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Resumen La identificacion proteomica de micobacterias no tuberculosas (MNTs) mediante MALDI-TOF presenta una mayor complejidad debido a la especial composicion de su pared celular, que complica la extraccion de proteinas. Un total de 106 aislamientos pertenecientes a diferentes especies de MNTs procedentes de muestras clinicas del Complejo Asistencial Universitario de Leon recogidas durante los anos 2019 y 2020 se han identificado por un metodo proteomico abreviado (MALDI-TOF Biotyper Bruker®) desarrollado en nuestro laboratorio. La identificacion se ha comparado con la realizada en paralelo en el Centro de Referencia de Majadahonda. Se analizaron un total de 22 especies diferentes de MNTs obteniendo una concordancia del 91,5%. Las nueve discrepancias detectadas se dieron entre especies pertenecientes al mismo grupo taxonomico. En el 67,92% de las identificaciones el score fue superior a 1,8. En el tiempo de procesamiento se obtuvo un ahorro aproximado de 24 minutos con respecto al recomendado por el fabricante.

Bronchiectasis is considered a consequence of the neutrophilic inflammatory response to infection. Mycobacterial infections, mainly from the Mycobacterium avium complex and M. abscessus, have been inextricably linked to bronchiectasis development. The most important pathogen that infect patients with bronchiectasis is Pseudomonas aeruginosa, associated with an increased risk of death. Patients with bronchiectasis are often co-infected with P. aeruginosa and M. avium complex, and it was studied whether they interacted in immune cell cultures. Peripheral blood mononuclear cells from healthy volunteers were infected overnight with clinical isolates of mycobacteria, 18 h later co-infected with P. aeruginosa and Pseudomonas multiplication was quantified. Inoculated P. aeruginosa multiply faster when cells were previously infected in vitro with M. avium complex or M. tuberculosis, but not with M. kansasii or M. gordonae, mycobacteria not regularly isolated from patients with bronchiectasis. The interaction between mycobacteria and P. aeruginosa also takes place in the absence of cells, but to a lower degree. Growth of Staphylococcus aureus, less frequently co-isolated with mycobacteria, was not affected by previous infection with mycobacteria. Surprisingly, multiplication of P. aeruginosa in neutrophil cultures did not vary in the presence of mycobacteria. Nevertheless, co-infection of mycobacteria and P. aeruginosa induced the production of IL-1β, a mediator of neutrophilic inflammation. P. aeruginosa stimulation by mycobacteria provides evidence for explaining their common clinical association. Strategies to control mycobacteria may be useful to impair P. aeruginosa colonization.

Resumen Introduccion La incidencia anual de tuberculosis (TB) humana por Mycobacterium bovis ha disminuido considerablemente en los paises industrializados desde inicios del siglo XX . El objetivo de este estudio fue conocer las caracteristicas epidemiologicas, clinicas y microbiologicas de esta enfermedad en Castilla y Leon (CyL). Metodos Estudio retrospectivo de los casos de TB por M. bovis de CyL en un periodo de 10 anos, comparando la epidemiologia, los factores de riesgo y la evolucion entre las formas pulmonares (TBP) y extrapulmonares (TBEP). Resultados Se recopilaron 75 casos de TB por M. bovis: 45 TBP y 31 TBEP. La incidencia acumulada de TB por M. bovis fue de 0,3 casos por 100.000 habitantes. Se mantuvo estable entre el primer y el segundo quinquenio (0,27 vs. 0,33, p = 0,656), a pesar del descenso de la incidencia global de la TB (13,58 vs. 10,71, p Conclusiones La incidencia de TB por M. bovis en CyL es superior a la de Espana y otros paises europeos, y se mantuvo estable a pesar del descenso de la TB por MTC. Afecto mayoritariamente a poblacion nacida en Espana que vivia en zonas rurales y con elevada media de edad.

