MASTer cell: chief immune modulator and inductor of antimicrobial immune response.

Mast cells have long been recognized for their involvement in allergic pathology through the immunoglobulin E (IgE)-mediated degranulation mechanism. However, there is growing evidence of other "non-canonical" degranulation mechanisms activated by certain pathogen recognition receptors. Mast cells release several mediators, including histamine, cytokines, chemokines, prostaglandins, and leukotrienes, to initiate and enhance inflammation. The chemical nature of activating stimuli influences receptors, triggering mechanisms for the secretion of formed and new synthesized mediators. Mast cells have more than 30 known surface receptors that activate different pathways for direct and indirect activation by microbes. Different bacterial strains stimulate mast cells through various ligands, initiating the innate immune response, which aids in clearing the bacterial burden. Mast cell interactions with adaptative immune cells also play a crucial role in infections. Recent publications revealed another "non-canonical" degranulation mechanism present in tryptase and chymase mast cells in humans and connective tissue mast cells in mice, occurring through the activation of the Mas-related G protein-coupled receptor (MRGPRX2/b2). This receptor represents a new therapeutic target alongside antibiotic therapy. There is an urgent need to reconsider and redefine the biological role of these MASTer cells of innate immunity, extending beyond their involvement in allergic pathology.

Antimicrobial peptides´ immune modulation role in intracellular bacterial infection.

Intracellular bacteria cause a wide range of diseases, and their intracellular lifestyle makes infections difficult to resolve. Furthermore, standard therapy antibiotics are often unable to eliminate the infection because they have poor cellular uptake and do not reach the concentrations needed to kill bacteria. In this context, antimicrobial peptides (AMPs) are a promising therapeutic approach. AMPs are short cationic peptides. They are essential components of the innate immune response and important candidates for therapy due to their bactericidal properties and ability to modulate host immune responses. AMPs control infections through their diverse immunomodulatory effects stimulating and/or boosting immune responses. This review focuses on AMPs described to treat intracellular bacterial infections and the known immune mechanisms they influence.

A combined antitumor strategy of separately transduced mesenchymal stem cells with soluble TRAIL and IFNß produces a synergistic activity in the reduction of lymphoma and mice survival enlargement.

As the understanding of cancer grows, new therapies have been proposed to improve the well-known limitations of current therapies, whose efficiency relies mostly on early detection, surgery and chemotherapy. Mesenchymal stem cells (MSCs) have been introduced as a promissory and effective therapy. This fact is due to several useful features of MSCs, such as their accessibility and easy culture and expansion in vitro, and their remarkable ability for 'homing' towards tumors, allowing MSCs to exert their anticancer effects directly into tumors. Additionally, MSCs offer the practicability of being genetically engineered to carry anticancer genes, increasing their specificity and efficacy for fighting tumors. In the present study, the antitumoral efficacy and post-implant survival of mice bearing lymphomas implanted intratumorally were determined using mouse bone marrow-derived (BM)-MSCs transduced with soluble TRAIL (sTRAIL), full length TRAIL (flTRAIL), or interferon ß (IFNß), naïve BM-MSCs, or combinations of these. The percentage of surviving mice was determined once all not-implanted mice succumbed. It was found that the percentage of surviving mice implanted with the combination of MSCs-sTRAIL and MSCs-IFN-ß was 62.5%. Lymphoma model achieved 100% fatality in the non-treated group by day 41. On the other hand, the percentage of surviving mice implanted with MSCs-sTRAIL was 50% and with MSCs-INFß 25%. All the aforementioned differences were statistically significant (P<0.05). In conclusion, all implants exhibited tumor size reduction, growth delay, or apparent tumor clearance. MSCs proved to be effective anti-lymphoma agents; additionally, the combination of soluble TRAIL and IFN-ß resulted in the most effective antitumor and life enlarging treatment, showing an additive antitumoral effect compared with individual treatments.

Near misdiagnosis of acute HIV-infection with ELISA-Western Blot scheme: Time for mindset change.

