Arginine Supplementation in MELAS Syndrome: What Do We Know about the Mechanisms?

MELAS syndrome, characterized by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes, represents a devastating mitochondrial disease, with the stroke-like episodes being its primary manifestation. Arginine supplementation has been used and recommended as a treatment for these acute attacks; however, insufficient evidence exists to support this treatment for MELAS. The mechanisms underlying the effect of arginine on MELAS pathophysiology remain unclear, although it is hypothesized that arginine could increase nitric oxide availability and, consequently, enhance blood supply to the brain. A more comprehensive understanding of these mechanisms is necessary to improve treatment strategies, such as dose and regimen adjustments; identify which patients could benefit the most; and establish potential markers for follow-up. This review aims to analyze the existing evidence concerning the mechanisms through which arginine supplementation impacts MELAS pathophysiology and provide the current scenario and perspectives for future investigations.

Efficacy and safety of fluoroless ureteroscopy and retrograde intrarenal surgery for the treatment of urolithiasis: A comparative study

INTRODUCTION

Ureteroscopy (URS) and retrograde intrarenal surgery (RIRS) are traditionally guided by fluoroscopy, but the risks of exposure to ionizing radiation may present a matter of concern for patients and urologists. The aim of this study was to evaluate the efficacy and safety of fluoroless URS and RIRS compared with conventional fluoroscopy-guided procedures for the treatment of ureteral and renal stones.

MATERIAL AND METHODS

Patients treated with URS or RIRS for urolithiasis between August 2018 and December 2019 were retrospectively evaluated and grouped according to the use of fluoroscopy. Data was collected from individual patient records. The main outcomes were stone-free rate (SFR) and complications, compared between the fluoroscopy and fluoroless groups. A subgroup analysis by type of procedure (URS and RIRS) and a multivariate analysis to identify predictors of residual stones were conducted.

RESULTS

A total of 231 patients met the inclusion criteria: 120 (51.9%) in the conventional fluoroscopy group and 111 (48.1%) in the fluoroless group. No significant differences were found between groups regarding SFR (82.5% vs 90.1%, p=.127) or postoperative complication rate (35.0% vs 31.5%, p=.675). In the subgroup analysis these variables did not present significant differences, regardless of the procedure considered. In the multivariate analysis the fluoroless technique was not an independent predictor of residual lithiasis (OR 0.991; 95% IC 0.407-2.411; p=.983), when adjusted for procedure type, stone size and stone number.

CONCLUSION

URS and RIRS can be done without fluoroscopic guidance in selected cases, without affecting the efficacy or safety of the procedure.

Cultural explanations of sleep paralysis: The spiritual phenomena

Introduction

Sleep paralysis (SP) is relatively frequent condition, occurring either at sleep onset or sleep offset. It occurs at least once in a lifetime in 40–50% of normal subjects. During SP, the patient experiences gross motor paralysis, while the sensory system is clear. Hypnogogic and hypnopompic hallucinations are common. This experience might be interpreted as a spiritual phenomenon in several cultures, each one with different interpretations and attributions.

Objective

The authors revisit the clinical presentation of sleep paralysis and how this sleep disorder is seen from a cultural perspective.

Aims

To describe several cultural interpretations of SP.

Methods

A literature review of the theme is shortly surveyed.

Results

It is very common during an episode of SP sensing the presence of menacing intruders in one's bedroom. Supernatural accounts of this hallucinated intruder are common across cultures. It has been traditionally labeled “ghost oppression” among the Chinese. In the Abruzzo region (Italy), the supernatural interpretation of the phenomena is called the Pandafeche attack. One study found that nearly half (48%) of the participants from the general Egyptian population believed their SP to be caused by the Jinn, a spirit-like creature. In Southwest Nigeria, Ogun Oru is a traditional explanation for nocturnal neuropsychiatric disturbances. The characteristics of the ‘a dead body climbed on top of me’ phenomenon suggest that is identical to sleep paralysis and a frequent experience among Mexican adolescents.

Conclusions

Depending on the etiological interpretations of SP, which is largely culturally determined, patients react to the event in specific ways.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Long term post PrePex male circumcision outcomes in an urban population in Uganda: a cohort study

Objective

The objective of this study was to determine the long term adverse events profile at least a year after safe male circumcision.

Results

A cohort study, investigating patients who had undergone a non surgical circumcision procedure called Prepex. The study variables included scar appearance and sexual experiences. Clients were contacted for a phone interview and data were collected using a questionnaire, for some, a physical examination was done. We obtained ethical committee approval. Data from 304 out of a possible 625 men were analyzed, the rest was lost to follow up. The follow up period was 12–24 months. The mean age was 28 years. Up to 97% were satisfied with the penile scar appearance and the absence of pain. There was no keloids formation, though one developed a hypertrophic scar. Participants reported improved sexual intercourse enjoyment (post circumcision). Up to 17% resumed sexual intercourse before the 6-week long mandatory abstinence period. The average self-reported healing time was 4.7 weeks. There was a high level of scar appearance satisfaction, there was no keloids formation. There was a perceived improvement of sexual enjoyment after circumcision.

Trial registration ClinicalTrials. Gov Identifier: NCT02245126 (Date of registration: September 19, 2014)

Religious and spiritual implication in the assessment and management of bipolar disorder

Introduction

Religion/spirituality and medicine have been related in one way or another sense the beginning of our know History. Patients’ beliefs, values and practices influence the way disease is perceived and managed. In order to provide adequate care the physician must have proper knowledge of the patients’ spiritual/religious context, otherwise it may fall prey to errors of diagnostic, inappropriate management and subsequent poor compliance.

Objectives

To present the case of an adult male (a preacher whose beliefs include mediunity) with delusional ideation of mystical content and mood elation, identified during a religious ceremony.

Aims

Questioning the frontier between spiritual/religious beliefs and psychopathology.

Methods

A case report is presented and a literature review of the theme is shortly surveyed.

