Normal wound healing compared to healing within porous Dacron implants

This study examined the hypothesis that healing within porous implants differs from that in normal connective tissue. Special attention was given to extracellular components including collagen, reticular fibers, and ground substance, and to enzymes associated with activated macrophages. Using Dacron velour and the rabbit as host, the healing of normal connective tissue and that of the tissue/implant interface were histologically compared 10 and 28 days postimplantation. The results exhibited significant differences between connective tissue healing, implant capsule formation, and granulation tissue generation. The healing of connective tissue and implant capsule formation were essentially complete at 28 days. However, tissue inside the implant was qualitatively different and did not significantly change between 10 and 28 days. It was characterized by macrophages and giant cells, a predominantly acid mucopolysaccharide ground substance, and qualitatively fewer and less well defined collagen and reticular fibers were observed than in normal wound healing. Thus we conclude that the connective tissue inside Dacron velour does not resemble normal connective tissue after 10 or 28 days of healing. Furthermore, the collagen never fully matures into orderly bundles, a phenomenon which may be related to an altered mucopolysaccharide composition and a diminished reticular network. The lysosomal enzymatic activity of the macrophages and perhaps the giant cells at the tissue/implant interface may be linked to these differences.     

北京鸭淋巴结毛细血管后微静脉的超微结构

对６周龄北京鸭淋巴结毛细胞血管后微静脉的电镜观察证明，其基本结构与哺乳动物有相似之处，但也有显著差异。毛细血管后微静脉多位于淋巴细胞聚集区（致密区），也见于淋巴组织索和结缔组织网状索内。管腔多不规则，管壁厚度不一。内皮游离面未见微绒毛。其横断面管径一般较细。管壁外调被网状细胞所环绕，管周未见巨噬细胞，内皮细胞基膜外有网状细胞及其突起，纤维和基质所环绕。可见淋巴细胞穿越管壁。     

The response of subcutaneous connective tissue to a new endodontic filling material

The purpose of this histopathologic study was to assess and compare the subcutaneous connective tissue reaction to a new root canal filling material, Resilon and gutta-percha. The test materials were directly inserted subcutaneously into the dorsal connective tissue of Wistar albino rats. Histopathological examinations were done at 7, 15, 30, and 60 days after the implantation procedure. The presence of inflammation, predominant cell types, and the thickness of fibrous connective tissue adjacent to each inserted sample were recorded. There were no differences in tissue reaction between Resilon cone material and gutta-percha cone groups for first three observation periods (p > 0.05). However, there were highly significant differences among observation periods within both groups (7, 15, 30, and 60 days) (p < 0.01). The tissues showed high tolerance to Resilon and gutta-percha at the 60th day. Resilon may serve as an alternative to gutta-percha in terms of biocompatibility.     

Autoradiographic study of 3H-methylated elastase in hamster lungs

An emphysemalike condition can be induced in animal lungs by the instillation of a single dose of elastase. Autoradiography was used to determine the location of 3H-methylated porcine pancreatic elastase in hamster lungs at four time points. Six hours after instillation of radiolabeled enzyme the distribution of silver grains was very patchy, but in heavily labeled areas grains were concentrated over macrophages, connective tissue areas and over some fibroblasts. By 24 hr the labeling of connective tissue areas was no longer evident and almost all silver grains were associated with macrophages or with the edema fluid that filled many alveoli at this time. By 4 days only macrophages exhibited concentrations of silver grains. The labeling of macrophages was still evident at 7 days. Elastase inactivated by N-acetyl-(L-alanyl)3-L-alanine chloromethyl ketone showed a different distribution 6 hr after instillation. Silver grains were concentrated over macrophages and alveolar type II cells but showed no affinity for connective tissue areas or fibroblasts. By 24 hr almost all grains were located over heavily labeled macrophages.     

In vivo responses of macrophages and perisinusoidal cells to cholestatic liver injury.

