with the distance between right and left lateral sacral crest S1 level. Dorsal sacral parameters predicts variance of the sacral hiatus dimension from 40 to 73% and this could be utilized for statistical model of the sacral hiatus.
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Sacro/anatomia & histologia , Variação Anatômica , Anestesia Caudal , Estudos Transversais , Espaço Epidural/anatomia & histologia , Humanos , Técnicas In Vitro , Modelos Anatômicos , Modelos Estatísticos , Bloqueio Nervoso , Análise de Componente Principal , Tomografia Computadorizada por Raios XRESUMO
Lung inflammation and damage is prominent in people infected with SARS-Cov-2 and a major determinant of morbidity and mortality. We report the deposition of complement components in the lungs of people who succumbed to COVID-19 consistent with the activation of the classical and the alternative pathways. Our study provides strong rationale for the expansion of trials involving the use of complement inhibitors to treat patients with COVID-19.
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COVID-19/imunologia , Ativação do Complemento/imunologia , Via Alternativa do Complemento/imunologia , Lesão Pulmonar/imunologia , Idoso , Idoso de 80 Anos ou mais , COVID-19/complicações , Inativadores do Complemento/farmacologia , Inativadores do Complemento/uso terapêutico , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Humanos , Imuno-Histoquímica , Pulmão/diagnóstico por imagem , Pulmão/imunologia , Pulmão/patologia , Lesão Pulmonar/complicações , Lesão Pulmonar/patologia , Lesão Pulmonar/virologia , Masculino , Pessoa de Meia-IdadeRESUMO
INTRODUCTION: The proximal insertion beyond coracoid process of pectoralis minor is considered as hidden culprit of rotator cuff disorders. The ectopic insertion is also associated with thoracic outlet syndrome. The current review was conducted to provide a comprehensive evidence-based assessment of the anatomical characteristics of ectopic insertion of pectoralis minor. MATERIALS AND METHODS: A through systematic search was conducted on the major electronic database, PubMed, EMBASE, Google Scholar and Journals of Anatomy, orthopedics, plastic surgery, sports medicine. The primary outcome was to measure the prevalence of ectopic insertion of pectoralis minor tendons. The data extraction was conducted for pooled estimation and metanalysis. RESULTS: A total of 25 studies were included for systematic review. The overall pooled estimate of ectopic insertion of Pectoralis Minor was 19.27% (95% CI 15-24%). The prevalence rate in dissected specimen was 21% (CI 15-28%) and in arthroscopic evaluation was 22% (95% CI 5-59%) which was marginally higher with wide confidence interval due small sample size. The prevalence rate in MRI and USG were 15 and 12%, because MRI and USG have almost similar sensitivity in the detection of anomalous insertion of Pectoralis Minor. The distribution of subtypes of anomalous or ectopic insertion based on Le Double classification was 34% for type I, 42 and 9% for Type III. The incidence of ectopic insertion of pectoralis minor was highest in Japanese population. The female and left side have slightly higher incidence at insignificant level. CONCLUSION: The preoperative MRI or at least USG evaluation of shoulder joint must be conducted for appropriate surgical planning, because the prevalence of ectopic insertion is around 20%. The preoperative detection of anomalous insertion of pectoralis minor can be crucial in minimizing the incidences of iatrogenic injuries of tendon or post-operative complications.
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Processo Coracoide/anormalidades , Músculos Peitorais/anormalidades , Lesões do Manguito Rotador/etiologia , Tendões/anormalidades , Processo Coracoide/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Músculos Peitorais/diagnóstico por imagem , Prevalência , Tendões/diagnóstico por imagem , UltrassonografiaRESUMO
Drug repurposing has the advantage of identifying potential treatments on a shortened timescale. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high-content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce mucin-1 (MUC1) protein abundance. Elevated MUC1 levels predict the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and correlate with poor clinical outcomes. Our screen identifies fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo, fostamatinib reduces MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro, SYK inhibition by the active metabolite R406 promotes MUC1 removal from the cell surface. Our work suggests fostamatinib as a repurposing drug candidate for ALI.
