AB0417 SHORT-TERM EFFECT OF METHOTREXATE ON APOLIPOPROTEINS AND LIPID PROFILE IN PATIENTS WITH ACTIVE RHEUMATOID ARTHRITIS

Background

Methotrexate (MTX) forms the first line therapy for rheumatoid arthritis (RA). The cardioprotective effect of MTX is well established, but whether this is just due to control of inflammation, or is also via an effect on serum lipoproteins, is unclear. Although a few studies have studied the effect of the MTX on the traditional lipid profile in RA1, there is no data on the effect of MTX on apolipoproteins (Apo A1, Apo B, ApoB/ApoA1), which are considered better cardiovascular risk predictors than the traditional lipid profile.

Objectives

To determine the short-term effect of MTX on apolipoproteins and traditional lipid profile in patients with active RA.

Methods

DMARD-naïve patients with active RA (SJC≥2 and TJC≥4) who had been enrolled in the multicentre, RCT comparing two different MTX escalation strategies in RA (MEIRA)2 and for whom paired serum samples were available before and after MTX treatment were included. All these patients received MTX monotherapy started at 15 mg/week and escalated to 25 mg/week by 4-8 weeks. Serum levels of apolipoprotein A1 (Apo A1), apolipoprotein B (Apo B), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides (TG) were measured before starting MTX and after 16 weeks of MTX monotherapy. Proatherosclerotic indices (TC/HDL and ApoB/ApoA1) were also calculated.

Results

A total of 103 patients [mean age 40 (8) years, 93 (90%) females, mean BMI 25.1 (4.8) kg/m2, all non-smokers and non-alcoholics] were included. No study participant had comorbid diabetes mellitus or coronary artery disease; none of them were taking glucocorticoids or hypolipidemic drugs. An increase in Apo A1 levels [by a mean of 5.6 mg/dL (p=0.02)], and HDL levels [by a mean of 1.6 mg/dL (p=0.04)] was seen after 16 weeks of MTX monotherapy. Although a numerical increase in levels of TC (mean 4.6 mg/dL, p=0.07), LDL (mean 2 mg/dL, p=0.34) and TG (mean 6.6 mg/dL, p=0.35) was also noted, none of these were statistically significant. No obvious change in Apo B levels and TC/HDL ratio occurred due to MTX therapy. However, the ApoB/ApoA1 ratio decreased significantly from 0.8 to 0.7 (p=0.002) with 16 weeks of MTX therapy (Table 1).

Table 1.

Baseline and end of treatment values of apolipoprotein A1 (Apo A1), apolipoprotein B (Apo B), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), and proatherosclerotic indices (TC/HDL and ApoB/ApoA1).

Parameter (mg/dL)BaselineAfter 16 weeks of MTX therapyp-valueApo A1126.0 (25.1)131.6 (23.4)0.02Apo B92.3 (18.9)92.0 (20.9)0.84ApoB/ApoA10.8 (0.2)0.7 (0.2)0.002TC164.5 (32.4)169.1 (36.8)0.07HDL40.9 (9.8)42.5 (9.7)0.04TC/HDL4.2 (1.1)4.1 (1.1)0.34LDL88.8 (25.2)90.8 (29.8)0.34TG139.8 (69.6)146.4 (91.3)0.35

All values represented as mean (SD).

Apo A1=apolipoprotein A1, ApoB=apolipoprotein B, TC=total cholesterol, LDL=low-density lipoprotein, HDL=high-density lipoprotein, TG=triglycerides

Conclusion

MTX therapy led to a mild but significant increase in HDL, ApoA1 and a reduction in ApoB/ApoA1 over short-term. This could potentially represent one of the mechanisms by which MTX exerts its cardioprotective effect; however, these changes need to be carefully interpreted over longer term and in context of the lipid paradox operating in RA.

References

[1]Navarro-Millán I, Charles-Schoeman C, Yang S, et al. Changes in lipoproteins associated with methotrexate or combination therapy in early rheumatoid arthritis: results from the treatment of early rheumatoid arthritis trial. Arthritis Rheum. 2013;65(6):1430-1438.

[2]Jain S, Dhir V, Aggarwal A, et al. Comparison of two dose escalation strategies of methotrexate in active rheumatoid arthritis: a multicentre, parallel group, randomised controlled trial. Ann Rheum Dis. 2021;80(11):1376-1384.

Disclosure of Interests

None declared

POS1011 PREDICTORS OF ENDOTHELIAL DYSFUNCTION IN ANKYLOSING SPONDYLITIS

Background:

Cardiovascular (CV) disease is the leading cause of death in Ankylosing Spondylitis (AS). Chronic systemic inflammation driven endothelial dysfunction leading to accelerated atherosclerosis results in premature mortality. Endothelial dysfunction is potentially treatable hence a therapeutic target. Predictive biomarkers for endothelial dysfunction would allow tailoring therapy to the individual.

Objectives:

To assess the endothelial dysfunction in AS in context of markers of inflammation and oxidative stress in AS patients.