We investigated the response of macrophages and perisinusoidal (Ito) cells (PSCs) during the development of secondary biliary cirrhosis after ligation and division of the common bile duct. Liver tissue was obtained from three groups of male Wistar rats: 1) untreated controls (n = 3); 2) common bile duct-ligated (CBDL) animals (n = 15); and 3) sham-operated controls (n = 15). Material from animal groups 2 and 3 was obtained on days 3, 7, 14, 21, and 28 after operation; in all animals 5-bromo-2-deoxyuridine was administered intraperitoneally before death. Monocytes and macrophages were detected using the monoclonal antibody ED1 and tissue macrophages using the antibody ED2. Cell proliferation within the macrophage population was demonstrated by double labeling for ED2 and incorporated 5-bromo-2-deoxyuridine. PSCs were demonstrated in tissue sections by immunolocalization of desmin; proliferating PSCs were identified by double labeling for desmin and incorporated 5-bromo-2-deoxyuridine. Evidence of phenotypic modulation of PSCs was sought using anti-alpha-smooth muscle actin (alpha-SMA) antibody. Increased numbers of ED1- and ED2-positive cells were seen in CBDL animals at all time points. Local proliferation of macrophages could be identified and reached a peak at day 3, thereafter falling toward control values. Compared with those of controls, livers of CBDL animals showed increased numbers of desmin-positive PSCs in periportal zones from day 3 on, reaching a peak at day 14 (127.8 +/- 10.99 cells/0.635 mm2) and followed by a plateau. PSC proliferation peaked at days 3 and 7 (labeling indices 11.2% and 11.2%, respectively) and thereafter fell toward control values; no expansion of the PSC population was seen in sham-operated rats. Increased alpha-SMA-positive cells were also noted from day 3, with a peak at day 21 (231.1 +/- 11.52 cells/0.635 mm2) and followed by a plateau. En face labeling experiments in days 14, 21, and 28 CBDL animals showed cells co-expressing alpha-SMA and desmin and cells expressing alpha-SMA alone. These results indicate that in response to chronic cholestatic liver injury, PSCs proliferate and undergo phenotypic modulation toward "myofibroblast-like" cells. The kinetics of the response are similar to those of the ED2-positive cell population in keeping with a hypothesis that PSC proliferation and activation may be mediated by factors released by macrophages in response to various forms of liver injury. We conclude that the responses of macrophages and PSCs to cholestatic injury are similar to those after toxin-induced hepatocyte necrosis.     

Short term in vivo biocompatibility testing of biodegradable poly(D,L-lactide)--growth factor coating for orthopaedic implants

Fracture healing can be stimulated by exogenous application of growth factors. Using porcine and rat models the efficacy of locally delivered IGF-I and TGF-beta1 from an implant coating has been demonstrated. A thin and biomechanical stable biodegradable poly(D,L-lactide) was used to coat implants and serve as a drug carrier. Due to reports of possible foreign body reactions caused by polymer materials in orthopedic surgery, this study investigated the biocompatibility of the polylactide implant coating and the locally released growth factors during the time course of rat tibial fracture healing (days 5, 10, 15, and 28 after fracture). Monocytes/macrophages and osteoclast were detected using an monoclonal antibody against ED1 (comparable to CD68 in mice and human). The antibody ED1 stains monocytes, macrophages and osteoclast in the bone marrow and in the newly formed fracture callus. A moderate density of the monocytes/macrophages was seen in the proximal part of the medullary canal, but almost no cells were detectable in the region distal to the fracture. The amount of stained cells increased during the observation time with a maximum at days 10 and 15 followed by a decrease at day 28. No differences were detectable between the investigated groups from day 5 to 15 post fracture indicating, that the used poly(D,L-lactide) or the incorporated growth factors do not evoke an elevated immunological response compared to the uncoated titanium implant at the investigated time points. A significantly higher amount of ED1 positive cells was measured 28 days after fracture in the control group compared to the groups with the coated implants. In conclusion, no indication of a foreign body reaction due to the use of the polylactide or the growth factors was found indicating a good short-term biocompatibility of this bioactive coating.     

Demonstration of connective tissue sheaths surrounding working myocardial cells and Purkinje cells of the sheep moderator band.

