Dependency on host vitamin B12 has shaped Mycobacterium tuberculosis Complex evolution

Human and animal tuberculosis is caused by the Mycobacterium tuberculosis Complex (MTBC), which has evolved a genomic decay of cobalamin (vitamin B12) biosynthetic genes. Accordingly, and in sharp contrast to environmental, opportunistic and ancestor mycobacteria; we demonstrate that M. tuberculosis (Mtb), M. africanum, and animal-adapted lineages, lack endogenous production of cobalamin, yet they retain the capacity for exogenous uptake. A B12 anemic model in immunocompromised and immunocompetent mice, demonstrates improved survival, and lower bacteria in organs, in B12 anemic animals infected with Mtb relative to non-anemic controls. Conversely, no differences were observed between mice groups infected with M. canettii, an ancestor mycobacterium which retains cobalamin biosynthesis. Interrogation of the B12 transcriptome in three MTBC strains defined L-methionine synthesis by metE and metH genes as a key phenotype. Expression of metE is repressed by a cobalamin riboswitch, while MetH requires the cobalamin cofactor. Thus, deletion of metE predominantly attenuates Mtb in anemic mice; although inactivation of metH exclusively causes attenuation in non-anemic controls. Here, we show how sub-physiological levels of B12 in the host antagonizes Mtb virulence, and describe a yet unknown mechanism of host-pathogen cross-talk with implications for B12 anemic populations.

Novel intravesical bacterial immunotherapy induces rejection of BCG-unresponsive established bladder tumors

Background

Intravesical BCG is the gold-standard therapy for non-muscle invasive bladder cancer (NMIBC); however, it still fails in a significant proportion of patients, so improved treatment options are urgently needed.

Methods

Here, we compared BCG antitumoral efficacy with another live attenuated mycobacteria, MTBVAC, in an orthotopic mouse model of bladder cancer (BC). We aimed to identify both bacterial and host immunological factors to understand the antitumoral mechanisms behind effective bacterial immunotherapy for BC.

Results

We found that the expression of the BCG-absent proteins ESAT6/CFP10 by MTBVAC was determinant in mediating bladder colonization by the bacteria, which correlated with augmented antitumoral efficacy. We further analyzed the mechanism of action of bacterial immunotherapy and found that it critically relied on the adaptive cytotoxic response. MTBVAC enhanced both tumor antigen-specific CD4⁺ and CD8⁺ T-cell responses, in a process dependent on stimulation of type 1 conventional dendritic cells. Importantly, improved intravesical bacterial immunotherapy using MBTVAC induced eradication of fully established bladder tumors, both as a monotherapy and specially in combination with the immune checkpoint inhibitor antiprogrammed cell death ligand 1 (anti PD-L1).

Conclusion

These results contribute to the understanding of the mechanisms behind successful bacterial immunotherapy against BC and characterize a novel therapeutic approach for BCG-unresponsive NMIBC cases.

Is Somatostatin Receptor and Dopamine Receptor profiling useful in the management of silent somatotroph tumors?

Silent somatotroph tumors (sSTs) are pituitary neuroendocrine tumors (PitNETs) which do not give rise to the clinical syndrome of acromegaly. Differently to their functioning counterparts, the adjuvant medical treatment with somatostatin analogues (SSAs) or dopamine receptors agonists (DAs) has been scarcely addressed in these tumors. As preliminary results of an ongoing research on silencing mechanisms involved in the pathogenesis of sSTs, we have characterized by qRT-PCR the expression of SSTRs and DRDs in a large series of 18 silent and 68 functioning STs. Although the expression of SSTR2 and SSTR5 was lower in sSTs than in functioning ones, we found a negative correlation between SSTR2 and the tumor size of the sSTs. Additionally, levels of expression of DRD2 were similar between the two subtypes suggesting a possible basis for the treatment of these tumors with SSAs and DAs.

Why don't corticotroph tumors always produce Cushing's disease?

OBJECTIVE

Silent corticotroph tumors are a pituitary neuroendocrine tumor subtype of corticotroph lineage that do not clinically express Cushing's disease. The silencing of this type of tumor is not fully understood. The aim of the present study was to delve into the lack of secretory activity, studying the post-transcriptional and post-translational regulation of POMC/ACTH in a series of molecularly identified functioning and silent corticotroph tumors.

DESIGN

We analyzed 24 silent corticotroph, 23 functioning corticotroph and 25 silent gonadotroph tumors.

