High-temperature Requirement Factor A1 Research Articles

Second and third trimester serum levels of HtrA1 in pregnancies affected by pre-eclampsia

IntroductionAltered placental expression of high temperature requirement factor A1 (HtrA1) is implicated in abnormal trophoblastic invasion and endothelial dysfunction in pre-eclampsia (PE). Serum levels of HtrA1 have been proposed as a novel biomarker to improve the prediction of PE. This study assesses serum HtrA1 levels in prospectively collected samples of women who developed PE compared to normotensive pregnancies. MethodsThis was a case-control study of serum HtrA1 levels in second and third trimester samples in women who later developed preterm or term PE compared to controls. Overall, 300 serum samples were drawn from a prospective observational study of adverse pregnancy outcomes in three different gestational age windows (19–24, 30-34 and 35–37 weeks) at the Fetal Medicine Research Institute, King's College Hospital, London. Serum HtrA1 levels were determined by enzyme-linked immunosorbent assay (ELISA) by a blinded laboratory professional. Median HtrA1 MoM values, adjusted for gestational age and maternal characteristics, were compared between cases and controls at each gestational age group. ResultsWomen who later developed PE, compared to controls, had significantly higher maternal weight and more frequently had chronic hypertension or a history of PE in a previous pregnancy. In normotensive pregnancies, serum HtrA1 increased with increasing gestational age, whereas, in PE pregnancies HtrA1 levels remained stable, but were not significantly different from control pregnancies at any gestational age. DiscussionSerum HtrA1 levels are not significantly different in women who develop PE compared to controls.

Association of HTRA1 and CFH gene polymorphisms with age-related macular degeneration in Ningbo, China.

Age-related macular degeneration (AMD) is one of the major causes of blindness, and the incidence of this disease has been increasing in recent years. To investigate the association between the single nucleotide polymorphisms (SNPs) of the high temperature requirement factor A-1 (HTRA1) and complement factor H (CFH) genes and susceptibility to AMD in Ningbo, China. Ninety-eight patients with AMD and seventy-three controls were recruited at the Sixth Hospital of Ningbo from August 2017 to April 2019 in China. Genomic DNA was extracted from the venous blood provided by the hospital, and the genotypes of the AMD susceptibility genes CFH and HTAR1 were detected by polymerase chain reaction and sequenced directly. The SNPs rs11200638 on the HTRA1 gene and rs3753394 on the CFH gene were selected for genotype and association analysis. The correlations between the different genotypes of HTRA1 and CFH and AMD were analysed by the Chi-squared test. All the genotypes adhered to the Hardy-Weinberg equilibrium. There were three genotypes (AA, AG and GG) in HTRA1 (rs11200638). The differences in genotypes and allele frequency between the AMD group and the control group were statistically significant (P < 0.05). The A allele was a risk allele (OR: 4.19, 95% Cl: 2.28 ~ 7.70, P < 0.05), with a frequency of 61.7% in patients versus 43.8% in controls. However, the rs3753394 SNP in CFH was not associated with AMD in our study (P > 0.05). The rs11200638 SNP of the HTRA1 gene is associated with AMD, and the AA genotype is a risk factor for AMD in the Ningbo population. There is no significant correlation between the rs3753394 SNP of the CFH gene and AMD.

HTRA1 rs11200638 variant and AMD risk from a comprehensive analysis about 15,316 subjects