Morphological studies were carried out to delineate the characteristics of connective tissue sheaths surrounding working myocardial cells and Purkinje cells in the moderator band of adult sheep hearts, using a series of techniques including silver staining, immunohistochemistry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). For SEM, tissue blocks were treated with 2N NaOH at room temperature to digest cellular elements. Individual working myocardial cells were ensheathed by thin argyrophil fibers (reticular fibers), while fascicles of 4-8 Purkinje cells (Purkinje strands) were encircled by rather thick reticular fibers. Some collagen fibers were located between masses of myocardial cells as well as between the Purkinje strands. Immunohistochemical analyses indicated that reticular fibers directly surrounding both myocardial cells and Purkinje strands showed moderately positive reactions for anti-type I collagen and intensely positive reactions for anti-type III collagen. Deserves particular note is that the three-dimensional architecture of the reticular sheaths varied widely at different places. The thin reticular sheaths surrounding each myocardial cell consisted of fibrils which were arranged in a coarse network and directed circularly along the long axis of cells. By contrast, the sheaths enclosing Purkinje strands were thicker, and their reticular fibrils were woven into a compact "felt-like" texture. The functional significance of these connective tissue sheaths is also discussed.     

Macrophages in resistance to rickettsial infections: early host defense mechanisms in experimental scrub typhus.

Several early nonspecific host defense mechanisms were examined in resistant (BALB/c) and susceptible (C3H/He) mice after intraperitoneal inoculation with Rickettsia tsutsugamushi strain Gilliam. Inflammatory exudates were formed in both mouse strains in response to rickettsial inoculation, but the inflammatory response of C3H animals was delayed several days, and influx of peroxidase-positive macrophages occurred late in infection. Peritoneal cells of C3H mice became progressively infected, with 40% of both macrophages and lymphocytes containing intracellular rickettsiae by day 10. The early flammatory response of BALB/c mice was unexpectedly associated with a low percentage of infected peritoneal cells (1 to 2%). In vitro, no difference was detected in ability of resident macrophages of either strain to support the growth of R. tsutsugamushi or to become activated by treatment with lymphokines for rickettsiacidal activity. In vivo, however, macrophages from C3H mice inoculated with Gilliam were not activated on days 6 and 7 after infection, whereas BALB/c macrophages were continuously activated beginning on day 4. The lack of in vivo C3H macrophage activation was not secondary to deficient lymphokine production by infected lymphocytes, as levels of lymphokines produced by peritoneal lymphocytes of both strains were similar and peaked on day 7 after infection. Susceptibility to infection appears to be related to defective regulation of macrophage responses rather than to defects in macrophage function.     

Tissue compatibility of two biodegradable tubular scaffolds implanted adjacent to skin or buccal mucosa in mice

Radiation therapy for cancer in the head and neck region leads to a marked loss of salivary gland parenchyma, resulting in a severe reduction of salivary secretions. Currently, there is no satisfactory treatment for these patients. To address this problem, we are using both tissue engineering and gene transfer principles to develop an orally implantable, artificial fluid-secreting device. In the present study, we examined the tissue compatibility of two biodegradable substrata potentially useful in fabricating such a device. We implanted in Balb/c mice tubular scaffolds of poly-L-lactic acid (PLLA), poly-glycolic acid coated with PLLA (PGA/PLLA), or nothing (sham-operated controls) either beneath the skin on the back, a site widely used in earlier toxicity and biocompatibility studies, or adjacent to the buccal mucosa, a site quite different functionally and immunologically. At 1, 3, 7, 14, and 28 days postimplantation, implant sites were examined histologically, and systemic responses were assessed by conventional clinical chemistry and hematology analyses. Inflammatory responses in the connective tissue were similar regardless of site or type of polymer implant used. However, inflammatory reactions were shorter and without epithelioid and giant cells in sham-operated controls. Also, biodegradation proceeded more slowly with the PLLA tubules than with the PGA/PLLA tubules. No significant changes in clinical chemistry and hematology were seen due to the implantation of tubular scaffolds. These results indicate that the tissue responses to PLLA and PGA/PLLA scaffolds are generally similar in areas subjacent to skin in the back and oral cavity. However, these studies also identified several potentially significant concerns that must be addressed prior to initiating any clinical applications of this device.     

