Intraepithelial Lymphocytes of the Intestine

The intestinal epithelium, which segregates the highly stimulatory lumen from the underlying tissue, harbors one of the largest lymphocyte populations in the body, intestinal intraepithelial lymphocytes (IELs). IELs must balance tolerance, resistance, and tissue protection to maintain epithelial homeostasis and barrier integrity. This review discusses the ontogeny, environmental imprinting, T cell receptor (TCR) repertoire, and function of intestinal IELs. Despite distinct developmental pathways, IEL subsets share core traits including an epithelium-adapted profile, innate-like properties, cytotoxic potential, and limited TCR diversity. IELs also receive important developmental and functional cues through interactions with epithelial cells, microbiota, and dietary components. The restricted TCR diversity of IELs suggests that a limited set of intestinal antigens drives IEL responses, with potential functional consequences. Finally, IELs play a key role in promoting homeostatic immunity and epithelial barrier integrity but can become pathogenic upon dysregulation. Therefore, IELs represent intriguing but underexamined therapeutic targets for inflammatory diseases and cancer. Expected final online publication date for the Annual Review of Immunology, Volume 42 is April 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

ATP1A3 related disease manifesting as rapid onset dystonia-parkinsonism with prominent myoclonus and exaggerated startle

We report ATP1A3-associated rapid-onset dystonia-parkinsonism with an atypical presentation including myoclonus and exaggerated startle in four patients. Their prominence over parkinsonism prompted consideration of a syndromic diagnosis of myoclonus dystonia. ATP1α3 dysfunction in GABAergic neurons could explain these examination findings. The spectrum of ATP1A3-associated movement disorders includes myoclonus-dystonia.

Dietary protein shapes the profile and repertoire of intestinal CD4+ T cells

The intestinal immune system must tolerate food antigens to avoid allergy, a process requiring CD4+ T cells. Combining antigenically defined diets with gnotobiotic models, we show that food and microbiota distinctly influence the profile and T cell receptor repertoire of intestinal CD4+ T cells. Independent of the microbiota, dietary proteins contributed to accumulation and clonal selection of antigen-experienced CD4+ T cells at the intestinal epithelium, imprinting a tissue-specialized transcriptional program including cytotoxic genes on both conventional and regulatory CD4+ T cells (Tregs). This steady state CD4+ T cell response to food was disrupted by inflammatory challenge, and protection against food allergy in this context was associated with Treg clonal expansion and decreased proinflammatory gene expression. Finally, we identified both steady-state epithelium-adapted CD4+ T cells and tolerance-induced Tregs that recognize dietary antigens, suggesting that both cell types may be critical for preventing inappropriate immune responses to food.

Dietary protein shapes the profile and repertoire of intestinal CD4 + T cells

The intestinal immune system must tolerate food antigens to avoid allergy, a process requiring CD4 ⁺ T cells. Combining antigenically defined diets with gnotobiotic models, we show that food and microbiota distinctly influence the profile and T cell receptor repertoire of intestinal CD4 ⁺ T cells. Independent of the microbiota, dietary proteins contributed to accumulation and clonal selection of antigen-experienced CD4 ⁺ T cells at the intestinal epithelium, imprinting a tissue specialized transcriptional program including cytotoxic genes on both conventional and regulatory CD4 ⁺ T cells (Tregs). This steady state CD4 ⁺ T cell response to food was disrupted by inflammatory challenge, and protection against food allergy in this context was associated with Treg clonal expansion and decreased pro-inflammatory gene expression. Finally, we identified both steady state epithelium-adapted CD4 ⁺ T cells and tolerance-induced Tregs that recognize dietary antigens, suggesting that both cell types may be critical for preventing inappropriate immune responses to food.

TCR-Vγδ usage distinguishes protumor from antitumor intestinal γδ T cell subsets

γδ T cells represent a substantial fraction of intestinal lymphocytes at homeostasis, but they also constitute a major lymphocyte population infiltrating colorectal cancers (CRCs); however, their temporal contribution to CRC development or progression remains unclear. Using human CRC samples and murine CRC models, we found that most γδ T cells in premalignant or nontumor colons exhibit cytotoxic markers, whereas tumor-infiltrating γδ T cells express a protumorigenic profile. These contrasting T cell profiles were associated with distinct T cell receptor (TCR)-Vγδ gene usage in both humans and mice. Longitudinal intersectional genetics and antibody-dependent strategies targeting murine γδ T cells enriched in the epithelium at steady state led to heightened tumor development, whereas targeting γδ subsets that accumulate during CRC resulted in reduced tumor growth. Our results uncover temporal pro- and antitumor roles for γδ T cell subsets.

Immunity to enteric viruses

Pathogenic enteric viruses are a major cause of morbidity and mortality, particularly among children in developing countries. The host response to enteric viruses occurs primarily within the mucosa, where the intestinal immune system must balance protection against pathogens with tissue protection and tolerance to harmless commensal bacteria and food. Here, we summarize current knowledge in natural immunity to enteric viruses, highlighting specialized features of the intestinal immune system. We further discuss how knowledge of intestinal anti-viral mechanisms can be translated into vaccine development with particular focus on immunization in the oral route. Research reveals that the intestine is a complex interface between enteric viruses and the host where environmental factors influence susceptibility and immunity to infection, while viral infections can have lasting implications for host health. A deeper mechanistic understanding of enteric anti-viral immunity with this broader context can ultimately lead to better vaccines for existing and emerging viruses.

