Production, characterization and in-vitro applications of single-domain antibody against thyroglobulin selected from novel T7 phage display library.

Single- domain antibodies (SdAbs) have been deployed in various biomedical applications in the recent past. However, there are no reports of their use in the immunoradiometric assays (IRMA) for thyroglobulin (Tg). Tg is the precursor molecule for the biosynthesis of thyroid hormones: thyroxine and triiodothyronine, which are essential for the regulation of normal metabolism in all vertebrates. Patients with differentiated thyroid cancer (DTC) require periodic monitoring of their serum thyroglobulin levels, as it serves as a prognostic marker for DTC. Here, we report a methodology to produce SdAbs against human-Tg, by a hybrid immunization/directed-evolution approach by displaying the SdAb gene-repertoire derived from a hyperimmune camel in the T7 phage display system. We have demonstrated the immunoreactivity of anti-Tg-SdAb (KT75) in immunoassays for thyroglobulin and measured its affinity by surface plasmon resonance (KD ~ 18 picomolar). Additionally, we have shown the quantitative-binding property of SdAb for the first time in IRMA for thyroglobulin. The serum Tg values obtained from SdAb-Tg-IRMA and in-house assay using murine anti-Tg-monoclonal antibody as tracer significantly correlated, r = 0.81, p < 0.05. Our results highlight the scope of using the T7 phage display system as an alternative for the conventional M13-phage to construct single-domain antibody display libraries.

Comparison of Serum Thyroglobulin Levels in Differentiated Thyroid Cancer Patients Using In-House Developed Radioimmunoassay and Immunoradiometric Procedures.

Thyroglobulin (Tg) is a proven tumor marker in the follow-up and post-operative management of patients with differentiated thyroid cancer (DTC). All assays for serum thyroglobulin (s-Tg) are based on immunoassays, however, the assay technique has a bearing on the variations seen in the estimations. We studied this using four in-house developed radioimmunoassays (RIA) and immunoradiometric assays (IRMA). Limit of detection, working range, recovery, dilution test, precision profiles and method comparison were evaluated. All four methods were used for the estimation of s-Tg in DTC patients and also compared for their performance using commercially available Tg IRMA kits from DiaSorin and Izotop. The s-Tg values measured by six different immunoassays showed very significant inter-method correlation (0.84-0.99, p < 0.001). However, among the in-house developed assays; the coated tube IRMA showed a better sensitivity and precision at the lower concentration range and hence, is preferable for the routine measurement of s-Tg in patients negative for Tg autoantibodies (TgAb). Although the second generation IRMAs offer practical benefits of having higher sensitivity, shorter turn-around time and convenience of automation, they, unfortunately, also have higher tendency for interference from both TgAb and heterophilic antibodies, if present in the sample. On the contrary, RIA is less prone to such interference and, hence, can be used in patients with TgAb. In order to effectively use this test, it is important that nuclear medicine physicians and endocrinologists understand these intrinsic technical limitations encountered during s-Tg measurement.

A Study of Microalbuminuria (MAU) and Advanced Glycation End Products (AGEs) Levels in Diabetic and Hypertensive Subjects.

The prevalence of non-communicable diseases like diabetes mellitus (DM) and hypertension (HTN) is growing worldwide. Both lead to nephropathy if not controlled effectively. Microalbuminuria (MAU) is recognized as an early predictor for nephropathy. Additionally, the timely detection of advanced glycation end products (AGEs) is also considered to be an important prognostic factor for diabetic nephropathies. Hence, screening for the early detection of MAU and AGEs would be an useful and relatively inexpensive laboratory test for early clinical diagnosis for the incidence of nephropathy in these diseases. This study was conducted in DM, HTN and pregnancy induced hypertensive (PIH) subjects. MAU and Nε-Carboxymethyllysine (CML) levels were estimated by in-house RIA kits in the patient groups and controls, while the total AGEs level in serum was determined by ELISA. The levels of MAU, CML and AGE-BSA were observed to be significantly higher in DM, HTN and PIH subjects compared to controls (p < 0.001). Increased serum CML and AGEs levels in DM, HTN and PIH subjects indicated ongoing glycemic damage and their susceptibility to develop renal complications.