METHODS

We used Sanger sequencing, quantitative real-time PCR and Western blot to analyze genetic alterations in POMC, gene expression of TBX19, NEUROD1, POMC, PCSK1, PCSK2, CPE and PAM and protein expression of POMC, PC1/3, PC2, CPE and PAM.

RESULTS

We found different polymorphisms in the POMC gene of corticotroph tumors, some of them related to deficiency of proopiomelanocortin. Silent corticotroph tumors showed lower PC1/3 gene and protein expression than functioning ones, especially compared to micro-functioning corticotroph tumors (all P < 0.05). Moreover, we found a positive correlation between PC2 and CPE gene and protein expression (rho ≥ 0.670, P < 0.009) in silent corticotroph tumors compared with functioning ones.

CONCLUSIONS

By studying the post-transcriptional and post-translational processing of POMC and ACTH, respectively, in a large series of silent and functioning corticotroph tumors, we found that the lack of secretory activity of these tumors is related to an impaired processing of POMC and a high degradation of ACTH, with the macro-functioning corticotroph tumor behaving as an intermediate state between micro-functioning and silent corticotroph tumors.

New insights into the transposition mechanisms of IS6110 and its dynamic distribution between Mycobacterium tuberculosis Complex lineages

The insertion Sequence IS6110, only present in the pathogens of the Mycobacterium tuberculosis Complex (MTBC), has been the gold-standard epidemiological marker for TB for more than 25 years, but biological implications of IS6110 transposition during MTBC adaptation to humans remain elusive. By studying 2,236 clinical isolates typed by IS6110-RFLP and covering the MTBC, we remarked a lineage-specific content of IS6110 being higher in modern globally distributed strains. Once observed the IS6110 distribution in the MTBC, we selected representative isolates and found a correlation between the normalized expression of IS6110 and its abundance in MTBC chromosomes. We also studied the molecular regulation of IS6110 transposition and we found a synergistic action of two post-transcriptional mechanisms: a -1 ribosomal frameshift and a RNA pseudoknot which interferes translation. The construction of a transcriptionally active transposase resulted in 20-fold increase of the transposition frequency. Finally, we examined transposition in M. bovis and M. tuberculosis during laboratory starvation and in a mouse infection model of TB. Our results shown a higher transposition in M. tuberculosis, that preferably happens during TB infection in mice and after one year of laboratory culture, suggesting that IS6110 transposition is dynamically adapted to the host and to adverse growth conditions.

Since the pioneering discovery of transposition by Barbara McClintock in eukaryotes and later in prokaryotes by Robert W. Hedges and Alan E. Jacob, it has become clear the key role of mobile genetics elements in chromosome remodelling, microbial evolution and host adaptation. The insertion sequence IS6110 is widely recognized for its utility in TB diagnosis and epidemiology because it is only present in the M. tuberculosis Complex (MTBC) and its transposition provides an excellent chromosomal polymorphic variability allowing the study of recent TB transmission. This inherent feature of IS6110 leads us to hypothesize that IS6110 plays a crucial role during the TB infectious cycle. However, the biological significance of IS6110 has been hindered by its almost exclusive use as an epidemiological marker. Here, we study the regulatory mechanisms and the distribution of IS6110 in the different MTBC lineages. We discuss the potential biological implications of IS6110, that is much more than an excellent TB epidemiological tool. Since IS6110 could play an important role in the adaptation of MTBC to the host, this study opens new avenues to decipher the biological roles of IS6110 in TB pathogenesis.

Biological markers of fertility (inhibin-B) in HIV-infected men: influence of HIV infection and antiretroviral therapy

OBJECTIVES

Inhibin B (IB) levels and the IB: follicle-stimulating hormone (FSH) ratio (IFR), biomarkers of global Sertoli cell function, show a strong relationship with male fertility. The aim of the study was to examine the prevalence of impaired fertility potential in HIV-infected men and the influence of antiretroviral therapy (ART) on fertility biomarkers.

METHODS

A cross-sectional study with sequential sampling was carried out. A total of 169 clinically stable patients in a cohort of HIV-infected men undergoing regular ambulatory assessment in a tertiary hospital were included. The mean [± standard deviation (SD)] age of the patients was 42.6 ± 8.1 years, all were clinically stable, 61.5% had disease classified as Centers for Disease Control and Prevention (CDC) stage A, and were na?ve to ART or had not had any changes to ART for 6 months (91.1%). Morning baseline IB and FSH concentrations were measured using an enzyme-linked immunosorbent assay (ELISA) and an electrochemiluminescent immunoassay (ECLIA), respectively. A multivariate logistic regression model was used to identify factors associated with impaired fertility, defined as IB < 119 pg/mL or IFR < 23.5.

