Lack Of Inflammation Research Articles

Complement Deposits on Ocular Tissues Adjacent to Sites of Inflammation

Purpose: The complement system plays important roles in a variety of chronic ocular diseases such as age-related macular degeneration. Here we examined the deposition of complement components in mouse eyes damaged by various mechanisms. Methods: Mouse eyes were damaged by light or by three models of inflammation, i.e., local transgenic expression of cytokines, interleukin-1 or -7, or by induction of experimental autoimmune uveitis. Eye tissues obtained from each model were immunostained with antibodies against complement components C1q, C3, and C4. Results: No complement deposition was seen in light damaged eyes, while in inflamed eyes we found complement deposition at sites of tissue damage and cellular infiltration. In addition to affected tissues, intense immunoreactivity against complement was unexpectedly observed in corneal tissues and lens capsule, despite lack of inflammation in these tissues. Conclusion: Our observations suggest that ocular tissues adjacent to inflammatory sites undergo changes that facilitate complement deposition.

Direct effects of dexamethasone on human podocytes

Glucocorticoids are widely used in the treatment of human glomerular diseases, but their mode of action is poorly understood particularly in steroid-sensitive nephrotic syndrome, which is most common in childhood and is characterized by a lack of inflammation in the kidney. The podocyte is a key cell in the glomerulus in health and disease: until recently, human podocytes have been difficult to study in vitro. We have developed a conditionally immortalized human podocyte cell line transfected with a temperature-sensitive simian virus 40 transgene: when the transgene is inactivated in vitro, these cells adopt the phenotype of differentiated podocytes. We have used these cells to evaluate, using immunocytochemistry, reverse transcriptase-polymerase chain reaction, and Western blotting, direct effects of the glucocorticoid dexamethasone at concentrations designed to mimic in vivo therapeutic corticosteroid levels. Dexamethasone upregulated expression of nephrin and tubulin-alpha, and downregulated vascular endothelial growth factor. Effects on cell cycle were complex with downregulation of cyclin kinase inhibitor p21 and augmentation of podocyte survival, without any effect on apoptosis. We report cytokine production by human podocytes, especially interleukin (IL)-6 and -8; IL-6 expression was suppressed by dexamethasone. These potent direct effects on podocytes illustrate a novel mode of action of glucocorticoids and suggest potential new therapeutic strategies for glomerular disease.

Fetal artery healing: Lack of inflammation and decreased upregulation of PDGF correlates with a lack of neointimal hyperplasia

INTRODUCTION: Following injury adult arteries heal with inflammation, neointimal hyperplasia (NIH) and vascular wall scar formation. How injured fetal arteries heal remains unknown. We hypothesize that the fetal artery injury response differs substantially from that of adult arteries with regard to cellular response, final morphology and the expression of cytokines, such as platelet derived growth factor (PDGF)-a mitogen known to mediate NIH in adult arteries. To investigate healing in fetal arteries we developed a novel model in which fetal surgery techniques were used to create a measured, reproducible injury in the carotid artery of fetal lambs, while the carotid artery of the mother served as an adult, scar-forming control.

Different Consequences of β1 Integrin Deletion in Neonatal and Adult Mouse Epidermis Reveal a Context-Dependent Role of Integrins in Regulating Proliferation, Differentiation, and Intercellular Communication

There are conflicting reports of the consequences of deleting beta1 integrins from the epidermis of transgenic mice. Epidermal thinning with normal differentiation and lack of inflammation has been observed; conversely, epidermal thickening, abnormal differentiation, and dermal fibrosis can occur. beta1 integrin deletion results in decreased epidermal proliferation, yet on wounding the proliferative defect is overcome. To distinguish primary from secondary consequences of beta1 integrin loss, we compared epidermal beta1 deletion at E14.5 via K5Cre and 4-hydroxy-tamoxifen induced deletion in adulthood via K14CreER. As reported previously, there was dermo-epidermal splitting, inflammation, reduced proliferation, and hair follicle and sebaceous gland loss in 30-d-old K5Cre beta1-null mice. These changes were not observed 30 d after beta1 integrin deletion in adult epidermis, however, and there were no changes in the hair follicle stem cell compartment. Deletion in adult epidermis revealed a previously unreported correlation between the level of beta1 integrins and proliferation in the interfollicular epidermis that was remarkably consistent with human epidermis. In addition, the number of melanocytes in interfollicular epidermis was greatly increased. Our results highlight the context-dependent effects of beta1 integrin deletion and suggest that inflammation may be responsible for some of the K5Cre beta1-null phenotype.