INTRODUCTION The annual incidence of tuberculosis (TB) from Mycobacterium bovis in humans has considerably declined in industrialised countries since the early twentieth century. The objective of this study was to determine the epidemiological, clinical and microbiological characteristics of patients with this illness in Castile and Leon (CyL). METHODS Retrospective study of all M. bovis TB cases in CyL over a 10-year period, comparing the risk factors, the epidemiology and the clinical course between pulmonary (PTB) and extrapulmonary TB (EPTB). RESULTS 75 cases of TB were due to M. bovis: 45 PTB and 31 EPTB. The annual incidence of TB due to M. bovis was 0.3 cases per 100,000. It remained stable between the first and second five-year period (0.27 vs. 0.33, p=0.656). However, the overall incidence of TB fell in both five-year periods (13.58 vs. 10.71, p

Proteomic techniques relaying upon mass spectrometry (MALDI_TOF) applied to nontuberculous mycobacteria (NTM) identification, constitute a difficult goal. Cell wall structure features complicates the protein extraction procedure. A total of 106 isolates belonging to a variety of MNTs species isolated from clinical samples taken at the Complejo Asistencial Universitario de León for a two years period (2019-20) were identified following a simplified method (MALDI-TOF Biotyper Bruker®) developped in our laboratory. The resultant identification was compared to a parallel one ruled on the Centro de Referencia de Majadahonda. A total of 22 different MNTs species were tested, obtaining an agreement of 91,5%. Only 9 minor discrepancies between species belonging to the same taxonomic group of MNTs were detected. The score obtained in the 67.92% of the cases was higher than 1.8. A time-saving of 24 minutes compared to the manufacturer's proceeding was achieved.

Introduction and objectives A retrospective study was conducted by collecting microbiological tuberculosis (TB) data in Castile and Leon during the year 2013 in order to determine the incidence and distribution of TB, and resistance to the tuberculostatic drug, and compare them with the epidemiological data provided by the Department of Epidemiological Surveillance (SIVE). Material and methods Microbiologists of the 14 hospitals of the Castile and Leon public health network (GRUMICALE) collected epidemiological, microbiological, and management data from the Microbiology laboratories in the community during the year 2013. A single isolate of Mycobacterium tuberculosis complex (MTC) per patient was considered. Results The study included a total of 270 MTC isolates (an incidence rate of 11.63 cases/100,000 inhab./year). A total of 288 cases of TB (11.43 cases/100,000 inhab. year) were recovered using epidemiological data, which included 243 confirmed, 29 suspected, and 16 as probable cases. Pulmonary TB was predominant, followed a long way off by the pleural TB and the remaining locations. A total of 27,620 samples were processed for mycobacterial detection. Mycobacterial growth was observed in 3.46% of automated fluid cultures, and 50.37% were positive by direct staining of the smear. Resistance to one tuberculostatic drug, mostly to isoniazid, was observed in 16 (5.92%) isolates of M. tuberculosis (MT). The province with greater incidence and number of isolates was Leon (24.23 cases/100,000 inhab./year), with the highest being observed in El Bierzo health area (30.46 cases/100,000 inhab./year). Conclusions An adequate collection of microbiological information is essential to determine the epidemiology of TB in our region.

Resumen Introduccion y objetivos Estudio retrospectivo que recoge datos microbiologicos de tuberculosis (TB) en Castilla y Leon durante el ano 2013 para conocer los datos microbiologicos de incidencia y distribucion de TB, resistencias a los farmacos antituberculosos y compararlos con los datos epidemiologicos ofrecidos por los servicios de vigilancia epidemiologica (SIVE). Material y metodos Microbiologos de los 14 hospitales de la red sanitaria publica de Castilla y Leon (GRUMICALE) han recogido datos epidemiologicos, microbiologicos y de funcionamiento de los laboratorios de microbiologia de la comunidad durante el ano 2013. Se considero un solo aislamiento de Mycobacterium tuberculosis complex (MTC) por paciente. Resultados Se obtuvieron 270 aislamientos de MTC (tasa de incidencia de 11,63 casos/100.000 hab./ano). Segun datos epidemiologicos, se recogieron un total de 288 casos de TB (11,43 casos/100.000 hab./ano), 243 confirmados, 29 sospechosos y 16 probables. Predomina la localizacion pulmonar, seguida de lejos por la pleural y por el resto. Se procesaron un total de 27.620 muestras para micobacterias. En un 3,46% de los medios de cultivos liquidos se obtuvo crecimiento de micobacterias, y en un 50,37% la tincion directa (baciloscopia) fue positiva. Dieciseis aislamientos de Mycobacterium tuberculosis (MT) presentaron resistencia a algun farmaco antituberculoso, predominando la resistencia a isoniazida (5,92%). La provincia con mayor incidencia y numero de aislamientos fue Leon (24,23 casos/100.000 hab./ano), siendo la maxima en el area sanitaria de El Bierzo (30,46 casos/100.000 hab./ano). Conclusiones Una adecuada recogida de la informacion microbiologica es fundamental para el conocimiento de la epidemiologia de la TB en nuestra comunidad.

