Segmental mediolytic arteritis--electronmicroscopic and immunohistochemical study

We examined specimens of human gastroepiploic artery aneurysm from a patient having several visceral aneurysms using electronmicroscopic and immunohistochemical techniques. The histopathological and ultrastructural findings confirmed the diagnosis of segmental mediolytic arteritis. Arterial smooth muscle cells from the gastroepiploic artery contained cytoplasmic vacuoles, media was thin and the internal elastic membrane showed distortion. X-ray microanalysis revealed calcium deposits in the medial extracellular space. Antigenic determinants of human immunoglobulins, fibrinogen, complement C3a and factor VIII were demonstrated in the injured artery wall, suggesting that immunocomplexes deposited in the artery wall may be associated with local injury. These findings support the role of autoimmune disorders in the pathogenesis of segmental mediolytic arteritis.

Interleukin 6 gene transcripts are expressed in human atherosclerotic lesions

Factors controlling the proliferation of vascular smooth muscle cells (SMC) are thought to be key elements in the progression of atherosclerosis. We have previously shown that interleukin 6 (IL-6) stimulates the growth of SMC in vitro and that IL-6 gene transcripts are expressed in atherosclerotic lesions of genetically hyperlipidemic rabbits. To understand the involvement of IL-6 in the development of human atherosclerosis, we investigated IL-6 mRNA expression in atherosclerotic arteries from patients undergoing surgical vascularization, utilizing reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization analyses. In RT-PCR analysis, the atherosclerotic arteries showed 10- to 40-fold levels of IL-6 mRNA expression over the non-atherosclerotic artery. In in situ hybridization analysis, IL-6 gene transcripts were observed in the thickened intimal layer of atherosclerotic lesions. These results strongly suggest the involvement of IL-6 in the development of human atherosclerosis.

Isolation of T-cell clones with specificity for arterial antigen from spontaneously hypertensive rats

OBJECTIVE

It has been postulated that hypertension in the spontaneously hypertensive rat (SHR) results from autoimmune damage to the SHR vasculature. The objective of this study was to isolate autoreactive T-cells specific for arterial antigens, and to characterize these cells.

DESIGN

The presence of autoreactive T-cells in the SHR has not been studied previously. Lymphocytes were isolated from spleens obtained from SHR and Wistar-Kyoto (WKY) rats aged 4, 8, 12, 16, 20, 24 and 28 weeks.

METHODS

Limiting dilution analysis was used to clone and to establish arterial antigen-reactive T-cell clones. The specificity of these clones was assessed by measuring lymphokine production and T-cell proliferation induced by arterial antigen and by irrelevant control antigens.

RESULTS

All of the SHR, regardless of age, possessed arterial antigen-specific CD4+, major histocompatability complex class II-restricted T-cells. The responses of freshly isolated spleen cells to arterial antigen were weaker than the proliferative responses of interleukin-2-expanded T-cells to arterial antigen. The T-cell clones also produced interleukin-2, interleukin-4 and interferon-gamma in response to arterial antigen. However, the presence of T-cells specific for arterial antigen is not unique to SHR, since a similar response was seen in normotensive WKY rats.

CONCLUSIONS

The results indicate the existence of T-cells specific for arterial antigen in the spleens of both SHR and WKY rats. Thus, arterial antigen-reactive T-cells cannot be the initial cause of hypertension, but the activation of such autoreactive T-cells might be important in the development of hypertension.

Rapamycin inhibits arterial intimal thickening caused by both alloimmune and mechanical injury. Its effect on cellular, growth factor, and cytokine response in injured vessels

The effect of rapamycin (RPM) on the extent of arterial intimal thickening was determined in rat recipients of orthotopic femoral artery allografts or in rats that had undergone balloon catheter injury to carotid arteries. In untreated rats, neointima comprised approximately 50% of the arterial wall area in both models. Although treatment of allograft recipients for 40 days with 1.5 mg/kg/day RPM was ineffective, a dose of 6 mg/kg/day (days 0-7) followed by 3 mg/kg/day (days 8-39) reduced intimal thickening by 98% (P < 0.0001). The higher RPM dose reduced T cell and macrophage infiltration significantly and decreased the expression of IL-2 receptor, class II Ag, and mRNAs for growth factors and cytokines. Treatment with 1.5 mg/kg/day RPM (days 0-13) after balloon-catheter injury reduced intimal thickening by 45% (P = 0.0254) and substantially decreased macrophage infiltration and expression of class II Ag in the adventitia. Within the neointima, however, mRNAs for platelet-derived growth factor-alpha, basic fibroblast growth factor, and transforming growth factor-beta were still expressed. In summary, we have shown that RPM inhibits not only the vascular response to injury caused by allograft rejection, but also the response to balloon catheter injury. This new information is important to our understanding of: (1) the fundamental processes responsible for intimal thickening regardless of the cause of vascular injury, (2) mechanisms of action of RPM that explain its effects on the response to very different types of vascular injury, and (3) the potentially diverse therapeutic applications of drugs, like RPM, that inhibit the actions of both immune and nonimmune cytokines and growth factors.