Differential activation of astrocytes and microglia after spinal cord injury in the fetal rat

As the immature spinal cord was nerve growth permissive, we examined glial reactions that influence regeneration of the spinal cord in a fetal rat spinal cord injury model. Three, 7, 21, and 35 days after intrauterine surgery, offspring were killed and the thoracic and lumbar spinal cords were carefully removed from the spinal column and then cut into 10 mum longitudinal sections. These sections were stained with hematoxylin-eosin, anti-glial fibrillary acidic protein antibody (GFAP) as a marker of astrocytes, and anti-complement CR3 antibody (OX-42) as a marker of microglia. A cordotomy model in a young adult rat was utilized as a control. In the present study, collagen fibers and scar formation were seen in the severed spinal cords of mature rats, but scar formation was not seen in the fetal rat cordotomy group, regardless of spinal continuity. In the control group, biological activity of GFAP-positive cells increased over time. In the fetal rat cordotomy model, activity elevated slightly immediately after cordotomy, and disappeared shortly thereafter. In the control group, OX-42-positive macrophage-like cells proliferated over time. However, in the fetal rat cordotomy model, OX-42- positive macrophage-like cells were recognized on postoperative days 3 and 7, and then disappeared. At 5 mm from the cordotomy site, reactive microglia were recognized in the white matter of control group spinal cords, but these microglia were not recognized in the fetal rat cordotomy model. In the present study, collagen fibers and scar formation were seen in the severed spinal cords of adult rats, but scar formation was not seen in the fetal rat cordotomy group. Lack of inflammation and scar formation thus appear advantageous for regeneration of the fetal spinal cord. Between fetal and mature rats, chronological changes in the immunohistochemical reactions of astrocytes and microglia following cordotomy were compared, and the results confirmed many differences. The results of the present study suggest that the presence of activated glial cells around damaged central nervous tissue and the quick disappearance of these cells after injury are important for the repair of damaged central nervous system tissue, and that the role of glial cells in nerve regeneration can change depending on the level of maturity of glial cells or surrounding cells, site of injury, or the state of tissue around the injury.

Radiographic and clinical changes of the patellar tendon after tibial plateau leveling osteotomy

SummaryPatellar tendon thickening (PTT) and patellar tendinosis (PTS) have been discussed in the veterinary literature as a post-operative complication of tibial plateau leveling osteotomy (TPLO). The purpose of this study was to define radiographic PTT, determine the frequency of and risk factors for PTT and PTS, and describe the clinical and histopathological findings of PTS after TPLO. We hypothesized that the location of the osteotomy alters forces placed on the patellar tendon resulting in PTT or PTS. Radiographs and medical records from 83 dogs undergoing 94 TPLO procedures were retrospectively evaluated. Two months post-operatively, 19 dogs (20.2%) had a normal patellar tendon or mild PTT, 51 (54.3%) had moderate PTT, and 24 (25.5%) had severe PTT. Seven of the 24 dogs (7.4%) with severe PTT had clinical signs consistent with PTS. Only dogs with severe PTT developed PTS (p < 0.0001). The risk factors for the development of PTT include: a cranial osteotomy, a partially intact cranial cruciate ligament (CCL) in conjunction with a cranial osteotomy, and post-operative tibial tuberosity fracture. The only risk factor identified for the development of PTS was a partially intact CCL. Four dogs with PTS improved with conservative therapy and one improved with surgical treatment. Two dogs had tendon biopsies with histopathological review that showed tendon degeneration with lack of inflammation. As only the dogs with severe PTT develop PTS, a caudal osteotomy for the prevention of PTT and subsequent PTS is recommended.

