Molecular detection of Candidatus Rickettsia asembonensis in fleas collected from pets and domestic animals in Puducherry, India.

Rickettsia are obligate intracellular pathogens transmitted by arthropod vectors. The re-emergence of several rickettsioses imposes severe global health burden. In addition to the well-established rickettsial pathogens, newer rickettsial species and their pathogenic potentials are being uncovered. There are many reports of spotted and typhus fever caused by rickettsiae in India. Hence, in this study we screened the ectoparasites of pet and domestic animals for the presence of rickettsia using polymerase chain reaction. Nine cat flea samples (Ctenocephalides felis felis), that tested positive for the presence of rickettsia were subjected to Multi Locus Sequence Typing. Nucleotide sequencing and Phylogenetic analysis of gltA, ompB and 16rrs genes revealed that the rickettsiae detected in cat fleas was Rickettsia asembonensis. Further studies are required to assess Rickettsia asembonensis pathogenic potential to human and its enzootic maintenance of in various hosts and vectors.

Genetic selection pressure in TLR9 gene may enforce risk for SLE in Indian Tamils.

Objectives Lupus is a classical systemic autoimmune disease with genetics as one of the well known causative factors for the disease pathogenesis. Toll-like receptors are the major pattern recognition receptors associated with innate immunity and also act as an interface with the adaptive immunity. Genetic polymorphisms in genes encoding TLRs were implicated in the development of infections, malignancies and autoimmune diseases. TLR9 is a member of TLR family, and recognizes the CpG DNA motifs of pathogens. Though the incidence rate of lupus in Asians was reported to be low (30 - 50/100,000 population), poor disease prognosis due to higher incidence of renal complications and aggressive disease worsens the scenario. The ability of TLR9 to detect and elicit an immune response against double-stranded DNA makes TLR9 a relevant factor to be tested for its association with the clinical and serological phenotypes of lupus. However, lack of relevant genetic data on normative frequencies of the TLR9 (rs187084) polymorphism may serve as a constraint to derive the sample size to conduct case control association studies. Hence this study was conducted to establish the normative frequency of TLR9 (rs187084) polymorphism in Indian Tamils. Materials and methods The TLR9 (rs187084) polymorphism was screened in South Indian Tamils ( n = 208) by PCR-RFLP. Results and discussion We observed a higher occurrence of the mutant allele (65%) in South Indian Tamils. No gender disparity with respect to the mutant allele frequency was observed. The higher incidence of mutant allele in both genders suggests that this population had undergone a genetic selection pressure as an evolutionary genetic measure to withstand the prevailing endemic infections like TB and malaria. Though the enhanced expression of TLR9 was protective against infections, it may also influence the development of autoimmune diseases. Conclusion The higher incidence of theTLR9 (rs187084) over-expression mutation in Indian Tamils is suggestive of a genetic adaptation or selection pressure to withstand the prevailing endemic infectious and parasitic diseases. However, this genetic adaptation poses a greater risk to develop autoimmune diseases like SLE etc through complex gene environment interactions. The normative frequency of the TLR9 (rs187084) polymorphism established in our population could now be used to define the sample size for future case control studies.

Haploinsufficiency of the 22q11.2 microdeletion gene Mrpl40 disrupts short-term synaptic plasticity and working memory through dysregulation of mitochondrial calcium.

Hemizygous deletion of a 1.5- to 3-megabase region on chromosome 22 causes 22q11.2 deletion syndrome (22q11DS), which constitutes one of the strongest genetic risks for schizophrenia. Mouse models of 22q11DS have abnormal short-term synaptic plasticity that contributes to working-memory deficiencies similar to those in schizophrenia. We screened mutant mice carrying hemizygous deletions of 22q11DS genes and identified haploinsufficiency of Mrpl40 (mitochondrial large ribosomal subunit protein 40) as a contributor to abnormal short-term potentiation (STP), a major form of short-term synaptic plasticity. Two-photon imaging of the genetically encoded fluorescent calcium indicator GCaMP6, expressed in presynaptic cytosol or mitochondria, showed that Mrpl40 haploinsufficiency deregulates STP via impaired calcium extrusion from the mitochondrial matrix through the mitochondrial permeability transition pore. This led to abnormally high cytosolic calcium transients in presynaptic terminals and deficient working memory but did not affect long-term spatial memory. Thus, we propose that mitochondrial calcium deregulation is a novel pathogenic mechanism of cognitive deficiencies in schizophrenia.

IRF5rs2004640 single nucleotide polymorphism is associated with susceptibility to rheumatoid arthritis in South Indian Tamils.

Polymorphism of interferon regulatory factor 5 (IRF5), a latent transcription factor gene has been associated with various auto-immune diseases. Our aim was to study the IRF5rs2004640 gene polymorphism and its association with disease susceptibility, disease phenotype and treatment response in South Indian Tamil patients with rheumatoid arthritis (RA).The study was conducted on 217 RA patients fulfilling the American College of Rheumatology (ACR) 2010 criteria and 482 healthy controls (HCs) without family history of autoimmune disease. The IRF5rs2004640 genotyping was performed using a TaqMan 5' allelic discrimination assay. We found that the IRF5rs2004640T allele [P < 0.0001, odds ratio (OR) 3.25, 95% confidence interval (CI) 2.55-4.12] and TT genotype (P < 0.0001, OR 4.60, 95% CI 3.23-6.57) were significantly more frequent in RA patients as compared with HCs. No association was found between IRF5rs2004640 polymorphism, clinical manifestations, autoantibody profile and treatment response. IRF5rs2004640 T (mutant) allele may be a susceptibility factor conferring risk for RA in South Indian Tamils, whereas G allele (wild type) may be protective.