The convergence of tuberculosis and diabetes represents a co-epidemic that threatens progress against tuberculosis. We have investigated type 2 diabetes as a risk factor for tuberculosis susceptibility, and have used as experimental model whole blood infected in vitro with Mycobacterium tuberculosis. Blood samples from diabetic patients were found to have a higher absolute neutrophil count that non-diabetic controls, but their immune functionality seemed impaired because they displayed a lower capacity to phagocytose M. tuberculosis, a finding that had been previously reported only for monocytes. In contrast, an increased production of TNFα was detected in infected blood from diabetic patients. Despite the altered phagocytic capacity showed by cells from these patients, the antimicrobial activity measured in both whole blood and monocyte derived macrophages was similar to that of controls. This unexpected result prompts further improvements in the whole blood model to analyze the immune response of diabetes patients to tuberculosis.

The increasing worldwide incidence of mycobacteriosis and the need to achieve improved clinical management makes nontuberculous mycobacteria (NTM) genotyping a useful tool. However, because of technical difficulties, medium size microbiology laboratories do not attempt to compare the genetic patterns that each of their isolates present. We have aimed to optimize a genotyping method with a reduced hands-on experimental time and that requires few technical resources. A strategy based on the Amplified Fragment Length Polymorphism (AFLP) methodology was developed using two rare-cutters enzymes (SacI and BglII). One out of seven primers was sequentially used in each amplification reaction that was analyzed by agarose gel electrophoresis. This approach makes it possible the timely genotyping of a moderate number of strains and its characterization without the need of image analysis software. We have genotyped 28 Mycobacterium intracellulare and 4 M. abscessus. Clinical researchers are encouraged to routinely genotype their NTM isolates.

The whole blood model for infection has proven useful to analyze the immunological response to Mycobacterium tuberculosis, because it exerts a significant antimicrobial activity. Although this activity has been generally assumed to be cellular, we have found that the leukocyte fraction of blood from healthy volunteers did not kill the bacilli. We have discovered that plasma was responsible for a large proportion, but not all, of the antimicrobial activity. Furthermore, infected monocytes controlled the mycobacterial multiplication when cultivated in the presence of plasma. Intriguingly, serum from the same donors did not share this activity, although it was able to eliminate the non-pathogenic Mycobacterium gordonae To identify the remaining components that participate in the antimycobacterial activity we fractionated blood in leukocytes, plasma, erythrocytes and platelets, and analyzed the bactericidal power of each fraction and their combinations using a factorial design. We found that erythrocytes, but not platelets, participated and showed by flow cytometry that mycobacteria physically associated with erythrocytes. We propose that in exposed healthy individuals that show 'early clearance' of the mycobacteria, the innate response is predominantly humoral, probably through the effect of antimicrobial peptides and proteins.

