Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.

IFN-beta decreases adhesion and transmigration capacities of lymphocytes in Guillain-Barré syndrome

The adhesion capacities, transmigration capacities, and integrin expression of lymphocytes from patients with Guillain-Barré syndrome incubated with interferon-beta were studied. Interferon-beta induced a dose-dependent inhibition of lymphocyte adhesion to recombinant vascular adhesion molecule-1 (p < 0.0001) and recombinant intercellular adhesion molecule-1 (rICAM-1) (p < 0.01) without modulation of very late activation molecule-4 and lymphocyte function-associated antigen-1 expressions and a dose-dependent decrease of lymphocyte transmigration across fibronectin (p < 0.0001). Inhibition of adhesion to rICAM-1 was similar after long (18 hours) or short (5 minutes) incubation time. These results support the potential therapeutic benefit of interferon-beta in Guillain-Barré syndrome.

Inhibition of the adhesion step of leukodiapedesis: a critical event in the recovery of Guillain-Barré syndrome associated with accumulation of proteolytically active lymphocytes in blood

Intraneural inflammation, that reflects emigration of immune cells from blood to nerve tissue, is a critical event in Guillain-Barré syndrome pathogenesis. To investigate the adhesion and transmigration phases of leukodiapedesis, we determined in a series of patients with GBS: (1) circulating levels of soluble forms of adhesion molecules (sICAM-1 and sVCAM-1); (2) attachment capacities of circulating lymphocytes to rICAM-1 and rVCAM-1; (3) fibronectin-penetrating capacities of circulating lymphocytes; and (4) lymphocyte intracellular concentrations of MMP-9 at the different phases of GBS and in healthy controls. Circulating levels of sVCAM-1 and sICAM-1 were above normal values at the time of progression, markedly increased at the time of plateau (sVCAM-1: P<0.03; sICAM-1: P<0.02), and tended to normalize during recovery. The percentage of cells with attachment capacities to rVCAM-1 and to rICAM-1 decreased from progression to recovery by 30 and 31%, respectively (P<0.02). The number of circulating lymphocytes with fibronectin penetrating capacities was lower than controls at the time of progression (P<0.01), then progressively increased to reach values higher than controls at the time of late recovery (P<0.02). Cellular concentrations of MMP-9 in circulating lymphocytes paralleled their fibronectin penetrating capacities. These results suggest early emigration of lymphocytes into nerve, followed by shedding of adhesion molecules from endothelium, and late decrease of lymphocyte adhesion capacities. Plateau and recovery are associated with accumulation in the vascular compartment of still proteolytically active lymphocytes that can no longer adhere to endothelial cells. Modulation of the adhesion step of leukodiapedesis may be crucially involved in the switch from progression to plateau of GBS.

Matrix metalloproteinase-9 is increased and correlates with severity in Guillain-Barré syndrome

OBJECTIVE

To study the expression and activity of matrix metalloproteinases (MMPs) MMP-2 (72-kd type IV collagenase, gelatinase A), MMP-3 (58-kd stromelysin-1), and MMP-9 (92-kd type IV collagenase, gelatinase B) and tissue inhibitors of MPs (TIMP) in patients with Guillain-Barre syndrome (GBS).

BACKGROUND

MMPs are able to proteolysis of basement membranes and other matrix components, promoting transmigration of inflammatory cells from circulation to nerve tissue.

METHODS

Twenty-five patients with GBS were analyzed according to the phase of the disease, i.e., progression, plateau, early recovery, and late recovery. Determinations of MMP-2, MMP-3, MMP-9, and TIMP-1 were performed using ELISA, zymography, and immunocytochemistry in circulation or peripheral nerve.

