Mannose-Binding Lectin Gene Variants as Disease Susceptibility Biomarkers in Rheumatoid Arthritis.

Background: Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disease characterized by progressive destruction of peripheral joints. About 1% of the human population worldwide is suffering from this disease. The pathophysiology of RA is largely being influenced by immune dysregulation. Mannose-binding lectin (MBL), an acute-phase protein, has been reported to play an important role in pathogenesis of RA by the activation of complement pathway. Various studies documented the established the role of MBL in pathogenesis of various autoimmune diseases, including RA. MBL protein is encoded by gene MBL2, mapped on chromosome 10q11.2-q21. Objective: Both MBL serum levels and activity are mainly determined genetically by its variants. So considering the putative clinical role of MBL2, this case-control association study was designed to assess its six functional variants in a northwestern Indian cohort. Methods: Genetic typing of six MBL2 variants was done by amplification refractory mutation system-polymerase chain reaction. Data were analyzed using suitable statistical tools. Results: Significant difference has been observed in genotypic and allelic distribution between cases and controls for rs11003125. Comparison of allelic distribution for rs1800450 showed significantly high prevalence of A allele in cases than controls. Conclusion: These results indicate that MBL2 variants may act as plausible marker for susceptibility toward RA. Keeping this in view, it is pertinent to screen these variants in other population groups of India.

Impact of 5' Near Gene Variants of Mannose Binding Lectin (MBL2) on Breast Cancer Risk.

The immune system plays a bifaceted role in tumour development through modulation of inflammation. MBL binds to damage-associated molecular patterns and induces inflammation through the activation of complement pathway. Dysregulated inflammation plays a major role in breast cancer pathogenesis, thereby suggesting its contribution towards breast cancer risk. Literature asserts single-nucleotide polymorphisms (SNPs) modulating serum MBL levels. Therefore, studying MBL2 SNPs in breast cancer might provide valuable insight in the disease pathogenesis. The present case-control association study aimed to elucidate the association between MBL2 5' near gene SNPs and breast cancer risk. Breast cancer patients were recruited from Government Medical College, G.N.D. Hospital, Amritsar. The age- and gender-matched genetically unrelated healthy individuals, from adjoining regions, with no history of malignancy up to three generations were recruited as controls. The SNPs of MBL2 from the 5' near gene region with putative functional significance were selected based upon the in silico analysis and literature review. The genotypic, allelic and haplotype frequencies for the studied variants were assessed and compared in the study participants by ARMS-PCR and PCR-RFLP. No difference in allelic, genotypic and haplotype frequencies was reported for rs7096206, rs7084554 and rs11003125 in both the participant groups. rs7084554 (CC) was found to confer risk towards hormone receptor-positive breast cancer. An intermediate LD was observed between rs7084554 and rs11003125. The study reports association between MBL2 variant (rs7084554) and hormone receptor-positive breast cancer risk. Further research in this direction might validate the findings.

Association of mannose binding lectin with chronic obstructive pulmonary disease susceptibility and its clinical outcomes.

BACKGROUND: The physiological interactions of MBL suggest its contribution towards the pathogenesis of COPD. OBJECTIVE: The present case-control study was undertaken to elucidate the role of MBL with COPD risk and clinical outcomes in north Indian cohort. METHODS: Patients were enrolled as per GOLD criteria. MBL2 variants were selected based on the literature and their putative functional significance. Genotyping of six single nucleotide polymorphisms of MBL2 comprising of two coding (rs1800450, rs1800451) and four non-coding variants (rs11003125, rs7096206, rs11003123 and rs7095891) was done by using PCR-RFLP and ARMS-PCR. Serum MBL levels were analysed by sandwich ELISA. RESULTS: Overall findings of the molecular genetic analysis of MBL2 indicated significant difference in frequency of three of the six studied variants, between patients and controls or among different disease severity stages. Heterozygous genotype of rs7095891 showed significant protective association towards severity of disease. Linkage disequilibrium (LD) analysis indicated a strong LD between rs1800450 and rs7095891 while intermediate LD was observed for rs11003123/rs11003125 and rs7096206/rs11003125. Haplotype analysis revealed 17.14-fold risk of developing exacerbations conferred by GGGTGG haplotype. Significantly low serum MBL levels observed in COPD patients as compared to controls. Significant difference in MBL deficiency levels were also observed for homozygous wild and variant genotypes of rs11003125 and rs7096206 respectively, as well as for all genotypes of rs11003123 than respective controls. CONCLUSION: The present study reinforces the role played by MBL in the susceptibility, protection and clinical outcomes of COPD. Therefore, including the reported associations at diagnostic, prognostic and therapeutic interventions may prove helpful.