Part of the susceptibility to tuberculosis has a genetic basis, which is clear in primary immunodeficiencies, but is less evident in apparently immunocompetent subjects. Immune responses were analysed in blood samples from tuberculosis patients and their healthy first-degree relatives who were infected in vitro with mycobacteria (either Mycobacterium tuberculosis or M. bovis BCG). The antimicrobial activity against M. tuberculosis in blood from relatives was significantly lower than that observed in healthy controls. Tuberculosis patients exhibited a higher number of neutrophils, and monocyte phagocytosis was inhibited in both relatives and tuberculosis patients. A remarkable finding was that the production of reactive oxygen species by infected neutrophils was higher in relatives than in healthy controls. A higher production of TNFα in infected blood from relatives was also observed. These results may indicate that relatives display a stronger inflammatory response and that their immune response to M. tuberculosis is different from those of unrelated controls. First-degree relatives may represent a highly informative group for the analysis of tuberculosis susceptibility.

It has been estimated that approximately 50% of individuals exposed to Mycobacterium tuberculosis never become tuberculin skin test positive, which may indicate that successful human immunological responses are able not only to inhibit mycobacterial growth, but also to kill the bacteria. Nevertheless, it has been extremely difficult to reproduce this effect in vitro and the ability of human phagocytes to eliminate the bacteria is controversial. This is one of the reasons why we do not fully understand either tuberculosis resistance or susceptibility. Nowadays there is a pressing need in tuberculosis vaccine research to find biomarkers of successful responses to tuberculosis and the use of in vitro models may allow the identification of the immunological mechanisms responsible for the mycobacterial killing that could be tested in clinical settings. Besides biosafety concerns, the manipulation of mycobacteria is technically very demanding, and the optimization of in vitro infection protocols have been difficult. As a result, there are a large number of variations in the methodology that make arduous the comparison of results obtained in different research groups. In this review an overview of the mycobacterial and human cellular models most frequently studied are presented, together with a description of several of the modifications tried in infection protocols, from the preparation of the inoculum to the quantification of surviving mycobacteria after infection. A comment about statistical methods that may improve the detection of relevant biological effects is also included.

In vitro analysis of mycobacterial pathogenicity or host susceptibility has traditionally relied on the infection of macrophages, the target cell of mycobacteria, despite difficulties reproducing their antimycobacterial activity. We have employed alternative models, namely whole blood and leukocytes in plasma, from QuantiFERON negative individuals, and performed infections with the pathogenic M. tuberculosis, the less pathogenic M. avium, M. kansasii and M. chelonae and the occasionally pathogenic M. gordonae and M. bovis. The anticoagulant used in blood extraction, heparin or EDTA, had a major influence in the outcome of the infection. Thus, while in the heparinized models a similar number of bacteria were enumerated in the inoculum and after seven days, in the presence of EDTA a killing effect was observed, despite the inhibitory effect of EDTA on cellular functions like the production of cytokines or reactive oxygen species (ROS). A special case was the rapidly growing mycobacteria M. chelonae, that multiplied in heparinized models but was eliminated in models with EDTA. We verified that EDTA is not responsible for the bactericidal effect, but acts as a bacteriostatic agent. Further work will determine whether blood derived models are a better alternative to the classical macrophage.

The whole blood model for infection has proven useful to analyze the immunological response to Mycobacterium tuberculosis, because it exerts a significant antimicrobial activity. Although this activity has been generally assumed to be cellular, we have found that the leukocyte fraction of blood from healthy volunteers did not kill the bacilli. We have discovered that plasma was responsible for a large proportion, but not all, of the antimicrobial activity. Furthermore, infected monocytes controlled the mycobacterial multiplication when cultivated in the presence of plasma. Intriguingly, serum from the same donors did not share this activity, although it was able to eliminate the non-pathogenic Mycobacterium gordonae To identify the remaining components that participate in the antimycobacterial activity we fractionated blood in leukocytes, plasma, erythrocytes and platelets, and analyzed the bactericidal power of each fraction and their combinations using a factorial design. We found that erythrocytes, but not platelets, participated and showed by flow cytometry that mycobacteria physically associated with erythrocytes. We propose that in exposed healthy individuals that show 'early clearance' of the mycobacteria, the innate response is predominantly humoral, probably through the effect of antimicrobial peptides and proteins.