Methods:

Sub group–analysis of our previous studies of AS1-3 was carried out and 80 AS patients were compared with 40 healthy controls matched for age and sex that were also part of these studies.2,3 Such analysis had so far not been performed in this cohort. Patients with traditional CV risk factors had been excluded in these studies. Flow-mediated dilatation (FMD), as a measure of endothelial function, was assessed by AngioDefender (Everist Health, Ann Arbor, MI). Inflammatory measures included: Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS) in AS. We also assayed markers of inflammation, including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), proinflammatory cytokines (interleukin [IL]-1, IL-6, and tumor necrosis factor [TNF]-α), and endothelial dysfunction, including lipids and nitrite and marker of oxidative stress, TBARS.

Results:

FMD was significantly lower in AS patients compared with controls [(5.80±0.35% vs. 9.09±0.35%, p≤0.05) reduced by approximately 36%] whereas serum nitrite, TBARS, total cholesterol and LDL levels were significantly higher in AS compared with controls (p≤0.05). Compared with controls, AS patients had significantly high BASDAI, ASDAS and increased concentrations of ESR, CRP, TNF-α, and IL-6. In AS, FMD inversely correlated with ASDAS, CRP (Figure 1A), TNF-α (Figure 1B), nitrite (Figure 1C) and TBARS (Figure 1) and positively correlated with HDL (p≤0.05).

Figure 1.

Correlation of FMD with CRP, TNF-α, Nitrite and TBARS

Conclusion:

In AS, FMD was impaired, indicating endothelial dysfunction. ASDAS, CRP, TNF-α, nitrite, and TBARS were independent predictors of FMD in AS. AS-related inflammatory mechanisms (TNF-α, IL-6) and markers of vascular function and oxidative stress (CRP, nitrite and TBARS) may all be involved in the development of cardiovascular disease in AS and these predictors could serve as a novel therapeutic targets for preventing CV risk in AS.

References:

[1]Garg N, Krishan P, Syngle A. Rosuvastatin improves endothelial dysfunction in ankylosing spondylitis. Clin Rheumatol. 2015;34:1065-1071.

[2]Verma I, Syngle A, Krishan P, Garg N. Endothelial Progenitor Cells as a Marker of Endothelial Dysfunction and Atherosclerosis in Ankylosing Spondylitis. International Journal of Angiology. 2017;26:36–42.

[3]Verma I, Krishan P, Syngle A. Predictors of Atherosclerosis in Ankylosing Spondylitis. Rheumatol Ther. 2015;2(2): 173–182.

Disclosure of Interests:

None declared.

Expression analysis of genes associated with sucrose accumulation and its effect on source-sink relationship in high sucrose accumulating early maturing sugarcane variety

Sucrose synthesis/accumulation in sugarcane depends on the source-sink communication wherein source responds to sink demand for photoassimilate supply. Sucrose in stalk (sink) acts as signal, and sends feedback to restrain further synthesis of sucrose by regulating photosynthetic efficiency of leaves (source). Hence sucrose synthesis/accumulation is controlled by many genes and regulatory sequences including 3 invertases (SAI, CWI, NI), sucrose synthase (SuSy) and sucrose phosphate synthase (SPS). SPS and invertase play key role in enhancing sink strength which ultimately promotes greater sucrose accumulation in the sink tissues. In present study, a significant positive correlation was found between sucrose% of source and sink tissues which was greater in the top (R ² = 0.679) than middle (R ² = 0.580) and bottom (R ² = 0.518) internodes, depicting that sucrose accumulation in the stalk bears a direct relation with sucrose translocation efficiency from source. Results indicated an increased sucrose% with maturity, while reducing sugar content decreased with crop growth. qRT-PCR results exhibited an elevated expression of invertase in immature sink tissues depicting increased sink requirement, which declined with maturity. Similarly, increased PEP carboxylase gene expression as observed supported the fact that higher sink demand results in enhanced photosynthetic rate and thus influences the source activity. SPS was found active at initial stage of cane development indicating its role in sucrose synthesis. Thus by studying expression patterns of the different genes both, in source and sink tissues, a better understanding of the sucrose accumulation pathway in sugarcane is possible, which in turn can help in elucidating ways to enhance sucrose concentration in sink.

Levels of circulating immune complexes containing Mycobacterium Tuberculosis-specific antigens in pulmonary tuberculosis and sarcoidosis patients

The present study was conducted to understand the aetiological link between tuberculosis (TB) and sarcoidosis. Sera from smear-positive TB subjects (n = 24), smear-negative TB subjects (n = 24), sarcoidosis patients (n = 24) and healthy controls (n = 24) were collected and circulating immune complexes were isolated. Sandwich ELISA was performed for detecting four highly specific mycobacterial regions of difference (RD) proteins (early secretory antigenic target 6 [ESAT6], 10 KDa culture filtrate protein [CFP10], 21 KDa CFP [CFP21] and mycobacterial protein from species TB [MPT 64]). Sensitivity and specificity was calculated, and receiver operating characteristic plots were plotted. Non-parametric Mann-Whitney U-test was used to calculate statistical significance. Seventy per cent of sarcoidosis patients showed the presence of immune complexes of mycobacterial RD proteins similar to that observed in the sera of smear-negative TB patients as opposed to antibody-based detection assay based on these RD proteins. Thus, immunoassays based on specific mycobacterial RD proteins also need to be developed and validated carefully to differentiate TB and sarcoidosis, a close mimic of smear-negative tuberculosis.