RESULTS

The mean (± SD) IB level was 250 ± 103 pg/mL, the median [interquartile range (IQR)] FSH concentration was 5.1 (3.3-7.8) UI/L and the median (IQR) IFR was 46.1 (26.3-83.7). The prevalence of impaired fertility was 21.9% [95% confidence interval (CI) 16.3-20.7%]. Negative correlations of body mass index and waist: hip ratio with FSH and IB levels were observed (P < 0.01), while a sedentary lifestyle and previous nevirapine exposure were associated with a decreased risk of IB levels ≤ 25th percentile in multivariate analysis. Only older age, as a risk factor, and sedentary lifestyle, with a protective effect, were independently associated with impaired fertility in multivariate analysis.

CONCLUSIONS

Global testicular Sertoli cell function and fertility potential, assessed indirectly through serum IB levels and IB: FSH ratio, appear to be well maintained in HIV-infected men and not damaged by ART.

Merits and pitfalls of mifepristone in Cushing's syndrome

OBJECTIVE

Mifepristone is the only available glucocorticoid receptor antagonist. Only few adult patients with hypercortisolism were treated to date by this drug. Our objective was to determine effectiveness and tolerability of mifepristone in Cushing's syndrome (CS).

DESIGN

Retrospective study of patients treated in seven European centers.

METHODS

Twenty patients with malignant (n=15, 12 with adrenocortical carcinoma, three with ectopic ACTH secretion) or benign (n=5, four with Cushing's disease, one with bilateral adrenal hyperplasia) CS were treated with mifepristone. Mifepristone was initiated with a median starting dose of 400 mg/day (200-1000). Median treatment duration was 2 months (0.25-21) for malignant CS, and 6 months (0.5-24) for benign CS. Clinical (signs of hypercortisolism, blood pressure, signs of adrenal insufficiency), and biochemical parameters (serum potassium and glucose) were evaluated.

RESULTS

Treatment was stopped in one patient after 1 week due to severe uncontrolled hypokalemia. Improvement of clinical signs was observed in 11/15 patients with malignant CS (73%), and 4/5 patients with benign CS (80%). Psychiatric symptoms improved in 4/5 patients within the first week. Blood glucose levels improved in 4/7 patients. Signs of adrenal insufficiency were observed in 3/20 patients. Moderate to severe hypokalemia was observed in 11/20 patients and increased blood pressure levels in 3/20 patients.

CONCLUSION

Mifepristone is a rapidly effective treatment of hypercortisolism, but requires close monitoring of potentially severe hypokalemia, hypertension, and clinical signs of adrenal insufficiency. Mifepristone provides a valuable treatment option in patients with severe CS when surgery is unsuccessful or impossible.

Outcome of pregnancy in a hypothyroid woman with resistance to thyroid hormone treated with triiodothyronine

Epidemiological and research data have shown the significant role of maternal thyroid hormone in fetal neurologic development. It has been suggested that maternal hypothyroxinemia is potentially damaging for the neurodevelopment of the fetus, independently of T3 levels. We present a pregnant woman with resistance to thyroid hormone and iatrogenic hypothyroidism who was treated with triiodothyronine during the whole pregnancy. Even though maternal hypothyroxinemia was severe the children showed a normal neuropsychological development.

Teratogenicity with angiotensin II receptor antagonists in pregnancy

Angiotensin converting enzyme (ACE) inhibitors and angiotensin II (AT-II)-receptor-antagonists have been demonstrated to cause fetotoxicity when administered to women during the second and third trimester of pregnancy. Although use of ACE inhibitors during the first trimester of pregnancy seems to be safe, with no associated teratogenicity, there is not sufficient information regarding the safety of first-trimester exposure to AT-II-receptor-antagonists. We report a case of exencephaly and unilateral renal agenesia in a fetus of a diabetic woman who became pregnant while taking irbesartan.

Acromegaly Quality of Life Questionnaire (ACROQOL) a new health-related quality of life questionnaire for patients with acromegaly: development and psychometric properties

OBJECTIVE

To develop a disease-specific questionnaire suitable to measure health-related quality of life (HRQOL) in acromegaly (ACROQOL).