In vivo evaluation of a novel electrically conductive polypyrrole/poly(D,L-lactide) composite and polypyrrole-coated poly(D,L-lactide-co-glycolide) membranes

This study evaluated the in vivo biocompatibility and biodegradation behavior of a novel polypyrrole (PPy)/poly(D,L-lactide) (PDLLA) composite and PPy-coated poly(D,L-lactide-co-glycolide) membranes. Test membranes were implanted subcutaneously in rats for 3-120 days. The biocompatibility was assessed by quantifying the alkaline and acid phosphatase secretion, the immunohistochemical staining of the ED-2-positive macrophages, and the histology at the tissue/material interface. The degradation was investigated using scanning electron microscopy. Pure PDLLA and poly(D,L-lactide-co-glycolide) membranes were used as references, whereas expanded polytetrafluoroethylene and a commercial styrene-butadiene rubber were used as controls. The enzyme activity of the PPy-containing specimens was shown to be similar to that of the references. The histological findings were consistent with the enzymatic results, showing a mild-to-moderate acute inflammation followed by a resolution of the inflammatory response with a decrease in inflammatory cells for each biodegradable membrane. The tissue reactions to the PPy, which was either in the form of nanoparticles or surface coating, were comparable to the response to the neighboring biodegradable materials. Elevated ED-2-positive macrophage populations appeared as early as day 3 in the loose connective tissue surrounding the implants. The density of these populations was related to the degree of inflammation. Scanning electron microscopy showed that the degradation of the PPy/PDLLA composite was not affected by the presence of PPy.     

Direct contact between reticular fibers and migratory cells in the paracortex of mouse lymph nodes: a morphological and quantitative study

Transmission electron microscope observation of mouse lymph nodes demonstrated that reticular fibers in the paracortex were invested not only by reticular cells, but occasionally also by migratory cells such as interdigitating cells, macrophages, and lymphocytes. Quantitative analysis of electron micrographs covering wide areas revealed that about 90% of the surface area of the reticular fiber was enclosed in the sheath of reticular cells in both nude and hetero mice, whereas the rest of the surface area was associated with migratory cells. In nude mice, whose lymph nodes contain more numerous interdigitating cells than hetero animals, about 9% of the surface area was occupied by interdigitating cells including Langerhans cells; in hetero mice only about 3% was associated with the interdigitating cells. Actively phagocytizing macrophages occupied about 3% of the surface area in both nude and hetero mice. Contact between lymphocytes and reticular fibers was observed in hetero mice, whereas this relation could not be demonstrated in nude mice whose lymph nodes contain very few lymphocytes. These results suggest that the association between reticular cells and reticular fibers in the paracortex of lymph node is flexible, allowing for the interposing of migratory cells.     

聚左乳酸己内酯-胶原蛋白静电纺人工血管的降解研究

探讨聚左旋乳酸己内酯-胶原蛋白构建的可降解人工血管材料的降解规律以及生物相容性。聚左旋乳酸己内酯-胶原蛋白混合溶液通过静电纺丝技术制成静电纺人工血管材料作为实验组(n=40),市售聚四氟乙烯人工血管材料作为对照组(n=40),分别植入兔背部脊柱两侧肌肉,于术后10、30、90、180 d取材,行形态学、组织学观察;并在400 倍光学显微镜视野下进行中性粒细胞、巨噬细胞和淋巴细胞的分类计数。结果镜下聚左旋乳酸己内酯胶原蛋白组材料周围组织炎症反应轻,术后90 d材料碎裂,纤维组织长入材料网孔间隙内,逐步取代材料部位,形成囊状纤维膜;术后180 d材料基本降解殆尽,植入区域组织重塑后形态接近正常组织。聚四氟乙烯组材料周围组织炎症反应轻,术后180 d仍基本保持原有结构,材料周围有薄层纤维组织膜包绕。细胞计数结果提示植入后不同时期两组材料引起的细胞反应类型和反应趋势相同;仅术后10 d时实验组中性粒细胞数量较对照组增多(2244±372 vs 1922±181 个/025 mm2, P<005),其余两组各期各类细胞均无明显差异(P>005)。实验材料降解时间为3～6月,具有生物相容性好、降解规律适宜的良好生物学性能,有作为血管替代物的潜在可能性。     