Expression analysis of genes associated with sucrose accumulation in sugarcane (Saccharum spp. hybrids) varieties differing in content and time of peak sucrose storage

Sucrose synthesis/accumulation in sugarcane is a complex process involving many genes and regulatory sequences that control biochemical events in source-sink tissues. Among these, sucrose synthase (SuSy), sucrose phosphate synthase (SPS), soluble acid (SAI) and cell wall (CWI) invertases are important. Expression of these enzymes was compared in an early (CoJ64) and late (BO91) maturing sugarcane variety using end-point and qRT-PCR. Quantitative RT-PCR at four crop stages revealed high CWI expression in upper internodes of CoJ64, which declined significantly in both top and bottom internodes with maturity. In BO91, CWI expression was high in top and bottom internodes and declined significantly only in top internodes as the crop matured. Overall, CWI expression was higher in CoJ64 than in BO91. During crop growth, there was no significant change in SPS expression in bottom internodes in CoJ64, whereas in BO91 it decreased significantly. Apart from a significant decrease in expression of SuSy in mature bottom internodes of BO91, there was no significant change. Similar SAI expression was observed with both end-point and RT-PCR, except for significantly increased expression in top internodes of CoJ64 with maturity. SAI, being a major sucrose hydrolysing enzyme, was also monitored with end-point PCR expression in internode tissues of CoJ64 and BO91, with higher expression of SAI in BO91 at early crop stages. Enzyme inhibitors, e.g. manganese chloride (Mn(++) ), significantly suppressed expression of SAI in both early- and late-maturing varieties. Present findings enhance understanding of critical sucrose metabolic gene expression in sugarcane varieties differing in content and time of peak sucrose storage. Thus, through employing these genes, improvement of sugarcane sucrose content is possible.

Interferon gamma release assay (QuantiFERON-TB Gold In Tube) in patients of sarcoidosis from a population with high prevalence of tuberculosis infection

BACKGROUND AND OBJECTIVE

Detecting latent tubercular infection (LTBI) in sarcoidosis has important treatment implications. Traditionally tuberculin skin test (TST) is relied upon for this purpose. However, sarcoidosis is known to produce tuberculin anergy, which is not affected by high prevalence of tuberculosis (TB) infection. Interferon gamma release assays (IGRAs) have a higher sensitivity and specificity for detecting Mycobacterium tuberculosis (MTB) infection than the conventional TST as they utilize antigens specific for MTB complex. However, there is limited data regarding the performance of these tests in sarcoidosis, particularly in a setting of high population prevalence of LTBI. Herein, we studied the utility of IGRAs in the diagnostic work up of patients with sarcoidosis.

PATIENTS AND METHODS

Prospectively enrolled, biopsy-confirmed, glucocorticoid naive cases of pulmonary sarcoidosis; pulmonary and extrapulmonary TB; and, healthy controls underwent TST using 0.1 mL (1 tuberculin unit) of purified protein derivative RT23, and IGRA using QuantiFERON-TB-Gold In Tube assay (QFT) in blood. For TST an induration > or =10 mm was taken as positive. QFT was performed and interpreted as per the manufacturer's instructions.

RESULTS

We studied 38 patients with sarcoidosis (22 men, 16 women; mean age 42.5 years), 30 patients of TB (18 pulmonary, 12 extrapulmonary) and 30 healthy controls. Patients with sarcoidosis were more likely to have a negative TST compared to healthy controls (89.5% vs. 60%, p = 0.004) or TB (89.5% vs. 23.3%, p < 0.001). However, QFT positivity was not significantly different in sarcoidosis compared to controls (34.2% vs. 50%, p = 0.19), but was higher in TB patients as compared to sarcoidosis (60% vs. 34.2%, p = 0.03).

CONCLUSIONS

There is anergy to tuberculin in sarcoidosis. However, the results of QFT are not similarly affected. QFT continues to remain positive in many patients with sarcoidosis, and thus may be more accurate to detect LTBI in these patients.

A structured simple form for ordering genetic tests is needed to ensure coupling of clinical detail (phenotype) with DNA variants (genotype) to ensure utility in publication and databases

Researchers and clinicians ideally need instant access to all the variation in their gene/locus of interest to efficiently conduct their research and genetic healthcare to the highest standards. Currently much key data resides in the laboratory books or patient records around the world, as there are many impediments to submitting this data. It would be ideal therefore if a semiautomated pathway was available, with a minimum of effort, to make the deidentified data publicly available for others to use. The Human Variome Project (HVP) meeting listed 96 recommendations to work toward this situation. This article is planned to initiate a strategy to enhance the collection of phenotype and genotype data from the clinician/diagnostic laboratory nexus. Thus, the aim is to develop universally applicable forms that people can use when investigating patients for each inherited disease, to assist in satisfying many of the recommendations of the HVP Meeting [Cotton et al., 2007]. We call for comment and collaboration in this article.