Some HIV-infection diagnostic guidelines and health care providers still rely on the ELISA-Western blot diagnostic algorithm. We present a near misdiagnosis case with discordant test results and a lack of proper counseling. We point out the need for an assertive update of health care providers on diagnostic HIV-tests.

The prognostic significance of serum XCL1 concentration in patients with acute lymphoblastic leukemia: a pilot study.

There is no information about XCL1 in patients with acute lymphoblastic leukemia (ALL). The objective of this study was to correlate the serum levels of XCL1 and survival in ALL patients. Only ALL patients older than 12 months were considered to participate. Serum XCL1 was measured at diagnosis, end of remission induction, and end of consolidation. Thirty-three ALL patients with median age of 21 years (1-78) were included. Higher XCL1 level (above 50 pg/mL) at ALL diagnosis correlated with higher survival (p = 0.038), whereas XCL1 level at end of induction and consolidation had no significant correlation. Concerning the behavior of serum XCL1 during treatment, higher survival at 5 years was observed in the group with progressively decreased levels of XCL1 (70%) than those with progressively increasing (29%) or no detectable XCL1 (14%). In conclusion, higher serum XCL1 levels at diagnosis and their progressive decline throughout chemotherapy could be correlated with higher survival.

Experimental Granulomatous Pulmonary Nocardiosis in BALB/C Mice.

Pulmonary nocardiosis is a granulomatous disease with high mortality that affects both immunosuppressed and immunocompetent patients. The mechanisms leading to the establishment and progression of the infection are currently unknown. An animal model to study these mechanisms is sorely needed. We report the first in vivo model of granulomatous pulmonary nocardiosis that closely resembles human pathology. BALB/c mice infected intranasally with two different doses of GFP-expressing Nocardia brasiliensis ATCC700358 (NbGFP), develop weight loss and pulmonary granulomas. Mice infected with 109 CFUs progressed towards death within a week while mice infected with 108 CFUs died after five to six months. Histological examination of the lungs revealed that both the higher and lower doses of NbGFP induced granulomas with NbGFP clearly identifiable at the center of the lesions. Mice exposed to 108 CFUs and subsequently to 109 CFUs were not protected against disease severity but had less granulomas suggesting some degree of protection. Attempts to identify a cellular target for the infection were unsuccessful but we found that bacterial microcolonies in the suspension used to infect mice were responsible for the establishment of the disease. Small microcolonies of NbGFP, incompatible with nocardial doubling times starting from unicellular organisms, were identified in the lung as early as six hours after infection. Mice infected with highly purified unicellular preparations of NbGFP did not develop granulomas despite showing weight loss. Finally, intranasal delivery of nocardial microcolonies was enough for mice to develop granulomas with minimal weight loss. Taken together these results show that Nocardia brasiliensis microcolonies are both necessary and sufficient for the development of granulomatous pulmonary nocardiosis in mice.

Mycetoma medical therapy.

Medical treatment of mycetoma depends on its fungal or bacterial etiology. Clinically, these entities share similar features that can confuse diagnosis, causing a lack of therapeutic response due to inappropriate treatment. This review evaluates the response to available antimicrobial agents in actinomycetoma and the current status of antifungal drugs for treatment of eumycetoma.

Nocardia brasiliensis induces formation of foamy macrophages and dendritic cells in vitro and in vivo.

Foamy cells have been described in various infectious diseases, for example in actinomycetoma induced by Nocardia brasiliensis. These cells are generally considered to be macrophages, although they present dendritic cell (DC)-specific surface markers. In this study, we determined and confirmed the lineage of possible precursors of foamy cells in vitro and in vivo using an experimental actinomycetoma model in BALB/c mice. Bone marrow-derived macrophages (BMDM) or DC (BMDC) were infected in vitro with N. brasiliensis or labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE). Both, macrophages and DC, differentiated into foamy cells after in vitro infection. CFSE-labeled BMDM or BMDC were tested for phagocytosis and CD11c/CD11b receptors markers expression before being transferred into the actinomycetoma lesion site of infected mice. In vivo studies showed that BMDM and BMDC were traced at the site where foamy cells are present in the experimental actinomycetoma. Interestingly, many of the transferred BMDM and BMDC were stained with the lipid-droplet fluorophore Nile Red. In conclusion, macrophages and DC cells can be differentiated into foamy cells in vitro and in vivo during N. brasiliensis infection.