BackgroundThe high-temperature requirement factor A1 (HTRA1) gene located at 10q26 locus has been associated with age-related macular degenerative (AMD), with the significantly related polymorphism being (rs11200638, −625G/A), however, above association is not consistent. We investigated a comprehensive analysis to evaluate the correlations between rs11200638 polymorphism and AMD susceptibility thoroughly addressing this issue.MethodsAn identification was covered from the PubMed and Wanfang databases until 27th Jan, 2020. Odds ratios (OR) with 95% confidence intervals (CI) were applied to evaluate the associations. After a thorough and meticulous search, 35 different articles (33 case-control studies with HWE, 22 case-control studies about wet/dry AMD) were retrieved.ResultsIndividuals carrying A-allele or AA genotype may have an increased risk to be AMD disease. For example, there has a significantly increased relationship between rs11200638 polymorphism and AMD both for Asians (OR: 2.51, 95%CI: 2.22–2.83 for allelic contrast) and Caucasians [OR (95%CI) = 2.63(2.29–3.02) for allelic contrast]. Moreover, a similar trend in the source of control was detected. To classify the type of AMD, increased association was also observed in both wet (OR: 3.40, 95%CI: 2.90–3.99 for dominant model) and dry (OR: 2.08, 95%CI: 1.24–3.48 for dominant model) AMD. Finally, based on the different genotyping methods, increased relationships were identified by sequencing, TaqMan, PCR-RFLP and RT-PCR.ConclusionsOur meta-analysis demonstrated that HTRA1 rs11200638 polymorphism may be related to the AMD development, especially about individuals carrying A-allele or AA genotype, who may be as identified targets to detect and intervene in advance. Further studies using Larger sample size studies, including information about gene-environment interactions will be necessary to carry out.

Htra1 is a Novel Transcriptional Target of RUNX2 That Promotes Osteogenic Differentiation.

Runt-related transcription factor 2 (Runx2) is a master regulator of osteogenic differentiation, but most of the direct downstream targets of RUNX2 during osteogenesis are unknown. Likewise, High-temperature requirement factor A1 (HTRA1) is a serine protease expressed in bone, yet the role of Htra1 during osteoblast differentiation remains elusive. We investigated the role of Htra1 in osteogenic differentiation and the transcriptional regulation of Htra1 by RUNX2 in primary mouse mesenchymal progenitor cells. Overexpression of Htra1 was carried out in primary mouse mesenchymal progenitor cells to evaluate the extent of osteoblast differentiation. Streptavidin agarose pulldown assay, chromatin immunoprecipitation assay, and dual luciferase assay were carried out to investigate the interaction of RUNX2 protein at the Htra1 promoter during osteoblast differentiation. Overexpression of Htra1 increased the production of mineralized bone matrix, upregulating several osteoblast genes, such as Sp7 transcription factor (Sp7) and Alkaline phosphatase, liver/bone/kidney (Alpl). In addition, Htra1 upregulated osteogenesis-related signalling genes, such as Fibroblast growth factor 9 (Fgf9) and Vascular endothelial growth factor A (Vegfa). A series of experiments confirmed Htra1 as a direct RUNX2 transcriptional target. Overexpression of Runx2 resulted in the upregulation of Htra1 mRNA and protein. Chromatin immunoprecipitation and streptavidin agarose pull-down assays showed that RUNX2 binds a proximal -400 bp region of the Htra1 promoter during osteogenic differentiation. Dual luciferase assays confirmed that RUNX2 activates the proximal Htra1 promoter during osteogenic differentiation. Mutation of putative RUNX2 binding sites revealed that RUNX2 interacts with the Htra1 promoter at -252 bp and -84 bp to induce Htra1 expression. We demonstrate that Htra1 is a positive regulator of osteogenic differentiation, showing for the first time that Htra1 is a direct downstream target of RUNX2.

Association between first trimester plasma htra1 level and subsequent preeclampsia: A possible early marker?

Preeclampsia (PE) is associated with risk of maternal and fetal mortality and morbidity. Several promising predictors of PE have been identified, but early pregnancy screening for PE remains insufficient, and randomized controlled trials that used biomarkers to identify high-risk women have been disappointed. Our aim is to identify a possible early marker of PE. 158 women attending a routine antenatal care visit were recruited from 2014 to 2016 and prospectively followed until delivery (14 of whom had a diagnosis of PE). We have tested the plasma concentration of High temperature requirement factor A1 (HtrA1) at 12 weeks of gestation by ELISA technique in order to identify women at risk for developing PE. A multiple logistic regression analysis was used to estimate the independent effect of women' characteristics on the probability of developing PE. Likelihood ratio test and Hosmer-Lemeshow test were used to select the most parsimonious model and to evaluate the model's goodness of fit. Predictiveness of preeclampsia was estimated by ROC curve. PE cases had significantly higher BMI, before and after pregnancy, shorter gestational age at delivery and higher HtrA1values than healthy women. In addition, higher HtrA1 values in the first trimester maternal plasma, BMI before pregnancy and gestational age at delivery are significantly associated with subsequent development of PE. ROC curve showed a good accuracy in predicting preeclampsia, with an AUC of 0.83. These results suggest the HtrA1 as early predictive marker of PE having a strong clinical relevance for disease prevention.