Sex-Based Differences in Human Immunodeficiency Virus Type 1 Reservoir Activity and Residual Immune Activation

Plasma human immunodeficiency virus type 1 (HIV-1) RNA levels in women are lower early in untreated HIV-1 infection compared with those in men, but women have higher T-cell activation and faster disease progression when adjusted for viral load. It is not known whether these sex differences persist during effective antiretroviral therapy (ART), or whether they would be relevant for the evaluation and implementation of HIV-1 cure strategies. We prospectively enrolled a cohort of reproductive-aged women and matched men on suppressive ART and measured markers of HIV-1 persistence, residual virus activity, and immune activation. The frequency of CD4+ T cells harboring HIV-1 DNA was comparable between the sexes, but there was higher cell-associated HIV-1 RNA, higher plasma HIV-1 (single copy assay), and higher T-cell activation and PD-1 expression in men compared with women. These sex-related differences in immune phenotype and HIV-1 persistence on ART have significant implications for the design and measurement of curative interventions.

Compartmentalized gut lymph node drainage dictates adaptive immune responses

The intestinal immune system has the challenging task of tolerating foreign nutrients and the commensal microbiome, while excluding or eliminating ingested pathogens. Failure of this balance leads to conditions such as inflammatory bowel diseases, food allergies and invasive gastrointestinal infections¹. Multiple immune mechanisms are therefore in place to maintain tissue integrity, including balanced generation of effector T (T_H) cells and FOXP3⁺ regulatory T (pT_reg) cells, which mediate resistance to pathogens and regulate excessive immune activation, respectively^1-4. The gut-draining lymph nodes (gLNs) are key sites for orchestrating adaptive immunity to luminal perturbations^5-7. However, it is unclear how they simultaneously support tolerogenic and inflammatory reactions. Here we show that gLNs are immunologically specific to the functional gut segment that they drain. Stromal and dendritic cell gene signatures and polarization of T cells against the same luminal antigen differ between gLNs, with the proximal small intestine-draining gLNs preferentially giving rise to tolerogenic responses and the distal gLNs to pro-inflammatory T cell responses. This segregation permitted the targeting of distal gLNs for vaccination and the maintenance of duodenal pT_reg cell induction during colonic infection. Conversely, the compartmentalized dichotomy was perturbed by surgical removal of select distal gLNs and duodenal infection, with effects on both lymphoid organ and tissue immune responses. Our findings reveal that the conflict between tolerogenic and inflammatory intestinal responses is in part resolved by discrete gLN drainage, and encourage antigen targeting to specific gut segments for therapeutic immune modulation.

Innate immune reconstitution with suppression of HIV-1

Progressive HIV-1 infection leads to both profound immune suppression and pathologic inflammation in the majority of infected individuals. While adaptive immune dysfunction, as evidenced by CD4⁺ T cell depletion and exhaustion, has been extensively studied, less is known about the functional capacity of innate immune cell populations in the context of HIV-1 infection. Given the broad susceptibility to opportunistic infections and the dysregulated inflammation observed in progressive disease, we hypothesized that there would be significant changes in the innate cellular responses. Using a cohort of patients with multiple samplings before and after antiretroviral therapy (ART) initiation, we demonstrated increased responses to innate immune stimuli following viral suppression, as measured by the production of inflammatory cytokines. Plasma viral load itself had the strongest association with this change in innate functional capacity. We further identified epigenetic modifications in the TNFA promoter locus in monocytes that are associated with viremia, suggesting a molecular mechanism for the observed changes in innate immune function following initiation of ART. These data indicate that suppression of HIV-1 viremia is associated with changes in innate cellular function that may in part determine the restoration of protective immune responses.

Elevated Levels of Microbial Translocation Markers and CCL2 Among Older HIV-1-Infected Men

The aging of the human immunodeficiency virus type 1 (HIV-1)-infected population obligates a focus on the interaction between aging, comorbid conditions, and HIV-1. We recruited a cohort of HIV-1-infected men aged ≤ 35 years or ≥ 50 years who were receiving fully suppressive antiretroviral therapy (ART). We analyzed plasma markers of inflammation; T-cell activation, exhaustion, proliferation; and innate cellular subsets and functional capacity. Levels of lipopolysaccharide and the plasma marker of chemokine (C-C motif) ligand 2 were significantly elevated in older HIV-infected men despite comparable cellular phenotypes. Compared with similarly age-stratified uninfected subjects, older HIV-1-infected adults were also more frequently in the upper quartile of soluble CD14 expression.