Current treatment for nocardia infections.

INTRODUCTION: Nocardiosis is an infectious actinomycetic disease with a variable clinical spectrum that makes it difficult to diagnose. It mainly affects immunosuppressed individuals. Advances in molecular genomic technology have helped in identifying new pathogenic Nocardia species. This has made identification of their specific antimicrobial sensitivity possible. AREAS COVERED: It is important to know the taxonomy, clinical features, diagnosis and precise species identification because of the multitude of pathogenic species involved and the different antibiotic susceptibility patterns. The authors review sulfonamides, aminoglycosides, penicillin derivatives, tetracyclines, glycylcyclines, oxazolidinones, carbapenems and the association of other potential drugs, the therapeutic effectiveness of traditional antimicrobials and new monotherapy and combined treatment alternatives. New oxazolidinones and the benzothiazinones are compounds that have been found effective in vitro and in experimental models. EXPERT OPINION: Clinicians should be aware of nocardiosis in patients with different forms of immunosuppression. The identification of organisms, their patterns of antibiotic susceptibility and the adverse effects related to these drugs must be considered. Treatments can vary from traditional schemes with trimethoprim-sulfamethoxazole to other combination therapies and new antibiotics and treatment modalities depending on the organ or site involved, the severity of infection and the presence of comorbidities.

Systemic increased immune response to Nocardia brasiliensis co-exists with local immunosuppressive microenvironment.

Human diseases produced by pathogenic actinomycetes are increasing because they may be present as opportunistic infections. Some of these microbes cause systemic infections associated with immunosuppressive conditions, such as chemotherapy for cancer, immunosuppressive therapy for transplant, autoimmune conditions, and AIDS; while others usually cause localized infection in immunocompetent individuals. Other factors related to this increase in incidence are: antibiotic resistance, not well defined taxonomy, and a delay in isolation and identification of the offending microbe. Examples of these infections are systemic disease and brain abscesses produced by Nocardia asteroides or the located disease by Nocardia brasiliensis, named actinomycetoma. During the Pathogenic Actinomycetes Symposium of the 16th International Symposium on Biology of Actinomycetes (ISBA), held in Puerto Vallarta, Mexico, several authors presented recent research on the mechanisms by which N. brasiliensis modulates the immune system to survive in the host and advances in medical treatment of human actinomycetoma. Antibiotics and antimicrobials that are effective against severe actinomycetoma infections with an excellent therapeutic outcome and experimental studies of drugs that show promising bacterial inhibition in vivo and in vitro were presented. Here we demonstrate a systemic strong acquired immune response in humans and experimental mice at the same time of a local dominance of anti inflammatory cytokines environment. The pathogenic mechanisms of some actinomycetes include generation of an immunosuppressive micro environment to evade the protective immune response. This information will be helpful in understanding pathogenesis and to design new drugs for treatment of actinomycetoma.

Host defenses in subcutaneous mycoses.

Subcutaneous mycoses include diverse clinical syndromes, characterized by invasion of the skin and subcutaneous tissue by saprobic fungi. Individuals living in rural areas constantly suffer lesions or trauma; however, only a few of them develop disease. In this contribution, we describe recent advances in the understanding of the virulence of these organisms, focusing on the most prevalent infections, sporotrichosis, chromoblastomycosis, and mycetoma. Although these infectious diseases are considered neglected tropical diseases, modern molecular techniques have been able to identify the etiologic agents and observe variations in the former monolithic concept of the species, which was based mostly on morphologic characteristics. The complete genetic characterization of the causative agents, along with that of their host, will help in the understanding of the factors on which the development of these infections depends.

