Osama Abdel-Razek

Role of surfactant proteins A and D in sepsis-induced acute kidney injury.

ABSTRACT Sepsis is a major cause of acute kidney injury (AKI) with high rates of morbidity and mortality. Surfactant proteins A and D (SP-A, SP-D) play a critical role in host defense and regulate inflammation during infection. Recent studies indicate SP-A and SP-D are expressed in the kidney. The current study examines the role of SP-A and SP-D in the pathogenesis of sepsis-induced AKI. Wild-type (WT) and SP-A/SP-D double-knockout (KO) C57BL/6 mice were treated by cecal ligation and puncture (CLP) or sham surgery. Histological, cellular, and molecular indices of kidney injury were investigated in septic mice 6 and 24 h after CLP. Twenty-four hours after CLP, kidney injury was more severe, renal function was decreased, and blood creatinine and blood urea nitrogen were higher in septic SP-A/SP-D KO mice (P < 0.05, versus septic WT mice). Kidney edema and vascular permeability were increased in septic SP-A/SP-D KO mice (P < 0.01, versus septic WT mice). Apoptotic cells increased significantly (P < 0.01) in the kidney of septic SP-A/SP-D KO mice compared with septic WT mice. Molecular analysis revealed levels of Bcl-2 (an inhibitor of apoptosis) were lower and levels of caspase 3 (a biomarker of apoptosis) were higher in the kidney of septic SP-A/SP-D KO mice (P < 0.01, versus septic WT mice). Furthermore, levels of nuclear factor &kgr;B and phosphorylated I&kgr;B-&agr; increased significantly in the kidney of septic SP-A/SP-D KO mice compared with septic WT mice, suggesting SP-A/SP-D KO mice have a more pronounced inflammatory response to sepsis. We conclude SP-A and SP-D attenuate kidney injury by modulating inflammation and apoptosis in sepsis-induced AKI.

Innate Immune Molecule Surfactant Protein D Attenuates Sepsis-induced Acute Pancreatic Injury through Modulating Apoptosis and NF-κB-mediated Inflammation

Sepsis causes multiple-organ dysfunction including pancreatic injury, thus resulting in high mortality. Innate immune molecule surfactant protein D (SP-D) plays a critical role in host defense and regulating inflammation of infectious diseases. In this study we investigated SP-D functions in the acute pancreatic injury (API) with C57BL/6 Wild-type (WT) and SP-D knockout (KO) mice in cecal ligation and puncture (CLP) model. Our results confirm SP-D expression in pancreatic islets and intercalated ducts and are the first to explore the role of pancreatic SP-D in sepsis. CLP decreased pancreatic SP-D levels and caused severe pancreatic injury with higher serum amylase 24u2009h after CLP. Apoptosis and neutrophil infiltration were increased in the pancreas of septic KO mice (pu2009<u20090.05, vs septic WT mice), with lower Bcl-2 and higher caspase-3 levels in septic KO mice (pu2009<u20090.05). Molecular analysis revealed increased NF-κB-p65 and phosphorylated IκB-α levels along with higher serum levels of TNF-α and IL-6 in septic KO mice compared to septic WT mice (pu2009<u20090.01). Furthermore, in vitro islet cultures stimulated with LPS produced higher TNF-α and IL-6 (pu2009<u20090.05) from KO mice compared to WT mice. Collectively, these results demonstrate SP-D plays protective roles by inhibiting apoptosis and modulating NF-κB-mediated inflammation in CLP-induced API.

Surfactant Proteins SP-A and SP-D Ameliorate Pneumonia Severity and Intestinal Injury in a Murine Model of Staphylococcus Aureus Pneumonia.