NUSAP1 influences the DNA damage response by controlling BRCA1 protein levels

NUSAP1 has been reported to function in mitotic spindle assembly, chromosome segregation, and regulation of cytokinesis. In this study, we find that NUSAP1 has hitherto unknown functions in the key BRCA1-regulated pathways of double strand DNA break repair and centrosome duplication. Both these pathways are important for maintenance of genomic stability, and any defects in these pathways can cause tumorigenesis. Depletion of NUSAP1 from cells led to the suppression of double strand DNA break repair via the homologous recombination and single-strand annealing pathways. The presence of NUSAP1 was also found to be important for the control of centrosome numbers. We have found evidence that NUSAP1 plays a role in these processes through regulation of BRCA1 protein levels, and BRCA1 overexpression from a plasmid mitigates the defective phenotypes seen upon NUSAP1 depletion. We found that after NUSAP1 depletion there is a decrease in BRCA1 recruitment to ionizing radiation-induced foci. Results from this study reveal a novel association between BRCA1 and NUSAP1 and suggests a mechanism whereby NUSAP1 is involved in carcinogenesis.

PIB is a non-specific imaging marker of amyloid-beta (Abeta) peptide-related cerebral amyloidosis

The in vivo imaging probe [11C]-PIB (Pittsburgh Compound B, N-methyl[11C]2-(4'-methylaminophenyl-6-hydroxybenzathiazole) is under evaluation as a key imaging tool in Alzheimer's disease (AD) and to date has been assumed to bind with high affinity and specificity to the amyloid structures associated with classical plaques (CPs), one of the pathological hallmarks of the disease. However, no studies have systematically investigated PIB binding to human neuropathological brain specimens at the tracer concentrations achieved during in vivo imaging scans. Using a combination of autoradiography and histochemical techniques, we demonstrate that PIB, in addition to binding CPs clearly delineates diffuse plaques and cerebrovascular amyloid angiopathy (CAA). The interaction of PIB with CAA was not fully displaceable and this may be linked to the apolipoprotein E-epsilon4 allele. PIB was also found to label neurofibrillary tangles, although the overall intensity of this binding was markedly lower than that associated with the amyloid-beta (Abeta) pathology. The data provide a molecular explanation for PIB's limited specificity in diagnosing and monitoring disease progression in AD and instead indicate that the ligand is primarily a non-specific marker of Abeta-peptide related cerebral amyloidosis.

The mandibular canal of the edentulous jaw

The morphology of the mandibular canal after loss of teeth has received little detailed attention. Improved documentation of this topic would allow better interpretation of dental radiographs and would enable those engaged in tooth implantation to better understand the nature of the tissue into which the prostheses are placed. In this study on mandibles from seven dissecting room cadavers panoramic radiographs usually showed the mandibular canal clearly, an incisive canal less so. The wall of the mandibular canal was similar in dentate and edentulous mandibles, and was highly perforated, as suggested by Cryer (Anderson et al., 1991). In edentulous specimens, it was composed mainly of cancellous bone with only occasional single osteons. The inferior alveolar nerve near the mandibular foramen was a large trunk, consisting of three to four nerve bundles with connective tissue sheaths. It became more loosely arranged toward the mental foramen. Medial to the mental foramen, the nerves were frequently in the form of small bundles in the marrow. Any incisive canal was ill-defined and neurovascular bundles, when present, ran through a labyrinth of intertrabecular spaces.

Physiological aspects of pig-to-primate renal xenotransplantation

BACKGROUND

Few data exist on the physiological aspects of pig-to-primate renal xenotransplantation.

METHODS

Use of organs transgenic for human decay accelerating factor has allowed assessment of the metabolic and hormonal functions of these xenografts.

RESULTS

Porcine renal xenografts largely maintain plasma electrolyte homeostasis. An increase in proteinuria was detected that may result from graft injury. In contrast to allotransplantation a severe anaemia developed requiring recipient treatment with exogenous human erythropoietin.

CONCLUSIONS

Our experience provides qualified encouragement for the likely physiological compatibility of pig and primate species, but identifies areas where a xenograft may not match the performance of an allograft.

[Epidemiological study of genetic and environmental factors in asthma, bronchial hyperresponsiveness and atopy. Protocol and potential selection bias]

BACKGROUND

The EGEA study combines a case-control study and a family study to assess genetic and environmental risk factors and their interactions for asthma, bronchial hyperresponsiveness and atopy. Information is scanty regarding potential selection biases, in particular regarding familial ressemblance in epidemiological surveys of this kind.

METHODS

Asthmatic probands (adult and paediatric) were recruited in chest clinics of six clinical centres. Controls were mostly population-based (electoral rolls) for adults and recruited in surgery departments for children.

RESULTS

The population examined includes 348 nuclear families ascertained by one asthmatic and 416 controls, totalling 1847 subjects (EGEA I) and an additional sample of 40 families ascertained by two asthmatic siblings (EGEA II). Potential biases for the various types of analyses have been studied. Quantification of the consequences of the greater participation of probands with a parental history of asthma shows it does not introduce a major bias in the estimates of familial resemblance. Cases and controls showed a good comparability regarding sex, age, area of residence and familial geographical origin, allowing proper associations studies for environmental and candidate genetic factors.

CONCLUSIONS

The case-control component of the study will allow to perform studies on environmental factors and association studies for various genetic polymorphisms. Using the family base collected, segregation and genetic linkage/association analyses with DNA markers may be performed.