RESULTS

MMP-9 plasma levels were increased in 67% of patients on admission and decreased from progression to late recovery (p < 0.002). During the course of GBS, MMP-9 was progressively balanced by its inhibitor TIMP-1, as assessed by the MMP-9/TIMP-1 ratio. MMP-9 and TIMP-1 plasma levels and the MMP-9/TIMP-1 ratio correlated positively with disability. MMP-2 expression was similar to controls. MMP-3 activity was not detected, and plasma levels were not different from those in controls. Positive MMP-9 immunolabeling was 51 +/- 11% of circulating lymphocytes. It was observed in some endothelial cells and mononuclear cells adherent to the endothelium and close to myelinated fibers.

CONCLUSIONS

Circulating matrix metalloproteinases (MMP-9) correlates with disease severity in Guillain-Barré syndrome (GBS). MMP-9 likely represents an important molecule in the pathogenesis of GBS and therefore could represent an interesting therapeutic target.

Differential expression of the IL-1 system components during in vitro myogenesis: implication of IL-1beta in induction of myogenic cell apoptosis

We evaluated the expression of IL-1 system by normal human myogenic cells during in vitro myogenesis and the effect of exogenous IL-1beta. Expression of IL-1alpha and beta, IL-1 receptor antagonist (IL-1Ra), IL-1RI and II, IL-1R accessory protein (IL-1RAcP) and IL-1beta converting enzyme (ICE) was studied by immunocytochemistry, immunoblotting, ELISA and RT - PCR. Cell proliferation was evaluated by [3H]thymidine incorporation, cell fusion by flow cytometry and cell death by in situ end-labelling. Human normal myogenic cells constitutively produced IL-1beta and ICE, with a maximum expression at time of cell fusion. IL-1Rs and IL-1RAcP expression reached a peak at time of commitment to fusion. Myogenic cells produced small amounts of IL-1Ra at latest stages of culture, and only the intracellular isoform. Exposure of cultures to exogenous IL-1beta (1-5 ng/ml) induced myogenic cell apoptosis, without effect on cell proliferation or fusion. IL-1beta-induced cell death was associated with morphological changes including spreading appearance of cells and alteration of cell alignment. We conclude that (1) human myogenic cells constitutively produce IL-1beta; (2) IL-1 system components are differentially expressed during in vitro myogenesis; (3) IL-1 system participates to the coordinated regulation of cell density during normal myogenesis, which could serve to control the muscle mass in vivo.

Primary brain lymphoma cell turnover differs in patients with and without AIDS: relationships to bcl-2 expression and host cell reaction

Primary central nervous system lymphomas (PCNSLs) are more resistant to radiotherapy and chemotherapy in AIDS (A-PCNSLs) than in non-AIDS patients (NA-PCNSLs). We investigated 23 A-PCNSLs and 24 NA-PCNSLs. Lymphoma cell kinetics (i.e. proliferation [mitotic index, MIB-1 and PCNA labeling indices], apoptosis and turnover) were determined and compared with bcl-2 and LMP-1 expression, and to the percentage of tumor-infiltrating T-lymphocytes (T-TILs) and macrophages. A-PCNSLs showed lower proliferation (p < 0.005), less apoptosis (p < 0.0001) and slower cell-turnover (p < 0.0001) than NA-PCNSLs. LMP-1 was detected in 90% of A-PCNSLs and 5% of NA-PCNSLs, a finding correlating positively with bcl-2 expression (p < 0.0007). In contrast, T-TIL counts and CD4/CD8 T-TIL ratios were similar in A-PCNSLs and NA-PCNSLs. T-TIL counts correlated negatively with proliferation indices (from p < 0.05 to p < 0.0005) in NA-PCNSLs, but not in A-PCNSLs. Macrophage counts correlated positively with apoptosis in both groups. We concluded the following: (i) A-PCNSLs are characterized by accumulation of slow-cycling, long-lived cells that might be protected from apoptosis by LMP-1 induced bcl-2 expression, and independently from the host response; (ii) NA-PCNSLs are characterized by a faster cell turnover associated with an insufficient antiproliferative host response; and (iii) A-PCNSLs and NA-PCNSLs constitute 2 entities with distinctive morphology and different kinetic profiles that could account for different responses to therapy.