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Betacoronavirus , Infecções por Coronavirus , Pandemias , Pneumonia Viral , COVID-19 , Complemento C3 , Humanos , SARS-CoV-2RESUMO
Drug repurposing is the only method capable of delivering treatments on the shortened time-scale required for patients afflicted with lung disease arising from SARS-CoV-2 infection. Mucin-1 (MUC1), a membrane-bound molecule expressed on the apical surfaces of most mucosal epithelial cells, is a biochemical marker whose elevated levels predict the development of acute lung injury (ALI) and respiratory distress syndrome (ARDS), and correlate with poor clinical outcomes. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce MUC1 protein abundance. Our screen identified Fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo , Fostamatinib reduced MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro , SYK inhibition by Fostamatinib promoted MUC1 removal from the cell surface. Our work reveals Fostamatinib as a repurposing drug candidate for ALI and provides the rationale for rapidly standing up clinical trials to test Fostamatinib efficacy in patients with COVID-19 lung injury.
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Current technologies and available scaffold materials do not support long-term cell viability, differentiation and maintenance of podocytes, the ultra-specialized kidney resident cells that are responsible for the filtration of the blood. We developed a new platform which imitates the native kidney microenvironment by decellularizing fibroblasts grown on surfaces with macromolecular crowding. Human immortalized podocytes cultured on this platform displayed superior viability and metabolic activity up to 28 days compared to podocytes cultured on tissue culture plastic surfaces. The new platform displayed a softer surface and an abundance of growth factors and associated molecules. More importantly it enabled podocytes to display molecules responsible for their structure and function and a superior development of intercellular connections/interdigitations, consistent with maturation. The new platform can be used to study podocyte biology, test drug toxicity and determine whether sera from patients with podocytopathies are involved in the expression of glomerular pathology.
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BACKGROUND: Activation of the complement system and complement deposition on red blood cells (RBCs) contribute to organ damage in trauma. We conducted a prospective study in subjects with traumatic injuries to determine the pattern of complement deposition on RBC and whether they are associated with clinical outcomes. METHOD: A total of 124 trauma patients and 42 healthy controls were enrolled in this prospective study. RBC and sera were collected at 0, 6, 24, and 72âh from trauma patients and healthy controls during a single draw. Presence of C4d, C3d, C5b-9, phosphorylation of band 3 and production of nitric oxide were analyzed by flow cytometry. RESULTS: RBC from trauma patients at all time points up to 24âh displayed significantly higher deposition of C4d on their RBC membrane as compared with healthy donors. Incubation of normal RBC with sera from trauma patients resulted in significant increase of C4d deposition (at 0, 6, 24, and 72âh), C5b-9 deposition (at 0 and 6âh), phosphorylation of band 3 (at 0 and 24âh), and nitric oxide production up to 24âh compared with sera from healthy subjects. Deposition of C4d and C5b-9 in patients with an Injury Severity Score (ISS) of 9 and above remained elevated up to 72âh. CONCLUSIONS: Our study demonstrates that the presence of C4d, C3d, and C5b-9 on the surface of RBC is linked to increased phosphorylation of band 3 and increased production of nitric oxide. Deposition of C4d and C5b-9 decreased faster over course of 3-day study in subjects with ISS less than 9.
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Biomarcadores/metabolismo , Proteínas do Sistema Complemento/metabolismo , Eritrócitos/metabolismo , Ferimentos e Lesões/metabolismo , Adulto , Idoso , Ativação do Complemento/fisiologia , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Óxido Nítrico/metabolismo , Estudos ProspectivosRESUMO
Trauma remains a major cause of death throughout the world, especially for patients younger than 45 years. Due to rapid advances in clinical management, both in the acute and prehospital settings, trauma patients survive devastating injuries at unprecedented rates. However, these patients can often face life threatening complications that stem from the robust innate immune response induced by severe hemorrhage, leading to further tissue injury rather than repair. The complement and coagulation cascades are key mediators in this disordered reaction, which includes the development of trauma-induced coagulopathy. There is increasing evidence that cross-talk between these two pathways allows rapid amplification of their otherwise targeted responses and contributes to overwhelming and prolonged systemic inflammation. In this article, we summarize the initial steps of innate immune response to trauma and review the complex complement and coagulation cascades, as well as how they interact with each other. Despite progress in understanding these cascades, effective therapeutic targets have yet to be found and further research is needed both to improve survival rates as well as decrease associated morbidity.
