Clinical Proteomics Profiling for Biomarker Identification Among Patients Suffering With Indian Post Kala Azar Dermal Leishmaniasis.

Background: Post Kala Azar Dermal Leishmaniasis (PKDL) is a non-fatal dermal sequel of Visceral Leishmaniasis (VL), affecting individuals worldwide. Available diagnostic tools lack sensitivity and specificity toward identifying macular (MAC) PKDL patients, due to low parasite load in patients' sample. Confirmatory test like punch biopsy are invasive and painful. Considering the rural nature of this disease and the prevailing situation of diagnostic scenario, PKDL patients mostly remains unattended from receiving proper medical care. They in turn act as "mobile parasite reservoir," responsible for VL transmission among healthy individuals (HI). This study aims to identify PKDL disease specific glycated protein biomarkers, utilizing the powerful LC-MS/MS technology, which is the tool of choice to efficiently identify and quantify disease specific protein biomarkers. These identified PKDL disease specific novel glycoproteins could be developed in future as immunochromatographic based assay for efficient case detection. Methodology: Previously our lab had identified importance of glycated (Circulating Immune Complexes) CICs, among PKDL patients. This study aims to further characterize disease specific glycated protein biomarkers, among MAC PKDL patients for both diagnostic and prognostic evaluation of the disease. LC-MS/MS based comparative spectral count analysis of MAC PKDL to polymorphic (POLY) PKDL, HI, and Cured (CR) individuals were performed. Proteins level alterations among all study groups were confirmed by Western blot and enzyme-linked immunosorbant Assay (ELISA). Results: Among MAC PKDL patients 43, 60, 90 proteins were altered compared to POLY PKDL, HI, and CR groups, respectively. Filtering for the most significant proteins, Plasminogen (PLG) and Vitronectin (VTN) were identified which promisingly identified MAC PKDL cases. Active surveillance results from endemic districts of West Bengal revealed drastic rise of MAC PKDL cases, alarming the urgency for field adaptive efficient biomarker. Conclusion: This current study aims to establish PLG and VTN as novel diagnostic and prognostic protein biomarker for MAC and POLY PKDL cases management.

Glycoproteins in circulating immune complexes are biomarkers of patients with Indian PKDL: A study from endemic districts of West Bengal, India.

BACKGROUND: Post Kala Azar Dermal Leishmaniasis (PKDL) occurs as dermal consequence of previous Visceral Leishmaniasis (VL) infection and serves as an important reservoir for transmission of VL. Diagnosis of PKDL is often challenging for its symptomatic resemblance to other co-endemic diseases like Leprosy or Vitiligo. Parasitological examination by slit-skin smear and culture are the standard methods but lack high sensitivity. Thus, for efficient control of VL, reliable diagnostic and prognostic assay of PKDL are required. OBJECTIVE: Previously, glycoproteins (9-OAcSA) have been reported as promising biomarkers of Indian VL patients. However, till date, the status of glycans in Indian PKDL patients remains unexplored. Accordingly, in this study, the glyco-profile of PKDL Circulating Immune Complexes (CICs) as compared to other cross diseases like Vitiligo and Leprosyhas been investigated. Further, a novel Glyco CIC assay has been developed for efficient Indian PKDL patient diagnosis. METHODS/PRINCIPAL FINDING: In the present study, 90 PKDL patients were enrolled from 3 VL endemic districts of West Bengal during 2015-16. Glycosylation profile of isolated CICs from sera of PKDL patients were initially analyzed through gradient SDS gel electrophoresis followed by PAS silver double staining, which revealed the presence of several glycan rich PKDL specific proteins of varying molecular weights. To further characterize the glyco-profile of acid dissociated affinity purified immuno-reactive antigens present in the CICs, glycosylation was demonstrated in these purified CIC antigens by DIG glycan differentiation kit with or without glycosidase as well as neuraminidase treatment. Diagnostic evaluation of the newly developed colorimetric Glyco CIC assay through Receiver Operating Characteristic (ROC) curve analysis revealed excellent (0.99) AUC value as compared to other conventional serodiagnostic assays like PEG CIC, Parasite ELISA (IgG and IgM). Additionally, longitudinal monitoring of 18 PKDL patients further revealed its good prognostic utility. CONCLUSION: These results highlight the glycosylation status of CICs among Indian PKDL patients present in all the studied endemic districts of West Bengal. These PKDL biomarkers were completely absent in cross diseases like Vitiligo and Leprosy. Further, the newly developed Glyco CIC assay had an improved sensitivity of 95.6%, specificity of 99.3%, NPV of 97.1% and PPV of 98.9%.

Cloning, Expression, Purification and Characterization of Oligomeric States of the Native 5HT2A G-Protein-Coupled Receptor.

BACKGROUND: The 5HT2A G-Protein Coupled Receptor (GPCR) is an important family of receptors involved in an array of neuromodulatory functions. Their dysregulation has been implicated in a number of psychiatric diseases. In spite of the importance of this GPCR, high resolution structure and mechanistic details of its function is unknown. Cholesterol plays an important role in the function of many receptors and reduced cholesterol levels can lead to disruption of serotonergic pathways. However, the role of cholesterol in the formation of GPCR oligomers has not been previously shown for this receptor. Given that receptor dimers have been shown to be the functional unit of this receptor, it is important to investigate the effect of cholesterol in the oligomeric state of 5HT2A receptor. OBJECTIVES: The main objective of this work is to clone, over-express and purify the 5HT2A receptor and investigate the effect of cholesterol in its oligomer formation. METHODS: The 5HT2A receptor (5HT2AR) DNA construct was subcloned into pFastBac-HT vector and the purified bacmid was used to transfect healthy Sf9 cells. After subsequent passages, a high titer baculovirus was used for over-expression in Sf9 cells. To verify whether the over-expressed receptor was localized in the membrane or cytosolic fraction, cells with and without baculoviral infection were analyzed by immunocytochemistry. Subsequently, the over-expression conditions required to obtain sufficient quantity of the receptor was optimized followed by the optimization of the purification conditions. Finally, the culture was scaled up and the receptor was purified by affinity chromatography. The over-expression of the receptor was checked by Western blotting and purity was analyzed by Coomassie stained SDS PAGE. Cryo-electron microscopy experiments were performed on the purified receptor in presence and absence of cholesterol and at multiple concentrations to rule out any concentration dependent effect on the oligomer formation. RESULTS: Immunocytochemistry experiments showed prominent nuclear staining; however, bright green staining along the cell membrane was observed only for the infected cells, suggesting appropriate trafficking of majority of the over-expressed receptors to the cell membrane. Results of cryoelectron microscopy show that the receptor with cholesterol had particles that were bigger in size (~11 - 12 nm) compared to the dimension of known GPCR homologs. In contrast, the receptor after removal of cholesterol revealed a uniform distribution of smaller particles (~5 - 6 nm) that is approximately half the size of 5HT2AR particles with cholesterol. Comparing the 2D average views of detergent-encapsulated 5HT2AR particles with the overall dimensions of other 5HT receptor analogs, we show that while a 5HT2AR dimer more closely matches the dimensions of particles with CHS, only a monomer can be fit to particles without CHS. Importantly, even at higher receptor concentration and particle density, the size for 5HT2AR particles without CHS remains the same, suggesting that dimerization is unlikely an effect of concentration. CONCLUSION: Our results indicated that 5HT2A receptor primarily forms a dimer in presence of cholesterol whereas it predominantly forms a monomer when cholesterol is removed.