Expression of the transforming growth factor beta isoforms in inflammatory cells of nasal polyps

OBJECTIVE

To determine the expression and the potential role of transforming growth factor beta (TGF-beta) in nasal polyposis.

DESIGN

Comparison of TGF-beta expression between normal and inflammatory nasal mucosa and polyps; in inflammatory nasal polyps, characterization of the TGF-beta isoforms expression and their potential location in macrophages and eosinophils.

SETTING

Patients and samples were selected at the Hôpital Intercommunal, Créteil, France, and immunohistochemistry and immunoblots were performed at the Institut National de la Sante et de la Recherche Medicale U296 (Universite Paris XII, France).

SUBJECTS

Nasal polyps and nasal mucosa were sampled in 21 patients during ethmoidectomy, and muscosa was sampled in 6 healthy patients during rhinoplasty.

METHODS

Immunohistochemistry and Western blot analysis were performed using specific antibodies to TGF-beta1-3, TGF-beta1, TGF-beta2, and TGF-beta3 isoforms. Double labeling was also performed using anti-TGF-beta1 antibody together with macrophages or eosinophil-specific antibodies.

RESULTS

The expression of TGF-beta(1-3) was significantly higher in inflammatory nasal polyps than in inflammatory nasal mucosa and higher in inflammatory nasal mucosa than in nasal mucosa from healthy patients. Transforming growth factor beta1 was the main isoform detected in inflammatory nasal polyps, and it was present in numerous macrophages and in some eosinophils.

CONCLUSIONS

Transforming growth factor beta, mainly TGF-beta1, is strongly expressed in inflammatory nasal mucosa, where it could be produced by macrophages and eosinophils. Transforming growth factor beta could induce epithelium and connective tissue modifications and therefore be involved in the pathogenesis of nasal polyposis.

Acute, relapsing brain oedema with diffuse blood-brain barrier alteration and axonal damage in the acquired immunodeficiency syndrome

A 38-year-old homosexual male with AIDS suffered four neurological episodes including headaches, confusion, visual impairment, memory disturbances, and dysarthria which resolved spontaneously in a few days. He was admitted to hospital during a fifth episode. Neurological examination revealed a cerebellar syndrome. General examination was normal. CD4 count was 90. CSF contained two WBCs/mm(3) and 12.30 mg/dL protein. MRI revealed diffuse ill defined increased signal on T2-weighted images in the white matter. His condition worsened rapidly with vomiting and he died 1 month after admission. Neuropathological examination revealed diffuse brain oedema with ventricular compression, central diencephalic herniation and bilateral tonsilar herniation in the absence of a focal lesion. Microscopical examination revealed predominant involvement of the white matter with diffuse myelin pallor and massive perivascular dilatation containing an exudate expressing serum proteins and occasional macrophages. The same exudate was also diffuse in the leptomeninges. Parenchymal damage predominated around the perivascular spaces and included loosening of tissue, axonal damage with spheroids and reactive astrocytosis. There was no evidence of productive HIV encephalitis, no multinucleated giant cells; p24 immunostaining and RT-PCR for HIV genome were negative. There was neither significant inflammation nor microglial activation. In this illustrative case, the relapsing course of the neurological signs, the diffuse topography of the blood-brain barrier breakdown and the absence of local cause make it likely that the diffuse leak and axonal damage could be related to circulating factors.

[Neuronal apoptosis in the central and peripheral nervous system in HIV infection]