Histological changes over time around the site of sustained release naltrexone-poly( dl-lactide) implants in humans

In order to assess the histological tissue changes over time around the site of implant, tissue biopsies were taken at 1 to 38 months post-implant from 54 (34 male) consenting human subjects who had received the Australian subcutaneous naltrexone-poly( dl-lactide) implant for heroin dependence. The implant consists of multiple tablets containing compressed naltrexone-poly[trans-3,6-dimethyl-1,4-dioxane-2,5-dione] ( dl-lactide) loaded microspheres. Assessment of tissue samples by pathologists showed an early phase (up to 12 months post-implant) of inflammation, foreign body reaction, and fibrosis. This subsided gradually over the next 12 months until tissue returned to normal by 25+ months. Sufficient evidence was not available to conclude that the poly( dl-lactide) implant matrix was totally biodegradable within the study period. While implant material was not identified in most of the latter biopsies, its presence was noted in one biopsy at 26 months post-implant. Nevertheless the study results did demonstrate the implant's biocompatibility by the lack of inflammation, foreign body reaction, and fibrosis detected by 25+ months. It seems highly probable that surgical technique rather than the implant itself was associated with the additional finding of fat necrosis. Moderate fat necrosis was observed as a common feature of biopsies carried out during the first 6 months following implant. It subsided to mild levels over the next 18 months, and was notably absent by 25+ months. The results of the study indicated that the Australian naltrexone-poly( dl-lactide) implant is well tolerated and may have a role for use in the management of medical conditions such as heroin dependence.

Hydrogen peroxide disrupts scarless fetal wound repair

Cutaneous wound healing is a complex process that leads to the formation of a permanent scar in adult skin. In contrast, early gestation fetal skin undergoes scarless repair. Normally, the repair process in the skin begins with an acute inflammatory response. However, one of the most important aspects of scarless fetal wound repair appears to be a lack of inflammation, suggesting that inflammation promotes scar formation in the skin. While it is well accepted that inflammation causes scar formation in the fetus, it is not known what specific factors produced during inflammation are responsible for these effects. Oxidants released by activated inflammatory cells have the potential to be involved, although this has never been examined. The present studies, using a murine fetal wound repair model, show that hydrogen peroxide interferes with scarless healing, possibly through the induction of transforming growth factor-beta1. Hydrogen peroxide also increased the proliferation of fetal fibroblasts, which could contribute to an increase in the fibrosis seen with hydrogen peroxide. Defining the factors produced during the inflammatory response that contribute to scar formation could be important for the development of new therapies designed to minimize scarring.

615. A Self-Limiting but Prolonged Inflammatory Response to AAV-Factor IX Gene Transfer to Skeletal Muscle

Immune responses to the transgene product are a major concern in gene therapy for genetic disease. Previously, we have shown that AAV-mediated gene transfer to skeletal muscle may lead to antibody formation to coagulation factor IX (F.IX) in animals not tolerant to the transgene product. A T helper cell dependent adaptive immune response initiated locally in the transduced muscle resulted in CD4+ T cell and B cell activation in the draining lymph nodes. Both Th1 and Th2 subsets were involved in this process. However, activation of CD8+ cells appeared to be inefficient. Consequently, local transgene expression in the muscle persisted because of a lack of cytotoxic T lymphocyte (CTL) responses and lack of inflammation, even when systemic F.IX expression was neutralized by antibodies. For most of these experiments, we deliberately expressed a human F.IX (hF.IX) transgene in C57BL/6 mice as a model to study characteristics of an immune response to F.IX in the context of AAV gene transfer. When a more effective AAV serotype 1 vector was injected into skeletal muscle, anti-hF.IX formation was transient, and systemic expression emerged around 2 months after gene transfer. In a new set of experiments in outbred CD-1 mice, we injected AAV-2 vector at 3 different doses (2|[times]|1010 vg, 1|[times]|1011 vg, and 1|[times]|1012 vg per animal, 4 sites of injection) into skeletal muscle. Systemic hF.IX expression was transient, again limited by a neutralizing antibody response. Inhibitory anti-hF.IX IgG was measured at all 3 vector doses. Antibody titers persisted for >4 months, and no hF.IX was detected in circulation beyond day 14 at low and mid doses. However, hF.IX antigen re-emerged in plasma 1.5 months after high dose vector administration in 5 of 7 mice. Moreover, inhibitors to hF.IX became undetectable by 5 months at this dose. Coagulation assays on serial dilutions of plasma showed an increase in clotting activity in these animals at 5 months. This illustrates that persistent expression of F.IX from AAV-transduced skeletal muscle can down-regulate immune-mediated neutralization of the transgene product over time. Surprisingly, when we analyzed muscle tissues, marked inflammation was evident at mid and high doses starting at >2 month after gene transfer. This inflammatory response included a CD8+ cellular infiltrate and was still present at 4 months. The inflamed tissue included muscle fibers with central nuclei indicating destruction and regeneration of fibers. Interestingly, the number of hF.IX expressing fibers declined only marginally over time as determined by immunohistochemistry and image analysis. At late time points (3-4 months), a proportion of the transgene expressing fibers had central nuclei, raising the possibility that myofiber precursors had been transduced. These data show that depending on the genetic background (here CD-1 vs. C57BL/6 mice) and vector dose, CD8 T cell activation and inflammatory responses may occur in the context of AAV-F.IX gene transfer to skeletal muscle. However, these responses were delayed and ultimately failed to eliminate transgene expression. The inflammatory response was prolonged and self-limiting, perhaps because sustained transgene expression caused activation of regulatory T cells in addition to effector T cells.