[The pathomorphological aspects of arteriopathies associated with viral and microbial infections]

Presence of Mycoplasma, Chlamydia, Rickettsia burnetii, influenza type B, herpes and adenoviruses was detected by immunofluorescence in artery fragments collected from patients with arteriopathy. Pathohistological examination of the samples revealed inflammatory--lympho-histiocytic infiltration--and mostly dystrophic alterations. Arteriopathies were localised mostly at the pelvic limb level, especially on femoral artery. Their incidence was statistically significant.

Subinvolution of the uteroplacental arteries: an immunohistochemical study

Subinvolution of uteroplacental arteries is a well-recognized cause of hemorrhage in the postpartum period. Although the physiological changes in these arteries during pregnancy are well documented, the sequence of events in normal involution is largely unknown. A recent immunohistochemical study has raised the possibility of an abnormal interaction between maternal uterine cells and fetal trophoblast in subinvolution. An indirect immunoperoxidase technique was used to compare deposition of complement components and immunoglobulin in subinvoluted and normally involuted uteroplacental arteries in 25 cases of postpartum hemorrhage. Deposits of C1q, C3d, C4, and C9 were detected within the walls of normally involuted vessels, whereas deposition of C1q, C3d, and C4 was absent in subinvoluted vessels; C9 was detected only focally. Deposition of immunoglobulins G, A, and M mirrored those described for complement components. The results suggest that immunological factors are necessary for the process of normal involution of uteroplacental arteries and are deficient in subinvoluted vessels.

[Immunopathological study on the uterine spiral arteries in pregnancy-induced hypertension]

The uterine spiral arteries were studied by the immunohistochemical ABC method in 30 cases of Pregnancy Induced Hypertension (PIH) and 10 cases of normal pregnant women. Depositions of IgM and/or C3 on the vessel wall were significantly observed only in PIH cases (15 cases, 50.0%; P < 0.05). Depositions of IgG were seen in 5 cases of PIH 16.7% showing significantly decrease. (P < 0.001), as compared with the normal pregnant women (9 cases, 90.0%). The results suggest that PIH is related to chronic rejection reaction resulting possibly from the decrease of local immunosuppression in pregnancy. Meanwhile the positive stain of IgG, IgM and C3 seen in the nuclei of decidual cells in some of PIH cases were discussed.

Transduction of a foreign histocompatibility gene into the arterial wall induces vasculitis

Autoimmune vasculitis represents a disease characterized by focal inflammation within arteries at multiple sites in the vasculature. Therapeutic interventions in this disease are empirical and often unsuccessful, and the mechanisms of immune injury are not well-defined. The direct transfer of recombinant genes and their expression in the arterial wall provides an opportunity to explore the pathogenesis and treatment of vascular disease. In this report, an animal model for vasculitis has been developed. Inflammation has been elicited by direct gene transfer of a foreign class I major histocompatibility complex gene, HLA-B7, to specific sites in porcine arteries. Transfer and expression of this recombinant gene was confirmed by a polymerase chain reaction and immunohistochemistry, and cytolytic T cells specific for HLA-B7 were detected. These findings demonstrate that expression of a recombinant gene in the vessel wall can induce a focal immune response and suggest that vessel damage induced by cell-mediated immune injury can initiate vasculitis.

[The demonstration by immunofluorescence of inframicrobial antigens on samples of peripheral blood vessels (artery and vein) from subjects with different vascular diseases]

The presence of fourteen inframicrobial agents was investigated by the immunofluorescence technique using specific antisera on 345 samples of arteries and veins collected during operation from patients with chronic vascular diseases (arteritis, varicosity) and on 50 samples of umbilical cord. Results indicated a positivity rate of 75.45%; most of the cases had associations of two to five antigens. Coxsackie A virus and mycoplasmas were the agents most frequently found.