Apart from the unique changes characteristic of "HIV encephalitis", the productive infection of central nervous system by HIV, which predominantly involves the white matter and basal ganglia, evidence is accumulating that the cerebral cortex may also be affected in AIDS patients. Neuronal loss, suspected at microscopic examination, has been demonstrated by a number of morphometric studies. However, the cause and mechanism of neuronal damage in HIV infection, are still unclear. In an attempt to look for an apoptotic process at the origin of neuronal loss in AIDS, we examined samples of frontal cortex, temporal cortex and basal ganglia from 12 patients who died from AIDS and 4 asymptomatic HIV-positive cases using in situ end labelling to demonstrate characteristic DNA fragmentation. These were compared with 5 asymptomatic seronegative controls, and 2 seronegative patients with Alzheimer's disease. We demonstrated neuronal apoptosis in all AIDS cases and in the Alzheimer's cases. Positive in situ end labelling was usually associated with morphological changes suggestive of neuronal apoptosis. Semiquantitative assessment of the density of apoptotic neurons showed that neuronal apoptosis was more severe in atrophic brains. In contrast, no correlation was found between the density of apoptotic neurons and the presence of HIV-encephalitis or a history of cognitive disorder. Only occasional apoptotic neurons were found in one asymptomatic, HIV-positive case. Apoptosis was never observed in asymptomatic seronegative cases. We also looked for apoptotic neurons in spinal ganglia of 20 AIDS cases, 5 of whom had a terminal sensory distal neuropathy, and 10 seronegative controls devoid of neuropathy. Apoptotic neurons were found in 6 of the AIDS patients and in none of the seronegative controls. However, no correlation was found between the severity of neuronal apoptosis in the spinal root ganglia and the presence of absence of a terminal distal sensory neuropathy. Experimental studies tend to support our in vivo findings. HIV-infection of primary cultures of human embryonic central nervous system induced frequent apoptosis of neurons. No apoptotic cell was identified in non infected control cultures.

Incidence of primary ciliary dyskinesia in children with recurrent respiratory diseases

The goal of the study was to evaluate the incidence of primary ciliary dyskinesia (PCD) in children suffering from recurrent respiratory tract infections (RRIs) by means of noninvasive method. Respiratory ciliated cells were collected by nasal brushing in 118 children (4.6 +/- 2.5 years) with RRIs. The ciliary beat frequency (CBF) was measured with a stroboscopic method, and when the CBF was abnormal, the ciliary ultrastructure was analyzed by a quantitative method. The CBF could be measured in 106 patients (90%) and was abnormal in 15 patients. The ciliary ultrastructure was found to be abnormal in 11 of 15 patients: PCD was diagnosed in 6 cases, and acquired ciliary defects were observed in the remaining 5 patients. Our conclusion, that PCD is rare but net exceptional (5.6%) in children with RRIs, justifies the systematic investigation of ciliated cells in such patients. For this purpose, nasal brushing can be used to sample ciliated cells even in young children.

Interleukin-1 expression in normal motor endplates and muscle fibers showing neurogenic changes

Histological features of neurogenic muscle involvement include type grouping, muscle fiber atrophy and target fibers. In zidovudine-induced myopathy and dermatomyositis, immunoreactivity for interleukin (IL)-1 has been reported in diseased muscle fibers involving myofibrillar breakdown and atrophy. Since IL-1 is a signal for muscle proteolysis, we studied myofiber expression of IL-1 in neurogenic muscle involvement, specially in atrophic myofibers and target fibers which are associated with myofilament breakdown. Muscle biopsy samples from patients with normal (5 cases) or neurogenic muscle involvement (25 cases) were studied by enzyme histochemistry and immunohistochemistry. In normal muscles, immunoreactivity for IL-1beta was restricted to the postsynaptic domain of motor endplates and that for IL-1alpha had a similar localization but was faint. Immunoreactivity for IL-1alpha and -beta was observed, respectively, in 42.5% and 75.5% of target fibers, in 8.5% and 10.4% of dark angulated fibers, in 0% and 0.3% of non-atrophic type-grouped fibers, in 14.2% and 16.5% of moderately atrophic fibers, and in 65% and 20.9% of severely atrophic fibers. Immunoblot study showed the presence of both proIL-1 (31 kDa) and mature IL-1 (17.5 kDa). From this study, we conclude that IL-1 is normally expressed in the muscular domain of neuromuscular junctions; that IL-1 is mainly expressed in neurogenic target fibers; and that IL-1 expression by muscle fibers in pathological conditions seems to be associated with myofibrillar protein breakdown and regeneration.