ABSTRACT Staphylococcus aureus pneumonia is an important cause of sepsis which causes gut injury, inflammation, and apoptosis. The surfactant proteins surfactant protein A (SP-A) and surfactant protein D (SP-D) bind bacterial pathogens and facilitate clearance of pathogens, apoptotic bodies, and modulate immune responses. SP-A and SP-D are expressed in both lung and gut epithelia. We hypothesize SP-A and SP-D regulate pneumonia severity and gut injury during pneumonia. Methods: Wild-type (WT) and SP-A and SP-D double knockout (SP-A/D KO) mice were subjected to S. aureus or sham pneumonia. Bronchoalveolar lavage and tissue harvest were performed 24u200ah later. Pneumonia severity, gut mucosal injury, inflammation, and apoptosis were measured using a combination of histology, immunohistochemistry, cytokine assay, TUNEL assay, quantitative real-time polymerase chain reaction, and Western blot analyses. Results: Pneumonia increased gut inflammation, apoptosis, and mucosal injury in both groups. Pneumonia histology and bacterial growth in bronchoalveolar lavage fluid demonstrate more severe infection in SP-A/D KO mice compared with WT controls. SP-A/D KO mice with pneumonia also demonstrate more severe histologic gut mucosal injury, increased gut apoptosis, elevated caspase-3 levels, and Bax/Bcl-2 mRNA expression compared with WT pneumonia mice. Nuclear factor &kgr;B (NF-&kgr;B) p65 expression and its nuclear translocation, gut levels of tumor necrosis factor &agr; and interleukin-1&bgr; were all increased in SP-A/D KO mice with pneumonia compared with WT controls. Conclusions: These data provide evidence SP-A and SP-D attenuate S. aureus pneumonia severity resulting in decreased intestinal mucosal injury, apoptosis, and inflammation. Improved pulmonary clearance of S. aureus decreased caspase-3 and Bax/Bcl-2 expressions and decreased activation of the NF-&kgr;B signaling pathway in intestine represent potential mechanisms for the effects of SP-A and SP-D on gut injury during pneumonia.

Protective Role of Surfactant Protein D in Ocular Staphylococcus aureus Infection

Staphylococcus aureus is one of the most common pathogens causing keratitis. Surfactant protein D (SP-D) plays a critical role in host defense and innate immunity. In order to investigate the role of SP-D in ocular S. aureus infection, the eyes of wild-type (WT) and SP-D knockout (SP-D KO) C57BL/6 mice were infected with S. aureus (107 CFU/eye) in the presence and absence of cysteine protease inhibitor(E64).Bacterial counts in the ocular surface were examined 3, 6, 12, 24 hrs after infection. Bacterial phagocytosis by neutrophils and bacterial invasion in ocular epithelial cells were evaluated quantitatively. S. aureus-induced ocular injury was determined with corneal fluorescein staining. The results demonstrated that SP-D is expressed in ocular surface epithelium and the lacrimal gland; WT mice had increased clearance of S. aureus from the ocular surface (p<0.05) and reduced ocular injury compared with SP-D KO mice. The protective effects of SP-D include increased bacterial phagocytosis by neutrophils (p<0.05) and decreased bacterial invasion into epithelial cells (p<0.05) in WT mice compared to in SP-D KO mice. In the presence of inhibitor (E64), WT mice showed enhanced bacterial clearance (p<0.05) and reduced ocular injury compared to absent E64 while SP-D KO mice did not. Collectively, we concluded that SP-D protects the ocular surface from S. aureus infection but cysteine protease impairs SP-D function in this murine model, and that cysteine protease inhibitor may be a potential therapeutic agent in S. aureus keratitis.

DIFFERENTIAL SUSCEPTIBILITY OF HUMAN SP-B GENETIC VARIANTS ON LUNG INJURY CAUSED BY BACTERIAL PNEUMONIA AND THE EFFECT OF A CHEMICALLY MODIFIED CURCUMIN.