Results

The case reports to a 53 years old man, who during a religious ceremony presented himself with agitation and disinhibition, removing all his cloths and living the church naked. Additionally it was identified the presence of insomnia, heteroaggressiveness, accelerated speech, mood elation and delusional ideation of mystical and megalomaniac content. Several studies demonstrate the importance of acknowledging the religious/spiritual beliefs of patients. This knowledge allows the psychiatry to correctly identify the existing psychopathology and organize an appropriate intervention plan for the patient.

Conclusions

Spiritual and religious beliefs’ influence the way disease is perceiver and managed. Physician should collect a brief spiritual story of the patient and learn about the different religious/spiritual beliefs and practices of their community, in order to understand the full dimension of the individual illness.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Implications of immunity and inflammation in schizophrenia and related psychotic disorders

Introduction

Intricate interactions between the immune system and the brain might have important etiological and therapeutic implications for neuropsychiatric brain disorders. A probable association between schizophrenia and the immune system was postulated over a century ago, and is supported by epidemiological and genetic studies pointing to links with infection and inflammation.

Objective

To describe some important areas of research regarding immune response in schizophrenia and related psychotic disorders and discuss potential mechanisms and therapeutic implications of these findings.

Aims

Associations between immune response, inflammation and schizophrenia and related psychotic disorders are reviewed.

Methods

A literature review of the theme is surveyed. Several articles were search on MEDLINE with the keywords: schizophrenia, psychosis, inflammation, immunity, infection.

Results

Schizophrenia is a multifactorial disease. It is associated with multiple genetic loci that confer risk, in addition to developmental and postnatal risk factors. Antipsychotic-naive first-episode psychosis and acute psychotic relapse seems to be associated with increased serum concentrations of interleukin 6 and other proinflammatory cytokines, which are normalized after remission of symptoms with antipsychotic treatment.

Conclusions

Inflammation and immune dysfunction might contribute to cognitive, negative, and positive symptoms in schizophrenia. Identification of specific inflammatory pathways for neuropsychiatric symptoms would provide novel targets for therapeutic intervention.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Accurate quantification of inter-domain partition coefficients in GUVs exhibiting lipid phase coexistence

Giant unilamellar vesicles (GUVs) with phase coexistence allow for the recovery of inter-domain partition coefficients (K_p) of fluorescent molecules through comparison of fluorescence intensities in each phase.

Analysis of health stories in daily newspapers in the UK

Objectives

To assess what makes a good piece of medical reporting in newspapers, to quantify what is being reported on in the major British newspapers, to identify the sources of the news threads, and to assess how these are reported.

Study design

Development and validation of a tool to assess the quality of reporting of health-related articles, and assessment of the quality of these articles in British newspapers.

Methods

Eight national daily newspapers from the UK were reviewed for 20 days over a 2-month period. All articles reporting newly emerging research pertaining to health in humans were included and reviewed independently by two raters. A descriptive analysis was performed. Subsequently, a quality assessment tool for use by a non-expert was developed and validated to objectively assess the quality of a newspaper article on a health-related topic.

Results

The quality assessment tool was found to have good internal consistency and inter-rater reliability. The Daily Mail published almost twice as many articles as its nearest rival, The Daily Express, and over eight times as many articles as The Guardian. Articles in The Times were, on average, more than twice as long as those in The Sun and The Daily Telegraph. The highest quality articles were in The Times and The Independent, with the lowest quality articles in The Sun. The quality scores of anonymous articles were significantly lower than those attributed to named journalists.

Conclusions

There are significant differences in the quality of reporting within and between major daily UK newspapers, with anonymous articles being the poorest quality, and widespread reliance on press releases from the major UK scientific journals.

Genetic basis for unresponsiveness to lipopolysaccharide in C57BL/10Cr mice

The unresponsiveness to LPS detected in C57BL/10Cr mice is inherited as a recessive trait and is determined by an autosomal gene linked to theMup-1 locus on chromosome 4. Since no complementation for LPS responsiveness was observed in F(1) hybrid mice between C3H/HeJ and C57BL/10Cr, we conclude that C57BL/10Cr mice carry a defective allele at the sameLps locus, previously identified by the mutation detected in the C3H/HeJ strain.

Complement and antibody primary immunodeficiency in juvenile systemic lupus erythematosus patients

OBJECTIVE

To evaluate the frequency of primary immunodeficiencies (PID) in juvenile systemic lupus erythematosus (JSLE) patients.

METHODS

Some 72 JSLE patients were analyzed for levels of immunoglobulin classes and IgG subclasses and early components of the classical complement pathway. Determination of C4 gene copy number (GCN) and detection of type I C2 deficiency (D) were also performed.

RESULTS

PID was identified in 16 patients (22%): C2D in three, C4D in three, C1qD in two, IgG2D (<20 mg/dl) in four, IgAD (<7 mg/dl) in three, and IgMD (<35 mg/dl) in three; one of these patients presented IgA, C2 and C4D. Two patients had low C4 GCN and two had type I C2D. Demographic data, family history of autoimmune disease and PID, JSLE clinical findings, occurrence of infections, disease activity and therapies were similar in patients with and without PID (p > 0.05). Remarkably, the median of Systemic Lupus International Collaborating Clinics/ACR-damage index (SLICC/ACR-DI) was significantly higher in JSLE patients with PID compared with patients without these abnormalities (p = 0.0033), likewise the high frequency of SLICC/ACR-DI > 1 (p = 0.023).

CONCLUSIONS

A high frequency of PID was observed in JSLE patients, suggesting that these defects may contribute to lupus development. Our findings indicate that these two groups of PID should be investigated in severe pediatric lupus.

Quantitative analysis of bone density in direct digital radiographs evaluated by means of computerized analysis of digital images

OBJECTIVES

minimal density variations of mineralized tissues can be reliably detected with quantitative image subtraction analysis. The aim of this study was to evaluate quantitative variations of in vitro mineral density by varying the exposure time of direct digital radiographs using a computer assisted densitometric image analysis (CADIA) program.