Activation of murine macrophages by G1-4A, a polysaccharide from Tinospora cordifolia, in TLR4/MyD88 dependent manner.

Macrophages are centrally placed in the innate immune system and their activation is crucial to the generation of appropriate immune response in the event of any pathogenic invasion, tumorigenesis or other human diseases. Many plant derived polysaccharides are known to activate macrophages. In the present study, effects of G1-4A, a polysaccharide derived from Tinospora cordifolia, on the activation of macrophages were investigated. Our data demonstrated the up regulation of expression of TNF-α, IL-ß, IL-6, IL-12, IL-10 and IFN-γ in RAW 264.7 cell line and peritoneal macrophages after G-14A treatment. Nitric oxide levels were also enhanced along with up-regulation of NOS2 expression in murine macrophages post G1-4A treatment. Further, G1-4A treatment up-regulated the surface expression of MHC-II and CD-86 in macrophages. Using siRNA against TLR4, MyD88 and anti-TLR4 blocking antibodies, we established that G1-4A activated macrophages by classical pathway in TLR4-MyD88 dependent manner. Additionally, G1-4A treatment activated p38, ERK and JNK MAPKs in macrophages. Using pharmaceutical inhibitors of above MAPKs we concluded that G1-4A activates the macrophages by activation of p38, ERK and JNK MAPKs in RAW264.7 macrophages. Thus our data suggests the activation of macrophages by classical pathway after treatment of G1-4A.

Improved method for preparing Ni(II) complex of (S)-tyrosine Schiff base and its use in the automated synthesis of O-(2'-[18F]fluoroethyl)-l-tyrosine using solid-phase extraction purification.

O-(2'-[18F]fluoroethyl)-l-tyrosine is reportedly suitable for PET-imaging of brain tumours. We report here the synthesis of Ni(II)-complex of Schiff's base (S)-[N-2-(N'-benzylprolyl)amino]-benzophenone,((S)BPB) and alkylated l-tyrosine precursor, Ni(II)-(S)-BPB-l-Tyr-O-CH2-CH2-OTs by an improved method. A fully-automated radio-synthesis including non-HPLC purification was developed with a radio-chemical yield of 24.6 ± 2% in 70 ± 2min (n = 5). Radiochemical and enantiomeric purity was > 98% and 94% respectively. Bio-distribution and micro-PET studies in C57BL/6 mice bearing B16F10 melanoma showed tumor to brain ratio of 3.36 and 3.62 respectively at 60min post-injection.

A Microarray Immunoassay for Serum Thyrotropin and Thyroglobulin Using Antibodies Immobilized on Track-Etched Membranes.

Serum thyroglobulin (Tg) and thyroid stimulating hormone (TSH) measurements have evolved as important analytes for monitoring the prognosis of patients with differentiated thyroid cancer, post-thyroidectomy. Individual analyte immunoassay is the current practice in clinical pathology, but the simultaneous assay for all relevant analytes for a given disease, can reduce assay costs, improve patient compliance and give the clinician more information for an unequivocal diagnosis. Microarray immunoassay (MI) can achieve this goal and, hence, we have developed and validated a immuno-radiometric MI for quantitation of serum TSH and Tg by using highly micro-porous polycarbonate (PC) track-etched membranes (TEM) to immobilize the monoclonal anti-TSH and polyclonal anti-Tg antibodies in ~1 mm diameter spots. Non-competitive immunoassays were performed using mixture of 125I labeled monoclonal anti-TSH and anti-Tg antibodies. Phosphorimager was used to quantify the bound radioactivity. TSH and Tg were detected with detection limit of 0.07 µIU/ml and 0.13 ng/ml respectively, which is lower than the clinically required cut-off level. The assay showed: acceptable intra-assay precision within 20 % and recovery in the range of 76-111.2 %. MI compared well with the established immunoradiometric assay (IRMA) with r = 0.98, p < 0.01 (n = 41). No cross-reactivity was seen between the immobilized antibodies. Although two hormones are addressed in this report, MI using PC TEM and isotopic/non-isotopic tracers has the potential for highly automated multiplexed analysis.

In-House Solid-Phase Radioassay for the Detection of Anti-thyroglobulin Autoantibodies in Patients with Differentiated Thyroid Cancer.