Designing meaningful industry metrics for clinical productivity for anesthesiology departments

IMPLICATIONS

Clinical productivity measurements that account for differences in clinical settings and concurrencies provided more precise comparisons between two anesthesiology groups. The data show that different concurrencies confound the current industry standard, "per full-time equivalent" measurements, whereas "per operating room site" and "per case" measurements allowed for more meaningful comparisons.

Genome screen for asthma and related phenotypes in the French EGEA study

A genome-wide search was conducted in 107 nuclear families with at least two siblings with asthma, as part of the French EGEA study. A two-stage analysis strategy was applied to the 107 families divided into two independent subsets of 46 and 61 families, where all regions detected in the first set of families were tested for replication in the second set. In addition, all regions reported by published genome scans in different populations were examined in the total sample. A total of 254 markers were typed in the first set of families and 70% of them in the second set. Linkage was investigated by model-free methods for asthma and four asthma-related phenotypes: bronchial responsiveness (BR), skin test response, total immunoglobulin E (IgE) levels, and eosinophil count. The two-stage analysis led to the detection of three regions: 11p13 for IgE, 12q24 for eosinophils, and 17q12-21 for asthma and skin tests. Among the regions reported by published genome screens, seven were found in the 107 French EGEA families: three being already detected by the two-stage analysis, 11p13 (p = 0.005), 12q24 (p = 0.0008), and 17q12-21 (p = 0.001), and four additional ones, 1p31 (p = 0.005) for asthma, 11q13 (p = 0.006) for IgE, 13q31 (p = 0.001) for eosinophils, and 19q13 (p = 0.02) for BR.

Association of PEEP with two different inflation volumes in ARDS patients: effects on passive lung deflation and alveolar recruitment

OBJECTIVE

To assess the effects of the association of positive end-expiratory pressure (PEEP) with different inflation volumes (V(T)'s) on passive lung deflation and alveolar recruitment in ARDS patients.

DESIGN

Clinical study using PEEP with two different V(T)'s and analyzing whether passive lung deflation and alveolar recruitment (Vrec) depend on end-inspired (EILV) or end-expired (EELV) lung volume in mechanically ventilated ARDS patients.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS AND PARTICIPANTS

Six mechanically ventilated consecutive supine patients with ARDS.

INTERVENTIONS

Time-course of thoracic volume decay during passive expiration and Vrec were investigated in six ARDS patients ventilated on PEEP with baseline V(T) (V(T),b) and 0.5V(T) (0.5V(T),b), and on zero PEEP (ZEEP) with V(T),b. Time constants of the fast (tau1) and slow (tau2) emptying compartments, as well as resistances and elastances were also determined.

MEASUREMENTS AND RESULTS

(a) the biexponential model best fitted the volume decay in all instances. The fast compartment was responsible for 84+/-7 (0.5V(T),b) and 86+/-5% (V(T),b) on PEEP vs 81+/-6% (V(T),b) on ZEEP (P:ns) of the exhaled V(T), with tau1 of 0.50+/-0.13 and 0.58+/-0.17 s vs 0.35+/-0.11 s, respectively; (b) only tau1 for V(T),b on PEEP differed significantly (P < 0.02) from the one on ZEEP, suggesting a slower initial emptying; (c) for the same PEEP, Vrec was higher with a higher volume (V(T)b) than at a lesser one (0.5V(T),b), reflecting the higher V(T).

CONCLUSIONS

In mechanically ventilated ARDS patients: (a) the behavior of airway resistance seems to depend on the degree of the prevailing lung distension; (b) alveolar recruitment appears to be more important when higher tidal volumes are used during mechanical ventilation on PEEP; (c) PEEP changes the mechanical properties of the respiratory system fast-emptying compartment.

EGEA (Epidemiological study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy)-- descriptive characteristics

The Epidemiological study on the Genetics and Environment of Asthma (EGEA) was planned to assess genetic, environmental risk factors and their interactions for asthma and for the two related traits of bronchial hyperresponsiveness and atopy. The population examined includes 348 nuclear families ascertained by one asthmatic (213 adult and 135 paediatric probands) and 416 controls, totalling 1,847 subjects (EGEA I). Prevalences of asthma, skin prick test response, high IgE and bronchial hyperresponsiveness were for parents, siblings, and offspring of cases intermediate between cases and spouses or controls, both in adults and children, confirming the familial resemblance for asthma and related traits. With an additional sample of 40 families ascertained by two asthmatic siblings (EGEA II), a total of 119 families with two asthmatic siblings has been ascertained for a genome screening.

Crystal structure of the N-terminal domain of MukB: a protein involved in chromosome partitioning

BACKGROUND

The 170 kDa protein MukB has been implicated in ATP-dependent chromosome partitioning during cell division in Escherichia coli. MukB shares its dimeric structure and domain architecture with the ubiquitous family of SMC (structural maintenance of chromosomes) proteins that facilitate similar functions. The N-terminal domain of MukB carries a putative Walker A nucleotide-binding region and the C-terminal domain has been shown to bind to DNA. Mutant phenotypes and a domain arrangement similar to motor proteins that move on microtubules led to the suggestion that MukB might be a motor protein acting on DNA.