The elderly account for a disproportionate share of all tuberculosis cases, and the population ageing may not fully explain this phenomenon. We have performed in vitro infection experiments to investigate whether there is an immunological basis for the apparent susceptibility of elders to tuberculosis. In our infection model, Mycobacterium tuberculosis induces a higher production of interleukin (IL)-6 and reactive oxygen species in macrophages from elders than from younger adults. This response did not prevent, however, an increased multiplication of M. tuberculosis in macrophages from elders as compared with the growth observed within cells from adults. By performing a factorial experiment, we have found that IFN-γ, but not IL-1β, IL-6 or TNF-α, stimulate the macrophages to restrict the multiplication of the bacterium in macrophages from elders. Although monocytes from elders seem to be in a higher level of activation, we present evidences that protein tyrosine phosphorylation response induced by M. tuberculosis is stronger in monocytes from adults than from elders. Using a protein array that detects 71 tyrosine phosphorylated kinases, we identified Pyk2 as the only kinase that displayed a difference of intensity larger than 50 % in adults than in elders. Furthermore, monocytes from elders that were incubated in the presence of tyrosine kinase inhibitors (genistein and PP2) allowed a higher level of bacterial multiplication. These observations may help to explain the susceptibility of elders to tuberculosis. An unexpected result was that both genistein and its negative control, daidzein, abundant soy isoflavones, promoted intracellular mycobacterial growth.

The use of cytokines for therapeutic purposes is limited by their high cost and toxicity. Nevertheless, the emergence of extensively drug-resistant tuberculosis (XDR TB), for which chemotherapy is ineffective, has again made cytokine-based therapy attractive as one of the last available options. The results of clinical trials treating pulmonary tuberculosis with cytokines have not been encouraging, making it clear that therapeutic strategies utilizing a single cytokine are inadequate. To develop effective cytokine-based XDR TB therapies, more basic research will be needed to achieve a better understanding of how cytokines promote a successful immune response. We not only have to investigate cytokines already known to participate in tuberculosis, but also the role of other cytokines and chemokines that may enhance both the mycobacterial killing activity of effector cells and the restriction of bacterial intracellular multiplication. There are already several patents involving cytokines for therapeutic use, in the hope of stimulating the immune system in a variety of infectious diseases, including tuberculosis. The validity of these patents needs to be reassessed from a clinical standpoint, and new applications of patents concerning cytokines potentially useful in XDR TB treatment should be encouraged.

Antimicrobial activity in human monocytes infected with Mycobacterium tuberculosis has been difficult to demonstrate in vitro, and the molecular mechanisms allowing the bacteria to survive intracellularly are unknown. As a means to test the influence of bacterial products in the microbicidal activity of monocytes we have developed an infection model with Legionella pneumophila, which is killed by interferon gamma activated cells. We demonstrate that this model is useful because M. tuberculosis lysates inhibit one hundred fold the interferon gamma induced activity against L. pneumophila. Comparable degrees of inhibition are also detected when we use lysates from the less pathogenic Mycobacterium gordonae and the pathogenic Staphylococcus aureus, suggesting the participation of a common mechanism. This hypothesis is supported by the fact that the pattern of cytokine secretion is similar in all cases. A significant difference is, however, observed when we used lysates from the non-pathogenic Escherichia coli, which resulted in the recovery of low numbers of bacteria, probably because they induce the cell death of infected monocytes.