T lymphocytes inhibit the vascular response to injury

The proliferation of vascular smooth muscle cells is controlled by specific growth factors and cytokines acting in paracrine networks. Macrophage products such as the platelet-derived growth factor and interleukin 1 promote smooth muscle proliferation and are released in the arterial wall during atherosclerosis and repair processes. T lymphocytes are also present in vascular tissue, but their role in vascular growth control in vivo has been unclear. We now demonstrate that rats in which T lymphocytes have been eliminated by a monoclonal antibody develop larger proliferative arterial lesions after balloon-catheter injury. Larger lesions also develop in athymic rnu/rnu rats that lack T lymphocytes, when compared with rnu/+ littermates with normal T-cell levels. Finally, injection of the lymphokine interferon gamma inhibits smooth muscle proliferation and results in smaller lesions compared with controls injected with buffer alone. These results indicate that T lymphocytes modulate smooth muscle proliferation during vascular repair. We propose that T lymphocytes may play an important, immunologically nonspecific role in tissue repair processes.

Analysis of complement C3 activation products in human atherosclerotic lesions

Cleavage of the complement C3 protein is essential for complement activation. Saline extracts of human atherosclerotic lesions were examined by various techniques for the presence of C3 cleavage fragments. Crossed intermediate gel immunoelectrophoresis revealed that native C3 was the predominate C3 protein in extracts and that the C3dg fragment was also detected. SDS-PAGE/Western blot analyses of lesion extracts employing monoclonal antibodies directed at C3c and C3dg fragment determinants demonstrated molecular weight bands corresponding to the known molecular weights of all the physiologic C3 cleavage fragments, except C3b which is known to have a short half-life. After C3, the two most common fragments observed were C3c and C3dg. No bands other than those corresponding to known C3 cleavage fragments were observed and control antibody stains were always negative. In some blots bands with a greater molecular mass than C3 were evident, indicating that some of the C3 in lesions may be covalently bound to an activator. We have previously identified a large (100-500 nm) nonapoprotein containing lipid particle (LCA) as a major complement activating structure in human atherosclerotic lesions. Fractionation of lesion extracts by molecular sieve chromatography and sucrose density gradient centrifugation failed to reveal a concordance between LCA and C3 antigens. The results indicate that complement activation, i.e. C3 convertase formation, takes place in human atherosclerotic lesions and that activated C3 is degraded according to normal complement regulatory mechanisms.

Spectrum of glomerular and tubulointerstitial renal lesions associated with monotypical immunoglobulin light chain deposition

The purpose of this study was to characterize the spectrum of renal lesions associated with plasma cell dyscrasias from a population of patients who had renal disease identified by kidney biopsy. Thirty-six patients (2.6% of 1361 kidney specimens examined over 6 years) had evidence of monotypical light chain with or without concomitant heavy chain deposition. A variety of lesions was found, including (a) AL-amyloid and glomerular nonamyloid light chain deposition manifesting as nodular, membranoproliferative, mesangioproliferative, and "minimal-change" glomerulopathies; (b) fibrillary glomerulopathy; (c) tubulointerstitial lesions (cast nephropathy, acute tubular necrosis, and tubulointerstitial nephritis); and (d) vascular (arterioles and small and medium-sized arteries) lesions. AL-amyloid was the most common renal lesion (39%), nonamyloid deposition occurred second most commonly (33%), and cast nephropathy ("myeloma kidney") was third most frequent (14%). Clinical and laboratory manifestations of a plasma cell dyscrasia were frequently subtle. Immunoelectrophoresis of both serum and urine did not demonstrate a monotypical light chain or immunoglobulin in almost 35% of this population. Thus, the correct diagnosis was not considered in the majority of these patients before biopsy. Progressive deterioration of renal function was common with all of the lesions, except for proximal tubule injury, which tended to improve over the period of study. Renal biopsy with careful examination for monotypical light chain with or without associated heavy chain deposition using immunofluorescence or immunoelectron microscopy was crucial in identifying and characterizing the varied lesions associated with lymphoplasmacytic disorders.

Cyclosporine inhibits the development of medial thickening after experimental arterial injury

Vascular proliferative lesions may occur after arterial injury and consist of inflammatory cells and proliferating smooth muscle cells. We studied the effect of cyclosporine on modulating the response to experimental arterial injury in rats. Arterial injury was created in 90 rats by rotating a 1 mm coronary dilator in the right common iliac artery. After treatment with parenteral cyclosporine 2 mg/kg/day or 5 mg/kg/day, or with saline solution, right and left iliac arteries were perfusion fixed and cross sectioned. The thickness of the tunica media was measured, and the groups were compared with a Student's t test. In the control groups the injured iliac artery had significant medial thickening when compared to the noninjured (p less than 0.05) from 1 to 42 days after injury. Injured arteries treated with cyclosporine 2 mg/kg/day for 14 days showed significantly less medial thickening when compared to controls (p less than 0.01). Cyclosporine 5 mg/kg/day for 14, 28, and 42 days showed a significant inhibition of medial thickening (p less than 0.05) for each time period. These results show that cyclosporine affects the response to experimental arterial injury by inhibiting the development of medial thickening. The most consistent effects were seen with a cyclosporine dose of 5 mg/kg/day for 2 to 6 weeks. These data also provide further evidence that immunologic mechanisms may modulate vascular proliferative lesions.