Sjögren's syndrome and the danger model

This review seeks to cover the data on primary Sjogren’s syndrome (SS) that has accumulated especially during recent years, and that apparently fits into a common theme of cellular stress abnormalities. This includes demonstrations of hyperactivity of danger-sensing antigen-presenting cells (APC), and of a strong response to DNA damage in many different cell types. The relevance of these findings for the pathogenesis of SS will be addressed by applying them to the danger model of immune activation [1, 2]. This model has been put forward by Matzinger, stating that immune activation, including the innate system as well as the adaptive lymphocyte response, is initiated by danger in a broad sense rather than solely by the presence of infectious non-self material. By means of danger signals, tissue stress is postulated to activate the APC of the innate immune system, in turn influencing also the adaptive immune cells, i.e. T and B lymphocytes. Thus, a consequence of the danger model of immune activation is that danger signals can be assumed to be a primary determinant of autoimmunity. A number of factors that threaten the integrity of a tissue or the host may act as danger signals. These are produced by, for example, necrotic cells, hypoxia, low pH and mechanical damage to blood vessels. Danger signals from necrotic cells that strongly stimulate APC to up-regulate HLA and costimulatory molecule expression include heat shock proteins transferred upon cell death to the cell surface [3], and the release from dying cells of high concentrations of crystalline uric acid [4]. CD40L on activated extravasating platelets, hyaluron modified in traumatized tissue, reactive oxygen species (ROS) and non-self molecules such as bacterial cell wall lipopolysaccharides can also act as potent danger signals, by the mechanism of binding to Tolllike receptors and other surface markers on APC [1, 2, 5–8]. Interestingly, physiological cell death manifested as apoptosis, posing no threat to the tissues, has been found to have a relatively minor influence on APC, in accordance with the lack of inflammation being typical of apoptosis [9].

Simple clinical variables predict liver histology in hepatitis C: Prospective validation of a clinical prediction model

Objective. A recent single-center multivariate analysis of hepatitis C (HCV) patients showed that having any two criteria: 1) ferritin ≥200 µg/l and 2)spider nevi and/or albumin ≤35 g/l predicted grade 2 or greater histological inflammation; the presence of any two of the following criteria: spider nevi, platelets ≤150×109/l, palpable splenomegaly and/or albumin ≤35 g/l predicted stage 2 or greater histological fibrosis. Absence of predictors also predicted a lack of inflammation and fibrosis. Our aim was prospectively to validate this clinical prediction model using an independent multicenter sample. Material and methods. Eighty-one patients with previously untreated active chronic HCV underwent physical examination, laboratory investigation, and liver biopsy. Biopsies were read, in blinded fashion, by a single pathologist, using a modified Hytiroglou (1995) scale. The clinical scoring system was correlated with histology; likelihood ratios (LRs), Fisher's exact p-values, and receiver operating characteristics (ROCs) were calculated. Results. Data recording was complete in 77 and 38 patients regarding fibrotic stage and inflammatory grade, respectively. For fibrosis, 3/3 patients with any three criteria (LR 17, positive predictive value (PPV) 100%), 4/5 patients with any two criteria (LR 5.1), and 15/47 with no criteria (LR 0.6, negative predictive value (NPV) 68%) had stage 2 or greater fibrosis on biopsy (p=0.01). For inflammation, 5/5 patients with both criteria (LR 15, PPV 100%), and 8/19 patients with no criteria (LR 0.5, NPV 58%) had moderate–severe inflammation on liver biopsy (p=0.036). When missing variables were assumed to be normal, recalculated LRs were almost identical. An alanine aminotransferase (ALAT) level <60 U/l may increase the NPVs. Conclusions. This independent multicenter data set has validated our published model which uses simple clinical variables accurately and significantly to predict hepatic fibrosis and inflammation in HCV patients.