Lung and blood mononuclear cell responses of tuberculosis patients to mycobacterial proteins

The differences in specificity of human lung and peripheral lymphocytes for mycobacterial antigens (Ag) need to be evaluated in order to identify vaccine candidates against pulmonary tuberculosis (TB). Therefore, the present study examined the response to low molecular weight secretory proteins of Mycobacterium tuberculosis in bronchoalveolar lavage (BAL) and peripheral blood mononuclear cells (PBMCs) from minimal pulmonary TB and non-TB patients. Ag85A, Ag85B, culture filtrate protein (CFP)-31, CFP-22.5, CFP-21, M. tuberculosis protein-64 and an as yet uncharacterised 19 kDa protein were found to be predominantly recognised by BAL cells of TB patients on the basis of lymphocyte proliferation and significant interferon-gamma release. However, recognition of CFP-8, 6-kDa early secreted antigenic target, CFP-10, CFP-14.5, M. tuberculosis secretory protein-17 and five other as yet uncharacterised low molecular weight polypeptides was found to be high on the basis of lymphocyte proliferation at the level of PBMCs. Furthermore, BAL macrophages, and not blood monocytes, were found to produce nitric oxide (NO) in response to mycobacterial Ags. Among polypeptides predominantly recognised by BAL lymphocytes, only Ag85A and Ag85B were found to induce both NO and interleukin-12 (p40) by alveolar macrophages. In conclusion, the present results indicate heterogeneity in antigen recognition by bronchoalveolar lavage cells and peripheral mononuclear blood cells of minimal tuberculosis patients, and also suggest the utility of antigen 85 complex polypeptides for the development of a future mucosal antituberculous vaccine.

Human immune recognition-based multicomponent subunit vaccines against tuberculosis

The cell-mediated immune response, with its shift in favour of type-1 over type-2 T-helper cell immune response, is generally regarded as essential to protection against mycobacterial infections. The aim of this study was to evaluate the protective potential of two multicomponent subunit vaccines (MSV-1 and MSV-2) against tuberculosis (TB) based on human immune recognition. MSV-1 consisted of five immunodominant antigens (TB10.4, early secretory antigenic target (ESAT)-6, culture filtrate protein (CFP)-8, CFP-10 and CFP-15) selected from a group of polypeptides, which induced a predominant T-cell response in immune human subjects, whereas MSV-2 consisted of antigens (CFP-11, CFP-21, CFP-22.5, Mycobacterium tuberculosis protein (MPT)-64 and CFP-31) selected from a group of polypeptides which induced a subdominant T-cell response along with the antibody response. Both of these sets of polypeptides were extensively recognised in healthy individuals with significant interferon gamma release compared to the diseased population. In C57BL/6J mice, at the level of the lungs, the order of protective efficacy for the test vaccines was: bacille Calmette-Guerin (BCG)>MSV-2>MSV-1. The protective efficacy of MSV-1 was found to be significantly less than that of MSV-2 and BCG at the level of spleen, whereas that of MSV-2 was comparable to that of BCG. The results of this study indicate that high T-helper cell type 1 response-inducing polypeptides selected on the basis of human immune recognition do not necessarily impart protection during vaccination experiments.

Cholesterol-sensor initiates M. tuberculosis entry into human macrophages

Cholesterol-mediated mycobacteria entry into and survival within macrophages has added a new dimension to Tuberculosis research. The molecular mechanism through which cholesterol initiates this process is still poorly understood. The present study addressed to resolve this mechanism revealed that Mycobacterium tuberculosis possesses cholesterol-specific Receptor 'Ck'-like molecule responsible for mycobacterial entry into macrophages. Further human Receptor-Ck was found to regulate transcriptional expression of a gene that codes for Tryptophan-Aspartate containing coat (TACO) protein responsible for survival of mycobacteria within cells. Based upon these results, we propose that interaction of Receptor-Ck with cholesterol-rich membrane domains helps to create a 'Synaptic-junction' between mycobacteria and macrophage resulting in signalling events that are responsible for mycobacterium entry into and survival within macrophages.

Prevention of tissue injury in an ascending mouse model of chronic pyelonephritis—role of free radical scavengers

The role of free radical scavengers in preventing the tissue injury using a non obstructive, ascending mouse model for chronic pyelonephritis was assessed. The parameters taken into consideration are Luminol Dependent Chemiluminescence (LDCL), histopathology and some biochemical investigations. We have observed that both catalase and Dimethyl-Sulfoxide (DMSO, free radical scavengers) were able to prevent the free radical mediated tissue injury and ultimate renal scarring, irrespective of the bacterial strain studied.