Modified epithelial cell distribution in chronic airways inflammation

Although airway epithelium is known to be modified during chronic respiratory diseases, epithelial cells have rarely been precisely quantified. We therefore intended to evaluate epithelial cell distribution in inflammatory airways, using a cytological approach. Nasal airway cells in 12 patients with nonallergic chronic rhinitis were sampled by brushing, quantified after cytocentrifugation and compared to those from eight controls. Cell populations were quantified after May-Grünwald Giemsa staining and alpha-tubulin immunolabelling to demonstrate ciliary differentiation. When compared to controls, rhinitis patients exhibited lower percentages of ciliated cells (59 +/- 4 versus 32 +/- 2%, respectively), and higher percentages of goblet (24 +/- 3 versus 37 +/- 2%) and basal cells (9 +/- 1 versus 18 +/- 2%). After tubulin immunolabelling, positive staining was specifically detected in cells with cilia (LC+), and in the cytoplasm of some small round cells without obvious cilia (LC-). Fewer immunolabelled cells were detected in rhinitis patients than in controls (with significantly lower percentages of LC+ and higher percentages of LC-). Nasal brushing is an effective technique for quantification of airway epithelial cells. Tubulin immunolabelling is useful to detect ciliated cells and distinguishes another cell population, possibly preciliated cells. These cytological findings suggest the presence of modifications of epithelial differentiation and proliferation, possibly related to local chronic inflammation.

Epithelial cell proliferation in nasal polyps could be up-regulated by platelet-derived growth factor

The modifications of epithelial differentiation and proliferation observed in nasal polyps (NP) could be related to local secretion of growth factors, among which platelet-derived growth factor (PDGF) could play a key role. We therefore prospectively studied, by immunohistochemistry, proliferating cell nuclear antigen (PCNA, an S-phase cell marker), PDGF, and CD-68 (activated macrophages marker) expression in NP and inferior turbinate mucosa (NM) in 11 patients. Our data show that PCNA and PDGF expression are increased in NP epithelium, while CD-68 expression is increased in NP epithelium and lamina propria when compared to NM. Increased local PDGF secretion by numerous activated macrophages could therefore be involved in epithelial cell proliferation up-regulation in NP. PDGF could also be involved in the pathogenesis of NP via its connective tissue remodeling actions.

Cytochrome c oxidase deficiencies in the muscle of patients with inflammatory myopathies

We studied mitochondrial function in inflammatory myopathies, using cytochrome c oxidase (COX) reaction on muscle biopsy samples from 30 patients (15 with dermatomyositis, 12 with polymyositis, and 3 with inclusion body myositis) and 30 age-matched controls. We also performed immunocytochemistry for COX II and COX IV subunits in 7 of these patients who had COX deficiency. COX-deficient fibers were a constant finding in patients or controls older than 65 years and the percentage of COX-deficient fibers correlated with age in both patients and controls. Focal COX deficiency was found in 24 patients (13 of 15 with dermatomyositis, 8 of 12 with polymyositis, and 3 of 3 with inclusion body myositis) and 18 controls. The percentages of COX-deficient fibers were higher in patients with inflammatory myopathies (range: 0-4.7%; mean: 1.2%) than in age-matched controls (range: 0-1.9%; mean: 0.4%) (P < 0.01). In the subgroup of patients under age 65, COX-deficient fibers were more frequent in dermatomyositis than in polymyositis (mean: 0.8% vs 0.2%, P = 0.02). In patients with dermatomyositis, capillary loss correlated positively with COX deficiency (P < 0.02). Immunocytochemistry for COX II and IV showed that 82% of COX-negative fibers were COX II-negative and 26% were COX IV-negative, suggesting that proteins encoded by mitochondrial DNA are predominantly, but not exclusively, involved in COX deficiency. We conclude that mitochondrial dysfunction and COX deficiency can occur in inflammatory myopathies. Such a mitochondrial dysfunction is not solely related to the aging process. We suggest that muscle ischemia contributes to mitochondrial dysfunction in dermatomyositis.