Interaction between resident luminal bacteria and the host: can a healthy relationship turn sour?

Interaction between resident luminal bacteria and the host: can a healthy relationship turn sour?

Lower Leg Pain in a 17-Year-Old BoyOrthopaedic-Radiology-Pathology Conference

Lower Leg Pain in a 17-Year-Old BoyOrthopaedic-Radiology-Pathology Conference

Histopathologic features of alopecia areata: a new look.

A peribulbar lymphocytic infiltrate is the expected histologic feature of alopecia areata, but it is absent in many scalp biopsy specimens. Other diagnostic criteria are needed. To establish the histologic features of alopecia areata in scalp biopsy specimens taken from different types of alopecia areata, using follicular counts to relate biopsy findings to stages of the disease. Fifty consecutive new patients with alopecia areata were studied. Four-millimeter punch biopsy specimens were taken from the scalp in areas of recent, active hair loss; old, inactive hair loss; or recent hair regrowth. Specimens were sectioned horizontally. Terminal and vellus-like hairs were counted. Inflammation and fibrosis around lower and upper follicles were rated. The histopathologic features of alopecia areata were not significantly affected by the sex, age, and race of the patient or by the type, percentage of hair loss, total duration, or regression of alopecia areata. The major factor affecting the histopathologic features was the duration of the current episode of alopecia areata. In the acute stage, bulbar lymphocytes surrounded terminal hairs in early episodes and miniaturized hairs in repeated episodes. In the subacute stage, decreased anagen and increased catagen and telogen hairs were characteristic. In the chronic stage, decreased terminal and increased miniaturized hairs were found, with variable inflammation. During recovery, increasing numbers of terminal anagen hairs from regrowth of miniaturized hairs and a lack of inflammation were noted. The histopathologic features of alopecia areata depend on the stage of the current episode. Alopecia areata should be suspected when high percentages of telogen hairs or miniaturized hairs are present, even in the absence of a peribulbar lymphocytic infiltrate.

Mouse models and genetic modifiers in X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder that affects 1 in 35000 males and is marked by neurodegeneration, adrenal insufficiency and infertility. All characteristics are not always present in every X-ALD patient and the rate of progression varies. X-ALD has a variety of phenotypes, the two major phenotypes are cerebral X-ALD (CALD) and adrenomyeloneuropathy (AMN)(Moser 2000). The Other patients only have adrenal insufficiency, or rarely, remain asymptomatic. As the nature of X-ALD is progressive, these adrenal and asymptomatic patients often develop nervous system involvement as they age. CALD most commonly presents in childhood (mean age of onset, 7.2 ±1.7 years) but can also strike adolescents and adults. There are focal sites of demyelination of the cerebral white matter associated with perivascular inflammation of the affected site. This inflammatory demyelination is rapidly progressive over the course of a few years and usually ends in early death. AMN presents in adulthood (mean age of onset, 28 ± 9 years) as a peripheral myelopathy with spinal cord involvement usually with no brain disease. There is a lack of inflammation at these sites and this disease progresses much more slowly than the cerebral form. A significant fraction of AMN patients eventually develop brain disease. Adrenal insufficiency is often, but not always, present in both cerebral and AMN patients.