Matrix metalloproteinase/integrin interactions as target for anti-angiogenic treatment strategies

Modulation of the balance between pro- and antiangiogenic factors holds great promise for the treatment of a broad spectrum of human disease ranging from ischemic heart disease to cancer. This requires both the identification of angiogenic regulators and their efficient delivery to target organs. Here, we demonstrate the use of a noncatalytic fragment of matrix metalloproteinase 2 (termed PEX) delivered by lentiviral vectors in different angiogenesis models. Transduction of human endothelial cells with PEX virus suppressed endothelial invasion and formation of capillary-like structures without affecting chemotaxis in vitro. Lentiviral delivery of PEX blocked basic fibroblast growth factor-induced matrix metalloproteinase 2 activation and angiogenesis on chicken chorioallantoic membranes. PEX expression also inhibited tumor-induced angiogenesis and tumor growth in a nude mouse model. Thus, our study shows that lentiviral vectors can deliver sufficient quantities of antiangiogenic substances to achieve therapeutic effects in vivo.

Gene therapy: reality or myth for the global bleeding disorders community?

In recent years, five different human gene therapy clinical studies have been initiated in the United States, covering a broad spectrum of gene transfer technologies. Both in vivo and ex vivo studies have been performed, and a variety of target organs/tissues have been studied. The results of this early human clinical research indicate that there is still much to be done before a safe and effective gene therapy procedure becomes commercially available, but there is strong evidence that the obstacles that remain will not prove insurmountable. Small increases in circulating clotting factor levels have been achieved in some patients without significant side-effects, providing proof of the principle that gene therapy can provide a therapeutic benefit for patients with haemophilia. Still unclear is whether gene therapy, when it becomes available, will be accessible to the global haemophilia community. As seen with recombinant and other high purity factor concentrates, technological advances do not always lead to improvements in care for the majority of the world's haemophilia patients. In fact, advances in technology can potentially increase the gulf in care if newer processes displace existing manufacturing technologies. A modified vaccine production model should be considered to make gene therapy more widely available to those who presently have inadequate access to treatment.

A multi-center study in order to further define the molecular basis of beta-thalassemia in Thailand, Pakistan, Sri Lanka, Mauritius, Syria, and India, and to develop a simple molecular diagnostic strategy by amplification refractory mutation system-polymerase chain reaction

The spectrum of the beta-thalassemia mutations of Thailand, Pakistan, India, Sri Lanka, Mauritius and Syria has been further characterized by a multi-center study of 1,235 transfusion-dependent patients, and the mutations discovered used to assess the fidelity of a simple diagnostic strategy. A total of 44 beta-thalassemia mutations were identified either by allele-specific oligonucleotide hybridization, amplification with allele-specific primers, or DNA sequencing of amplified product. The results confirm and extend earlier findings for Thailand, Pakistan, India, Mauritius and Syria. This is the first detailed report of the spectrum of mutations for Sri Lanka. Two novel mutations were identified, codon 55 (-A) and IVS-I-129 (A-->C), both found in Sri Lankan patients. Two beta-thalassemia mutations were found to coexist in one beta-globin gene: Sri Lankan patients homozygous for the beta0 codon 16 (-C) frameshift were also homozygous for the beta+ codon 10 (C-->A) mutation. Studies of Sri Lankan, Pakistani, and Indian carriers suggest the codon 10 (C-->A) mutation is just a rare polymorphism on an ancestral allele, on which the beta0 codon 16 (-C) mutation has arisen. Each country was found to have only a few common mutations accounting for 70% or more of the beta-thalassemia alleles. A panel of primers to diagnose the majority of the mutations by the amplification refractory mutation system was developed, enabling a simple molecular diagnostic strategy to be introduced for each country participating in the multi-center study.

Biochemical effects of sparfloxacin on cell envelope of mycobacteria

Sparfloxacin, a difluorinated quinolone is a potent anti-mycobacterial agent used in the treatment of mycobacterial infections. We have investigated whether sparfloxacin had other, more subtle effects on mycobacteria besides its interaction with DNA gyrase that could contribute to its therapeutic efficacy. Mycobacterium smegmatis cells grown in media with sub-inhibitory concentration of sparfloxacin were observed to have significant reduction in the biosynthesis of vital macromolecules, as shown by the incorporation of various radiolabelled precursors. The analysis of subcellular distribution of phospholipids of sparfloxacin-treated cells demonstrated an increase in the cell membrane and reduction in the cell wall, suggesting changes in the cell envelope architecture by sparfloxacin. Significant changes were also observed in other chemical constituents of the cell wall, especially in the arabinose and glucosamine contents. Mycolic acids, the major component of mycobacterial cell wall were reduced in the presence of MIC50 of sparfloxacin. There was a decrease in the limiting fluorescence intensity (Fmax) of 1-anilinonaphthalene 8-sulfonate (ANS) indicating alterations in the organization and conformation of mycobacterial cell surface. These results suggest that the mechanism of action of anti-mycobacterial action of sparfloxacin involves mycobacterial cell envelope.