METHODS

in a human mandibular segment a three-wall periodontal defect was created mesial to a molar. Bone chips were created from the marrowbone of the same mandible with masses of 1 to 5 mg. A triplicate radiograph of the defect was taken as a baseline for seven different exposure times. The bone chips were inserted into the defect and another triplicate series of radiographs for the seven exposure times were taken as follow-up images. The images were analysed using CADIA software to detect variations in bone density.

RESULTS

the results of CADIA revealed increased density when the size of the inserted bone chip increased. The 2 mg chip was underestimated owing to mass reduction during insertion. The regression line of the CADIA values was consistent with the weight of the bone chips of 1, 3, 4 and 5 mg. The exposure time f6 (0.178 s) showed the best correlation with the bone chip weight. Loss of information in the images occurred when the exposure time exceeded the sensor's latitude.

CONCLUSIONS

CADIA analysis is a reliable and sensitive tool for detecting subtle bone density variations. More reliable results are obtained with increased exposure time; however, excessive exposure should be avoided.

Routine versus clinically driven laboratory monitoring of HIV antiretroviral therapy in Africa (DART): a randomised non-inferiority trial

BACKGROUND

HIV antiretroviral therapy (ART) is often managed without routine laboratory monitoring in Africa; however, the effect of this approach is unknown. This trial investigated whether routine toxicity and efficacy monitoring of HIV-infected patients receiving ART had an important long-term effect on clinical outcomes in Africa.

METHODS

In this open, non-inferiority trial in three centres in Uganda and one in Zimbabwe, 3321 symptomatic, ART-naive, HIV-infected adults with CD4 counts less than 200 cells per microL starting ART were randomly assigned to laboratory and clinical monitoring (LCM; n=1659) or clinically driven monitoring (CDM; n=1662) by a computer-generated list. Haematology, biochemistry, and CD4-cell counts were done every 12 weeks. In the LCM group, results were available to clinicians; in the CDM group, results (apart from CD4-cell count) could be requested if clinically indicated and grade 4 toxicities were available. Participants switched to second-line ART after new or recurrent WHO stage 4 events in both groups, or CD4 count less than 100 cells per microL (LCM only). Co-primary endpoints were new WHO stage 4 HIV events or death, and serious adverse events. Non-inferiority was defined as the upper 95% confidence limit for the hazard ratio (HR) for new WHO stage 4 events or death being no greater than 1.18. Analyses were by intention to treat. This study is registered, number ISRCTN13968779.

FINDINGS

Two participants assigned to CDM and three to LCM were excluded from analyses. 5-year survival was 87% (95% CI 85-88) in the CDM group and 90% (88-91) in the LCM group, and 122 (7%) and 112 (7%) participants, respectively, were lost to follow-up over median 4.9 years' follow-up. 459 (28%) participants receiving CDM versus 356 (21%) LCM had a new WHO stage 4 event or died (6.94 [95% CI 6.33-7.60] vs 5.24 [4.72-5.81] per 100 person-years; absolute difference 1.70 per 100 person-years [0.87-2.54]; HR 1.31 [1.14-1.51]; p=0.0001). Differences in disease progression occurred from the third year on ART, whereas higher rates of switch to second-line treatment occurred in LCM from the second year. 283 (17%) participants receiving CDM versus 260 (16%) LCM had a new serious adverse event (HR 1.12 [0.94-1.32]; p=0.19), with anaemia the most common (76 vs 61 cases).

INTERPRETATION

ART can be delivered safely without routine laboratory monitoring for toxic effects, but differences in disease progression suggest a role for monitoring of CD4-cell count from the second year of ART to guide the switch to second-line treatment.

FUNDING

UK Medical Research Council, the UK Department for International Development, the Rockefeller Foundation, GlaxoSmithKline, Gilead Sciences, Boehringer-Ingelheim, and Abbott Laboratories.

Independent segregation of two functional markers expressed on the same B-cell subset in the mouse: the Mls determinants and LPS receptors

Mice of the C3H/Tif strain display a mixed leukocyte reaction (MLR) with all H-2k strains carrying any of the known alleles of the Mls locus. In particular, C3H/Tif is incompatible with the related substrain C3H/HeJ, from which it also differs at the locus responsible for the recognition of lipopolysaccharides (LPS) as B-cell mitogens, and at the Mod-1 locus. Our genetic analysis indicates that the MLR incompatibility between these strains is not H-2-linked and segregates as controlled by a single locus, most probably identical to Mls, for which the C3H/Tif strain expresses a previously unidentified allele, Mlse. Moreover, segregation data show that this locus assorts independently of LPS responsiveness and that neither marker is closely linked to the Mod-1 locus in linkage group II.

'What if they ask how I got it?' Dilemmas of disclosing parental HIV status and testing children for HIV in Uganda

BACKGROUND

Limited research has been conducted outside Western settings on how HIV-positive parents decide to test and disclose their own HIV status to children. We conducted a qualitative study in 2001 and 2005 to assess parent attitudes and current counselling policy and practice regarding child testing and parental disclosure in Uganda prior to the roll-out of antiretroviral therapy.

METHODS

Parent perspectives were obtained through extended in-depth interviews with 10 HIV-positive parents recruited from The AIDS Support Organization (TASO), Entebbe branch. Counselling policy and practice were explored through key informant interviews with directors and two counsellors from each of five Ugandan counselling institutions with national or regional coverage.

RESULTS

Respondents had 51 children ranging from 4 to 36 years with a median age of 13. Five of 10 parents had disclosed their status to their children, usually to all, and four of these had tested one child for HIV. All those who tested any child had also disclosed their status to some or all of their children. Parents regularly worried that their children may be infected, but all preferred to wait for emergence of symptoms before considering HIV tests, citing fear of children's emotional reaction and lack of perceived benefits from knowing status. Counselling policy directors confirmed the absence of policy and training guidelines on the subject of parent-child disclosure. Counsellors reported improvising and giving inconsistent advice on this common concern of clients.