Thyroglobulin autoantibodies (TgAb) are estimated to detect potential interferences in thyroglobulin (Tg) immunoassays and also for the diagnosis of autoimmune thyroid disease. A user friendly and robust in-house solid-phase radioassay was standardized and parameters like sensitivity, reproducibility and stability were assessed. Further, it was validated and evaluated for the detection of autoantibodies in differentiated thyroid cancer (DTC) patients. Totally 301 samples received in our laboratory for routine serum Tg estimation were studied. The samples were analyzed for TgAb by the solid-phase radioassay developed in-house and compared with commercial anti-hTg IRMA kit (Immunotech, France). The control group comprised of 37 euthyroid males from our Centre. The intra- and inter-assay CVs for the two quality control samples (Control A = 104 ± 12.6 IU/mL and Control B = 1029 ± 114 IU/mL) were found less than or equal to 6.05 and 13.85 % respectively. Solid-phase radioassay showed a good agreement on comparison with Immunotech IRMA (r = 0.99). Using the proposed cut-off thresholds (in-house solid-phase radioassay 52 IU/mL and Immunotech IRMA 30 IU/mL), 5.4 % of the control subjects were positive for TgAb by both the methods. Prevalence of TgAb in DTC patients was 17.3 and 16.6 % using the Immunotech kit and in-house solid-phase radioassay respectively. The in-house solid-phase radioassay has the requisite sensitivity for the evaluation of TgAb comparable to commercial kit and also suitable for routine use as it is rapid, user friendly and economical.

Radiochemical studies, pre-clinical investigation and preliminary clinical evaluation of 170Tm-EDTMP prepared using in-house freeze-dried EDTMP kit.

The objective of the present work is to formulate 170Tm-EDTMP using an in-house freeze-dried EDTMP kit and evaluate its potential as a bone pain palliation agent. Patient dose of 170Tm-EDTMP was prepared with high radiochemical purity using the lyophilized kit at room temperature within 15min. Pre-clinical evaluation in normal Wistar rats revealed selective skeletal accumulation with extended retention. Preliminary clinical investigation in 8 patients with disseminated skeletal metastases exhibited selective uptake in the bone and retention therein for a long duration.

A multi-analyte immunoassay for thyroid related analytes.

We describe the development and validation of multianalyte immunoassays (MAIA) for three analytes, viz., thyroxine (T4), thyroid stimulating hormone (TSH), and thyroglobulin (Tg) essential for assessment of thyroid function but having widely varying molecular weights. Using polycarbonate (PC) track-etched membranes (TEM) as an immobilization support and 125I as the tracer, both competitive assay for T4 and non-competitive assay for TSH and Tg were performed on the same TEM. MAIA was found to be highly sensitive and precise with clinically useful working range and correlated very well with individual analyte immunoassays. While we have demonstrated this assay format with radiotracer, it can be used with non-isotopic tracers equally well.

G1-4A, a Polysaccharide from Tinospora cordifolia Inhibits the Survival of Mycobacterium tuberculosis by Modulating Host Immune Responses in TLR4 Dependent Manner.

Rapid emergence of drug resistance in Mycobacterium tuberculosis (MTB) is a major health concern and demands the development of novel adjunct immunotherapeutic agents capable of modulating the host immune responses in order to control the pathogen. In the present study, we sought to investigate the immunomodulatory effects of G1-4A, a polysaccharide derived from the Indian medicinal plant Tinospora cordifolia, in in-vitro and aerosol mouse models of MTB infection. G1-4A treatment of MTB infected RAW264.7 macrophages significantly induced the surface expression of MHC-II and CD-86 molecules, secretion of proinflammatory cytokines (TNF-α, IL-ß, IL-6, IL-12, IFN-γ) and nitric oxide leading to reduced intracellular survival of both drug sensitive (H37Rv) as well as multi drug resistant strains (Beijing and LAM) of MTB, which was partially attributed to G1-4A induced NO production in TLR4-MyD88 dependent manner. Similarly, bacillary burden was significantly reduced in the lungs of MTB infected BALB/c mice treated with G1-4A, with simultaneous up-regulation of the expression of TNF-α, INF-γ and NOS2 in the mouse lung along with increased levels of Th1 cytokines like IFN-γ, IL-12 and decreased levels of Th2 cytokine like IL-4 in the serum. Furthermore, combination of G1-4A with Isoniazid (INH) exhibited better protection against MTB compared to that due to INH or G1-4A alone, suggesting its potential as adjunct therapy. Our results demonstrate that modulation of host immune responses by G1-4A might improve the therapeutic efficacy of existing anti-tubercular drugs and provide an attractive strategy for the development of alternative therapies to control tuberculosis.