Genetic association with intravitreal ranibizumab response for neovascular age-related macular degeneration in Hispanic population.

BACKGROUND/PURPOSE:Age-related macular degeneration (AMD) is the leading cause of visual impairment in patients over 55 years. Currently, the most common therapies for neovascular AMD (nAMD) are intravitreal antiangiogenics. Studies suggest that genetic factors influence on antiangiogenics therapy outcomes. The purpose of this work was to establish the association between complement factor H (CFH) (Y402H), age-related maculopathy susceptibility 2 (ARMS2) (A69S), and high-temperature requirement factor A1 (HTRA1) (rs11200638) polymorphisms and the response to treatment with ranibizumab in patients with nAMD.METHODS:A cross-sectional study with 61 eyes with nAMD treated with ranibizumab was performed. Association between polymorphisms from CFH, ARMS2, and HTRA1 with the response to treatment was established.RESULTS:The mean age of patients was 76.6 (51–91) years. Only 37.7% of patients had a functional response and 26.2% had an anatomic response. TT polymorphism Y402H from CFH gene was associated with an increased likelihood of functional response to treatment. Otherwise, there was not a statistically significant association between anatomic and functional response to gene polymorphisms rs11200638 from HTRA1 and rs10490924 from ARMS 2.CONCLUSIONS:This study suggests that the response to intravitreal antiangiogenic therapy with ranibizumab was not associated to main polymorphisms from genes HTRA1 and ARMS2. However, it was found that the response to treatment differed according to CFH genotype, suggesting that further investigations are needed to establish if patients with the CC and TC genotype may need to be monitored more closely for disease recurrence than the TT genotype.

HtrA1 expression and the prognosis of high-grade serous ovarian carcinoma: a cohort study using digital analysis

BackgroundThe expression of high temperature requirement factor A1 (Htra1) has been reported to be decreased in ovarian carcinoma, but its prognostic effect remains undetermined.MethodsWe evaluated the impact of HtrA1 downregulation in tumoral tissues on cancer progression and death in women with serous ovarian carcinoma. HtrA1 staining was performed on tissue microarrays (TMA) comprised of tumor samples from a cohort of 106 women who were diagnosed with primary high-grade serous ovarian carcinoma and receiving standard treatment at the Québec University Hospital between 1993 and 2006. HtrA1 expression was assessed visually (percentage of positive nuclei) and by digital image analysis (percentage of positive area). Cox regression multivariate models included standard prognostic factors and were used to estimate adjusted hazard ratios (aHR) for progression or death in the cohort.ResultsBy visual analysis, a low percentage of HtrA1-positive nuclei (< 10% vs ≥10%) tend to be associated with a lower risk of progression (aHR = 0.71; 95% Confidence interval (CI) = 0.46–1.09; P = 0.11) and mortality (aHR = 0.65; 95% CI = 0.41–1.04; P = 0.07). Low nuclear HtrA1 expression assessed by digital image analysis (< median % vs ≥ median %) showed a significant association with lower risk of progression (aHR = 0.62; 95% CI = 0.40–0.95; p = 0.03) and death (aHR = 0.60; 95% CI = 0.38–0.95; p = 0.03).ConclusionAltogether, our results demonstrate that nuclear downregulation of HtrA1 is associated with a better prognosis in women with high grade serous ovarian carcinoma.

High temperature requirement factor A1 (HTRA1) regulates the activation of latent TGF-β1 in keloid fibroblasts.