Antineutrophil cytoplasm autoantibodies in patients with tuberculosis are directed against bactericidal/permeability increasing protein and are detected after treatment initiation.

OBJECTIVES: To determine the prevalence of antineutrophil cytoplasm autoantibodies (ANCA) and its antigenic specificities in sera of patients with pulmonary tuberculosis (Tb) before and after treatment. PATIENTS AND METHODS: Sixty-eight patients with culture-proven Tb were studied for the presence of ANCA, both by indirect immunofluorescence (IIF) and ELISA against proteinase-3 (PR3), myeloperoxidase (MPO) and bactericidal/permeability increasing protein (BPI). They were sought before treatment and in 52 of them also after therapy for the infection. High sensitivity C-reactive protein (CRP) was also measured at both times. RESULTS: ANCA by IIF were found in 3/68 (4.4%) sera prior to treatment, one C-ANCA and two P-ANCA, all recognizing BPI. After treatment, this increased to 15/52 (28.8%), 3 C-ANCA and 12 P-ANCA, the majority directed against BPI (11/15, 73%). BPI-ANCA were positive in 6/68 (8.8%) and 15/52 (28.8%) before and after Tb after treatment initiation (p=0.003). PR3-ANCA and MPO-ANCA were negative in all Tb sera. A positive ANCA test correlated with CRP as inflammatory marker (p=0.001). CONCLUSIONS: The prevalence of ANCA in culture positive Tb patients is modified by Tb chemotherapy. BPI is the main target antigen for ANCA in tuberculosis and BPI-ANCA increase after treatment.

Mycetoma.

Mycetoma is a granulomatous infection affecting mainly the feet and lower extremities. It can be caused either by aerobic, branched actinomycetes or by eumycetes. Most cases are found in tropical and subtropical regions. The infection is usually produced by the introduction of the etiologic agents through minor wounds caused by thorns and wood splinters. Clinically the disease begins as small, firm nodules that can enlarge to form extensive lesions with fistulae and abscesses with pus containing granules of the causative microorganisms. Antimicrobials and surgery are used in the management of mycetoma. The actinomycetomas generally respond well to antimicrobials. For eumycetomas, surgery may be required. New therapeutic options for drug-resistant cases are discussed.

Expression of Nocardia brasiliensis superoxide dismutase during the early infection of murine peritoneal macrophages.

Nocardia brasiliensis is the main agent of actinomycetoma in Mexico, but little is known about its virulence and molecular pathogenic pathways. These facultative intracellular bacteria are able to survive and divide within the host phagocytic cells, in part by neutralizing the reactive oxygen intermediates. Superoxide dismutase (SOD) participates in the intracellular survival of several bacterial species and, in particular, constitutes one of Nocardia asteroides virulence factors. To clarify SOD participation in the N. brasiliensis early infective process, we report its isolation and the consequent comparison of its transcript level. A 630 bp polymerase chain reaction fragment that included most of the coding sequence of N. brasiliensis sodA was cloned. A competitive assay was developed, allowing comparison of bacterial sod expression in exponential culture and 1 h after infecting peritoneal macrophages from BALB/c mice. At that time, there were viable bacteria in the macrophages. The intracellular bacteria presented a clear decrease in their sod transcript amount, although their 16S rRNA (used as an internal control) and hsp levels were maintained or slightly increased, respectively. These results indicate that sodA transcription is not maintained within the SOS bacterial response induced by phagosomal conditions. Further kinetics will be necessary to precisely define sod transcriptional regulation during N. brasiliensis intra-macrophage growth.

Immunogenicity and biophysical properties of a Nocardia brasiliensis protease involved in pathogenesis of mycetoma.