Knee Pain in a 13-Year-Old Boy

Knee Pain in a 13-Year-Old Boy

Hereditary hypotrichosis simplex: report of a family.

We report a family with hereditary hypotrichosis simplex of the scalp, a rare disorder that was first described in 1974. In our family, four out of 10 siblings were affected, including three females and one male. Examination showed thinning of the scalp hair and sparse body hair. Eyebrows, eyelashes, pubic and axillary hair were normal. Skin, nails and teeth were also normal. Hair shaft examination did not reveal any structural abnormalities. Normal follicular units, hair shafts within follicles, eccrine glands and a lack of inflammation were seen on histopathology. The primary pathology underlying this genodermatosis is unclear, but the anagen phase of the hair cycle is clearly compromised.

A nonfibrillar form of the fusogenic prion protein fragment [118-135] induces apoptotic cell death in rat cortical neurons.

Neuronal loss is a salient feature of prion diseases. However, its cause and mechanism, particularly its relationship with the accumulation and precipitation of the pathogenic, protease-resistant isoform PrP(Sc) of the cellular prion protein PrP(C), are still an enigma. Several studies suggest that neuronal loss could occur through a process of programmed cell death, which is consistent with the lack of inflammation in these conditions. By analogy with the pathological events occurring during the development of Alzheimer's disease, controversies still exist regarding the relationship between amyloidogenesis, prion aggregation, and neuronal loss. We recently demonstrated that a prion protein fragment (118-135) displayed membrane-destabilizing properties and was able to induce, in a nonfibrillar form, the fusion of unilamellar liposomes. To unravel the mechanism of prion protein neurotoxicity, we characterize the effects of the human Pr[118-135] peptide on rat cortical neurons. We demonstrate that low concentrations of the Pr[118-135] peptide, in a nonfibrillar form, induce a time- and dose- dependent apoptotic cell death, including caspase activation, DNA condensation, and fragmentation. This toxicity might involve oxidative stress, because antioxidant molecules, such as probucol and propyl gallate, protect neurons against prion peptide toxicity. By contrast, a nonfusogenic variant Pr[118-135, 0 degrees ] peptide, which displays the same amino acid composition but several amino acid permutations, is not toxic to cortical neurons, which emphasizes the critical role of the fusogenic properties of the prion peptide in its neurotoxicity. Taken together, our results suggest that the interaction between the Pr[118-135] peptide and the plasma membrane of neurons might represent an early event in a cascade leading to neurodegeneration.

Fibrin scaffold as an effective vehicle for the delivery of acidic fibroblast growth factor (FGF-1).

The effect of wound healing by fibrin and acidic fibroblast growth factor (FGF-1) in an in vivo model was evaluated in this study. Four full-thickness wounds were made on the dorsum of each rabbit (n = 5). Each of these wounds had different treatment groups: control, topical FGF-1 (100 microg/9 cm2), fibrin (2.0 mL at 60 mg/mL fibrinogen), and FGF-1 (100 microg/9 cm2)/fibrin. The animals were sacrificed at the end of 2 weeks. Histomorphometric analysis and mechanical testing were conducted to assess the healing response. FGF-1/fibrin treatment improved the mechanical properties of the healed tissue. Fibrin scaffold exhibited the desired tissue response, as demonstrated by the lack of inflammation, and was deemed an effective carrier for FGF-1.

Fibrin Scaffold as an Effective Vehicle for the Delivery of Acidic Fibroblast Growth Factor (FGF-1)*

The effect of wound healing by fibrin and acidic fibroblast growth factor (FGF-1) in an in vivo model was evaluated in this study. Four full-thickness wounds were made on the dorsum of each rabbit (n = 5). Each of these wounds had different treatment groups: control, topical FGF-1 (100 μg/9 cm 2 ), fibrin (2.0 mL at 60 mg/mL fibrinogen), and FGF-1 (100 μg/9 cm 2 )/fibrin. The animals were sacrificed at the end of 2 weeks. Histomorphometric analysis and mechanical testing were conducted to assess the healing response. FGF-1/fibrin treatment improved the mechanical properties of the healed tissue. Fibrin scaffold exhibited the desired tissue response, as demonstrated by the lack of inflammation, and was deemed an effective carrier for FGF-1.