Scar treatments are considered a major issue in the plastic surgery field. Activation of the transforming growth factor-β (TGF-β)-mediated signaling pathway plays a key role in the scar pathogeneses, and high temperature requirement factor A1 (HTRA1) inhibits TGF-β1 activation in tumor cells. Our study aims to investigate the role of HTRA1 in the pathogenesis of scars. The mRNA levels of HTRA1 was evaluated by real time PCR, HTRA1 protein expression was determined using western blot and immunohistochemistry, and a luciferase assay was applied to measure dynamic changes of TGF-β1 activity. We found that the expression of HTRA1 was significantly elevated in keloid tissues, compared to normal skin, and TGF-β1 mRNA levels slightly increase in the keloid tissue. Furthermore, active TGF-β1 protein levels and Smad2 phosphorylation significantly increased in the keloid tissue. Treatment with the latent TGF-β1 or recombinant human HTRA1 (rhHTRA1), alone or in combination, increased Smad2 phosphorylation levels in keloid fibroblasts and active TGF-β1 contents of associated supernatants. Our results suggest that HTRA1 is involved in the pathogenesis of scars through regulating activation of latent TGF-β1 in keloid fibroblasts, and our study reveals that HTRA1 is a novel target that regulates scar formation.

Proteolytic Degradation and Inflammation Play Critical Roles in Polypoidal Choroidal Vasculopathy

Polypoidal choroidal vasculopathy (PCV) is a common subtype of wet age-related macular degeneration in Asian populations, whereas choroidal neovascularization is the typical subtype in Western populations. The cause of PCV is unknown. By comparing the phenotype of a PCV mouse model expressing protease high temperature requirement factor A1 (HTRA1) in retinal pigment epithelium with transgenic mice expressing the inactive HTRA1S328A, we showed that HTRA1-mediated degradation of elastin in choroidal vessels is critical for the development of PCV, which exhibited destructive extracellular matrix remodeling and vascular smooth muscle cell loss. Compared with weak PCV, severe PCV exhibited prominent immune complex deposition, complement activation, and infiltration of inflammatory cells, suggesting inflammation plays a key role in PCV progression. More important, we validated these findings in human PCV specimens. Intravitreal delivery of an HTRA1 inhibitor (DPMFKLboroV) was effective (36% lesion reduction; P = 0.009) in preventing PCV initiation but ineffective in treating existing lesions. Anti-inflammatory glucocorticoid was effective in preventing PCV progression but ineffective in preventing PCV initiation. These results suggest that PCV pathogenesis occurs through two stages. The initiation stage is mediated by proteolytic degradation of extracellular matrix proteins attributable to increased HTRA1 activity, whereas the progression stage is driven by inflammatory cascades. This study provides a basis for understanding the differences between PCV and choroidal neovascularization, and helps guide the design of effective therapies for PCV.

A Phenotyping Regimen for Genetically Modified Mice Used to Study Genes Implicated in Human Diseases of Aging.

Age-related diseases are becoming increasingly prevalent and the burden continues to grow as our population ages. Effective treatments are necessary to lessen the impact of debilitating conditions but remain elusive in many cases. Only by understanding the causes and pathology of diseases associated with aging, can scientists begin to identify potential therapeutic targets and develop strategies for intervention. The most common age-related conditions are neurodegenerative disorders such as Parkinson's disease and blindness. Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. Genome wide association studies have previously identified loci that are associated with increased susceptibility to this disease and identified two regions of interest: complement factor H (CFH) and the 10q26 locus, where the age-related maculopathy susceptibility 2 (ARMS2) and high-temperature requirement factor A1 (HtrA1) genes are located. CFH acts as a negative regulator of the alternative pathway (AP) of the complement system while HtrA1 is an extracellular serine protease. ARMS2 is located upstream of HtrA1 in the primate genome, although the gene is absent in mice. To study the effects of these genes, humanized knock-in mouse lines of Cfh and ARMS2, knockouts of Cfh, HtrA1, HtrA2, HtrA3 and HtrA4 as well as a conditional neural deletion of HtrA2 were generated. Of all the genetically engineered mice produced only mice lacking HtrA2, either systemically or in neural tissues, displayed clear phenotypes. In order to examine these mice thoroughly and systematically, an initial phenotyping schedule was established, consisting of a series of tests related to two main diseases of interest: AMD and Parkinson's. Genetically modified mice can be subjected to appropriate experiments to identify phenotypes that may be related to the associated diseases in humans. A phenotyping regimen with a mitochondrial focus is presented here alongside representative results from the tests of interest.