DESIGN, PATIENTS AND MEASUREMENTS

For the development of the ACROQOL questionnaire different sources of information were used: First, a literature search was performed to identify relevant papers describing the impact of acromegaly in HRQOL. Second, 10 endocrinologists identified the main domains of impact on HRQOL in patients with acromegaly. Third, 10 in-depth, semistructured interviews were conducted in acromegalic patients to identify domains and items related to the self-perceived impact of acromegaly in patients' life. Qualitative analyses of the information were performed identifying domains and items to be included in the questionnaire. Those items considered ambiguous, complicated to read, double-barrelled, with jargon terms, too long, or negatively worded were excluded. Each remaining item was subsequently rated by the same panel of endocrinologists and experts in HRQOL evaluation, and assessed according to clarity of wording, frequency of occurrence and importance among patients with acromegaly. Analysis of internal consistency of the questionnaire was evaluated with a Cronbach's Alpha. A preliminary questionnaire was administered to 72 patients with acromegaly. Rasch analysis (dichotomous logistic response model) of the answers given by these patients allowed parameter estimates and model data fit indices to be computed and misfitting items deleted. Frequency of occurrence and degree of agreement with the statements were selected as response choices in a 5-point Likert type scale.

RESULTS

The following domains related to HRQOL in acromegaly were identified: physical and psychological functions, social, daily activities, symptoms, cognition, general health perception, sleep, sexual function, pain, energy and body image. An initial set of 204 expressions were identified from the initial transcripts of the patient interviews. After elimination of ambiguous or unclear expressions, 142 items remained drafted in question form. From the quantitative analysis of the item rank position within each of the three areas of clarity, frequency and importance, the 38-item questionnaire was produced, with satisfactory internal consistency (Cronbach's Alpha 0.94). Rasch analysis produced a further reduction to the final 22-item questionnaire (Cronbach's Alpha 0.91) containing two scales that evaluate physical (eight questions) and psychological aspects related to appearance and personal relations (seven items each). The evaluation of the item parameters confirmed the construct validity of the new instrument. The substantial reliability of the questionnaire suggested the sample was well targeted by the questionnaire. The initial Spanish version was translated into English and presented to five English-speaking Australian patients with acromegaly to assess and correct for comprehension, clarity, cultural relevance and suitable wording.

CONCLUSIONS

We present the ACROQOL questionnaire, developed and preliminarily validated to specifically assess HRQOL in patients with acromegaly.

Ectopic growth hormone-releasing hormone secretion by thymic carcinoid tumour

The case of a 33-year-old-woman with Multiple Endocrine Neoplasia Type 1 (MEN1) syndrome and acromegaly due to ectopic growth hormone-releasing hormone (GHRH) secretion by a thymic carcinoid tumour is reported. Immunohistochemistry revealed positive immunoreactivity for GHRH, vasoactive intestinal polypeptide, somatostatin and alpha-subunit in the tumour cells. A previously undescribed new germ line mutation of the MEN1 protein gene was revealed.

Prevalence of macroprolactin detected by Elecsys 2010

BACKGROUND

Macroprolactin or big-big PRL is, usually, a complex of little prolactin (PRL) with anti-PRL autoantibody. There are some patients with hyperprolactinemia showing a high proportion of serum macroprolactin. However, its clinical significance is not clear. Immunoassays used to determine PRL differ in their ability to detect macroprolactin. Moreover, in recent years, PRL assays have changed from isotopic methods (radioimmunoassays and immunoradiometric assays) to non-isotopic automated immunoassays. The effect of macroprolactin on currently used methods is often unknown. The aim of this work was to study the different reactivity of macroprolactin in two immunoassays systems, Elecsys 2010 and ACS Centaur, and to assess the clinical repercussion of this condition.

METHODS

We studied retrospectively 956 consecutive routine patients. Samples with a PRL value >636 mIU/l (211 samples) were subjected to the polyethylene glycol (PEG) precipitation test to detect macroprolactin, and 2 of them also to gel filtration chromatography for further confirmation. PRL was measured by Elecsys 2010 and, alternatively, by ACS Centaur.

RESULTS

By Elecsys 2010, macroprolactin was detected in 19 patients (9%). After removing macroprolactin, PRL levels were within the normal range in every case but one. When original sera from patients with macroprolactin were processed with ACS Centaur. PRL levels were normal or only marginally elevated. The correlation of PRL values in samples with and without macroprolactin assayed by both systems was 0.64 and 0.98, respectively.

CONCLUSIONS

Nearly 9% of hyperprolactinemic patients detected by Elecsys 2010 may have macroprolactin, but the detection rate obtained using ACS Centaur is much lower. As macroprolactin seems to have minimal clinical relevance, it would be important that the users of PRL assays be aware to what extent macroprolactin interferes with their assays, and have available a validated method, such as the PEG precipitation test, to confirm the presence of macroprolactin.