We isolated and purified to homogeneity a caseinolytic protease from a Nocardia brasiliensis cell extract. Preparative polyacrylamide gel electrophoresis and electroelution were employed for purification. This purified protease was injected in BALB/c mice and induced IgM and IgG anti-protease antibodies. Active immunization of mice with this protease prevented mycetoma development in experimentally infected animals. Passive immunization with hyperimmune sera containing a high anti-protease antibody titer conferred partial but transient protection when collected 30 days after donor's immunization. The protective effect of hyperimmune sera was lost when obtained from donors after 60 days from their immunization despite its higher anti-protease antibody concentration. Cytokines are good candidates to explain these findings.

6,6'-Dimycoloyl trehalose from a rapidly growing Mycobacterium: an alternative antigen for tuberculosis serodiagnosis.

Mycobacterial O-acyltrehaloses have been described as highly specific and sensitive reagents for tuberculosis immunodiagnosis. An O-acyltrehalose-containing lipid fraction from the rapidly growing Mycobacterium fortuitum was found to include additional antigens, which presented high cross-reactivity with sera from tuberculosis-infected patients. Based on a combination of selective chemical degradations, thin-layer-chromatography analyses and (1)H-nuclear magnetic resonance spectroscopy, the antigenic by-product was identified as 6,6'-dimycoloyl trehalose, the so-called cord factor. The lipid was purified and tested in ELISA for pulmonary tuberculosis serodiagnosis. Sensitivity and specificity of the test were found to be 66.6-74.1% and 95.2-99.0%, respectively, showing a slightly higher efficiency as compared to the ELISA performed using 6,6'-dimycoloyl trehalose from Mycobacterium tuberculosis. No cross-reactivity was found with sera from Nocardia-infected individuals.

Anticuerpos Anti-nocardia brasiliensis en pacientes con actinomicetoma y su utilidad clínica / Anti-Nocardia brasiliensis antibodies in patients with actinomycetoma an their clinical usefulness

El objetivo de este trabajo es determinar la respuesta de anticuerpos anti-Nocardia brasiliensis en pacientes con actinomicetoma y conocer su utilidad clínica. Se preparó un extracto celular de la cepa de N. brasiliensis identificada como Hospital Universitario José Eleuterio González, HUJEG-1 y registrada como ATCC # 700358. Las proteínas del extracto se transfirieron a papel de nitrocelulosa, las tirillas se incubaron con suero de pacientes con micetoma, tuberculosis, lepra o con sueros de personas sanas. Se identificaron los antígenos inmunodominantes y de ellos se decidió escoger a la P24 para una prueba inmunoenzimática en fase sólida (ELISA), también se aisló una proteasa y se utilizó como antígeno. Los valores de absorbancia de los sueros de pacientes con micetoma activo fueron superiores a 0.3 con la P24 como antígeno y variables contra la proteasa. Los pacientes con micetoma curados mostraron valores iguales a los de las personas sanas, se confirma la utilidad clínica de la prueba de ELISA para el diagnóstico serológico y para evaluar la respuesta al tratamiento cuando se usa el antígeno P24 pero no cuando se usa la proteasa. Esta es la única prueba en el mundo que es específica y sensible para uso clínico de rutina.

Anticuerpos anti-virus linfotrópicos de células T humanas en sujetos de alto riesgo para la infección por VIH en Monterrey / Anti-HTLV-1/2 antibodies in a population of high risk for HIV infection in Monterrey, Mexico

El VIH es el agente etiológico del síndrome de la inmunodeficiencia adquirida o SIDA y el HTLV-1 se ha asociado a la leucemia/linfoma de las células T de adultos y a la paraparesis espástica tropical. En México existe poca información sobre la incidencia de la infección por HTLV-1. En el presente trabajo buscamos la presencia de anticuerpos dirigidos contra HTLV-1 en 100 sueros de pacientes de alto riesgo para la infección por VIH, del área de Monterrey, N. L. En 93 sueros se detectaron anticuerpos anti VIH y dos dieron resultados indeterminados por inmunoelectrotransferencia. Tres sueros VIH positivos dieron también positiva la prueba de aglutinación para HTLV-1; sin embargo, en la prueba confirmatoria de inmunoelectrotransferencia, las tres muestras resultaron negativas para HTLV-1