Biochemical mechanism of combined effect of ethambutol and sparfloxacin against Mycobacterium smegmatis

M. smegmatis cells grown in the presence of combination of ethambutol (EMB) and sparfloxacin (SPX) had decreased level of total cellular lipids as compared to control as well as cells grown in the presence of sub-inhibitory concentration (MIC50) of individual drugs. Amongst various phospholipids analyzed, maximum decrease was observed in the content of phosphatidylinositolmannosides (PIMs) of the cells grown in combination of EMB and SPX. In contrast, the subcellular distribution of phospholipids revealed a significant increase in PIMs content of both cell wall and cell membrane of the cells grown in the presence of combination of drugs as compared to control as well as individual drugs. Mycolic acids of M. smegmatis cells were found to be main targets as combination of drugs resulted in significant decrease in total cellular as well as cell wall mycolic acids as compared to control and individual drugs. Changed lipid composition of M. smegmatis cells grown in the presence of MIC50 of EMB, SPX and combination resulted in significant surface changes as was evident from decreased limiting fluorescence (Fmax) intensity of 1-anilinonaphthalene-8-sulfonate (ANS). Thus, the results of this study suggested that ethambutol and sparfloxacin in combination exerted their antimycobacterial effect principally due to their action on phosphatidylinositolmannosides (PIMs) and mycolic acids, which form the permeability barrier of mycobacteria.

Therapeutic potential of human neutrophil peptide 1 against experimental tuberculosis

The therapeutic efficacy of human neutrophil peptide 1 (HNP-1) against experimental tuberculosis in mice on the basis of numbers of CFU has been examined. Mice infected with 1.5 x 10(4) CFU of Mycobacterium tuberculosis H(37)Rv and treated with different doses of HNP-1 injected subcutaneously exhibited significant clearance of bacilli from lungs, livers, and spleens. There were time- and dose-dependent decreases in the bacillary load in lungs, livers, and spleens of the HNP-1-treated animals compared to that in controls (untreated animals). These observations strongly suggest the therapeutic activity of HNP-1 against tuberculosis.

Cytoplasmic catalytic subunit of protein kinase A mediates cross-repression by NF-kappa B and the glucocorticoid receptor

Negative transcriptional regulation or cross-coupling between NF-kappa B (RelA) and the glucocorticoid receptor (GR) is proposed to play a regulatory role in human physiology and disease. Despite previous advances, the biochemical basis of this phenomenon remains a subject of controversy. We show here that the inhibition of GR activity by RelA does not require the RelA DNA binding, transactivation, or nuclear localization domains. Surprisingly, RelA repression of GR is abolished by mutation of the conserved protein kinase A (PKA) site at amino acid residue 276 of RelA. We show that GR associates in vivo and in vitro with the catalytic subunit of PKA (PKAc) in a ligand-independent manner and that GR transcription depends on PKA signaling. Indeed, we demonstrated that GR-mediated inhibition of NF-kappa B transactivation is PKAc-dependent. In contrast to previous models, we suggest that the cross-coupling requires a cytoplasmic step and is regulated by a PKAc-associated signaling.

Antibacterial activity of human neutrophil peptide-1 against Mycobacterium tuberculosis H37Rv: in vitro and ex vivo study

The aim of the study was to investigate the activity of human neutrophil peptide (HNP)-1 to kill Mycobacterium tuberculosis H37Rv in vitro and ex vivo in the murine macrophage cell line J744A.1 on the basis of colony forming units. Macromolecular biosynthesis was studied by monitoring the incorporation of radioactive precursors into different macromolecules. The binding and localization studies were carried out with radioiodinated HNP-1 whereas the cytotoxicity of HNP-1 to macrophages was determined by trypan blue exclusion assay. A concentration dependent inhibition in the growth of M. tuberculosis H37Rv was observed in the presence of HNP-1. The minimum inhibitory concentration and median inhibitory concentration of HNP-1 were found to be 2.5 microg x mL(-1) and 0.8 microg x mL(-1). Treatment of both in vitro grown and phagocytosed mycobacterial cells with HNP-1 resulted in generalized inhibition in the macromolecular biosynthesis with maximum inhibition in deoxyribonucleic acid and lipid biosynthesis. HNP-1 exhibited equilibrium binding with respect to time and two-thirds of bound radioactivity was shown to be present inside the macrophages. Approximately 50% and 98% killing of intracellular mycobacteria was observed after 3 days of treatment with 5 microg x mL(-1) and 40 microg x mL(-1) of HNP-1, respectively. HNP-1 exhibited low cytotoxicity towards the macrophage cell line at the bactericidal concentration to mycobacteria. From the results of this study, it is concluded that human neutrophil peptide-1 possesses potent bactericidal activity against virulent mycobacteria in vitro as well as mycobacteria replicating within macrophages.