Electrospinning of silk fibroin nanofibers and its effect on the adhesion and spreading of normal human keratinocytes and fibroblasts in vitro

An electrospinning method was used to fabricate silk fibroin (SF) nanofiber nonwovens for cell culture of normal human keratinocytes and fibroblasts. The electrospinning of regenerated SF was performed with formic acid as a spinning solvent. For insolubilization, as-spun SF nanofiber nonwovens were chemically treated with an aqueous methanol solution of 50%. Morphology and microstructure of as-spun and chemically treated SF nanofibers were investigated by scanning electron microscopy and mercury porosimetry. As-spun SF nanofibers exhibited a circular cross-section with a smooth surface. From the image analysis, they had an average diameter of 80 nm and their diameters ranged from 30 to 120 nm. During the chemical treatment for 60 min, porosity of nonwovens composed of SF nanofibers decreased from 76.1% up to 68.1%. To assay the cytocompatibility and cell behavior onto the electrospun SF nanofibers, cell attachment and spreading of normal human keratinocytes and fibroblasts seeded on the SF nanofibers and interaction between cells and SF nanofibers were studied. Cell morphology on SF nanofibers was examined by scanning electron microscopy. Our results indicate that the SF nanofibers may be a good candidate for the biomedical applications, such as wound dressing and scaffolds for tissue engineering.     

Acute cigarette smoke-induced connective tissue breakdown requires both neutrophils and macrophage metalloelastase in mice

The cells/proteases responsible for the development of smoke-induced emphysema is an area of intense investigation. Mice with knockout of macrophage metalloelastase genes (MME(-/-)) do not develop emphysema after smoke exposure, but we also observed that neutrophils (PMN) in lavage appeared to be a requirement for acute connective tissue breakdown. In this study we exposed mice to cigarette smoke and examined lavage PMN, macrophages (MAC), desmosine (DES, a measure of elastin breakdown) and hydroxyproline (HP, a measure of collagen breakdown) 24 h afterwards. MME(+/+) mice exposed to smoke showed elevations in PMN, DES, and HP, but no elevations were seen in MME-deficient mice. Both PMN influx and increased levels of DES/HP could be restored by administering MAC from MME(+/+) mice to MME-deficient mice and then exposing them to smoke. RS113456, a metalloprotease inhibitor, also prevented PMN influx and connective tissue breakdown. Western blots against mouse alpha(1)-antitrypsin (alpha(1)AT) showed that alpha(1)AT was not protected in MME-deficient mice, nor by administration of RS113456. We conclude that, in mice, acute smoke-induced connective tissue breakdown, the precursor to emphysema, requires both PMN and MME, that PMN influx appears to be secondary to MAC activation, and that this process initially does not involve protection of alpha(1)AT from metalloprotease attack.     

Transient early expression of TNF-alpha in sciatic nerve and dorsal root ganglia in a mouse model of painful peripheral neuropathy

The proinflammatory cytokine tumor necrosis factor-alpha (TNF) is an important mediator in neuropathic pain. We investigated the temporal pattern of TNF mRNA expression in the sciatic nerve, in dorsal root ganglia (DRG) and spinal cord in the mouse chronic constriction injury model of neuropathy with quantitative real-time polymerase chain reaction. Neuropathic pain-like behaviour was monitored by evaluating thermal hyperalgesia and mechanical allodynia. Pain-related behaviour and TNF expression were evaluated 6 h, 1, 3, 7 and 14 days after injury. Naive animals and sham-operated mice were used as controls. We found an early upregulation of sciatic nerve TNF mRNA levels in chronic constriction injury (CCI) and sham-operated animals 6 h after surgery: 1 day later TNF overexpression was present in CCI mice only and disappeared 3 days after injury. The mRNA cytokine levels were elevated in DRG 1 and 3 days after surgery in CCI animals only, while the cytokine was not modulated in the spinal cord. A significant hyperalgesia was present in CCI and sham-operated mice at 6 h and 1 day, while at later time point only CCI mice presented lower thresholds. Mechanical allodynia was already present only in CCI animals 6 h from surgery and remained constant up to the 14 th day. The results indicate that a transient early TNF upregulation takes place in peripheral nervous system after CCI that can activate a cascade of proinflammatory/pronociceptive mediators.     