Differences in the activity of monocytes/macrophages, important target cells of Mycobacterium tuberculosis, might influence tuberculosis progression. With the purpose of identifying candidate genes for tuberculosis susceptibility we infected monocytes from both healthy elderly individuals (a tuberculosis susceptibility group) and elderly tuberculosis patients with M. tuberculosis, and performed a microarray experiment. We detected 78 differentially expressed transcripts and confirmed these results by quantitative PCR of selected genes. We found that monocytes from tuberculosis patients showed similar expression patterns for these genes, regardless of whether they were obtained from younger or older patients. Only one of the detected genes corresponded to a cytokine: IL26, a member of the interleukin-10 (IL-10) cytokine family which we found to be down-regulated in infected monocytes from tuberculosis patients. Non-infected monocytes secreted IL-26 constitutively but they reacted strongly to M. tuberculosis infection by decreasing IL-26 production. Furthermore, IL-26 serum concentrations appeared to be lower in the tuberculosis patients. When whole blood was infected, IL-26 inhibited the observed pathogen-killing capability. Although lymphocytes expressed IL26R, the receptor mRNA was not detected in either monocytes or neutrophils, suggesting that the inhibition of anti-mycobacterial activity may be mediated by lymphocytes. Additionally, IL-2 concentrations in infected blood were lower in the presence of IL-26. The negative influence of IL-26 on the anti-mycobacterial activity and its constitutive presence in both serum and monocyte supernatants prompt us to propose IL26 as a candidate gene for tuberculosis susceptibility.

rZIP is an approx. 32 kDa, multi-domain protein of Dictyostelium discoideum whose structural motifs include a RING (zinc-binding) domain, a leucine zipper, a glutamine repeat, an SH3-binding region and a consensus phosphorylation site for MAP kinase. In vitro, rZIP forms homodimers and interacts specifically with the SH3 domain(s) of the Nck adaptor protein. rZIP is expressed maximally during cell differentiation at approximately equivalent levels in all cells. Disruption of the rZIP gene rzpA results in altered cellular aggregation, impaired slug migration, and aberrant patterning of prespore and prestalk cells, the major progenitor classes. In rzpA− strains, presporespecific genes are overexpressed and prestalk expression zones are reduced. Conversely, constitutive overexpression of rzpA markedly decreases prespore-specific gene expression and significantly increases the expression of prestalk-specific genes. Further, induced transdifferentiation of prespore cells into prestalk cells is inhibited in rzpA− slugs. In light of these patterning defects, we suggest that the RING/zipper protein rZIP plays an important role in early cell fate decisions in Dictyostelium, acting as a positive regulator of prestalk differentiation and an inhibitor of prespore differentiation.

We have recently identified the protein product of the c-cbl proto-oncogene as an SH3 binding protein expressed in macrophages. To investigate the possibility that p120c-cbl is involved in signaling pathways initiated by cell surface receptors for IgG (Fc gamma R), lysates of HL60 cells were examined for tyrosine phosphorylation of p120c-cbl upon Fc gamma R engagement. Our findings demonstrate that p120c-cbl is tyrosine-phosphorylated upon Fc gamma R engagement and that this molecule represents the major tyrosine kinase substrate in this signaling pathway. Protein complexes containing p120c-cbl, p72syk, and p56lyn were observed either in resting or activated cells. In vitro studies showed that the direct association between p120c-cbl and p56lyn was mediated by the SH3 domain of p56lyn.

Hemos investigado el papel de CXCL7 en la respuesta inmune de los fagocitos humanos contra las bacterias intracelulares Mycobacterium tuberculosis y Legionella pneumophila. Observando que los neutrófilos polimorfonucleares (PMN) quimiotaxis inducida por los sobrenadantes de los macrófagos derivados de monocitos infectados (MDM) puede ser atribuido a CXCL8 en lugar de CXCL7, aunque ambas quimiocinas están presentes en grandes cantidades. También hemos encontrado que CXCL7 está presente no sólo en los sobrenadantes de MDM, sino también en los sobrenadantes de PMN de algunos, pero no todos, los individuos. El análisis de transferencia reveló que, en ambos sobrenadantes de MDM y PMN apareció dos bandas con pesos moleculares consistentes con la proteína básica de plaquetas (PBP) y la proteína activadora de neutrófilos-2 tamaños (NAP-2). En cuanto a la influencia en las células infectadas, NAP-2 recombinante mejora la actividad antimicrobiana de IFNI activa MDM contra L. pneumophila, pero no contra M. tuberculosis. Además, las células U937 transfectadas con una construcción de NAP-2 inhibe la multiplicación intracelular de L. pneumophila, apoyando su papel en la modulación de la actividad antimicrobiana. Finalmente, Las células U937 transfectadas con el constructo NAP-2 mostraron una adhesión que fue aumenta drásticamente cuando se fibronectina sustrato. Se concluye que la humana fagocitos producen variantes CXCL7 que pueden tener una influencia significativa en el respuesta inmune contra los patógenos bacterianos