Peptide-induced bio-mineralization as a bio-mimetic means of detecting proteins in a mineralizing bio-context

Pathological bio-mineralization can be induced by diseases such as preeclampsia. Inspired by these naturally occurring bio-mineralization processes, we have designed a process called protein-controlled peptide assembly tandem peptide-templated bio-mineralization. The technique provides bio-context-associated data on the activity of target proteins, and facilitates the evaluation of protein function in the associated biological microenvironment. It is a bio-mimetic process that leads to the formation of Ag nanoparticle-decorated peptide nanowires, which can offer efficient signal amplification with high sensitivity for biosensing applications. Consequently, high-temperature requirement factor A1 (HtrA1) can be assayed quantitatively in clinical serum samples to offer information for the diagnosis of preeclampsia and the improved treatment of the disease. The results suggest that the process has considerable potential for use in clinical practice.

FPR1 interacts with CFH, HTRA1 and smoking in exudative age-related macular degeneration and polypoidal choroidal vasculopathy.

PurposeTo determine the genetic association of an inflammation-related gene, formyl peptide receptor 1 (FPR1), in exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).MethodsThe coding region of FPR1 gene was sequenced in 554 unrelated Chinese individuals: 155 exudative AMD patients, 179 PCV patients, and 220 controls. Interactions and combined effects of FPR1 with complement factor H (CFH), high temperature requirement factor A1 (HTRA1), and smoking were also investigated.ResultsA total of 28 polymorphisms in FPR1 were identified. Single nucleotide polymorphisms (SNP) rs78488639 increased the risk to exudative AMD (P=0.043) and PCV (P=0.016), whereas SNP rs867229 decreased the risk to exudative AMD (P=0.0026), but not PCV. Homozygous G allele of rs1042229 was associated with exudative AMD (P=0.0394, odds ratio (OR)=2.27, 95% confident interval: 1.08–4.74), but not with PCV. Exudative AMD, but not PCV, was associated with the heterozygous genotypes of rs2070746 (P=0.019, OR=0.57) and rs867229 (P=0.0082, OR=0.54). Significantly, interactions were identified among FPR1 rs78488639, CFH rs800292, and HTRA1 rs11200638 in both exudative AMD and PCV. Combined heterozygous risk alleles of CFH rs800292 GA and FPR1 rs78488639 CA were posed to PCV (P=2.22 × 10−4, OR=10.47), but not exudative AMD. Furthermore, FPR1 rs78488639 CA combining with HTRA1 rs11200638 and smoking was also predisposed risks to exudative AMD and PCV.ConclusionFPR1 is associated with exudative AMD and PCV in a Hong Kong Chinese cohort. FPR1 rs78488639 interacted with CFH rs800292, HTRA1 rs11200638, and smoking, enhancing risk to exudative AMD and PCV.

Low-Density Lipoprotein Receptor–Related Protein-1

Low-density lipoprotein receptor–related protein-1 (LRP1) is a large endocytic and signaling receptor that is widely expressed. In the liver, LRP1 plays an important role in regulating the plasma levels of blood coagulation factor VIII (fVIII) by mediating its uptake and subsequent degradation. fVIII is a key plasma protein that is deficient in hemophilia A and circulates in complex with von Willebrand factor. Because von Willebrand factor blocks binding of fVIII to LRP1, questions remain on the molecular mechanisms by which LRP1 removes fVIII from the circulation. LRP1 also regulates cell surface levels of tissue factor, a component of the extrinsic blood coagulation pathway. This occurs when tissue factor pathway inhibitor bridges the fVII/tissue factor complex to LRP1, resulting in rapid LRP1-mediated internalization and downregulation of coagulant activity. In the vasculature LRP1 also plays protective role from the development of aneurysms. Mice in which the lrp1 gene is selectively deleted in vascular smooth muscle cells develop a phenotype similar to the progression of aneurysm formation in human patient, revealing that these mice are ideal for investigating molecular mechanisms associated with aneurysm formation. Studies suggest that LRP1 protects against elastin fiber fragmentation by reducing excess protease activity in the vessel wall. These proteases include high-temperature requirement factor A1, matrix metalloproteinase 2, matrix metalloproteinase-9, and membrane associated type 1-matrix metalloproteinase. In addition, LRP1 regulates matrix deposition, in part, by modulating levels of connective tissue growth factor. Defining pathways modulated by LRP1 that lead to aneurysm formation and defining its role in thrombosis may allow for more effective intervention in patients.