CONCLUSIONS

Concerns over disclosure to children of parent's HIV status and testing children for HIV represent a major psychological burden for HIV-positive parents. Further research is needed, but current counselling practice could be improved now by adapting lessons learned from existing research.

Pre-/post-otic rhombomeric interactions control the emergence of a fetal-like respiratory rhythm in the mouse embryo

How regional patterning of the neural tube in vertebrate embryos may influence the emergence and the function of neural networks remains elusive. We have begun to address this issue in the embryonic mouse hindbrain by studying rhythmogenic properties of different neural tube segments. We have isolated pre- and post-otic hindbrain segments and spinal segments of the mouse neural tube, when they form at embryonic day (E) 9, and grafted them into the same positions in stage-matched chick hosts. Three days after grafting, in vitro recordings of the activity in the cranial nerves exiting the grafts indicate that a high frequency (HF) rhythm (order: 10 bursts/min) is generated in post-otic segments while more anterior pre-otic and more posterior spinal territories generate a low frequency (LF) rhythm (order: 1 burst/min). Comparison with homo-specific grafting of corresponding chick segments points to conservation in mouse and chick of the link between the patterning of activities and the axial origin of the hindbrain segment. This HF rhythm is reminiscent of the respiratory rhythm known to appear at E15 in mice. We also report on pre-/post-otic interactions. The pre-otic rhombomere 5 prevents the emergence of the HF rhythm at E12. Although the nature of the interaction with r5 remains obscure, we propose that ontogeny of fetal-like respiratory circuits relies on: (i) a selective developmental program enforcing HF rhythm generation, already set at E9 in post-otic segments, and (ii) trans-segmental interactions with pre-otic territories that may control the time when this rhythm appears.

Thymic commitment of regulatory T cells is a pathway of TCR-dependent selection that isolates repertoires undergoing positive or negative selection