ABSTRACT Staphylococcus aureus is a common cause of nosocomial pneumonia frequently resulting in acute respiratory distress syndrome (ARDS). Surfactant protein B (SP-B) gene expresses two proteins involved in lowering surface tension and host defense. Genotyping studies demonstrate a significant association between human SP-B genetic variants and ARDS. Curcumins have been shown to attenuate host inflammation in many sepsis models. Our hypothesis is that functional differences of SP-B variants and treatment with curcumin (CMC2.24) modulate lung injury in bacterial pneumonia. Humanized transgenic mice, expressing either SP-B T or C allele without mouse SP-B gene, were used. Bioluminescent labeled S. aureus Xen 36 (50u200a&mgr;L) was injected intratracheally to cause pneumonia. Infected mice received daily CMC2.24 (40u200amg/kg) or vehicle alone by oral gavage. Dynamic changes of bacteria were monitored using in vivo imaging system. Histological, cellular, and molecular indices of lung injury were studied in infected mice 48u200ah after infection. In vivo imaging analysis revealed total flux (bacterial number) was higher in the lung of infected SP-B-C mice compared with infected SP-B-T mice (Pu200a<u200a0.05). Infected SP-B-C mice demonstrated increased mortality, lung injury, apoptosis, and NF-&kgr;B expression compared with infected SP-B-T mice. Compared with controls, CMC2.24 treatment significantly reduced the following: mortality, total bacterial flux and lung tissue apoptosis, inflammatory cells, NF-&kgr;B expression (Pu200a<u200a0.05), and MMPs-2, -9, -12 activities (Pu200a<u200a0.05). We conclude that mice with SP-B-C allele are more susceptible to S. aureus pneumonia than mice with SP-B-T allele, and that CMC2.24 attenuates lung injury thus reducing mortality.

The role of high airway pressure and dynamic strain on ventilator-induced lung injury in a heterogeneous acute lung injury model

BackgroundAcute respiratory distress syndrome causes a heterogeneous lung injury with normal and acutely injured lung tissue in the same lung. Improperly adjusted mechanical ventilation can exacerbate ARDS causing a secondary ventilator-induced lung injury (VILI). We hypothesized that a peak airway pressure of 40xa0cmH2O (static strain) alone would not cause additional injury in either the normal or acutely injured lung tissue unless combined with high tidal volume (dynamic strain).MethodsPigs were anesthetized, and heterogeneous acute lung injury (ALI) was created by Tween instillation via a bronchoscope to both diaphragmatic lung lobes. Tissue in all other lobes was normal. Airway pressure release ventilation was used to precisely regulate time and pressure at both inspiration and expiration. Animals were separated into two groups: (1) over-distension + high dynamic strain (OD + HDS, nu2009=u20096) and (2) over-distension + low dynamic strain (OD + LDS, nu2009=u20096). OD was caused by setting the inspiratory pressure at 40xa0cmH2O and dynamic strain was modified by changing the expiratory duration, which varied the tidal volume. Animals were ventilated for 6xa0h recording hemodynamics, lung function, and inflammatory mediators followed by an extensive necropsy.ResultsIn normal tissue (NT), OD + LDS caused minimal histologic damage and a significant reduction in BALF total protein (pu2009<u20090.05) and MMP-9 activity (pu2009<u20090.05), as compared with OD + HDS. In acutely injured tissue (ALIT), OD + LDS resulted in reduced histologic injury and pulmonary edema (pu2009<u20090.05), as compared with OD + HDS.ConclusionsBoth NT and ALIT are resistant to VILI caused by OD alone, but when combined with a HDS, significant tissue injury develops.