RESULTS

We have cloned, overexpressed and crystallized a 26 kDa protein consisting of 227 N-terminal residues of MukB from E. coli. The structure has been solved using multiple anomalous dispersion and has been refined to 2.2 A resolution. The N-terminal domain of MukB has a mixed alpha/beta fold with a central six-stranded antiparallel beta sheet. The putative nucleotide-binding loop, which is part of an unexpected helix-loop-helix motif, is exposed on the surface and no nucleotide-binding pocket could be detected.

CONCLUSIONS

The N-terminal domain of MukB has no similarity to the kinesin family of motor proteins or to any other nucleotide-binding protein. Together with the finding of the exposed Walker A motif this observation supports a model in which the N- and C-terminal domains come together in the dimer of MukB to form the active site. Conserved residues on one side of the molecule delineate a region of the N-terminal domain that is likely to interact with the C-terminal domain.

Analysis of hsp70 gene polymorphism in allergic asthma

BACKGROUND

Allergic asthma is a multifactorial and probably multigenic inflammatory disease of the upper airways, and has been associated with the HLA class II alleles DR4 and DR7. Here we investigated possible associations with other polymorphic susceptibility/resistance genes located within the major histocompatibility complex, i.e., the genes coding the major 70-kDa heat-shock proteins (HSP; Hsp70) hsp70-1, hsp70-2, and hsp70-HOM, whose products are overexpressed in the bronchi of asthmatic patients.

METHODS

Genomic DNA was extracted from peripheral blood lymphocytes or buccal epithelial cells of 48 patients with allergic asthma and 31 selected nonatopic control subjects, in whom we previously reported a strong association of atopy with DR4/DR7 alleles.

RESULTS

No evidence was found for an independent role of hsp70 gene polymorphism in susceptibility to allergic asthma. However, hsp70 alleles might be involved in extended haplotypes of HLA markers.

CONCLUSIONS

Our data suggest that Hsp70 overexpression in asthma results from complex interactions between environmental exposures and genetic background rather than from specific genetic variations in hsp70 genes.

Nucleotide-dependent interaction of the N-terminal domain of MukB with microtubules

The MukB protein from Escherichia coli has a domain structure that is reminiscent of the eukaryotic motor proteins kinesin and myosin: N-terminal globular domains, a region of coiled-coil, and a specialised C-terminal domain. Sequence alignment of the N-terminal domain of MukB with the kinesin motor domain indicated an approximately 22% sequence identity. These observations raised the possibility that MukB might be a prokaryotic motor protein and, due to the sequence homology shared with kinesin, might bind to microtubules (Mts). We found that a construct encoding the first 342 residues of MukB (Muk342) binds specifically to Mts and shares a number of properties with the motor domain of kinesin. Visualisation of the Muk342 decorated Mt complexes using negative stain electron microscopy indicated that the Muk342 smoothly decorates the outside of Mts. Biochemical data demonstrate that Muk342 decorates Mts with a binding stoichiometry of one Muk342 monomer per tubulin monomer. These findings strongly suggest that MukB has a role in force generation and that it is a prokaryotic homologue of kinesin and myosin.

Silver/silver chloride electrodes for measurement of potential difference in human bronchi

BACKGROUND

An easy and reliable method to measure potential difference (PD) in the lower airways would be of interest in the field of cystic fibrosis. We have developed silver/silver chloride (Ag/AgCl) electrodes to measure PD in the lower airways.

METHODS

To validate this technique the nasal PD measured with Ag/AgCl electrodes and with conventional perfused electrodes was compared in 16 patients. The range of PD measured with Ag/AgCl electrodes in the lower airways during fibreoptic bronchoscopy was determined in 14 adult patients and in nine the reproducibility of this technique was examined.

RESULTS

Nasal PD values measured with Ag/AgCl and perfused electrodes were highly correlated (r = 0.985, p < 0.0001) and the limits of agreement (mean +/- 2SD of the difference) between the two methods were -1.91 mV and 1.53 mV. In the lower airways a progressive and slight decrease in PD values with decreasing airway diameter was observed in most patients. The mean (2SD) of the differences between the two tracheal measurements was 0.21 (1.73) mV.

CONCLUSIONS

The use of Ag/AgCl electrodes gives a reliable and reproducible measurement of PD in the lower airways in humans.

Interaction of the N-terminal domain of MukB with the bacterial tubulin homologue FtsZ

The MukB protein is involved in the process of chromosome partition in Escherichia coli and has a domain structure reminiscent of the eukaryotic motor proteins kinesin and myosin. This has led to the suggestion that MukB may function as a motor protein in vivo. In order to test this idea we have recombinantly expressed the N-terminal domain of MukB (residues 1-342) as a poly-His tagged fusion protein for biochemical characterisation. The purified protein (Muk342) is monomeric and has low basal Mg-ATPase (1.23 min(-1)) and Mg-GTPase (0.17 min(-1)) activities. Muk342 binds with high affinity to the prokaryotic tubulin homologue FtsZ and we have evidence that FtsZ can stimulate nucleotide turnover by Muk342. These properties are consistent with MukB functioning as a motor protein using FtsZ as a track or anchor for generating force within E. coli.