LRP1 Protects the Vasculature by Regulating Levels of Connective Tissue Growth Factor and HtrA1

Low-density lipoprotein receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is abundant in vascular smooth muscle cells. Mice in which the lrp1 gene is deleted in smooth muscle cells (smLRP1(-/-)) on a low-density lipoprotein receptor-deficient background display excessive platelet derived growth factor-signaling, smooth muscle cell proliferation, aneurysm formation, and increased susceptibility to atherosclerosis. The objectives of the current study were to examine the potential of LRP1 to modulate vascular physiology under nonatherogenic conditions. We found smLRP1(-/-) mice to have extensive in vivo aortic dilatation accompanied by disorganized and degraded elastic lamina along with medial thickening of the arterial vessels resulting from excess matrix deposition. Surprisingly, this was not attributable to excessive platelet derived growth factor-signaling. Rather, quantitative differential proteomic analysis revealed that smLRP1(-/-) vessels contain a 4-fold increase in protein levels of high-temperature requirement factor A1 (HtrA1), which is a secreted serine protease that is known to degrade matrix components and to impair elastogenesis, resulting in fragmentation of elastic fibers. Importantly, our study discovered that HtrA1 is a novel LRP1 ligand. Proteomics analysis also identified excessive accumulation of connective tissue growth factor, an LRP1 ligand and a key mediator of fibrosis. Our findings suggest a critical role for LRP1 in maintaining the integrity of vessels by regulating protease activity as well as matrix deposition by modulating HtrA1 and connective tissue growth factor protein levels. This study highlights 2 new molecules, connective tissue growth factor and HtrA1, which contribute to detrimental changes in the vasculature and, therefore, represent new target molecules for potential therapeutic intervention to maintain vessel wall homeostasis.

Association of Genetic Polymorphisms and Age-Related Macular Degeneration in Chinese Population

We explored associations between age-related macular degeneration (AMD) and genetic variants of 10 genes in a nationwide Chinese population. In this multicenter case-control study, 535 AMD patients and 469 controls were recruited from 16 centers that spread from the north to the south of China. All participants underwent comprehensive eye examinations, and 40 single nucleotide polymorphisms (SNPs) of 10 genes were selected. DNA samples were genotyped with the MassArray system. The effect of the genotypes and haplotypes on AMD was assessed with logistic regression analysis, adjusted for age, sex, long-term residence, and family origin. In our study, 11 SNPs in complement H (CFH), 2 in age-related maculopathy susceptibility 2 (ARMS2), and 2 in high-temperature requirement factor A1 (HTRA1) were associated significantly with AMD. They were rs551397, rs800292, rs1329424, rs1061170, rs10801555, rs12124794, rs10733086, rs10737680, rs2274700, rs1410996, and rs380390 in CFH; rs10490924 and rs2736912 in ARMS2; and rs11200638 and rs3793917 in HTRA1. Three haplotypes in CFH, predisposed the patients significantly to AMD (P<0.001, P=0.001, and P<0.001, respectively). With the sample size of our study, no relationship was found for AMD and the SNPs tested in complement 3 (C3); serpin peptidase inhibitor, clade G, member 1 (SERPING1); vascular endothelial growth factor (VEGF); cholesterol ester transfer protein (CETP); lipoprotein lipase (LPL); hepatic lipase (LIPC); and metallopeptidase inhibitor 3 (TIMP3) genes. Gene variants in CFH, ARMS2, and HTRA1 contribute to AMD in the Chinese population.