Obesity: a prognostic factor of severity in acute pancreatitis

This study was conducted to assess the prognostic value of obesity in acute pancreatitis and to determine the role played by obesity-associated diseases in the course of the disease. We prospectively studied 49 patients with acute pancreatitis who were divided into three groups according to their body mass index (BMI). There were 22 patients in group I (BMI < or = 25 kg/m2, normal or low weight); 15 in group II (BMI >25 and < or = 29 kg/m2, overweight); and 12 in group III (BMI >29 kg/m2, obese). Other anthropometric parameters also were measured. The severity of pancreatitis was assessed according to the Atlanta classification system. Systemic complications were significantly more common among obese than nonobese patients (p < 0.05). Patients with severe pancreatitis had a higher body-fat percentage, measured by the subscapular skin-fold thickness, and a larger abdominal circumference than patients with mild pancreatitis. Although hypertensive or diabetic patients developed more systemic complications, the multivariate analysis demonstrated that the presence of these underlying diseases did not modify the prognostic role of obesity in acute pancreatitis. We conclude that obesity is a prognostic factor of outcome in acute pancreatitis. Obesity-associated diseases do not vary the prognostic value of obesity. It seems that truncal adiposity is the kind of obesity related to worse outcome of acute pancreatitis.

Genetic and clinical analysis in 10 Spanish patients with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) is characterised by the combination of tumours of the parathyroid, endocrine pancreas and anterior pituitary glands. In 1988 the MEN 1 gene was mapped to chromosome 11q13 and it was cloned in 1997. This gene contains 10 exons and extends across 9 Kb of genomic DNA; it encodes for a product of 610 amino acid named menin whose function is unknown. We have studied 10 unrelated MEN 1 kindreds by a complete sequencing analysis of the entire gene; mutations were identified in nine of them: five deletions, one insertion, two nonsense mutation and a complex alteration consisting of a deletion and an insertion that can be explained by a hairpin loop model. Two of the mutations have been previously described; the other seven were novel, and they were scattered throughout the coding sequence of the gene. As in previous series, no correlation was found between phenotype and genotype.

Higher incidence of carpal tunnel syndrome in oophorectomized women

To determine whether the hormonal changes of the menopause are related to the onset of carpal tunnel syndrome (CTS), 53 healthy women, younger than 44 years, and subjected to bilateral oophorectomy between 1 and 4 years before the study, were evaluated. Seventy healthy menstruating women matched for age were used as controls. In those complaining of symptoms and presenting signs suggestive of CTS, sensory and motor nerve conduction studies were done. In the oophorectomized group, 17 of 53 (32%) had clinical CTS, while only seven of 70 of the control group (10%) did so (relative risk for the oophorectomized group = 4.25; 95% confidence intervals 1.47 and 12.61). The nerve conduction studies were abnormal in 14 of 16 oophorectomized women (87.5%), and in only one of seven of the control group (14.2%; P less than 0.002). Symptoms tended to be milder in the controls. Symptoms developed in the first year after oophorectomy in 14 of the 17 women with CTS. This suggests that women develop CTS after oophorectomy more frequently than controls.

Interaction of thyrotrophin releasing hormone and the enkephalin analogue DAMME on pituitary hormone secretion

Because TRH counteracts the inhibitory effect of opiate peptides on LH secretion in cultured cells from normal pituitaries, six normal postmenopausal women were studied to determine whether TRH interacts in vivo with opioid peptides in the regulation of pituitary hormone secretion. At two different times a constant 3 h infusion of either saline or TRH (5 micrograms/min) was initiated. At 60 min a 250 micrograms bolus of the opiate agonist peptide D-Ala2-MePhe4-met-enkephalin-0-ol (DAMME) was injected in one of the two saline and TRH infusion tests. The four treatments, i.e. saline infusion alone, saline infusion with a DAMME bolus, TRH infusion alone; and TRH infusion with DAMME bolus were given at random with an interval of at least 7 d. Blood samples were taken every 15 min during the 3 h study. DAMME induced a significant fall (P less than 0.05) in serum LH (from 35 +/- 8.5 to 18.3 +/- 5.1 mIU/ml) (mean +/- SEM) without significantly affecting FSH levels (from 29 +/- 11.2 to 26.9 +/- 12.4 mIU/ml). These changes were not antagonized by the continuous infusion of TRH. PRL had a monophasic response pattern to continuous isolated TRH infusion; the basal levels increased from 4.2 +/- 1.2 to 24.5 +/- 6.8 ng/ml at 30 min and then slowly decreased with a plateau from 90 min until the end of the study. DAMME administration at 60 min induced a significant second peak of PRL secretion (44 +/- 6.5 ng/ml) 30 min later (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)