Identification of a novel class of quinoline-oxadiazole hybrids as anti-tuberculosis agents.

A series of novel quinoline-oxadiazole hybrid compounds was designed based on stepwise rational modification of the lead molecules reported previously, in order to enhance bioactivity and improve druglikeness. The hybrid compounds synthesized were screened for biological activity against Mycobacterium tuberculosis H37Rv and for cytotoxicity in HepG2 cell line. Several of the hits exhibited good to excellent anti-tuberculosis activity and selectivity, especially compounds 12m, 12o and 12p, showed minimum inhibitory concentration values<0.5µM and selectivity index>500. The results of this study open up a promising avenue that may lead to the discovery of a new class of anti-tuberculosis agents.

Mycobacterium tuberculosis H37Rv infected THP-1 cells induce epithelial mesenchymal transition (EMT) in lung adenocarcinoma epithelial cell line (A549).

Chronic infections of Mycobacterium tuberculosis (MTB) cause oxidative stress, TLR activation and production of inflammatory cytokines and thus can create an environment reinforcing tumorigenesis, progression and metastasis. Epidemiological studies have established a relation between lung cancer and tuberculosis but cellular mechanism is still poorly understood. In present study, we have shown for the first time that MTB infection in human monocytic cell line (THP-1) enhances invasion and induces EMT characteristics in lung adenocarcinoma cell line (A549) during co-culture. After co-culture with MTB infected THP-1 cells A549 cells exhibited morphological and molecular signatures of EMT. During co-culture, expression of inflammatory cytokines like TNF-α, IL-1ß and IL-6 was enhanced in the microenvironment of A549 cells in comparison to single culture of A549 cells. Using pharmacological inhibitors of JNK (SP-600125) and p38 MAPK (SB-203580), we demonstrated the involvement of JNK and p38 MAPK in MTB induced EMT induction in A549 cells. To the best of our knowledge this is the first report demonstrating the role of MTB infection in induction of metastasis associated EMT in lung cancer.

A Novel Folate-Targeted Nanoliposomal System of Doxorubicin for Cancer Targeting.

Targeted drug delivery systems for cancer improves anti-tumor efficacy and reduces systemic toxicity by restricting availability of cytotoxic drugs within tumors. Targeting moieties, such as natural ligands (folic acid, transferrin, and biotin) which are overexpressed on tumors, have been used to enhance liposome-encapsulated drug accumulation within tumors and resulted in better control. In this report, we explored the scope of targeting ligand folic acid, which is incorporated in liposome systems using folic acid-modified cholesterol (CPF), enabled highly selective tumor-targeted delivery of liposome-encapsulated doxorubicin and resulted in increased cytotoxicity within tumors. Folate-tagged poloxamer-coated liposomes (FDL) were found to have significantly higher cellular uptake than conventional poloxamer-coated liposomes (DL), as confirmed by fluorometric analysis in B16F10 melanoma cells. Biodistribution study of the radiolabeled liposomal system indicated the significantly higher tumor uptake of FDL as compared to DL. Anti-tumor activity of FDL against murine B16F10 melanoma tumor-bearing mice revealed that FDL inhibited tumor growth more efficiently than the DL. Taken together, the results demonstrated the significant potential of the folate-conjugated nanoliposomal system for drug delivery to tumors.

Design and Synthesis of a Focused Library of Diamino Triazines as Potential Mycobacterium tuberculosis DHFR Inhibitors.