A provider assessment of the Massachusetts Medicaid Managed Behavioral Health Program: year four

A stratified, random sample of 80 providers in the Massachusetts Medicaid Managed Mental Health/Substance Abuse Program were interviewed by phone to assess their views of the program in year four. Providers continued to believe that access and quality were the same or better than a year earlier, that client severity continued to increase while length of stay decreased, that readmissions and emergency room admissions were the same as a year earlier, and that aftercare was the same or better than a year earlier. Substantial problems were reported in the integration of services, in linkages with support services, and with administration of the program.

Kinetic evidence for low chemical processivity in ncd and Eg5

The kinesin molecular motor "walks" processively along microtubules, touching down with alternate motor domains and transiently bridging between sites spaced 8 nm apart axially. To allow bridging, the coiled coil tail of kinesin would need to unzip a region immediately adjacent to the heads, and the tail region sequence at this point indeed contains potentially destabilising interruptions in the regular hydrophobic heptad repeat. We noticed that such interruptions are substantially absent from the coiled coil tails of Eg5, a slow kinesin homologue, and ncd, a reverse-directed homologue, and we wondered if this precluded their processivity. We measured the temperature dependence of kcat/K50% MTs, an index of the chemical processivity of a motor, the number of ATPs split per productive diffusional encounter of motor with microtubule. We found two-headed ncd (GSTMC5) and two-headed Eg5 (E437GST) constructs to be slightly if at all processive in solution over the range 4 degrees C to 30 degrees C. By contrast, two-headed kinesin constructs K401 and K430 were processive, and became substantially more so with increasing temperature. Arrhenius plots for the solution ATPase were linear for all three motors. Arrhenius plots for MT gliding assays were linear and essentially parallel for E437GST and GSTMC5 (Ea = 61 and 63 kJ mol-1) but for K430 the plot was biphasic, with a break at 17 degrees C, corresponding to a 30% reduction in Ea from 84 to 57 kJ mol-1. The data indicate that ncd and Eg5 are only slightly if at all processive, and suggest that this may be related to structural differences in their coiled coil neck regions.

Epidemiological study of the genetics and environment of asthma, bronchial hyperresponsiveness, and atopy: phenotype issues

The Epidemiological Study of the Genetics and Environment of Asthma (EGEA) combined a case-control study and a family study. The total sample of 1,854 consisted of 348 patients with asthma selected through chest clinics and 416 control subjects and nuclear families ascertained through the cases. The protocol included standardized questionnaires, bronchial responsiveness, allergen skin-prick tests according to international protocols, total serum immunoglobulin E (IgE) level measurements, and blood eosinophilia. Criteria used to select subjects with asthma and determine asthma status of relatives for affected sibling pair linkage analysis are described. Based on figures from the 348 asthma cases of the EGEA study, issues relative to the definition of severe asthma and intermediate phenotypes such as bronchial responsiveness and allergic markers are discussed. Given the phenotypic heterogeneity involved, relevant phenotypes that may lead to the detection of genetic factors will depend on the hypothesis tested. Standardization of primary data and subphenotypes is a prerequisite for pooling data, which will be needed in the future to better understand the genetics and environmental factors of asthma.

[Occupational asthma caused by buckwheat flour]

Buckwheat flour, mainly used for pancakes, may induce asthma following inhalation and anaphylactic reactions following ingestion. These allergic reactions are mediated by specific IgE and may be confirmed by skin test and radio-allergo-sorbent test. The occupational asthma of a patient working in pancake restaurant was confirmed by specific challenge test with a computerised device to generate particles. A very small amount of buckwheat flour (10 micrograms) induced an immediate fall of the FEV1 to 56% of the initial value. No bronchial reaction was observed with lactose nor with wheat flour. Specific bronchial challenge identifies the allergen responsible for asthma, measures the level of sensitization and thus can prevent the occupational exposure.

HLA class II antigens and T lymphocytes in human nasal epithelial cells. Modulation of the HLA class II gene transcripts by gamma interferon

BACKGROUND

Nasal polyps are characterized by a proliferation of the epithelial layer of the mucosa, cellular infiltrates and other pathological changes; however the mechanisms involved in polyp pathogenesis remain largely unclear.

OBJECTIVES

We have taken two different approaches to study the cellular events involved in nasal polyposis.

METHODS

First, through use of immunohistochemical methods, we have studied the expression of HLA class II antigens in epithelial cells of nasal polyps and the distribution of lymphocytes in the epithelium and in the subepithelial layer in patients with clinical conditions, such as asthma, atopy, aspirin intolerance or cystic fibrosis, and in subjects with an absence of concomitant diseases. Second, in order to investigate whether HLA class II expression is controlled at the pre- or post-transcriptional level, we studied the effect of interferon gamma (INF gamma) on epithelial cells in primary culture, which were derived from HLA class II negative and HLA class II positive nasal polyps. Total RNA was extracted from the cells and reverse-transcribed, and the c-DNA corresponding to DR, DP, DQ loci was amplified by PCR.