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Development of implantable devices based on the principles of in vitro organogenesis has been hindered due to the prolonged time required to develop an implantable device. Herein we assessed the influence of serum concentration (0.5% and 10%), oxygen tension (0.5%, 2% and 20%) and macromolecular crowding (75 µg/ml carrageenan) in extracellular matrix deposition in human corneal fibroblast culture (3, 7 and 14 days). The highest extracellular matrix deposition was observed after 14 days in culture at 0.5% serum, 2% oxygen tension and 75 µg/ml carrageenan. These data indicate that low oxygen tension coupled with macromolecular crowding significantly accelerate the development of scaffold-free tissue-like modules. Copyright © 2016 John Wiley & Sons, Ltd.
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Córnea/citologia , Matriz Extracelular/metabolismo , Fibroblastos/citologia , Substâncias Macromoleculares/química , Oxigênio/farmacologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Colágeno Tipo I/metabolismo , Matriz Extracelular/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Metaloproteinases da Matriz/metabolismoRESUMO
C3a is important in the regulation of the immune response as well as in the development of organ inflammation and injury. Furthermore, C3a contributes to liver regeneration but its role in intestinal stem cell function has not been studied. We hypothesized that C3a is important for intestinal repair and regeneration. Intestinal organoid formation, a measure of stem cell capacity, was significantly limited in C3-deficient and C3a receptor (C3aR) 1-deficient mice while C3a promoted the growth of organoids from normal mice by supporting Wnt-signaling but not from C3aR1-deficient mice. Similarly, the presence of C3a in media enhanced the expression of the intestinal stem cell marker leucine-rich repeat G-protein-coupled receptor 5 (Lgr5) and of the cell proliferation marker Ki67 in organoids formed from C3-deficient but not from C3aR1-deficient mice. Using Lgr5.egfp mice we showed significant expression of C3 in Lgr5+ intestinal stem cells whereas C3aR1 was expressed on the surface of various intestinal cells. C3 and C3aR1 expression was induced in intestinal crypts in response to ischemia/reperfusion injury. Finally, C3aR1-deficient mice displayed ischemia/reperfusion injury comparable to control mice. These data suggest that C3a through interaction with C3aR1 enhances stem cell expansion and organoid formation and as such may have a role in intestinal regeneration.
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Intestinal ischemia followed by reperfusion leads to local and remote organ injury attributed to inflammatory response during the reperfusion phase. The extent to which ischemia contributes to ischemia/reperfusion injury has not been thoroughly studied. After careful evaluation of intestinal tissue following 30 min of ischemia, we noticed significant local mucosal injury in wild-type mice. This injury was drastically reduced in C3-deficient mice, suggesting C3 involvement. Depletion of circulating complement with cobra venom factor eliminated, as expected, injury recorded at the end of the reperfusion phase but failed to eliminate injury that occurred during the ischemic phase. Immunohistochemical studies showed that tissue damage during ischemia was associated with increased expression of C3/C3 fragments primarily in the intestinal epithelial cells, suggesting local involvement of complement. In vitro studies using Caco2 intestinal epithelial cells showed that in the presence of LPS or exposure to hypoxic conditions the cells produce higher C3 mRNA as well as C3a fragment. Caco2 cells were also noted to produce cathepsins B and L, and inhibition of cathepsins suppressed the release of C3a. Finally, we found that mice treated with a cathepsin inhibitor and cathepsin B-deficient mice suffer limited intestinal injury during the ischemic phase. To our knowledge, our findings demonstrate for the first time that significant intestinal injury occurs during ischemia prior to reperfusion and that this is due to activation of C3 within the intestinal epithelial cells in a cathepsin-dependent manner. Modulation of cathepsin activity may prevent injury of organs exposed to ischemia.