Preclinical Interventions in Mouse Models of Frontotemporal Dementia Due to Progranulin Mutations.

Heterozygous loss-of-function mutations in progranulin (GRN) cause frontotemporal dementia (FTD), a leading cause of early-onset dementia characterized clinically by behavioral, social, and language deficits. There are currently no FDA-approved therapeutics for FTD-GRN, but this has been an active area of investigation, and several approaches are now in clinical trials. Here, we review preclinical development of therapies for FTD-GRN with a focus on testing in mouse models. Since most FTD-GRN-associated mutations cause progranulin haploinsufficiency, these approaches focus on raising progranulin levels. We begin by considering the disorders associated with altered progranulin levels, and then review the basics of progranulin biology including its lysosomal, neurotrophic, and immunomodulatory functions. We discuss mouse models of progranulin insufficiency and how they have been used in preclinical studies on a variety of therapeutic approaches. These include approaches to raise progranulin expression from the normal allele or facilitate progranulin production by the mutant allele, as well as approaches to directly increase progranulin levels by delivery across the blood-brain barrier or by gene therapy. Several of these approaches have entered clinical trials, providing hope that new therapies for FTD-GRN may be the next frontier in the treatment of neurodegenerative disease.

Impaired ß-glucocerebrosidase activity and processing in frontotemporal dementia due to progranulin mutations.

Loss-of-function mutations in progranulin (GRN) are a major autosomal dominant cause of frontotemporal dementia. Most pathogenic GRN mutations result in progranulin haploinsufficiency, which is thought to cause frontotemporal dementia in GRN mutation carriers. Progranulin haploinsufficiency may drive frontotemporal dementia pathogenesis by disrupting lysosomal function, as patients with GRN mutations on both alleles develop the lysosomal storage disorder neuronal ceroid lipofuscinosis, and frontotemporal dementia patients with GRN mutations (FTD-GRN) also accumulate lipofuscin. The specific lysosomal deficits caused by progranulin insufficiency remain unclear, but emerging data indicate that progranulin insufficiency may impair lysosomal sphingolipid-metabolizing enzymes. We investigated the effects of progranulin insufficiency on sphingolipid-metabolizing enzymes in the inferior frontal gyrus of FTD-GRN patients using fluorogenic activity assays, biochemical profiling of enzyme levels and posttranslational modifications, and quantitative neuropathology. Of the enzymes studied, only ß-glucocerebrosidase exhibited impairment in FTD-GRN patients. Brains from FTD-GRN patients had lower activity than controls, which was associated with lower levels of mature ß-glucocerebrosidase protein and accumulation of insoluble, incompletely glycosylated ß-glucocerebrosidase. Immunostaining revealed loss of neuronal ß-glucocerebrosidase in FTD-GRN patients. To investigate the effects of progranulin insufficiency on ß-glucocerebrosidase outside of the context of neurodegeneration, we investigated ß-glucocerebrosidase activity in progranulin-insufficient mice. Brains from Grn-/- mice had lower ß-glucocerebrosidase activity than wild-type littermates, which was corrected by AAV-progranulin gene therapy. These data show that progranulin insufficiency impairs ß-glucocerebrosidase activity in the brain. This effect is strongest in neurons and may be caused by impaired ß-glucocerebrosidase processing.

Reduction of microglial progranulin does not exacerbate pathology or behavioral deficits in neuronal progranulin-insufficient mice.

Loss-of-function mutations in progranulin (GRN), most of which cause progranulin haploinsufficiency, are a major autosomal dominant cause of frontotemporal dementia (FTD). Individuals with loss-of-function mutations on both GRN alleles develop neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disorder. Progranulin is a secreted glycoprotein expressed by a variety of cell types throughout the body, including neurons and microglia in the brain. Understanding the relative importance of neuronal and microglial progranulin insufficiency in FTD pathogenesis may guide development of therapies. In this study, we used mouse models to investigate the role of neuronal and microglial progranulin insufficiency in the development of FTD-like pathology and behavioral deficits. Grn-/- mice model aspects of FTD and NCL, developing lipofuscinosis and gliosis throughout the brain, as well as deficits in social behavior. We have previously shown that selective depletion of neuronal progranulin disrupts social behavior, but does not produce lipofuscinosis or gliosis. We hypothesized that reduction of microglial progranulin would induce lipofuscinosis and gliosis, and exacerbate behavioral deficits, in neuronal progranulin-deficient mice. To test this hypothesis, we crossed Grnfl/fl mice with mice expressing Cre transgenes targeting neurons (CaMKII-Cre) and myeloid cells/microglia (LysM-Cre). CaMKII-Cre, which is expressed in forebrain excitatory neurons, reduced cortical progranulin protein levels by around 50%. LysM-Cre strongly reduced progranulin immunolabeling in many microglia, but did not reduce total brain progranulin levels, suggesting that, at least under resting conditions, microglia contribute less than neurons to overall brain progranulin levels. Mice with depletion of both neuronal and microglial progranulin failed to develop lipofuscinosis or gliosis, suggesting that progranulin from extracellular sources prevented pathology in cells targeted by the Cre transgenes. Reduction of microglial progranulin also did not exacerbate the social deficits of neuronal progranulin-insufficient mice. These results do not support the hypothesis of synergistic effects between progranulin-deficient neurons and microglia. Nearly complete progranulin deficiency appears to be required to induce lipofuscinosis and gliosis in mice, while partial progranulin insufficiency is sufficient to produce behavioral deficits.