Distribution of serotonin-immunoreactive cells around arteries arising from the common carotid artery in the chicken

By using an immunoperoxidase method with antiserotonin antiserum, the distribution of serotonin-immunoreactive cells in the carotid body region was investigated in chickens. The thyroid gland, cranial and caudal parathyroid glands, carotid body, and ultimobranchial gland of chickens were located along the common carotid artery as a continuous series and were supplied with branches arising from the artery. Almost all chief cells of the chick carotid bodies were immunoreactive for serotonin. Furthermore, numerous serotonin-immunoreactive cells were widely distributed in the adventitial connective tissue around those arteries that issued from the common carotid artery to supply each endocrine organ, i.e., the carotid body artery, the esophagotracheobronchial artery, the ascending esophageal artery, and the inferior thyroid artery. These arteries usually arose by one trunk from the lateral aspect of the middle portion of the common carotid artery. The serotonin cells were most numerous around the carotid body artery and were dispersed along the whole length of the artery. In addition, they were detected around the common trunk of each artery and the roots of the ascending esophageal artery, the inferior thyroid artery, and the esophagotracheobronchial artery. The serotonin cells were also distributed in the tunica media of the common carotid artery. In that place, they were concentrated around the origin of the common trunk of each artery and were scattered below the origin along the longitudinal axis and on the opposite side of the origin. The serotonin-immunoreactive cells distributed around and in the arteries may be involved in the control of blood flow and may have chemoreceptive properties.

Demonstration of interleukin-1 beta on perifollicular endothelial cells in the thyroid glands of patients with Graves' disease

We examined the presence of interleukin-1 (IL-1) in the thyroid glands of 20 patients with Graves' disease and 10 control subjects, using anti-IL-1 monoclonal antibodies in conjunction with immunohistochemical techniques. In 13 (65%) Graves' disease patients, IL-1 beta, but not IL-1 alpha, was demonstrated on the capillary endothelial cells (EC) around follicles (perifollicular EC). However, the EC of arteries and veins were negative for both IL-1 beta and IL-1 alpha. In the control group, none of the thyroid glands showed positive staining for IL-1 beta or IL-1 alpha. There was a significant correlation (P less than 0.025) between the presence of IL-1 beta on perifollicular EC and the presence of serum antimicrosomal antibodies. These results provide an important insight into the involvement of IL-1 beta in the development of Graves' disease.

The human placental bed: histology, immunohistochemistry and pathology

There has been much interest recently on local intra-uterine materno-fetal interactions particularly in the placental bed where cellular relationships between mother and fetus are at their most intimate. While few histopathologists are expected to interpret formal placental bed biopsy specimens, confrontation with tissue from this site is common following abortion, post-partum haemorrhage or molar gestation. This review gives an account of recent advances in our knowledge of the histology, immunohistochemistry and pathology of the placental bed. It focuses particularly on extravillous trophoblast populations and their relationship to maternal cells and emphasizes the importance of vascular changes.

Co-localization of terminal C5b-9 complement complexes and macrophages in human atherosclerotic arterial walls

The co-localization of terminal C5b-9 complement complexes and macrophages was investigated in human arteries with atherosclerosis using a double-labeling immunohistochemical technique. Macrophages were found in all the atherosclerotic arteries, with the accumulation correlating positively with the degree of atherosclerosis. This accumulation was associated with an increase of C5b-9 deposits, as well as with an increase in the number of deposits containing both complement components and macrophages ('co-localization'). This co-localization was found to pertain both to intact macrophages and to macrophage remnants. These data suggest that C5b-9 complement complex might be formed on macrophages with subsequent promotion of inflammatory events and progression of the atherosclerotic lesions.