Summary CCL20 is a chemokine that attracts immature dendritic cells. We show that monocytes, cells characteristic of the innate immune response, infected with Mycobacterium tuberculosis express the CCL20 gene at a much higher level than the same cells infected with non-tuberculous mycobacteria. Interferon (IFN)-γ, a fundamental cytokine in the immune response to tuberculosis, strongly inhibits both the transcription and the translation of CCL20. We have also confirmed that dendritic cells are a suitable host for mycobacteria proliferation, although CCL20 does not seem to influence their intracellular multiplication rate. The chemokine, however, down-regulates the characteristic production of reactive oxygen species (ROS) induced by M. tuberculosis in monocytes, which may affect the activity of the cells. Apoptosis mediated by the mycobacteria, possibly ROS-dependent, was also inhibited by CCL20.

Non-pathogenic mycobacteria, like Mycobacterium gordonae, are rarely associated to disease. The analysis of the mechanisms which are successful against them in the human host may provide useful information to understand why they fail against the pathogenic M. tuberculosis. We have developed an infection model to test the ability of human phagocytes to kill two strains of M. gordonae, HL184G and an attenuated variety, HL184Gat. As controls we included a strain of M. tuberculosis (HL186T) and another one of L. pneumophila (ATCC13151). We observed that human phagocytes lack the intrinsic ability to eliminate either M. gordonae or M. tuberculosis, but they can kill the attenuated strain. We found a relationship between pathogenicity and the pattern of cytokine production. Thus, both the pathogenic M. tuberculosis and Legionella pneumophila, but not the non-pathogenic M. gordonae, induced the production of significantly different levels of IL-1beta, IL-6 and TNF-alpha in monocytes and IL-8 in neutrophils. Although both monocytes and neutrophils killed HL184Gat, but not HL184G, the patterns of cytokine production induced by either strain were identical. Addition of INF-gamma and/or TNF-alpha did not enhance the antimycobacterial activity of phagocytes.

A method for the rapid screening of drugs targeting the bioenergetic metabolism of Leishmania spp. was developed. The system is based on the monitoring of changes in the intracellular ATP levels of Leishmania donovani promastigotes that occur in vivo, as assessed by the luminescence produced by parasites transfected with a cytoplasmic form of Phothinus pyralis luciferase and incubated with free-membrane permeable D-luciferin analogue D-luciferin-[1-(4,5-dimethoxy-2-nitrophenyl) ethyl ester]. A significant correlation was obtained between the rapid inhibition of luminescence with parasite proliferation and the dissipation of changes in mitochondrial membrane potential (ΔΨm) produced by buparvaquone or plumbagin, two leishmanicidal inhibitors of oxidative phosphorylation. To further validate this test, a screen of 14 standard leishmanicidal drugs, using a 50 μM cutoff, was carried out. Despite its semiquantitative properties and restriction to the promastigote stage, this test compares favorably with other bioenergetic parameters with respect to time and cell number requirements for the screening of drugs that affect mitochondrial activity., This work was supported by grants from the Fondo de Investigaciones Sanitarias (99/0025-02), the Comunidad Autónoma de Madrid Programa General de Grupos Estratégicos, and grants 08-2/0029.2,and EU IC 18-CT97-0213 to L.R. and from Sir Halley Stewart Trust to S.L.C.

In order to determine whether in vitro Leishmania exposure to conditions comparable to those encountered inside the host cell would induce specific signals, we have studied tyrosine phosphorylation patterns in Leishmania pifanoi. Incubation of L. pifanoi at acidic pH resulted in the phosphorylation of several proteins including three of 27, 43 and 51 kDa, as well as the dephosphorylation of a 175 and a 39 kDa proteins in promastigotes recently transformed. In contrast, heat shock at 37 degrees C did not change the tyrosine phosphorylation pattern. Phosphorylation only occurs at pH 5.0 or lower and reached completion after 1 h. Changes returned to the initial conditions in 2 h after pH medium neutralization, indicating a reversible mechanism of phosphorylation.