Alterations in macromolecular composition and cell wall integrity by ciprofloxacin in Mycobacterium smegmatis

The present study has been undertaken to explore the biochemical mechanism of antimycobacterial action of a potent fluoroquinolone i.e. ciprofloxacin in Mycobacterium smegmatis. Cells grown in the presence of a subinhibitory concentration (IC50) of ciprofloxacin had a significantly lower content of all the major macromolecules i.e. DNA, RNA, proteins and lipids with maximum inhibition in DNA concentration as compared to control. Significant quantitative changes were also observed in the various chemical constituents of cell wall of ciprofloxacin grown cells. A decrease in the number of binding sites for a fluorescent probe L-anilinonapthalene-8-sulphonate (ANS) in ciprofloxacin grown cells suggested structural changes on the cell surface. Significant changes were also observed in the morphology of cells grown in the presence of ciprofloxacin by scanning electron microscopy (SEM). Our results suggest that ciprofloxacin exerts its antimycobacterial activity by affecting the cell wall as well as various macromolecules, particular DNA, the vital component for cell survival and growth.

Biochemical interaction of human neutrophil peptide-1 with Mycobacterium tuberculosis H37Ra

The biochemical mechanism of action of human neutrophil peptide-1 (HNP-1) against Mycobacterium tuberculosis H37Ra was studied. Mycobacteria grown in the presence of a subinhibitory concentration (IC50) of HNP-1 showed a significant decrease in the biosynthesis of vital macromolecules, as shown by the incorporation of various radiolabeled precursors. Mycobacterial cells grown in the presence of HNP-1 exhibited surface changes, as was evident from the increased number of binding sites for L-anilinonaphthalene 8-sulfonate. Permeability studies carried out with spheroplasts showed a significantly high permeability to a fluorescent probe, N-phenyl naphthylamine, in the presence of HNP-1. Significant changes in the cell wall and cell membrane were observed when HNP-1-grown cells were analysed by transmission electron microscopy. Our results suggest the mycobacterial cell wall/membrane to be the major target(s) of HNP-1.

Cellular immune response to adenoviral vector infected cells does not require de novo viral gene expression: implications for gene therapy

Replication-defective adenoviral (RDAd) vectors can be generated at high titers and infect both dividing and nondividing cells. Long term expression in the transduced tissue, however, has been a problem because of the cellular immune responses against the infected cells. We demonstrate that mice injected with RDAd vectors containing mouse leptin gene reduce food intake and lose weight for only 7 to 10 days. Splenocytes obtained from infected mice are able to lyse target cells infected with RDAd vectors. Surprisingly, target cells infected with psoralen-treated, UV-crosslinked, biologically inactive RDAd also were lysed efficiently by the effector cells. Furthermore, splenocytes obtained from mice injected with inactive RDAd vectors efficiently lysed target cells infected with RDAd vectors. Whether RDAd vectors were injected i.m. or i.v. or through an i.p. route, the extent of lysis was similar. We propose that cells infected with RDAd vectors present antigens for recognition by class 1 major histocompatibility complex-restricted cytotoxic T lymphocytes by a mechanism that does not require viral replication or de novo protein synthesis. These results should prompt reevaluation of the use of RDAd vectors for gene therapy when long-term expression is required.

Immunoreactivity of mycobacterial 70 kDa protein in different physico-chemical forms

The immunoreactivity of 70 kDa culture filtrate protein of Mycobacterium tuberculosis H37 Ra has been examined as such and by increasing its hydrophobicity through its conjugation to stearic acid ester (70 kDa-FAester). The cell mediated immune responses produced by 70 kDa-FAester encapsulated in phosphatidylcholine (PC) liposomes were significantly higher particularly at the 3rd week post immunization (wk p. im.) than that produced by the 70 kDa protein in PC liposomes, whereas humoral immune responses were non-significant. Further, these immune responses were comparable to that elicited by 70 kDa protein complexed with Freund's incomplete adjuvant (70 kDa-FIA). Results of this study suggest that changes in physicochemical nature of 70 kDa protein influences both the humoral and cellular immunoreactivity.

Immunobiological properties of a 30 kDa secretory protein of Mycobacterium tuberculosis H37Ra

Six different secretory proteins of molecular weights (15, 26, 30, 41, 55 and 70 kDa) were isolated from 8-day-old culture filtrate of Mycobacterium tuberculosis H37Ra using different column chromatography techniques. These proteins were further examined for their ability to induce cell mediated (T-cell proliferation assay) and humoral immune response (ELISA) in mice immunized with total culture filtrate proteins. Out of six proteins, three proteins showed good reactivity. However, the activity was at a maximum with 30 kDa antigen. The immune response induced by 30 kDa antigen emulsified in Freund's incomplete adjuvant (FIA) was investigated and was found to be dose dependent. The T-cell response induced by this protein was skewed towards T-helper (Th1) cells as determined by the pronounced secretion of interleukin-2 (IL-2) and gamma-interferon (IFN-gamma). The protective activity of the 30 kDa protein was also evaluated and compared with reference to Bacillus Calmette Guerin (BCG) vaccine in the mice challenged with virulent M. tuberculosis H37Rv. The degree of protection afforded by the 30 kDa antigen on the basis of mortality and the significant decrease in c.f.u.'s recovered from different organs (lung, liver, spleen) after 30 days of challenge with LD50 of M. tuberculosis H37Rv was significantly higher in comparison to BCG vaccinated animals. However, the degree of immunity induced by this antigen decreased with time (when challenged 8 and 12 weeks post-immunization) but it was still comparable with BCG. These findings suggest that 30 kDa secretory protein of M. tuberculosis is the key immunoprotective antigen and may be a suitable candidate for the development of an alternative subunit vaccine against tuberculosis.