The seminal work of Le Douarin and colleagues (Ohki et al. 1987; Ohki et al. 1988; Salaun et al. 1990; Coutinho et al. 1993) first demonstrated that peripheral tissue-specific tolerance is centrally established in the thymus, by epithelial stromal cells (TEC). Subsequent experiments have shown that TEC-tolerance is dominant and mediated by CD4 regulatory T cells (Treg) that are generated intrathymically by recognition of antigens expressed on TECs (Modigliani et al. 1995; Modigliani et al. 1996a). From these and other observations, in 1996 Modigliani and colleagues derived a general model for the establishment and maintenance of natural tolerance (MM96) (Modigliani et al. 1996b), with two central propositions: (1) T cell receptor (TCR)-dependent sorting of emergent repertoires generates TEC-specific Treg displaying the highest TCR self-affinities below deletion thresholds, thus isolating repertoires undergoing positive and negative selection; (2) Treg are intrathymically committed (and activated) for a unique differentiative pathway with regulatory effector functions. The model explained the embryonic/perinatal time window of natural tolerance acquisition, by developmental programs determining (1) TCR multireactivity, (2) the cellular composition in the thymic stroma (relative abundance of epithelial vs hemopoietic cells), and (3) the dynamics of peripheral lymphocyte pools, built by accumulation of recent thymic emigrants (RTE) that remain recruitable to regulatory functions. We discuss here the MM96 in the light of recent results demonstrating the promiscuous expression of tissue-specific antigens by medullary TECs (Derbinski et al. 2001; Anderson et al. 2002; Gotter et al. 2004) and indicating that Treg represent a unique differentiative pathway (Fontenot et al. 2003; Hori et al. 2003; Khattri et al. 2003), which is adopted by CD4 T cells with high avidity for TEC-antigens (Bensinger et al. 2001; Jordan et al. 2001; Apostolou et al. 2002). In the likelihood that autoimmune diseases (AID) result from Treg deficits, some of which might have a thymic origin, we also speculate on therapeutic strategies aiming at selectively stimulating their de novo production or peripheral function, within recent findings on Treg responses to inflammation (Caramalho et al. 2003; Lopes-Carvalho et al., submitted, Caramalho et al., submitted). In short, the MM96 argued that natural tolerance is dominant, established and maintained by the activity of Treg, which are selected upon high-affinity recognition of self-ligands on TECs, and committed intrathymically to a unique differentiative pathway geared to anti-inflammatory and antiproliferative effector functions. By postulating the intrathymic deletion of self-reactivities on hemopoietic stromal cells (THC), together with the inability of peripheral resident lymphocytes to engage in the regulatory pathway, the MM96 simultaneously explained the maintenance of responsiveness to non-self in a context of suppression mediating dominant self-tolerance. The major difficulty of the MM96 is related to the apparent tissue specificity of Treg repertoires generated intrathymically. This difficulty has now been principally solved by the work of Hanahan, Kyewski and others (Jolicoeur et al. 1994; Derbinski et al. 2001; Anderson et al. 2002; Gotter et al. 2004), demonstrating the selective expression of a variety of tissue-specific antigens by TECs, in topological patterns that are compatible with the MM96, but difficult to conciliate with recessive tolerance models (Kappler et al. 1987; Kisielow et al. 1988). While the developmentally regulated multireactivity of TCR repertoires (Gavin and Bevan 1995), as well as the peripheral recruitment of Treg among RTE (Modigliani et al. 1996a) might add to this process, it would seem that the establishment of tissue-specific tolerance essentially stems from the "promiscuous expression of tissue antigens" by TEC. The findings of AID resulting from natural mutations (reviewed in Pitkanen and Peterson 2003) or the targeted inactivation (Anderson et al. 2002; Ramsey et al. 2002) of the AIRE transcription factor that regulates promiscuous gene expression on TECs support this conclusion. The observations on the correlation of natural or forced expression of the Foxp3 transcription factor in CD4 T cells with Treg phenotype and function (Fontenot et al. 2003; Hori et al. 2003; Khattri et al. 2003) provided support for the MM96 contention that Treg represent a unique differentiative pathway that is naturally established inside the thymus. Furthermore, Caton and colleagues (Jordan et al. 2001), as well as several other groups (Bensinger et al. 2001; Apostolou et al. 2002), have provided direct evidence for our postulate that Treg are selected among differentiating CD4 T cells with high affinity for ligands expressed on TECs (Modigliani et al. 1996b). Finally, the demonstration by Caramalho et al. that Treg express innate immunity receptors (Caramalho et al. 2003) and respond to pro-inflammatory signals and products of inflammation (Caramalho et al., submitted) brought about a new understanding on the peripheral regulation of Treg function. Together with the observation that Treg also respond to ongoing activities of "naïve/effector" T cells--possibly through the IL-2 produced in these conditions--these findings explain the participation of Treg in all immune responses (Onizuka et al. 1999; Shimizu et al. 1999; Annacker et al. 2001; Curotto de Lafaille et al. 2001; Almeida et al. 2002; Shevach 2002; Bach and Francois Bach 2003; Wood and Sakaguchi 2003; Mittrucker and Kaufmann 2004; Sakaguchi 2004), beyond their fundamental role in ensuring self-tolerance (e.g., Modigliani et al. 1996a; Shevach 2000; Hori et al. 2003; Sakaguchi 2004; Thompson and Powrie 2004). Thus, anti-inflammatory and anti-proliferative Treg are amplified by signals that promote or mediate inflammation and proliferation, accounting for the quality control of responses (Coutinho et al. 2001). In turn, such natural regulation of Treg by immune responses to non-self may well explain the alarming epidemiology of allergic and AID in wealthy societies (Wills-Karp et al. 2001; Bach 2002; Yazdanbakhsh et al. 2002), where a variety of childhood infections have become rare or absent. Thus, it is plausible that Treg were evolutionarily set by a given density of infectious agents in the environment. With hindsight, it is not too surprising that natural Treg performance falls once hygiene, vaccination, and antibiotics suddenly (i.e., 100 years) plunged infectious density to below some critical physiological threshold. As the immune system is not adapted to modern clean conditions of postnatal development, clinical immunologists must now deal with frequent Treg deficiencies (allergies and AID) for which they have no curative or rational treatments. It is essential, therefore, that basic immunologists concentrate on strategies to selectively stimulate the production, survival, and activity of this set of lymphocytes that is instrumental in preventing immune pathology. We have argued that the culprit of this inability of basic research to solve major clinical problems has been the self-righteousness of recessive tolerance champions, from Ehrlich to some of our contemporaries. It is ironical, however, that none of us--including the heretic opponents of horror autotoxicus--had understood that self-tolerance, or its robustness at least, is in part determined by the frequency and intensity of the responses to non-self. In the evolution of ideas on immunological tolerance, the time might be ripe for some kinds of synthesis. First, conventional theory reduced self-tolerance to negative selection and microbial defense to positive selection, while the MM96 solution was the precise opposite: positive selection of autoreactivities for self-tolerance (Treg) and negative selection (of Treg) for ridding responses. In contrast, it would now appear that positive and negative selection of autoreactive T cells are both necessary to establish either self-tolerance or competence to eliminate microbes, two processes that actually reinforce each other in the maintenance of self-integrity. Second, V-region recognition has generally been held responsible for specific discrimination between what should be either tolerated or eliminated from the organism. In contrast again, it would now seem that both processes of self-tolerance and microbial defense (self/non-self discrimination) also operate on the basis of evolutionarily ancient, germ-line-encoded innate, nonspecific receptors (Medzhitov and Janeway 2000) capable of a coarse level of self/non-self discrimination (Coutinho 1975). It could thus be interesting to revisit notions of cooperativity between V-regions and such mitogen receptors, both in single cell functions (Coutinho et al. 1974) and in the system's evolution (Coutinho 1975, 1980) as well. After all, major transitions in evolution were cooperative (Maynard-Smith and Szathmary 1995).

V-region-specific alterations of serum IgM production in multiple myeloma of IgG class

INTRODUCTION

Multiple myeloma is accompanied by decreased polyclonal serum immunoglobulin concentrations. This suppression might be due to non-specific effects on the polyclonal lymphocyte populations as previously suggested, or it could include specific variable region-dependent mechanisms. Thus, differentiation, survival and activation to Ig secretion of B-lineage cells are dependent on the expression and signalling through the variable Ig receptor. The present study addresses the question whether such variable region-specific alterations were present in the peripheral repertoire of IgM antibodies in patients with IgG-secreting MM.

MATERIALS AND METHODS

IgM reactivity repertoires towards a large panel of antigens in extracts of homologous tissues (liver, brain, stomach and heart muscle) and bacteria (Bacillus macquarensis) were analysed in sera from 22 patients diagnosed with IgG1 MM. Healthy, matched volunteers served as control donors. A modified Western assay was used, and values obtained from area integration by image analyses were submitted to multiparametric statistics.

RESULTS AND CONCLUSION

The results confirm previous observations on the depression of serum IgM concentrations in multiple myeloma, and demonstrate concentration-independent, patient- and V-region-specific alterations in the polyclonal reactivity repertoires. Since the scoring of IgM reactivities by this technique is independent of IgG and because the deviations of IgM reactivity are not coincident with reactivities of (myeloma) IgG in the individual sera, the results indicate that the immunological syndrome of MM includes significant V-region-specific alterations in the polyclonal repertoires of IgM antibodies.