Long- but not short-term estradiol treatment induces renal damage in midlife ovariectomized Long-Evans rats.

Clinical recommendations limit menopausal hormone therapy to a few years, yet the impact of a shorter treatment duration on cardiovascular health is unknown. We hypothesized that both short- and long-term estradiol (E2) treatment exerts positive and lasting effects on blood pressure, vascular reactivity, and renal health. This study was designed to mimic midlife menopause, followed by E2 treatment, that either followed or exceeded the current clinical recommendations. Female Long-Evans retired breeders were ovariectomized (OVX) at 11 mo of age and randomized into three groups: 80-day (80d) vehicle (Veh>Veh), 40-day (40d) E2 + 40d vehicle (E2>Veh), and 80d E2 (E2>E2). In comparison to Veh>Veh, both the E2>Veh and E2>E2 groups had lower systolic blood pressure and enhanced mesenteric relaxation in response to estrogen receptor-α stimulation. Despite the reduced blood pressure, E2>E2 induced renal and cardiac hypertrophy, reduced glomerular filtration, and increased proteinuria. Interestingly, kidneys from E2>Veh rats had significantly fewer tubular casts than both of the other groups. In conclusion, long-term E2 lowered blood pressure but exerted detrimental effects on kidney health in midlife OVX Long-Evans rats, whereas short-term E2 lowered blood pressure and reduced renal damage. These findings highlight that the duration of hormone therapy may be an important factor for renal health in aging postmenopausal women.

GPER-novel membrane oestrogen receptor.

The recent discovery of the G protein-coupled oestrogen receptor (GPER) presents new challenges and opportunities for understanding the physiology, pathophysiology and pharmacology of many diseases. This review will focus on the expression and function of GPER in hypertension, kidney disease, atherosclerosis, vascular remodelling, heart failure, reproduction, metabolic disorders, cancer, environmental health and menopause. Furthermore, this review will highlight the potential of GPER as a therapeutic target.

GPER activation ameliorates aortic remodeling induced by salt-sensitive hypertension.

The mRen2 female rat is an estrogen- and salt-sensitive model of hypertension that reflects the higher pressure and salt sensitivity associated with menopause. We previously showed that the G protein-coupled estrogen receptor (GPER) mediates estrogenic effects in this model. The current study hypothesized that GPER protects against vascular injury during salt loading. Intact mRen2 female rats were fed a normal (NS; 0.5% Na(+)) or high-salt diet (HS; 4% Na(+)) for 10 wk, which significantly increased systolic blood pressure (149 ± 5 vs. 224 ± 8 mmHg;P< 0.001). Treatment with the selective GPER agonist G-1 for 2 wk did not alter salt-sensitive hypertension (216 ± 4 mmHg;P> 0.05) or ex vivo vascular responses to angiotensin II or phenylephrine (P> 0.05). However, G-1 significantly attenuated salt-induced aortic remodeling assessed by media-to-lumen ratio (NS: 0.43; HS+veh: 0.89; HS+G-1: 0.61;P< 0.05). Aortic thickening was not accompanied by changes in collagen, elastin, or medial proliferation. However, HS induced increases in medial layer glycosaminoglycans (0.07 vs. 0.42 mm(2);P< 0.001) and lipid peroxidation (0.11 vs. 0.51 mm(2);P< 0.01), both of which were reduced by G-1 (0.20 mm(2)and 0.23 mm(2); both P< 0.05). We conclude that GPER's beneficial actions in the aorta of salt-loaded mRen2 females occur independently of changes in blood pressure and vasoreactivity. GPER-induced attenuation of aortic remodeling was associated with a reduction in oxidative stress and decreased accumulation of glycosaminoglycans. Endogenous activation of GPER may protect females from salt- and pressure-induced vascular damage.