We report design of a series of 2,4-diamino triazines as Mycobacterium tuberculosis (Mtb) dihydrofolate reductase inhibitors. The synthesized compounds were evaluated against Mtb (H37Rv and Dormant stage H37Ra), their cytotoxicity was assessed (HepG2 and A549 cell lines), and selectivity toward Mtb was evaluated by testing against other bacterial strains. Some derivatives showed promising activity along with low cytotoxicity. The most potent compound in the whole cell assay (MIC 0.325 µM against H37Rv) showed selectivity in the enzyme assay and exhibited synergy with second line anti-TB agent p-amino salicylic acid. This study therefore provides promising molecules for further development as antituberculosis DHFR inhibitors.

Antifolate Activity of Plant Polyphenols against Mycobacterium tuberculosis.

With the view of exploring phytochemicals as Mycobacterium tuberculosis (Mtb) dihydrofolate reductase inhibitors, known plant polyphenols from various classes were subjected to detailed docking studies. From this in-silico screening, seven polyphenols were selected and tested against Mtb H37 Rv in whole cell assays. The phytochemicals exhibited potential activity ranging from 3 to 183 µm. These molecules were then tested against the pathogenic and human enzymes in a high-throughput microtitre assay. Epigallocatechin gallate showed the best activity and selectivity. The in-silico analysis was in agreement with the assay results. Of these 7 polyphenols, 5 exhibiting minimum inhibitory concentration values of ≤15 µm were tested for synergistic activity with first line drug Ethambutol and second line folate inhibitor para-amino salicylic acid. Epigallocatechin gallate, Magnolol and Bakuchiol exhibited moderate synergistic association by lowering the minimum inhibitory concentration of these drugs. These simple phytochemicals could hence be considered as leads for further studies, or for preparation of semi-synthetic derivatives to be used in combination therapy, for increased anti-tuberculosis activity after validation in-vivo.

Rational drug design, synthesis and biological evaluation of dihydrofolate reductase inhibitors as antituberculosis agents.

BACKGROUND: A series of 2,4-diamino-s-triazines was designed, with potential for activity against Mycobacterium tuberculosis (Mtb) dihydrofolate reductase enzyme, on the basis of virtual screening results and structure-based drug design. RESULTS: The compounds were evaluated against Mtb (H37Rv) and their cytotoxicity was assessed using VERO cell lines. Of particular note, two compounds were found to have the most promising antituberculosis activity (6b minimum inhibitory concentration: 1.76 µM and 6i minimum inhibitory concentration: 1.57 µM) along with low cytotoxicity (CC50: >300 µM). The enzyme assay results of these two indicated significant inhibition of Mtb dihydrofolate reductase along with selectivity. Selected derivatives were tested against dormant tubercle bacilli in vivo and ex vivo indicating potential inhibition. CONCLUSION: This study provides promising antituberculosis dihydrofolate reductase inhibitors that can act as potential leads for further development.

E84G mutation in dihydrofolate reductase from drug resistant strains of Mycobacterium tuberculosis (Mumbai, India) leads to increased interaction with Trimethoprim.

BACKGROUND: Dihydrofolate reductase (DHFR) (dfrA gene) is an essential enzyme for cell survival and an unexplored target in Mycobacterium tuberculosis (Mtb). This study was carried out to analyze mutations in the dfrA gene amongst 20 clinical DNA samples from Mtb isolates obtained from Mumbai, India. METHODS: Sequencing of the PCR amplified dfrA gene from these DNA isolates revealed a point mutation in one strain, leading to a glutamic acid to glycine change. In silico simulation studies revealed a surface alteration in the enzyme due to this E84G mutation. The amplified mutant gene was cloned and expressed. The mutant protein was assessed against known DHFR inhibitors: Methotrexate and Trimethoprim. RESULTS: An increased affinity for inhibitor Trimethoprim and native substrate dihydrofolate was observed with the mutant. Methotrexate did not vary in its activity with both the enzyme forms. CONCLUSIONS: The Glu84Gly point mutation may lead to a variation in the strain which may cause resistance in the future.

Early gestation screening of pregnant women for iodine deficiency disorders and iron deficiency in urban centre in Vadodara, Gujarat, India.