Grafts of supplementary thymuses injected with allogeneic pancreatic islets protect nonobese diabetic mice against diabetes

In nonobese diabetic (NOD) mice, the autoimmune attack of the beta-cells in pancreatic islets is now believed to result from abnormal thymic selection. Accordingly, grafts of thymic epithelium from NOD donors to athymic recipients promote autoimmune islet inflammation in normal strains, and intrathymic islet grafts decrease the incidence of disease in NOD animals. Two competing hypotheses of abnormal thymic selection in diabetic mice have been proposed: deficient negative selection with poor elimination of aggressive organ-specific T cells vs. deficient positive selection of protective T regulatory cells. We have now addressed these alternatives by grafting, into young NOD mice whose own thymus was left intact, newborn NOD thymuses containing allogeneic pancreatic islets. If the NOD defect represented poor negative selection, these animals would develop disease at control rates, as the generation of autoreactive T cells proceeds undisturbed in the autologous thymus. In contrast, if NOD thymuses are defective in the production of T regulatory cells, lower disease incidence is expected in the chimeras, as more protective cells can be produced in the grafted thymus. The results show a reduced incidence of diabetes in the chimeras (24%) as compared with control (72%) NOD mice, throughout adult life. We conclude that amelioration of NOD mice by intrathymic islet grafts is not caused by enhanced negative selection and suggest that autoimmune diabetes in this system is the result of inefficient generation of T regulatory cells in the thymus.

Regulatory T cells: the physiology of autoreactivity in dominant tolerance and "quality control" of immune responses

Little progress has been achieved over the last 20 years on the clinical management of several conditions that relate to self-tolerance and to the regulation of immune responses: autoimmune diseases, transplantation tolerance, tumor immunity, allergy and vaccine development in chronic infections. These failures, it is argued, are due to the inability of the prevalent "recessive tolerance" concepts to accommodate physiological autoreactivity and the regulatory potential it embodies. In this review, the advantages of "dominant tolerance" models are underlined in the light of critical evidence and in the general context of the natural autoimmune activities. The role of regulatory T cells is discussed, notably in the regulation of inflammatory reactions and, more generally, in the "quality control" of immune responses. It is anticipated that progress will be brought about by dominant tolerance approaches, and through an increased knowledge of the differentiative pathways, repertoires, mechanisms of activation and effector functions of autoreactive, regulatory T cells.

Significant association between the skewed natural antibody repertoire of Xid mice and resistance to Trypanosoma cruzi infection

The Xid mutation predominantly affects the development of B cells and consequently the levels and composition of natural antibodies in sera. In contrast to the congenic and susceptible BALB/c strain, immunodeficient BALB.Xid mice display a resistant phenotype both to acute Trypanosoma cruzi infection and to the development of severe cardiopathy. Because natural antibodies are known to be basically self-antigen driven, IgM and IgG natural antibody repertoires (NAR) were compared before and during infection in these two strains. The analysis revealed fundamental alterations of IgM and IgG NAR in pre- and post-infected Xid mice. In particular, relatively increased natural (pre-existing) autoreactive IgG, dominated by the unique recognition of a single band in autologous heart extracts, was typical for uninfected Xid mice. This natural autoreactive IgG directed to heart antigens disappeared early after infection not only in Xid, but also in individual BALB/c mice that survived the acute infection. Conversely, the subgroup of BALB/c mice that died early after infection presented the most pronounced instances of the rapid, relative increase of IgM reactivities to self and non-self proteins. These results suggest that self-reactive NAR may play a role in an immunoregulatory mechanism relevant for the determination of susceptibility/resistance to infections. This may act either by influencing specific responses, or by modulating the self-aggressive components responsible for pathology.

Immunophenotypic Aberrations, DNA Content, and Cell Cycle Analysis of Plasma Cells in Patients with Myeloma and Monoclonal Gammopathies

We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

A B-cell mitogen from a pathogenic trypanosome is a eukaryotic proline racemase

Lymphocyte polyclonal activation is a generalized mechanism of immune evasion among pathogens. In a mouse model of Trypanosoma cruzi infection (American trypanosomiasis), reduced levels of polyclonal lymphocyte responses correlate with resistance to infection and cardiopathy. We report here the characterization of a parasite protein with B-cell mitogenic properties in culture supernatants of infective forms, the cloning of the corresponding gene and the analysis of the biological properties of its product. We characterized the protein as a co-factor-independent proline racemase, and show that its expression as a cytoplasmic and/or membrane-associated protein is life-stage specific. Inhibition studies indicate that availability of the racemase active site is necessary for mitogenic activity. This is the first report to our knowledge of a eukaryotic amino acid racemase gene. Our findings have potential consequences for the development of new immune therapies and drug design against pathogens.

Germ-line selection ensures embryonic autoreactivity and a positive discrimination of self mediated by supraclonal mechanisms

It is necessary to clarify principles and mechanisms of natural tolerance to body tissues, in order to derive appropriate diagnostics, therapeutics and prognostics of autoimmune diseases (AID). I will argue that AIDs result from deficits in autoreactive regulatory T cell generation and/or function, and propose a model that explains why relatively few prototypes of AID exist, as well as their organ-specificity or systemic nature. The model suggests that natural tolerance is achieved through evolutionarily selected developmental genetic programs: (i) for patterns of V-region expression early in life that ensure auto(multi)reactivity at the outset of the system; (ii) for a cellular composition of thymic stroma that 'breeds' and activates regulatory (autoreactive) T cells in early development; (iii) for lymphocyte differentiation and population dynamics, that results in peripheral 'education' of regulatory tissue-specific cells, while allowing for 'unregulated' clonal responses to nonself. In the present model, S/NS discrimination is 'supraclonal' and 'dominant', related to other 'systemic' properties such as the regulation of total lymphocyte numbers, the 'open-endedness' of repertoires, and their differences in health and disease. Dominant tolerance models in general, also solve the paradox that pathogenic autoreactivity is rare, in spite of the extensive V-region degeneracy of lymphocyte recognition and the high frequency of cross-reactivity between S/NS; in short, it is astonishing that we are not autoimmune every time we get infected. As in other areas of biomedical science, time is perhaps ripe to move from component (clonal) analysis to system's biology, as some have proned for years.