Biocompatibility and inflammatory response in vitro and in vivo to gelatin-based biomaterials with tailorable elastic properties

Hydrogels prepared from gelatin and lysine diisocyanate ethyl ester provide tailorable elastic properties and degradation behavior. Their interaction with human aortic endothelial cells (HAEC) as well as human macrophages (M?) and granulocytes (G?) were explored. The experiments revealed a good biocompatibility, appropriate cell adhesion, and cell infiltration. Direct contact to hydrogels, but not contact to hydrolytic or enzymatic hydrogel degradation products, resulted in enhanced cyclooxygenase-2 (COX-2) expression in all cell types, indicating a weak inflammatory activation in vitro. Only M? altered their cytokine secretion profile after direct hydrogel contact, indicating a comparably pronounced inflammatory activation. On the other hand, in HAEC the expression of tight junction proteins, as well as cytokine and matrix metalloproteinase secretion were not influenced by the hydrogels, suggesting a maintained endothelial cell function. This was in line with the finding that in HAEC increased thrombomodulin synthesis but no thrombomodulin membrane shedding occurred. First in vivo data obtained after subcutaneous implantation of the materials in immunocompetent mice revealed good integration of implants in the surrounding tissue, no progredient fibrous capsule formation, and no inflammatory tissue reaction in vivo. Overall, the study demonstrates the potential of gelatin-based hydrogels for temporal replacement and functional regeneration of damaged soft tissue.     

The relationship between the sympathetic nerves and immunocytes in the spleen

Ever since Galen, the ancient Greek physician, said "Melancholic women develop disease more than sanguine women," it has been said that the mental condition affects the physical condition. However, there is hardly any scientific verification. About half a century ago, Selye (1936) proposed a relationship between stress and immune function, and it is becoming increasingly clear that the nervous system and immune system interact with each other. Also researchers have strongly hoped to demonstrate the existence of specific pathways by which immunocytes can be directly regulated by the nervous elements instead of by the humoral influence of immunomodulators. In this study, the author showed by electron microscopic observation how the immunocytes in the guinea pig spleen are directly innervated. The sustentacular supporting element of the guinea pig spleen is the connective tissue system which includes the capsulo-trabecular, peri-vascular and reticular systems. The latter system is composed of the outer sheath of the reticular cell or its cellular processes which have abundant microfilaments and the inner minute connective tissue space in which lamina densa-like material, collagenous fibrils, elastic fibers and nervous elements are present. The sympathetic adrenergic nerves for the spleen enter the organ, and scatter around the arterial walls. All components of the connective tissue system are continuous with each other, and the nervous elements appearing in the reticular system are the elongated ones from other connective tissue systems, especially peri-vascular connective tissue. Thus, the adrenergic nerves are more abundant in the white pulp, into which the central artery penetrates, than in the red pulp which arterioles or capillaries pass through. The minute connective tissue space of the reticular system may be called the noradrenalin (NA) canal because catecholamine released from the naked adrenergic nerve terminals in this tissue diffuses and is stored in this enclosed space. The reticular system in the spleen divides the parenchyma into small non-endothelial vascular spaces owing to its meshwork, and free mobile immunocytes, such as T-cells, B-cells and macrophages, stagnate in these spaces. This stagnation of the mobile immunocytes and the presence of the adrenergic nerves in the NA canals provide the chance for the immunocytes and nerves to meet each other in the following fashion; the reticular cell sheaths show the exposed phenomena owing to the contraction of the microfilament-rich reticular cell processes, caused by noradrenalin in the NA canal, and the nervous elements in the NA canals can face the nonendothelial vascular spaces where mobile immunocytes pass freely.(ABSTRACT TRUNCATED AT 400 WORDS)     

Loss of tumor necrosis factor alpha potentiates transforming growth factor beta-mediated pathogenic tissue response during wound healing