As an approach toward identification and isolation of cellular proteins that may act as substrates or effectors of the SRC-family of protein-tyrosine kinases, fusion proteins containing noncatalytic elements of two highly related SRC-family members were tested for their ability to recognize distinct molecules present in lysates of cells known to normally express both enzymes. Our results demonstrate differences of protein binding between the SH2 elements of FYN and FGR kinases, but do not discriminate proteins binding to their SH3 domains.

We have cloned a new gene, cbl-b, with homology to the c-cbl proto-oncogene. A large protein is predicted (approx. MW 108,000) that has a proline rich domain, a nuclear localization signal, a C3HC4 zinc finger and a putative leucine zipper. There is striking nucleotide and amino acid homology to the c-cbl proto-oncogene most notably in the structural motifs described above. Cbl-b is expressed in normal and malignant mammary epithelial cells, in a variety of normal tissues, and in hematopoietic tissue and cell lines. Cbl-b expressions is up-regulated with macrophage/monocyte differentiation of the HL60 and U937 cell lines. There is direct association of the cbl-b protein with the Src Homology 3 domains of several proteins including signaling, cytoskeletal and adaptor proteins. Our data suggest that cbl-b encodes a protein which can interact with signal transduction proteins to regulate their function or to be regulated by them. Together, cbl-b and c-cbl are members of a novel family of proto-oncogenes involved in signal transduction.

To investigate the nature of proteins recognized by Src homology 3 (SH3) domains, a cDNA expression library was prepared from macrophages and screened with a probe representing the three SH3 domains of p47nck. Two clones were isolated, and one, designated SAKAP I (for Src A box Nck-associated protein I), contained the carboxyl-terminal half of the cbl proto-oncogene product. Studies in vitro demonstrated reactivity between SAKAP I and SH3 domains derived from a variety of molecules. Wide variations in this assay suggested a high degree of specificity inherent in SAKAP I binding. Moreover, it was possible to demonstrate an in vivo association between p47nck and p120c-cbl in HL60 cells. These findings suggest that proteins containing SH3 elements regulate Cbl function.

In the second of a series of experiments designed to identify p47nck-Src homology 3 (SH3)-binding molecules, we report the cloning of SAKAP II (Src A box Nck-associated protein II) from an HL60 cDNA expression library. This molecule has been identified as a cDNA encoding the protein product of WASP, which is mutated in Wiskott-Aldrich syndrome patients. Studies in vivo and in vitro demonstrated a highly specific interaction between the SH3 domains of p47nck and Wiskott-Aldrich syndrome protein. Furthermore, anti-Wiskott-Aldrich syndrome protein antibodies recognized a protein of 66 kDa by Western blot (immunoblot) analysis. In vitro translation studies identified the 66-kDa protein as the protein product of WASP, and subcellular fractionation experiments showed that p66WASP is mainly present in the cytosol fraction, although significant amounts are also present in membrane and nuclear fractions. The main p47nck region implicated in the association with p66WASP was found to be the carboxy-terminal SH3 domain.

To investigate the nature of proteins recognized by Src homology 3 (SH3) domains, a cDNA expression library was prepared from macrophages and screened with a probe representing the three SH3 domains of p47nck. Two clones were isolated, and one, designated SAKAP I (for Src A box Nck-associated protein I), contained the carboxyl-terminal half of the cbl proto-oncogene product. Studies in vitro demonstrated reactivity between SAKAP I and SH3 domains derived from a variety of molecules. Wide variations in this assay suggested a high degree of specificity inherent in SAKAP I binding. Moreover, it was possible to demonstrate an in vivo association between p47nck and p120c-cbl in HL60 cells. These findings suggest that proteins containing SH3 elements regulate Cbl function.