High Temperature Requirement Factor A1 (HTRA1) Gene Regulates Angiogenesis through Transforming Growth Factor-β Family Member Growth Differentiation Factor 6

Genome-wide association study (GWAS) has identified genetic variants in the promoter region of the high temperature requirement factor A1 (HTRA1) gene associated with age-related macular degeneration (AMD). As a secreted serine protease, HTRA1 has been reported to interact with members of the transforming growth factor-β (TGF-β) family and regulate their signaling pathways. Growth differentiation factor 6 (GDF6), a member of the TGF-β family, is involved in ectoderm patterning and eye development. Mutations in GDF6 have been associated with abnormal eye development that may result in microphthalmia and anophthalmia. In this report, we identified a single nucleotide polymorphism (SNP) rs6982567 A/G near the GDF6 gene that is significantly associated with AMD (p value = 3.54 × 10(-8)). We demonstrated that the GDF6 AMD risk allele (rs6982567 A) is associated with decreased expression of the GDF6 and increased expression of HTRA1. Similarly, the HTRA1 AMD risk allele (rs10490924 T) is associated with decreased GDF6 and increased HTRA1 expression. We observed decreased vascular development in the retina and significant up-regulation of GDF6 gene in the RPE layer, retinal and brain tissues in HTRA1 knock-out (htra1(-/-)) mice as compared with the wild-type counterparts. Furthermore, we showed enhanced SMAD signaling in htra1(-/-) mice. Our data suggests a critical role of HTRA1 in the regulation of angiogenesis via TGF-β signaling and identified GDF6 as a novel disease gene for AMD.

HTRA1 in Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is a leading cause of severe visual impairment and irreversible blindness in most developed countries, affecting more than 50 million of elderly people worldwide. Current treatments, such as intravitreal injection of antiangiogenic agents, mitigate the effect of advanced AMD but cannot completely cure the disease. Comprehensive understanding of the AMD pathological mechanisms is important for the development of new therapies. Previously, we identified a single-nucleotide polymorphism (rs11200638) in the promoter region of the high temperature requirement factor A1 (HTRA1) gene on chromosome 10q26 to be associated with exudative AMD. In further biological studies, we have provided evidence that HTRA1 could be a potential disease-causing gene within the 10q26 locus. In this review, we summarize the pathology of AMD and the molecular function of the HtrA1 protein. Also evaluated are the genetic effects of HTRA1 polymorphism on AMD in different populations and interactions with other AMD-associated genes, especially with the complement factor H (CFH) gene, which was identified for nonexudative AMD. The biological roles of HtrA1 are exhaustively examined on its contribution to the multifactorial pathogenic mechanism of AMD. Although HtrA1 should play a part in AMD pathogenesis, a host of other genetic and environmental factors, known and unknown, is involved and warrants intensive future research.

Pharmacogenetic Influence of LOC387715/HTRA1 on the Efficacy of Bevacizumab Treatment for Age-Related Macular Degeneration in a Korean Population

PurposeThe purpose of this study was to determine the pharmacogenetic effects of complement factor H (CFH) Y402H, LOC387715 and high-temperature requirement factor A1 (HTRA1) genotypes on the treatment of exudative age-related macular degeneration (AMD) by intravitreal bevacizumab injection in a Korean population.MethodsSeventy-five patients diagnosed with exudative AMD were treated with intravitreal bevacizumab (2.5 mg) monotherapy. All patients received three initial intravitreal bevacizumab injections every four weeks and were then treated "as needed" based on clinical findings, optical coherence tomography and fluorescein angiography during the 12 month follow-up period after the third injection.ResultsThe difference in visual acuity improvement among the three genotypes of LOC387715 were statistically significant at six months post-treatment (logarithm of the minimum angle of resolution; TT, 0.346; GT, 0.264; GG, 0.188; p = 0.037). Among the LOC387715 genotypes, the number of additional injections was lower in patients who had the risk T allele (GG, 2.143; GT, 2.000; TT, 1.575; p = 0.064). There was no significant difference between visual acuity and central macular thickness change in the CFH Y402H polymorphism group during the 12 month follow-up period. However, the TC group of CFH Y402H required more additional bevacizumab injections than the TT group (TT, 1.517; TC, 3.363; p = 0.020).ConclusionsThis study demonstrated that different LOC387715/HTRA1 genotypes resulted in different bevacizumab treatment responses on exudative AMD. Patients with the risk allele had an improved treatment response and less need for additional injections. However, patients with the CFH Y402H risk allele needed more additional injections of bevacizumab in order to improve visual acuity. This study illustrates how pharmacogenetic factors may help determine treatment modality and dosing. This could ultimately provide basic data for 'personalized medicine' in AMD.