Animal cornea is an avascular transparent tissue that is suitable for research on wound healing-related scarring and neovascularization. Here we show that loss of tumor necrosis factor alpha (TNFalpha) potentiates the undesirable, pathogenic response of wound healing in an alkali-burned cornea in mice. Excessive invasion of macrophages and subsequent formation of a vascularized scar tissue were much more marked in TNFalpha-null knockout (KO) mice than in wild-type mice. Such an unfavorable outcome in KO mice was abolished by Smad7 gene introduction, indicating the involvement of transforming growth factor beta or activin/Smad signaling. Bone marrow transplantation from wild-type mice normalized healing of the KO mice, suggesting the involvement of bone marrow-derived inflammatory cells in this phenomenon. Co-culture experiments showed that loss of TNFalpha in macrophages, but not in fibroblasts, augmented the fibroblast activation as determined by detection of alpha-smooth muscle actin, the hallmark of myofibroblast generation, mRNA expression of collagen Ialpha2 and connective tissue growth factor, and detection of collagen protein. TNFalpha in macrophages may be required to suppress undesirable excessive inflammation and scarring, both of which are promoted by transforming growth factor beta, and for restoration of tissue architecture in a healing alkali-burned cornea in mice.     

Liver-type fatty acid-binding protein attenuates renal injury induced by unilateral ureteral obstruction

Liver-type fatty-acid-binding protein (L-FABP), which has high affinity for long-chain fatty acid oxidation products, may be an effective endogenous antioxidant. To examine the role of L-FABP in tubulointerstitial damage, we used a unilateral ureteral obstruction (UUO) model. We established human L-FABP (hL-FABP) gene transgenic (Tg) mice and compared the tubulointerstitial pathology of the Tg mice (n = 23) with that of the wild-type (WT) mice (n = 23). Mice were sacrificed on days 2, 4, 5, or 7 after UUO. Although mouse L-FABP was not expressed in WT mice, hL-FABP was expressed in the proximal tubules of the Tg mice with UUO (UUO-Tg) and in sham-operated Tg mice. The expression of renal hL-FABP was significantly increased in UUO-Tg compared with sham-operated Tg mice. The number of macrophages (F4/80) infiltrating the interstitium and the level of expression of MCP-1 and MCP-3 were significantly lower in UUO-Tg kidneys compared with UUO-WT kidneys. In UUO-Tg kidneys, the degree of the tubulointerstitial injury and the deposition of type I collagen were significantly lower than that of UUO-WT kidneys. On day 7, lipid peroxidation product accumulated in the UUO-WT kidneys but not in that of UUO-Tg kidneys. In conclusion, renal L-FABP may reduce the oxidative stress in the UUO model, ameliorating tubulointerstitial damage.     

Reticular cells in peripheral lymphoid tissues express the phosphatidylinositol-linked BP-3 antigen.

The murine BP-3 antigen was initially described as a variably glycosylated cell surface protein of Mr 38,000 to 48,000 on lymphoid and myeloid cells. In the present experiments we found that this antigen is released from the surface of pre-B cells and macrophages by treatment with phosphatidylinositol-specific phospholipase C (PI-PLC), suggesting a glycosyl-phosphatidylinositol (GPI) linkage with the plasma membrane. When the tissue distribution of the BP-3-reactive cells was examined by immunohistology, high levels of the antigen were observed on brush borders of the intestinal epithelial cells, within collecting tubules of the kidney and on a subpopulation of reticular cells located on lymph nodes. Peyer's patches and the white pulp areas of the spleen. In contrast, reticular cells located in the thymus, bone marrow and splenic red pulp did not express the BP-3 antigen. Ontogenic studies revealed that BP-3 was expressed by the reticular cells in peripheral lymphoid tissues in the neonatal period near the time of lymphocyte immigration into these organs. BP-3+ reticular cells were observed in the collapsed periarterial lymphatic sheaths of adult mice depleted of T and B cells by cyclophosphamide treatment and in mice with severe combined immunodeficiency (scid), indicating that development of this reticular network is lymphocyte independent. The BP-3 antigen on the splenic reticular cells was also GPI anchored but its glycosylation pattern differed from that of the BP-3 molecules on pre-B cells. A specific subpopulation of reticular cells is thus marked by the BP-3 antigen, and the distribution and biochemical properties of the molecule make it an attractive candidate for a role in lymphocyte-stromal interactions in the peripheral lymphoid tissues.