Pregnancy is a special condition where many metabolic changes may occur because of increased requirement of essential micronutrients such as iron and iodine. Foetal thyroid starts producing its own thyroid hormones after 12 weeks of gestation. Therefore, the first trimester is very crucial for meeting thyroid hormone requirements of the mother and foetus. Iodine deficiency and iron deficiency may affect mental and physical growth of the foetus. Hence, it is very important to establish a programme on the screening of pregnant women for thyroid dysfunction tests along with established iron status assessment. Thus, the study was aimed to screen the pregnant women for iodine deficiency disorders and iron deficiency during early gestation, situational analysis on thyroid insufficiency and iron deficiency in pregnant women (gestational age <15 weeks) in urban Vadodara, Gujarat. n = 256 healthy pregnant women with uncomplicated singleton pregnancy were selected. The thyroid hormone was estimated by RIA, UIE using simple microplate technique and haemoglobin (Hb) concentration by acid hematin method. Median thyrotropin (TSH), free thyroxine (FT4), total thyroxine (TT4) and UIE concentrations were 1.88 µIU/ml, 0.83 ng/dl, 10.24 µg/dl and 297.14 mcg/l, respectively. There was a significant correlation between TSH, FT4 and month of gestation. Mean Hb concentration was 9.27 ± 1.09 g/dl. The prevalence of iodine insufficiency (based on UI) was 16.79% and iron deficiency was 91%. Screening programme for iodine deficiency during early gestation should be implemented along with the existing programme of haemoglobin estimation at first prenatal visit. This would help prevent damage to the developing brain and growth of the foetus and also to trace at-risk pregnant women.

Rational drug design based synthesis of novel arylquinolines as anti-tuberculosis agents.

A series of novel arylquinoline derivatives was designed retaining significant pharmacophoric features and three dimensional geometry of bedaquiline. In silico ADME study was performed to assess drug likeness and toxicity profiles of the designed molecules. The compounds were evaluated for activity against Mycobacterium tuberculosis H37Rv using Resazurin Microtitre Assay (REMA) plate method and cytotoxicity in VERO C1008 cell line. Several of the synthesized compounds exhibited good antituberculosis activity and selectivity, especially compounds, 12i (MIC: 5.18 µM and MIC/CC50: 152.86) and 12l (MIC: 5.59 µM and MIC/CC50: 160.57). The study opens up a new platform for the development of arylquinoline based drugs for treating tuberculosis.

An in-house multiplex PCR test for the detection of Mycobacterium tuberculosis, its validation & comparison with a single target TB-PCR kit.

BACKGROUND & OBJECTIVES: The conventional techniques used in TB diagnosis like AFB (acid fast bacilli) smear microscopy lack sensitivity and the gold standard, culture test takes time. A test based on multiplex polymerase chain reaction (PCR) targeting the 38 kDa gene and IS6110 insertion sequence, specific to Mycobacterium tuberculosis was developed to further increase the sensitivity of a TB-PCR kit targeting only 38 kDa gene developed earlier in the same laboratory. The multiplex test was validated using sputum samples from pulmonary TB (PTB) cases. The sensitivity and specificity were compared with AFB smear examination and Lowenstein-Jensen (LJ) culture test. METHODS: Multiplex PCR amplifying 340 and 245 bp sequence of 38 kDa gene and IS6110, respectively was standardized and analytical sensitivity was verified. Sputum samples (n=120) obtained from PTB cases were subjected to AFB smear examination, LJ culture and a multiplex as well as single target PCR test. Additionally, 72 non-TB respiratory samples were included in the study as negative controls. RESULTS: Analytical sensitivity of multiplex PCR was found to be 100 fg for 38 kDa gene and 1 fg for IS6110. Multiplex PCR, using both the targets, showed highest sensitivity of 81.7 per cent, followed by 69.2 per cent for L-J culture test and 53.3 per cent for AFB smear when clinical diagnosis was considered as a gold standard. The sensitivity of detection of M. tuberculosis in AFB smear positive and negative samples by multiplex PCR was 93.7 and 67.9 per cent, respectively. Sensitivity of 77.1 per cent observed for the detection of M. tuberculosis with single target PCR increased to 89.2 per cent with multiplex PCR in culture positive samples. Four samples showed positive PCR results only with primers for 38 kDa gene. INTERPRETATION & CONCLUSIONS: Multiplex PCR increased the sensitivity of single target PCR and will be useful in diagnosing paucibacillary smear negative samples. Further, it can also be used to detect samples with M. tuberculosis strains lacking IS6110.