Genetic Predictors of Response to Photodynamic Therapy

In Western countries, therapeutic management of patients affected by choroidal neovascularization (CNV) secondary to different typologies of macular degeneration represents a major health care problem. Age-related macular degeneration is the disease most frequently associated with CNV development. Schematically, CNVs can be distinguished into classic and occult subtypes, which are characterized by variable natural history and different responsiveness to some therapeutic procedures. At present, the dramatic vision loss due to CNV can be mainly treated by two interventional strategies, which are utilizable in either single or combined modalities: photodynamic therapy with verteporfin (PDT-V), and intravitreal administration of drugs acting against vascular endothelial growth factor. The combined use of PDT-V and anti-angiogenic drugs represents one of the most promising strategies against neovascular macular degeneration, but it unavoidably results in an expensive increase in health resource utilization. However, the positive data from several studies serve as a basis for reconsidering the role of PDT-V, which has undergone a renaissance prompted by the need for a more rational therapeutic approach toward CNV. New pharmacogenetic knowledge of PDT-V points to exploratory prospects to optimize the clinical application of this intriguing photothrombotic procedure. In fact, a Medline search provides data regarding the role of several single nucleotide polymorphisms (SNPs) as genetic predictors of CNV responsiveness to PDT-V. Specifically, correlations between SNPs and different levels of PDT-V efficacy have been detected by examining the gene variants influencing (i) thrombo-coagulative pathways, i.e. methylenetetrahydrofolate reductase (MTHFR) 677C>T (rs1801133), factor V (F5) 1691G>A (rs6025), prothrombin (F2) 20210G>A (rs1799963), and factor XIII-A (F13A1) 185G>T (rs5985); (ii) complement activation and/or inflammatory processes, i.e. complement factor H (CFH) 1277T>C (rs1061170), high-temperature requirement factor A1 (HTRA1) promoter -512G>A (rs11200638), and two variants of the C-reactive protein (CRP) gene (rs2808635 and rs876538); and (iii) production and bioavailability of vascular endothelial growth factor (VEGFA -2578C>A [rs699947] and rs2146323). This article critically evaluates both the clinical plausibility and the opportunity to utilize the most important SNP-response interactions of PDT-V for an effective upgrade of the current anti-CNV therapeutic scenario. In addition, the pharmacogenetics of a very severe post-PDT-V adverse event, i.e. a decrease in acute vision, is briefly discussed. A comprehensive appraisal of the findings reviewed in this article should be carefully considered to design future trials aimed at verifying (after proper genotypic stratification of the enrolled patients) whether these innovative pharmacogenetic approaches will be able to improve the multifaceted interventional management of neovascular macular degeneration.

Interactive Expressions of HtrA1 and VEGF in Human Vitreous Humors and Fetal RPE Cells

High-temperature requirement factor A1 (HtrA1) is associated with exudative age-related macular degeneration, an angiogenic retinal disease related to vascular endothelial growth factor (VEGF). This study investigates the interactive relationship between the expressions of HtrA1 and VEGF. METHODS; The vitreous humor levels of HtrA1, VEGF, and pigment epithelium-derived factor were determined in 55 unrelated Han Chinese patients who underwent ocular surgeries. Expressions of HTRA1 and VEGFA were studied interactively and under stress conditions in primary human fetal retinal pigment epithelial (RPE) cells to evaluate their regulations. Vitreous levels of HtrA1 were significantly associated with that of VEGF in vitreous samples from all patients (Pearson's correlation coefficient test, r = 0.650, P = 7.91 × 10(-8)) and from patients with retinal detachment (r = 0.835, P = 2.14 × 10(-7)). On stress induction, HTRA1 and VEGFA were upregulated in human fetal RPE cells treated by tunicamycin and dithiothreitol, but reduced after treatment by MG132. However, HtrA1 and VEGF did not regulate each other in their expressions. This study revealed an association between HtrA1 and VEGF in human vitreous humors and RPE cells. They are both related to stress and inflammatory conditions.