Acquired ciliary abnormalities of nasal mucosa in marrow recipients

Respiratory symptoms are frequent after bone marrow transplantation (BMT). Most studies focus on lesions of the lower respiratory tract. However, sinusitis is also common in this setting, especially after allogeneic BMT. The nasal respiratory epithelium is the first line of airway defense and is very similar to the bronchial epithelium, especially in terms of ciliary beat frequency and ultrastructural pattern of ciliated cells. We have prospectively studied the nasal respiratory epithelium of 20 marrow recipients (four autologous, 16 allogeneic) with or without sinusitis, by brushing and biopsy of the median turbinate between 2.5 and 148 months after transplant. Samples were studied for ciliary beat frequency, cytology, ultrastructural pattern and HLA-DR expression. We found that 17 of our 20 patients had abnormalities of their nasal epithelium, mainly consisting of either squamous metaplasia or heterogeneous axonemal defects of peripheral and central microtubules. No relationship between these findings and the presence of acute or chronic sinus infection, previous irradiation, graft-versus-host disease or immunosuppressive therapy could be demonstrated in this preliminary study. These abnormalities probably have multiple causes. Prospective studies are needed to determine the respective roles of treatments, infections and immune disorders associated with BMT in these abnormalities, and to know their natural evolution over time and their impact on the occurrence of upper or lower respiratory tract infections.

Increased epithelial cell proliferation in nasal polyps

OBJECTIVE

To detect, quantify, and compare respiratory epithelial cell proliferation in nasal mucosa and polyps from patients with nasal polyposis.

DESIGN

Cohort study.

SETTING

Patients and samples were selected at the Hôpital Intercommunal de Créteil (France). Flow cytofluorometry and immunohistochemistry were performed at Hôpitaux Tenon and Mondor (Université Paris [France] VI et XII).

PATIENTS

Twenty-one patients undergoing endoscopic ethmoidectomy for treatment of nasal polyposis.

METHODS

In 10 cases, epithelial cells were removed from frozen inferior turbinate mucosa and polyps by mechanical disaggregation and were then analyzed by flow cytofluorometry, providing the cell DNA content (propidium iodide labeling) and the percentage of S-phase cells. In 11 cases, inferior turbinate mucosa and polyps were fixed in formaldehyde and embedded in paraffin. Proliferating cell nuclear antigen expression in the epithelium was quantified by immunohistochemistry; a proliferating cell nuclear antigen index was calculated for each sample in the basal area, suprabasal area, and full height of the epithelium.

RESULTS

All cell populations studied were diploid, and percentages of S-phrase cells were significantly higher in nasal polyps than in mucosa. Proliferating cell nuclear antigen indexes were significantly higher in nasal polyps than in the suprabasal area and full height of the mucosal epithelium.

CONCLUSION

Cell proliferation is increased in epithelium from nasal polyps. Epithelial damage caused by inflammatory mediators could induce this increased cell proliferation via epithelial repair processes. Inflammatory cells could up-regulate epithelial cell proliferation by secreting growth factors.

Cytochrome c oxidase deficiency in zidovudine myopathy affects perifascicular muscle fibres and arterial smooth muscle cells

In order to assess the pathogenesis of myopathological alterations induced by zidovudine, we studied muscle samples from 21 patients infected by human immunodeficiency virus with zidovudine myopathy. Cytochrome c oxidase histoenzymatic reaction was evaluated in skeletal muscle fibres and arterial smooth muscle cells. Other investigations included immunocytochemistry for membrane attack complex and endomysial capillary counts. All patients had partial cytochrome c oxidase deficiency. A perifascicular distribution of cytochrome c oxidase-deficient fibres was found in 14 of 21 patients. Cytochrome c oxidase-deficient fibres were significantly more frequent in perifascicular areas than in the complete muscle sections (28% vs 12%, P < 0.001). Cytochrome c oxidase-deficient arteries were found in 11 patients, of whom 10 also had a perifascicular deficiency. Mononuclear microvascular inflammation was observed in four patients and membrane attack complex deposition in capillary walls in two patients. The capillary counts were not significantly different in the patients and in the controls. These results suggest that, in addition to a direct action of zidovudine on mitochondrial DNA, chronic muscle ischaemia related to zidovudine-induced vascular dysfunction might be implicated at the inception of muscle damage in zidovudine myopathy.