Immunoglobulin-like transcripts 6 (ILT6) polymorphism influences the anti-Ro60/52 autoantibody status in South Indian SLE patients.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with complex etiology. Loss of immune tolerance against self-antigens results in activation of the immune system to produce autoantibodies, which in turn contribute to the clinical manifestations of the disease. Immune cells harbor a plethora of regulatory receptors. Immunoglobulin-like transcripts (ILTs) exhibit both immune activation and inhibitory properties. Genetic defects in genes encoding these receptors may predispose to development of autoimmune diseases secondary to loss of their function. The aim of our study was to analyze the presence or absence of the 6.7 kb segment in the ILT6 gene and its association with susceptibility to SLE and its different manifestations. METHOD: A total of 188 SLE patients and 192 age-, sex similar-, ethnicity-matched controls were recruited. They were genotyped to test the presence or absence of the 6.7 kb segment of the ILT6 gene by polymerase chain reaction. RESULTS: The mutant allele lacking the 6.7 kb gene segment had an equal frequency in patients as well as controls (20% and 18%, respectively). The mutant allele was not associated with SLE or its clinical manifestations. However, the mutant allele was associated with the presence of anti-Ro60 (p = 0.0005, OR 3.5, 95% CI 1.8-7.1) and anti-Ro52 (p = 0.0027, OR 2.99, 95% CI 1.5-6.06) autoantibodies. CONCLUSION: ILT6 deletion polymorphism does not appear to be a lupus susceptibility gene in South Indian Tamils, but may behave as a genetic modifier of autoantibody phenotype by influencing the production of anti-Ro60 and anti-Ro52 autoantibodies and thus indirectly contribute to autoimmune responses in SLE.

The CTLA4 +49 A/G (rs231775) polymorphism influences susceptibility to SLE in South Indian Tamils.

Systemic lupus erythematosus (SLE) is a prototype autoimmune disease with complex etiology. Loss of immune tolerance and synthesis of autoantibodies against nuclear antigens contributes to the disease. Genetic aberrations disrupting the functions of immune regulatory receptors may facilitate the development of autoimmune diseases. Cytotoxic T-lymphocyte antigen 4 (CTLA4) is an inhibitory receptor for T cells and this study was carried out to analyze the influence of CTLA4 +49A/G (rs231775) polymorphism on susceptibility to SLE in ethnic Tamils. Three hundred SLE patients and 460 age and sex similar, ethnicity-matched controls were screened for the +49 A/G polymorphism by real time polymerase chain reaction (PCR). The wild allele (A) frequency in controls and cases was 63% and 47%, respectively. The presence of heterozygous (AG) and homozygous mutant (GG) genotype was associated with a significant risk to develop SLE (P = 0.0001, OR-2.29, 95% confidence interval (CI), 1.6-3.3) and (P = 0.0001, OR-4.3, 95% CI, 2.8-6.99). The frequency of mutant allele (G) in patients was also significantly associated with SLE (P = 0.0001, OR-1.9, 95% CI, 1.5-2.4). However, this polymorphism did not influence the clinical or serological phenotypes in our study. Therefore the CTLA4 +49 A/G polymorphism is a potential genetic risk factor for lupus susceptibility in South Indian Tamils, but does not appear to influence either the clinical or serological phenotype.

Studies on serum 8-hydroxy guanosine (8-OHdG) as reliable biomarker for psoriasis.

BACKGROUND: Oxidative stress was implicated in the psoriasis disease development and may damage DNA leading to keratinocytes cell death. No serum biomarker was available for the oxidative DNA damage. OBJECTIVES: To evaluate the 8-OHdG (8-Hydroxy guanosine) as reliable biomarker for the oxidative stress in psoriatic patients with severity. METHODS: A total of 30 patients were considered for the study and graded according to the Psoriasis Area Severity Index (PASI) and 10 healthy controls. Blood was collected under aseptic condition, and serum was separated. Serum 8-OHdG and total antioxidant capacity was measured by competitive enzyme linked immunosorbent assay using `8-OHdG Check' and PAO kit (JaICA, Fukuroi City, Japan). RESULTS: The average serum 8-OHdG level in the control, mild, moderate and severe groups were 1.18 ± 0.93 ng/mL, 3.46 ± 0.82 ng/mL, 3.68 ± 0.67 ng/mL and 4.86 ± 1.7 ng/mL respectively. There was no significant difference in the average level of total antioxidant capacity of control, mild, moderate and severe groups, and the values presented were 295.88 ± 206 µmol/L, 1392.20 ± 225 µmol/L, 1199.57 ± 257 µmol/L and 1184.24 ± 207 µmol/L respectively. CONCLUSION: Serum 8-OHdG levels could be used as good biomarker for the early diagnosis of psoriasis and its management.