Serum IgM repertoire reactions to MBP/CFA immunization reflect the individual status of EAE susceptibility

Lewis rats develop experimental allergic encephalomyelitis (EAE) in response to immunization with myelin basic protein (MBP) in CFA, while Fischer rats are usually resistant. These strains, while comparably producing anti-MBP antibodies, also differ in their repertoire reactions to immunization, as measured by patterns of serum IgM reactivity with various autologous proteins. We have now scored IgM repertoire reactions to MBP/CFA immunization after treatments that alter EAE susceptibility in either strain. The results show that abrogation of EAE susceptibility in Lewis rats by a previous experience of T cell-induced passive EAE provoked a novel set of IgM reactivities that otherwise characterized the Fischer's repertoire reaction. Conversely, these reactivities were delayed in the response of Fischer rats that had been rendered EAE-susceptible by cyclophosphamide. Another IgM reactivity with a significant association to individual EAE severity in Lewis rats behaved reciprocally. Together with previous results, these observations suggest that putative regulatory mechanisms concordantly affect EAE resistance and IgM repertoire reactions, operating naturally in Fischer rats and abrogatable by cyclophosphamide treatment, whereas naturally suppressed, but restorable in Lewis rats. Other treatments altering EAE susceptibility, however, did not share these characteristics and may thus be mediated by other mechanisms.

Screening of army soldiers for Wuchereria bancrofti infection in the metropolitan Recife region, Brazil: implications for epidemiological surveillance

Between 1989 and 1995, blood surveys were performed for Wuchereria bancrofti infection in several barracks of the Brazilian army in the metropolitan Recife region. For initial screening, 60 microliters of capillary blood were examined for microfilaria. All men who tested positive had microfilaria quantified by filtration of venous blood through a polycarbonate membrane. Of 23,773 men screened, 585 (2.5%) had microfilaria (mf). Microfilarial density ranged from < 1-8706 mf/ml of blood. Thirteen individuals had ultra-low microfilarial densities (1 mf/11 ml of blood). Characterization of 174 autochthonous cases made it possible to map 8 new districts in 4 cities within metropolitan Recife region where transmission of W. bancrofti was previously unknown. Routine screening of soldiers in the military may provide important surveillance data for national programmes to eliminate transmission of W. bancrofti.

Structured reactions of serum IgM repertoires to immunization are dependent on major histocompatibility complex genes

In normal animals, responses to immunization include alterations in the serum IgM antibody repertoire, as scored on autologous tissue antigens with no respect for the immunizing antigen. These immunogen-nonspecific antibody reactions were found previously to display specific structures dependent on strain and immunization protocols. Using major histocompatability complex (MHC)-congenic Lewis rats, we show that such IgM repertoire reactions are under the control of MHC-linked genes, including a class I locus. This strongly suggests the involvement of T cells restricted by both class I and class II MHC, in regulating serum IgM repertoires. Immunogen-nonspecific repertoire reactions to immunization may, therefore, represent degenerate, but prototypical, reactions or regulatory mechanisms embodying the natural repertoires of T- and B cells connected to autoantigens. Natural (auto)immunity could so serve to regulate the effector class of adaptive immune responses, particularly in order to avoid pathogenic autoreactivity following specific immunization with self-cross-reacting antigens. Appropriate analysis of nonspecific repertoire reactions could therefore contribute to the understanding of general structures of immune regulation and natural tolerance.

Type I IFN sets the stringency of B cell repertoire selection in the bone marrow

Locally produced type I interferon (IFN-I) enhances the sensitivity of bone marrow B cell to IgM receptor ligation. The establishment of B cell repertoires, on the other hand, seems to involve selective processes that are critically dependent on B cell receptor (BCR) ligation. In order to assess the importance of BCR triggering thresholds on the selection of polyclonal unmanipulated B cell populations, we compared VH gene expression and reactivity repertoires in various B cell compartments of wild-type and IFN-I receptor-deficient mice (IFN-I-R-/-). These analyses demonstrate that increased B cell sensitivity to BCR ligation mediated by IFN-I in the bone marrow (BM) has consequences on the stringency of B cell repertoire selection. Thus, the normal counter-selection of both VH7183 gene family expression and multireactivity was impaired among immature BM B cells from mutant mice. Furthermore, as a result of reduced efficiency of BCR ligation-dependent inhibition of terminal differentiation, IFN-I-R-/- animals produce, in BM and thymus, higher numbers of plasma cells secreting antibodies that are more multireactive than wild-type animals. Finally, mutant serum IgM natural antibodies display a more reactive repertoire than controls, a likely reflection of the BM resident plasma cell repertoire. The present observations demonstrate, therefore, that local modulation of BCR triggering thresholds leads to important modifications in the generation and/or selection of normal B cell populations.

Dynamics of serum IgM autoreactive repertoires following immunization: strain specificity, inheritance and association with autoimmune disease susceptibility

Immunization of Lewis rats with myelin basic protein (MBP) in complete Freud's adjuvant (CFA) provokes experimental allergic encephalomyelitis (EAE). Here we compare, irrespective of antigen specificity, the structure and dynamics of serum IgM autoreactive repertoires following immunization with MBP/CFA in EAE-susceptible Lewis and relatively resistant Fischer rats. Prior to the appearance of clinical symptoms, Lewis rats developed a specific modification of serum IgM autoreactivities that, scored on other determinants than MBP itself, showed a prognostic association with EAE symptoms. Although comparable in their production of MBP-specific serum IgM and IgG antibodies, Fischer rats did not share these MBP/CFA-induced IgM autoreactivities of Lewis rats when immunized in the same manner. Moreover, while the Lewis-type repertoire reaction was specific for MBP/CFA alone, the respective Fischer reaction was not qualitatively different from that observed in this strain upon non-pathogenic immunization with self-related or -unrelated antigens. In general, the repertoire reactions differed qualitatively between the strains, consisting of components with typical behavior and strain preferences. The EAE-associated, as well as the other components of both Lewis- and Fischer-type repertoire reactions were usually co-dominantly inherited in F1 animals. These results indicate that a global antibody repertoire analysis may serve as a tool to describe prototypical response structures, possibly involved in immune regulation and susceptibility to pathogenic autoimmunity.