Neuronal apoptosis in HIV infection in adults

Productive infection of the central nervous system by HIV predominantly involves the white matter and basal ganglia. Involvement of the cerebral cortex with neuronal loss is also described in AIDS patients but not in asymptomatic HIV-positive patients. The mechanism of neuronal damage is unknown. To enquire whether neuronal loss in AIDS may be due to an apoptotic process, we examined the cerebral cortex from 12 patients who died from AIDS using two different methods: in situ end labelling and gel electrophoresis of DNA to demonstrate DNA fragmentation. None of the patients had cerebral opportunistic infection or tumour. Four patients had no significant neuropathological changes, eight patients had variable cerebral atrophy and four of them also had productive HIV infection of the brain. These patients were compared with four HIV-positive asymptomatic patients, five seronegative asymptomatic controls, and two seronegative patients with Alzheimer's disease. We demonstrated neuronal apoptosis in the cortex in all AIDS patients, as well as in the Alzheimer's patients. Apoptosis was not observed in the asymptomatic cases whether seropositive or seronegative. Neuronal apoptosis was more severe in atrophic brains, and did not directly correlate with productive HIV infection, suggesting an indirect mechanism of neuronal damage is most likely.

Quantitative competitive PCR with bronchoalveolar lavage fluid for diagnosis of toxoplasmosis in AIDS patients

Of 121 AIDS patients, 12 (10%) had Toxoplasma gondii DNA detected by competitive PCR in their bronchoalveolar lavage samples. Quantitation of the PCR results showed a correlation between the parasite burden and the serum lactic dehydrogenase titer. Quantitative competitive PCR could be useful to assess the diagnosis and the severity of pulmonary toxoplasmosis.

Detection of Aspergillus species DNA in bronchoalveolar lavage samples by competitive PCR

A competitive PCR assay involving the use of bronchoalveolar lavage (BAL) samples for the diagnosis of invasive pulmonary aspergillosis (IPA) was developed. For this purpose, a 1-kb mitochondrial DNA fragment of Aspergillus fumigatus was sequenced. The primers used allowed amplification of A. fumigatus, A. flavus, A. terreus, and A. niger DNAs but not DNAs of other fungi and yeasts. BAL samples from 55 consecutively enrolled patients were tested. Three samples were excluded because of failure of correct amplification of the internal competitive control. Of 28 immunocompromised patients, 6 were PCR positive; 3 died of IPA and their BAL cultures yielded A. fumigatus; and 3 were culture negative and did not develop IPA. Of 15 human immunodeficiency virus-positive patients and 9 immunocompetent patients, 5 and 4, respectively, were both PCR positive and culture negative, and none developed aspergillosis. Thus, PCR confirmed IPA in three patients but gave positive results for 25% (12 of 49) of the patients who did not develop aspergillosis. The predictive value of PCR-positive results seems low for patients at risk for aspergillosis. Moreover, the risk of contamination of reaction buffers or biological samples with Aspergillus conidia seems high and has to be weighed in regard to the potential diagnostic benefit of PCR testing as a routine procedure.