RESULTS

Expression of HLA class II antigens by the epithelia of nasal polyps was more common in the presence rather than in the absence of concomitant asthma, atopy or cystic fibrosis (59% versus 40%). HLA-DR was the only HLA class II antigen expressed in the seven polyps taken from cystic fibrosis patients. The number of CD8+ cells was significantly higher in polyps associated with known clinical conditions and HLA class II antigen expression than it was in 'isolated' polyps and in HLA class II negative polyps. RNA transcripts for at least one or all three HLA-DR, DP and DQ antigens were detected in 10 cultures of the II HLA class II positive polyps. Conversely, 8 of 10 cultures derived from HLA class II negative polyps did not express HLA class II transcripts in the absence of INF gamma. Adding INF gamma (100 U/ml) to the latter cell cultures caused expression of transcripts of one or more HLA class II genes.

CONCLUSIONS

We have shown that HLA class II antigens were more frequently detected in polyps of patients with an identified clinical syndrome than in those of asymptomatic subjects. Our results also suggest that IFN gamma regulates expression of HLA class II antigens in airway epithelial cells of the nasal polyps at the transcriptional level, and that cultured cells from nasal polyps represent a suitable model to investigate immune mechanisms involved in diseases such as atopy, asthma and cystic fibrosis.

Three-dimensional cryoelectron microscopy of 16-protofilament microtubules: structure, polarity, and interaction with motor proteins

We present a three-dimensional (3D) map, reconstructed from electron microscope (EM) images of naturally occurring 16-protofilament (PF) microtubules (MTs) in ice. We compare it with the tubulin in six 3D maps of MTs decorated with motor domains, three from frozen MTs decorated with kinesin or ncd in the tightly bound AMP-PNP state, and three from negatively stained MTs decorated with kinesin in different nucleotide states. The comparison confirms that kinesin and ncd bind to identical sites and interact with both monomers of a tubulin dimer. Maps of specimens in negative stain and in ice are similar except that the protein in the top half of a motor domain appears denser in negative stain. The interactions have only a small effect on tubulin structure; the outward appearance is unchanged, but there seems to be a small internal rearrangement. The relative polarity of undecorated and decorated MTs is evident from their 3D structures. This agrees with the absolute polarities indicated by the orientations of motors in decorated specimens and by polar superposition patterns calculated for undecorated MTs. An image of tubulin PFs in zinc-induced sheets has been tentatively oriented by similar criteria.

[Ion transports across the respiratory epithelium]

The electrolytes and water transport across the respiratory epithelium have aroused particular interest for 20 years ago, with regard to the essential role they play in the regulation of the bronchial mucus composition and volume. The development of new in vitro and in vivo, techniques, allow better knowledge of these transport systems and their regulation. Transport involves two main ionic movements: chloride secretion and sodium absorption by the epithelial cells, associated with parallel water movements. In cystic fibrosis, the modification of bronchial mucus results from a defective protein-kinase dependent regulation of chloride secretion. This defect blocks water and chloride secretion by the respiratory epithelium causing dehydration of the mucus.

[Physiopathology of asthma: what role for leukotrienes?]

Leukotrienes are newly formed mediators derived from arachidonic acid that are released from membrane phospholipids upon stimulation of phospholipases. As a result of their various paracrine effects, these mediators-among which the most important are leukotrienes B4, C4, D4 and E4 (LTB4, LTC4, LTD4 and LTE4, respectively)-are likely to play a central role in bronchial obstruction in asthma. Indeed, LTC4 et LTD4 act on all three effectors of bronchial obstruction, namely bronchial smooth muscle, vessels and mucus secretory cells, whereas LTB4 is a potent chemotactic factor recruiting neutrophils and, in a lesser extent, eosinophils. Urinary excretion of LTE4 is also increased during acute asthma and after bronchial provocation tests with various agonists. Increased production of leucotrienes, however, does necessarily imply they are directly involved in asthma. This is, nevertheless, likely according to results obtained from numerous clinical trials assessing the therapeutical effects of competitive antagonists of LTC4 and LTD4 and 5-lipoxygenase (5-LO) inhibitors. Pretreatment with various LTC4 antagonists and 5-LO inhibitors reduces bronchial obstruction induced by exercise, hyperventilation, aspirin and allergens. However, it is still necessary to wait for results of clinical trials looking at the effects of these drugs in a large group of individuals studied over a long period, before one can assess the real therapeutical benefit of suppressing either the production or the action of leucotrienes in asthma.

The impact of managed care on Massachusetts mental health and substance abuse providers

Medicaid managed care programs are becoming more widespread. To investigate the clinical, organizational, and financial impacts on service providers, a stratified, random sample of providers in the Massachusetts Managed Mental Health/Substance Abuse Program were surveyed by phone in Years 3 and 4 of the initiative. Providers reported that they were making widespread clinical changes such as more use of group, brief, and episodic therapies. They were increasing utilization review, Total Quality Management, and outcomes measurement. They were increasing in size, affiliating with other agencies, and providing a greater range of services. They were preparing for capitation. Compared to before the program and a year earlier, about 40 percent of providers were doing better financially and a quarter were doing worse. The study documents the hypothesis that a widespread and continuing transformation is taking place in response to managed care.