Surfactant protein D attenuates acute lung and kidney injuries in pneumonia-induced sepsis through modulating apoptosis, inflammation and NF-κB signaling

Pneumonia and sepsis are major risk factors for acute kidney injury (AKI). Patients with pneumonia and AKI are at increased risk for morbidity and mortality. Surfactant protein D (SP-D) expressed in lung and kidney plays important roles in innate immunity. However, little is known about the role of organ-specific SP-D in the sepsis. The current study uses wild type (WT), SP-D knockout (KO), and humanized SP-D transgenic (hTG, lung-specific SP-D expression) mice to study organ-specific role of SP-D in pneumonia-induced sepsis. Analyses demonstrated differential lung and kidney injury among three-type mice infected with Pseudomonas aeruginosa. After infection, KO mice showed higher injurious scores in both lung and kidney, and decreased renal function than WT and hTG mice. hTG mice exhibited comparable lung injury but more severe kidney injury compared to WT mice. Increased renal tubular apoptosis, NF-κB activation and proinflammatory cytokines in the kidney of KO mice were found when compared with WT and hTG mice. Furthermore, in vitro primary proximal tubular epithelial cells from KO mice showed more apoptosis with higher level of activated caspase-3 than those from WT mice after LPS treatment. Collectively, SP-D attenuates AKI in the sepsis by modulating renal apoptosis, inflammation and NF-κB signaling.

A Mouse Model for Ocular Surface Staphylococcus aureus Infection.

Creation of an appropriate animal model that accurately reflects the disease and host immune response to bacterial infection in humans is a major challenge in ocular‐surface infection research. For decades, mice have been the ideal small animal model for ocular‐surface infection research because of the availability and relatively low cost of various genetic backgrounds, targeted defects, and immunologic reagents. By employing different combinations of mouse and bacterial strains, murine infection models can be used to explore a complete picture of bacterial infection and innate immunity of the ocular surface. A murine model of Staphylococcus aureus infection under normal ocular circumstances is presented here as a convenient and tractable model system in which to study mammalian host responses to pathogens.

Role of surfactant protein D on in vivo alveolar macrophage phagocytosis of Cryptococcus neoformans by the regulation of p38 MAPK pathway activation

Surfactant proteins A and D (SP-A and SP-D) are involved in innate immunity against various pathogens. Under normal conditions SP-A and SP-D can bind to signal regulatory protein α (SIRPα), inhibit p38 mitogen-activated protein kinase (p38 MAPK) activation. Previous study demonstrated that SP-A and SP-D double knockout (KO) mice have increased levels of phosphorylated p38 MAPK (p-p38 MAPK) compared to wild-type mice. In this study we studied effects of p38 MAPK activity and SP-D on in vivo phagocytosis of C. neoformans by alveolar macrophages using genetic modified murine model. SP-A and SP-D double KO, and humanized SP-D transgenic (hTG SP-D), and wild-type C57BL/6 mice (8-12 weeks) were used. Mice were treated with or without p38 inhibitor prior to intratracheal injection with 1 × 106 CFU/mouse of C. neoformans, and then mice were sacrificed six hours post-infection. The phagocytosis of C. neoformans was determined using phagocytic index of alveolar macrophages and number of colony-forming units (CFU) in BAL fluid. Data are means ± SE and p<0.05 by t-test was considered significant. The results showed that basal level of p38 MAPK phosphorylation was significantly higher in KO mice than in WT mice; but it decreased to normal level after treating with p38 inhibitor in KO mice. In treatment with p38 inhibitor KO mice significantly decreased its ability of in vivo phagocytosis (42.8 ± 5.2) compared to the sham group (65.5 ± 9.03) (p<0.05). The treated group with p38 inhibitor showed higher CFU counts (496 ± 53.5) in the BALF compared to the control (274 ± 54.7) (p<0.05). Furthermore, transgenic SP-D expression in the hTG SP-D mice decreased p-p38 level and showed enhanced in vivo phagocytic activity of C. neoformans when compared to KO mice (p<0.05). We concluded that both p38 MAPK activation and SP-D play roles in the in vivo phagocytosis of C. neoformans. Correspondence to: Guirong Wang, PhD (Dr. rer. Nat.), Department of Surgery, RM8715, SUNY Upstate Medical University, Syracuse, NY 13210, USA, Tel: 315464-6283; E-mail: wangg@upstate.edu