Self-reactive antibodies (natural autoantibodies) in healthy individuals

Antibodies that are present in the serum of healthy individuals in the absence of deliberate immunization with any antigen, are refered to as natural antibodies. A vast majority of natural antibodies react with one or more self antigens and are termed as natural autoantibodies. The importance of natural autoantibodies in immune regulation has long been neglected, since tolerance to self was thought to be primarily dependent on the deletion of autoreactive clones, rather than on peripheral suppressive mechanisms. Clonal deletion and energy cannot account, however, for the prevalence of natural autoreactivity among healthy individuals. It is now well established that autoreactive antibodies and B cells, and autoreactive T cells, are present in healthy individuals, and in virtually all vertebrate species. Autoreactive repertoires are predominantly selected early in ontogeny. Questions pertaining to the role of natural antibodies in the regulation of the immune response and maintenance of immune homeostasis and to the distinction between natural autoreactivity and pathological autoimmunity have not been adequately addressed. Here, we focus on the current knowledge on the physicochemical and functional properties of NAA in man, and the use of NAA for therapeutic intervention. reserved.

Naturally activated CD4+ T cells are highly enriched for cytokine-producing cells

Most T cells in a normal non-immunized individual are in a resting state. However, a small proportion of splenic T cells are large activated cells both in specific pathogen-free and antigen-free mice. To further elucidate the effector functions associated with these "naturally" activated CD4+ T cells, we have characterized the expression of various membrane markers, cytokine production and T helper activity by these cells. We show that naturally activated CD4+ T cells express activation markers and contain tenfold higher proportions of cells producing IL-4, IL-10 and IFN-gamma as compared to small CD4+ T cells. Despite the high proportion of IFN-gamma producers, naturally activated CD4+ T cells still induce B cell proliferation and differentiation. These results are discussed in the context of normal physiological autoreactivity.

Functional diversity and clonal frequencies of reactivity in the available antibody repertoire

The present experiments address functional antibody diversity and clonal distribution in murine available repertoires. IgM-containing supernatants were prepared by unbiased, polyclonal stimulation of resting splenic B cells from C57BL/6 mice, to ensure similar numbers of responding clones/culture and equivalent growth and maturation of all clones. The repertoires of clones and clonal mixtures were quantitatively assayed by limiting dilution analysis (LDA) on immunoblots of sodium dodecylsulfate polyacrylamide gel electrophoresis of homologous liver extracts, allowing to determine specific clonal frequencies towards the many hundred blotted antigens. The clonal frequency of reactivity of B cells with the extract was shown to be a bi-modal distribution of specific frequencies between 1/220 and 1/100,000. Cross-correlation analysis of reactivity to different bands in individual supernatants revealed low levels of cross-reactivity, suggesting that the blotted extract provides a very diverse set of antigens. Investigation of the affinity/concentration thresholds for detection of antigen-antibody interactions of our assay supports the notion that global repertoire analyses on immunoblots were highly discriminative and non-degenerate. Furthermore, reactivity patterns obtained with complex antibody mixtures correlated with the frequency of clonal reactivities as determined by LDA. The results demonstrate a large functional diversity of resting B lymphocytes, indicating a minimal repertoire size that is orders of magnitude higher than previous theoretical proposals suggested, and extensively heterogeneous in the size of clonal specificities.

Genetic control of natural antibody repertoires: I. IgH, MHC and TCR beta loci

Global analysis of natural antibody repertoires has revealed a marked conservation of reactivity patterns within inbred mouse strains, and characteristic strain-specific differences. We have now analyzed the genetic control of reactivity repertoires, aiming at identifying the respective selection mechanisms. Multiparametric statistics of a large number of serum antibody reactivities scored by quantitative Western blot analyses using extracts from homologous tissues and bacteria readily distinguish the reactivity patterns of C57BL/6 and BALB/c, revealing homogeneity among genetically identical individuals. Antibody repertoires in the prototype strains can also be segregated from those expressed by the respective IgH congenics, BC.8 and CB.20, demonstrating that IgH-linked genes contribute to determining natural antibody repertoires. Conversely, strains sharing IgH haplotype also express distinct reactivity patterns, indicating that other genes participate in the selection of serum IgM repertoires. Two such non-IgH loci were now identified. Thus, analysis of four MHC-congenic strains demonstrated that MHC-linked control of natural antibody repertoires is likely to operate through differential selection of T cell repertoires, since (1) mice that are congenic at the TCR beta locus, and (2) BALB/c nude mice grafted at birth with pure thymic epithelium from either C57BL/6 or BALB/c also differ in their natural antibody repertoires.

Administration to mouse of endotoxin from gram-negative bacteria leads to activation and apoptosis of T lymphocytes

Lipopolysaccharide (LPS) from gramnegative bacteria is a well-known T cell-independent B lymphocyte mitogen and macrophage/monocyte activator. While the conventional view holds that LPS is ignored by T cells, we report here that administration of LPS to mice activates all B cells, but also engages most CD4 and CD8 T cells, as measured by the expression of the activation markers CD69 and CD25 and by size increase. T cells recruited in endotoxin-treated mice showed, following in vitro stimulation by concanavalin A, altered patterns of cytokine production. In vivo, massive T cell apoptosis was evidenced in the days following LPS exposure. The present observation may contribute novel insights into the mechanisms of endotoxin shock and of the immunological consequences of gram-negative infections.