Secrets and lies of host-microbial interactions: MHC restriction and trans-regulation of T cell trafficking conceal the role of microbial agents on the edge between health and multifactorial/complex diseases.

Here we critically discuss data supporting the view that microbial agents (pathogens, pathobionts or commensals alike) play a relevant role in the pathogenesis of multifactorial diseases, but their role is concealed by the rules presiding over T cell antigen recognition and trafficking. These rules make it difficult to associate univocally infectious agents to diseases' pathogenesis using the paradigm developed for canonical infectious diseases. (Cross-)recognition of a variable repertoire of epitopes leads to the possibility that distinct infectious agents can determine the same disease(s). There can be the need for sequential infection/colonization by two or more microorganisms to develop a given disease. Altered spreading of infectious agents can determine an unwanted activation of T cells towards a pro-inflammatory and trafficking phenotype, due to differences in the local microenvironment. Finally, trans-regulation of T cell trafficking allows infectious agents unrelated to the specificity of T cell to modify their homing to target organs, thereby driving flares of disease. The relevant role of microbial agents in largely prevalent diseases provides a conceptual basis for the evaluation of more specific therapeutic approaches, targeted to prevent (vaccine) or cure (antibiotics and/or Biologic Response Modifiers) multifactorial diseases.

Study of the effects of Lemna minor extracts on human immune cell populations.

OBJECTIVE: Lemna minor is a plant with a huge repertoire of secondary metabolites. The literature indicates that extracts of Lemna minor have antioxidant, antiradical, immunomodulatory and anti-inflammatory properties. The objective of the present study was to find a suitable technique to extract active compounds from this plant and verify whether these extracts have immunomodulatory activity. MATERIALS AND METHODS: We grew L. minor on a standard medium with Gamborg B5 and vitamins. We extracted compounds from the plant by maceration and decoction. The phytochemical profile of the extracts was characterized by chromatography, spectrophotometry, and spectroscopy. The extracts were tested on cultures of mononuclear cells from four human subjects. These cells were pulsed with carboxyfluorescein succinimidyl ester, grown in triplicate in standard culture medium without (control) and with increasing concentrations of Lemna extracts. Flow cytometry was used to evaluate cell death and proliferation of the total mononuclear cell population and of CD4+, CD8+, B cell and monocyte populations. RESULTS: The Lemna extracts were not cytotoxic and did not cause cell necrosis or apoptosis in immune cells. At low concentrations, they induced very limited proliferation of CD4+ cells within 48 hours. At high concentrations, they induced proliferation of CD8+ cells and B lymphocytes within 48 hours. CONCLUSIONS: Unfortunately, we failed to confirm any immunomodulatory activity of Lemna extracts. Growth and death rates of human immune cells were not significantly affected by adding Lemna extracts to the culture medium.

Skewed T-cell receptor repertoire: more than a marker of malignancy, a tool to dissect the immunopathology of inflammatory diseases.

The highly diverse heterodimeric surface T cell receptor (TCR) gives the T lymphocyte its specificity for MHC-bound peptides needed to initiate antigen-recognition. In normal peripheral blood, spleen and lymph nodes, the TCR repertoire of the T lymphocytes is usually polyclonal. However, in malignancies such as leukemias, as well as in lymphoproliferative diseases of mature T cells, the TCR is a reflection of the clonality of the malignant cells and is therefore monoclonal. Several clinical conditions (mainly solid tumors and autoimmune diseases) have been described where the TCR repertoire is restricted. The ability to demonstrate clonal TCR usage provides a useful tool to dissect the immunopathology of inflammatory diseases. In this review we discuss these findings and propose to sub-divide diseases with restricted TCR repertoire into a group of conditions in which there is a known TCR ligand, as opposed to diseases in which the restricted TCR repertoire is the result of impaired T-cell development. This classification sheds light on the pathogenesis of several inflammatory diseases.

Androgen receptors are required for full masculinization of nitric oxide synthase system in rat limbic-hypothalamic region.

The neuronal nitric oxide synthase (nNOS) is involved in the control of male and female sexual behavior and its distribution in several regions of the limbic-hypothalamic system, as well as its coexistence with gonadal hormones' receptors, suggests that these hormones may play a significant role in controlling its expression. However, data illustrating the role of gonadal hormones in controlling the nNOS expression are, at present, contradictory, even if they strongly suggest an involvement of testosterone (T) in the regulation of nNOS. The action of T may be mediated through androgen (AR) or, after aromatization to estradiol (E(2)), through estrogen receptors. To elucidate the role of AR on nNOS expression, we compared male and female rats with a non-functional mutation of AR (Tfm, testicular feminization mutation) to their control littermates. We investigated some hypothalamic and limbic nuclei involved in the control of sexual behavior [medial preoptic area (MPA), paraventricular (PVN), arcuate (ARC), ventromedial (VMH) and stria terminalis (BST) nuclei]. In BST (posterior subdivision), VMH (ventral subdivision), and MPA we detected a significant sexual dimorphism in control animals and a decrease of nNOS positive elements in Tfm males compared to their littermate. In addition, we observed a significant increase of nNOS positive elements in BST (posterior) of Tfm females. No significant changes were observed in the other nuclei. These data indicate that, contrary to current opinions, androgens, through the action of AR may have a relevant role in the organization and modulation of the nNOS hypothalamic system.

Effect of cloricromene on intermittent claudication. A randomized, double-blind, placebo-controlled trial in patients treated with aspirin: effect on claudication distance and quality of life. CRAMPS Investigator Group. Cloricromene Randomized Arteriopathy Multicenter Prospective Study.

The main aim of medical treatment for intermittent claudication (IC) is the reduction of mortality and morbidity from ischemic cardiovascular disease. However, symptomatic treatment with the aim of improving exercise performance and the overall quality of life may also be an important target of the clinical management of patients with intermittent claudication. Cloricromene, a drug with antithrombotic and anti-ischemic activities, has previously shown some promising results in patients with claudication. We have carried out a clinical trial to assess the effect of cloricromene on the claudication distance and on the quality of life of patients with IC chronically treated with aspirin. A total of 159 patients with IC, Stage II (Fontaine), were enrolled in a double-blind, randomized, prospective, multicenter study comparing cloricromene (100 mg orally b.i.d.) or an identical placebo for 6 months. All patients received 160 mg/day aspirin. The primary end-point was the improvement of initial claudication distance (ICD) at 6 months as measured by a standardized treadmill test. The secondary end-points were the absolute claudication distance (ACD) at 6 months, the percentage of patients defined as responders to treatment (improvement of ICD of at least 40%), changes in the ischemic window (IW), quality of life as assessed by the SF-36 questionnaire, and the occurrence of major cardiovascular events. The ICD increased in both treatment groups, with a non-significant difference at 6 months in favor of cloricromene of +12.3 m. The ACD, percentage of responders to treatment and ischemic window also improved in both groups with a slight, non-significant trend in favor of cloricromene. Pretreatment quality of life scores showed only a slight worsening compared with an age-matched, healthy population and did not change upon treatment. A post hoc subgroup analysis showed a significant benefit from cloricromene in patients with an ICD at enrollment higher than the median of the patient population. In conclusion, treatment with cloricromene for 6 months does not significantly improve claudication in patients with Stage II Fontaine peripheral arteriopathy chronically treated with aspirin. An improvement of 40-60 m in the ICD on a standardized treadmill test does not translate into a self-perceived improvement in the quality of life as assessed by the SF-36 questionnaire.