Complement component deposition in uteroplacental (spiral) arteries in normal human pregnancy

There is conflicting evidence for the deposition of complement in spiral arteries in normal and abnormal human pregnancies. The immunogold silver staining (IGSS) technique was used to investigate the distribution of C1q, C3d, C4, C6 and C9 within the spiral arteries of formalin-fixed normal pregnancy hysterectomy specimens ranging in gestational age from 4 to 40 weeks. Deposition of complement components studied was observed in all cases suggesting classical pathway activation. Reactivity was not confined to vessels showing endovascular trophoblast though the latter showed a characteristic linear deposition subjacent to the trophoblast. Reactivity was most intense for C3d and C9. An appreciation of complement deposition as a feature of normal pregnancy is essential before significant immunopathology can be recognised in placental bed vessels in abnormal pregnancy.

Investigation of the expression of amnion antigens by spiral arteries in human utero-placental tissues

Two monoclonal antibodies raised against human amnion, GB3 and GB5, were used in an indirect immunoperoxidase method to investigate the expression of amnion antigens by spiral arteries in pregnant and nonpregnant uterine tissues. GB3 showed focal reactivity with occasional spiral arteries in the placental bed throughout pregnancy, but no GB3-staining was observed in nonpregnant endometrium. In contrast, GB5 showed bandlike circumferential reactivity with spiral arteries at all gestational ages examined. GB5-positivity showed no relation to the presence of endovascular or perivascular trophoblast. In nonpregnant endometrium, GB5 labeled rare spiral arteries. However, in a premenstrual specimen showing pseudodecidual change, there was circumferential reactivity with GB5 resembling that in pregnancy. The reaction patterns of GB3 or GB5 were not similar to those for two other basement-membrane components, fibronectin and type IV collagen. The results suggest that expression of the GB5 antigen may in part be regulated by hormones.

Progressive systemic sclerosis: autoimmune arteriopathy

In a case of progressive systemic sclerosis (PSS), widespread deposition of IgM was found in the media and internal elastic lamina of small muscular arteries. IgA and C3 were also found in some vessels. Antibody eluted from the kidney bound to smooth muscle and elastica of small arteries. These findings suggest that PSS is a vasculopathy which is mediated by complement-fixing antibodies.

The localisation of immunoglobulin in chronic periaortitis

An immunohistochemical study was undertaken in an attempt to localise immunoglobulin in sections of human advanced atherosclerosis with thinning of the media (sub-clinical periaortitis) and without thinning of the media as well as sections of artery from patients with clinical periaortitis. The findings were that in routinely processed sections of advanced atherosclerosis showing medial attenuation and in sections from cases of clinical periaortitis IgG, and to a lesser extent IgM, was localised to insoluble lipid, ceroid, within the atheroma itself. It is suggested that these observations support the hypothesis that chronic periaortitis has an auto-allergic cause and that the allergen may be a component of ceroid, which is elaborated within the atheroma.

Duration of delayed-type autoimmunity against arterial vessel-wall antigens following acute hypertensive damage to arterial vessels in rats

Acute hypertensive damage to small arteries and arterioles in rats was induced by intravenous injections of Hypertensin. The in vitro immunological method of the agarose migration technique was used to demonstrate delayed-type autoimmunity against arterial vessel-wall antigens. By this technique the autoimmunity could be demonstrated for about 16 weeks after the acute hypertensive damage to the arterial vessels. The results of the autoimmunity were given as migration indices. These were lowest during the first 4-5 weeks after the damage to the vessels whereupon they showed higher and higher values, and finally the migration indices were identical with those of the control rats after about 16 weeks.

Microvascular deposition of complement membrane attack complex in dermatomyositis

We examined the role of the complement system in the pathogenesis of dermatomyositis. Using an antibody against the neoantigens of the terminal C5b-9 membrane attack complex, we performed immunocytochemical studies that localized this complex to the intramuscular microvasculature (arterioles and capillaries) of muscle biopsy specimens from 10 of 12 patients (83 percent) with childhood dermatomyositis and 5 of 19 patients (26 percent) with adult dermatomyositis. Fifty-two control specimens, including 14 from patients with polymyositis and 12 from patients with denervation atrophy (a condition known to be associated with necrotic capillaries), showed no deposition of membrane attack complex in the microvasculature. These findings indicate that the complement system is deposited, bound, and activated to completion within the intramuscular microvasculature of patients with dermatomyositis. In addition to providing further evidence for the presence of vasculopathy in dermatomyositis, these findings suggest a primary role for complement in mediating vessel injury in the disease, particularly in its childhood form.

Isolated arteritis of the epididymis

The clinical, histological, and immunohistochemical features of two cases of apparently isolated arteritis of the epididymis are presented. The aetiology and pathogenesis of the condition are discussed. Immunoglobulin and complement were shown in the acute arterial lesions, but this is not conclusive evidence that isolated arteritis is either an immune complex disease or a forme fruste of polyarteritis nodosa.