Three-dimensional cryoelectron microscopy of dimeric kinesin and ncd motor domains on microtubules

Kinesin and ncd motor proteins are homologous in sequence yet move in opposite directions along microtubules. We have previously shown that monomeric kinesin and ncd bind in the same orientation on equivalent sites relative to the ends of tubulin sheets of known polarity. We now report cryoelectron microscope images of 16-protofilament microtubules decorated with both single- and double-headed kinesin and double-headed ncd. Three-dimensional density maps and difference maps show that, in adenosine 5'-[beta,gamma-imido]triphosphate, both dimeric motors bind tightly to microtubules via one head, leaving the other free, though apparently in a fixed position. The attached heads of dimers bind to tubulin in the same way as single kinesin heads. The second heads are connected to the tops of the first but, whereas the second kinesin head is closely associated with the first, pairs of ncd heads are splayed apart. There is also a distinct difference in orientation: the second kinesin head is tilted toward the microtubule plus end, while the second head of ncd points toward the minus end.

Phenotypic and quantitative changes in mast cells after syngeneic unilateral lung transplantation in the rat

1. Lung transplantation causes a total interruption of the inneration and vascularization within the transplanted organ, followed by repair processes. This is frequently associated with bronchial hyper-responsiveness. A common feature of tissue repair is an increase in the number of mast cells. Three phenotypically distinct mast cell subsets, with respect to their protease content, have been identified in rat lung, and it is probable that mast cells of differing protease phenotype fulfil different functions. 2. We have compared the number, protease phenotype and distribution of mast cells in left lung from transplanted and control Lewis rats 1 month after syngeneic unilateral left lung transplantation, without interference of inflammation, graft rejection or of any treatment. Connective and mucosal-type mast cell phenotypes were characterized using antibodies directed against their specific rat mast cell proteases, RMCPI and RMCPII, respectively. 3. After transplantation, RMCPI and RMCPII tissue concentrations increased by 172% and 239%, respectively, compared with controls (13.1 +/- 1.2 and 5.6 +/- 1.0 micrograms/g). 4. Localization of mast cell phenotypes was studied by immunohistochemistry after double immunostaining. The number of mast cells increased after transplantation: the increase in the number of RMCPI-immunoreactive mast cells (RMCPI+) was significant around bronchioles and arterioles, around large vessels and in the pleura. The number of RMCPII+ mast cells also significantly increased around bronchioles and arterioles, as well as in the smooth muscle layer of large airways. Some mast cells stained for the presence of both RMCPI and RMCPII, supporting the existence of co-expressing phenotype in rat lung. The number of mast cells of the RMCPI+/II+ phenotype significantly increased around bronchioles and arterioles and in the pleura. Moreover, the distribution of the mast cell phenotypes was modified in the different areas after transplantation. 5. This indicates a local differentiation/maturation of mast cells after transplantation.

Evidence of a strong, positive association between atopy and the HLA class II alleles DR4 and DR7

BACKGROUND

Atopy, with or without associated asthma, provides a useful model for evaluating the genetic factors that control human immune responsiveness. HLA class II gene products are involved in the control of immune responses.

OBJECTIVES

We investigated whether susceptibility or resistance to the disease was associated with HLA class II genes.

METHODS

Blood samples were obtained from two groups of unrelated European-born white adults: 56 atopic patients (52 of them with asthma) and 39 healthy controls with no personal or familial history of asthma or atopy. Genomic DNA was extracted from peripheral blood lymphocytes. The exons of DQA1, DQB1, DRB and DPB1 genes were selectively amplified by the polymerase chain reaction (PCR) method. Genotyping was carried out by digestion of the amplified DNA products with allele-specific endonucleases (PCR-RFLP), which can recognize allelic variations in the polymorphic exon.

RESULTS

We found no significant differences in the frequency of DPB1 alleles between patients and controls. HLA class II DR4 and DR7 alleles were present in 39.2% of the patients and in 2.5% of the healthy subjects (Pc*2 < or = 3.9 10(-3)). Conversely, DQA1*0103 and DQB1*0502 alleles were more frequent in the control subjects. These results confirm a previous study of an extended pedigree, which showed that DR4 and DR7 alleles were absent in all healthy members of the family and were frequently observed in atopic and/or in asthmatic subjects.

CONCLUSION

We observed that HLA-DR 4 and DR7 alleles are significantly implicated in their susceptibility to the disease and suggest that this susceptibility is more related to atopy than to specific responses to allergens. According to previous studies, we could also submit that in atopic patients with asthma, DR4 alleles at the least, could be more closely associated with atopy than with asthma per se. Conversely, we suggest that some allelic DQA1 and DQB1 sequences might confer protection against the disease.

Microtubule minus ends can be labelled with a phage display antibody specific to alpha-tubulin

To investigate the orientation of alpha- and beta-tubulin heterodimers within microtubules, we cloned a phage display antibody to alpha-tubulin. The N-terminal 100 residues of alpha-tubulin were bacterially expressed and used to select clones from a large repertoire of antibody-expressing phagemid particles. One clone reacted with the expressed alpha-tubulin N terminus and native tubulin dimer but not with the expressed beta-tubulin N terminus. Electron microscopy showed 30 nm gold beads coated with the antibody binding to one end of brain microtubules. The beads bound to the minus ends of axonemes but not to the brain tubulin extensions from their plus ends. In sliding motility assays with a plus end directed motor, beads were pushed ahead of the microtubules. Our results indicate that an N-terminal epitope of alpha-tubulin is exposed only at the minus ends of microtubules.