Overexpression of the FosB2 gene in thymocytes causes aberrant development of T cells and thymic epithelial cells

We have examined the role of the AP-1 transcription factor on thymocyte maturation and thymus architecture by overexpressing FosB2 in transgenic mice. FosB2 is a naturally occurring splice variant of the FosB2 gene, encoding a truncated protein which lacks two domains necessary for transcriptional activation. The expression of FosB2 in the thymocytes severely affected their maturation and the structure of the whole thymus: the phenotype developed slowly during the first months of life, resulting in a progressive expansion of the medulla and concomitant reduction of the cortex. CD4+ thymocytes represented the major thymocyte population, whereas the CD4+ 8+ thymocytes were virtually absent. This phenotype appeared to be an intrinsic property of bone marrow derived cells, as it could be reproduced in bone marrow chimaeric mice. This pathology was very reminiscent to that observed in mice overexpressing c-Fos in thymic epithelium: also in that case the thymus underwent with age a progressive expansion of the epithelium and major changes in the ratio of thymocyte subsets, but the phenotype appeared to be an intrinsic property of the epithelial cells since it could not be reproduced by transgenic bone marrow transplantation. We speculate that both overexpression of FosB2 in thymocytes and overexpression of c-Fos in thymic epithelium results in aberrant signaling between thymocytes and stroma, that ultimately alters the thymic micromilieu, leading to this severe pathology.

Cellular immune responses to cell wall peptidoglycan associated protein antigens in tuberculosis patients and healthy subjects

We have isolated cell wall peptidoglycan associated proteins (CW-Pr) of Mycobacterium tuberculosis H37Ra by chemical treatment with trifluoromethanesulfonic acid:anisole (2:1), which further resolved into 71, 60 and 45 kDa proteins on SDS-PAGE. A study was carried out to investigate the immunoreactivity of these proteins with blood samples from 4 categories, including 15 tuberculous patients (TB), 5 tuberculous patients on ATT (TBT), 10 PPD non-reactive healthy controls (HPPD-) and 11 PPD reactive healthy controls (HPPD+). Comparing the proliferative responses to cell wall protein antigens, it was observed that the 71 kDa protein gave maximum stimulation with PBMCs from the TB and HPPD+ groups. The adherent PBMCs from the TB group also demonstrated enhanced phagocytosis, particularly in the presence of 71 and 45 kDa proteins, and the phagocytic index was significantly higher (P < 0.05) than the TBT group. However, PBMCs from of the groups recognized the 60 kDa cell wall antigen. Our results suggest that the 71 kDa protein from the cell wall of M. tuberculosis is highly immunogenic.

Memory. A model with good CREdentials

The sea snail Aplysia provides a relatively simple model system for studying both short-term and long-term memory; a known transcriptional mechanism is implicated in establishment of the latter.

Strategy for reliable prenatal detection of normal male carriers of the fragile X syndrome

Prenatal diagnosis of fragile X syndrome identifying full mutations has been described. Here we report on a case of a prenatal test concerning a normal male carrier of the fragile X syndrome. Southern blot analysis of the fragile X gene resulted in the identification of a premutation in DNA isolated from the chorionic villus sample. Using a polymerase chain reaction (PCR)-based assay the CGG repeat length was determined to be 82 CGG repeat units. Confirmation of this premutation in the chorionic villus sample was based on the cytogenetic analysis of the expression of the fragile site at Xq27 applied on a cordocentesis-derived blood sample.

Purified I kappa B-beta is inactivated upon dephosphorylation

In uninduced cells, the NF-kappa B transcription factor resides in the cytoplasm in complex with an inhibitory protein, I kappa B. I kappa B is a specific inhibitor of DNA binding and apparently prevents nuclear uptake of NF-kappa B. Stimulation of cells, for instance with the cytokine tumor necrosis factor, releases I kappa B and allows nuclear translocation and DNA binding of NF-kappa B to regulatory DNA sequences in many genes. We recently reported on the purification of a major form of I kappa B, referred to as I kappa B-alpha, with a molecular size of 37 kDa. Here, we purified and characterized I kappa B-beta, a chromatographically distinct second form of I kappa B. I kappa B-beta has a size of 43 kDa and, as I kappa B-alpha, an acidic isoelectric point between 4.8 and 5.0. Both forms of I kappa B were inactivated by a treatment with protein kinases A and C in vitro. In contrast to I kappa B-alpha, I kappa B-beta lost its inhibiting activity upon a treatment with phosphatase. Phosphatase treatment also released active NF-kappa B from its inactive complex with I kappa B-beta suggesting that the activation of NF-kappa B in intact cells might not only rely on phosphate transfer onto I kappa B but also on phosphate removal from one form of I kappa B.