Cytokine expression in the muscle of HIV-infected patients: evidence for interleukin-1 alpha accumulation in mitochondria of AZT fibers

To evaluate the possible role of cytokines in human immunodeficiency virus (HIV)-associated muscular disorders, we performed immunocytochemistry for interleukin-1 alpha, -1 beta, and -6 and tumor necrosis factor-alpha on frozen muscle biopsy specimens from HIV-infected patients with various myopathies (HIV polymyositis in 5, HIV-wasting syndrome in 5, zidovudine myopathy in 10) and from seronegative individuals (normal muscle in 2, mitochondrial cytopathies in 10). The HIV-infected patients showed positive reactivities in vessels (interleukin-1) and in inflammatory cells (mainly interleukin-1 and tumor necrosis factor-alpha), including perivascular hemosiderin-laden macrophages in 5 patients. In zidovudine myopathy, a majority of AZT fibers (i.e., ragged-red fibers with marked myofibrillar changes) showed mild to marked expression of interleukin-1. Expression of interleukin-1 in the other mitochondrial myopathies was much weaker. Interleukin-1 beta messenger RNA was demonstrated in muscle fibers by in situ hybridization, implying that interleukin-1 was produced in muscle cells. Immunoelectron microscopy showed that interleukin-1 alpha was mainly bound to mitochondrial membranes in AZT fibers. Proinflammatory and destructive effects of the studied cytokines might be responsible for several myopathological changes observed in HIV-infected patients, including inflammation and hemosiderin deposits in muscle tissue, and prominent myofibrillar breakdown in AZT fibers.

Cell localization and regulation of expression of cytochrome P450 1A1 and 2B1 in rat lung after induction with 3-methylcholanthrene using mRNA hybridization and immunohistochemistry

In order to characterize the response of various pulmonary cell types to polycyclic aromatic hydrocarbons, the expression of cytochrome P450 (CYP) 1A1 and 2B1 mRNA in the lung of rats, with or without induction by 3-methylcholanthrene (3MC), was analyzed by in situ hybridization using appropriate 35S-labeled riboprobes. The expression of the corresponding proteins was investigated immunohistochemically. Following induction with 3MC, the kinetics of mRNA expression differed considerably between Clara cells and type II pneumocytes and venous endothelial cells. In Clara cells, mRNA expression was detected as early as 1 h after induction, peaked between 2 and 4 h, and was completely undetectable at 14 h. In contrast, venous endothelial cells and type II pneumocytes exhibited permanent mRNA expression of CYP 1A1 in 3MC-pretreated rats. These kinetic results explain the striking absence of correlation between mRNA and protein expression observed in Clara cells 24 h after the end of the induction protocol, as these cells exhibited intense protein expression with no mRNA. In contrast, a good correlation was observed for mRNA and protein expression of CYP 2B1, with similar expressions for Clara cells and type II pneumocytes, but no expression in endothelial cells. This study clearly distinguished the regulation of CYP 1A1 expression in the rat lung from that described in the liver. The differences observed in the various lung cell types, whatever the post-transcriptional mechanisms involved, emphasize that studies must be performed at the cellular level in order to understand the specific response to xenobiotics, not only of this organ as a whole but also of its various anatomic structures.

Changes in chromogranin A-immunoreactive guinea-pig pulmonary neuroendocrine cells after sensitization and challenge with ovalbumin

Immunohistochemical study with antisera to chromogranin A and neuron-specific enolase, a general marker for nerves and endocrine cells, was used to quantify changes in bronchial neuroendocrine cells in guinea-pigs sensitized and challenged with ovalbumin. Actively sensitized animals were killed 2, 6, 24, 48, 72, and more than 144 hours after being challenged by an aerosolized solution of ovalbumin. The number of chromogranin A-immunoreactive cells was significantly greater in sensitized but unchallenged animals and in sensitized animals killed 2 and 6 h after challenge when compared to controls; it decreased significantly in animals killed more than 24 h after challenge when compared to sensitized, unchallenged animals. The number of neuron-specific-enolase-immunoreactive cells did not change. We conclude that the peptide content of bronchial neuroendocrine cells increases during sensitization and in the early phase of a hypersensitivity reaction, and that the cells release their granule contents in the late phase of such a reaction. They may therefore play a role in immunoallergic events in the lung.