The prognostic value and potential immunotherapeutic efficacy of ACVR1 in treating gastric cancer.

Background: The discovery of biomarkers has facilitated the treatment of cancer. At present, the relationship between activin A receptor type-1 (ACVR1) and gastric cancer is gradually discovered. The aim of this study was to explore the expression of ACVR1 in gastric cancer and its clinical significance, to study the relationship between ACVR1 and tumor microenvironment (TME) for the prognosis of gastric cancer, and to further identify new targets for immunotherapy in gastric cancer. Methods: ACVR1 was first selected as a study gene according to several cancer and gastric cancer public datasets. Its pancancer expression was explored using the UCSC Xena database. The expression level, prognosis, and clinicopathological features of ACVR1 in gastric cancer were analyzed using The Cancer Genome Atlas (TCGA) database. Immunohistochemistry (IHC)-based experiments were conducted to study the expression of ACVR1 at the protein level. The IHC data were analyzed for correlations between ACVR1 expression and various clinicopathological factors and prognosis. The correlation of this gene with the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, immune infiltration, immune checkpoints, drug therapy, tumor mutation burden (TMB), microsatellite instability (MSI), and mismatch repair (MMR) system was analyzed using R software. Results: TCGA data showed that the expression of ACVR1 was higher in gastric cancer tissues than in paracancerous tissues. Moreover, the IHC experiments indicated that ACVR1 was upregulated in gastric cancer tissues at the protein level. Both univariate Cox and multivariate Cox results showed that the increase of ACVR1 was closely associated with tumor stage, size, lymph node metastasis, and age. High ACVR1 expression was linked to a poor prognosis of gastric cancer. The results also revealed that ACVR1 was closely related to suppressive immune cells and pathways. Analyses of immune checkpoints, antitumor drug, TMB, and immune microenvironment indicated that ACVR1 had an antitumor immune effect, promoting gastric cancer development and leading to poor immunotherapy. Conclusions: High ACVR1 expression can be used as an independent prognostic factor to predict the prognostic survival of patients with gastric cancer. ACVR1 expression in gastric cancer tissues was significantly correlated with immune infiltration and may thus serve as a potential therapeutic target for gastric cancer immunotherapy.

Role of ROR2 in promoting gastric cancer metastasis by enhancing c-JUN-mediated MMP3 transcription.

Background: Receptor tyrosine kinase-like orphan receptor 2 (ROR2) is a transmembrane receptor that has a complex role in cancer, acting either to promote or inhibit tumor progression in different tumor types. The effect of ROR2 on gastric cancer is unclear. Methods: Immunohistochemistry was used to investigate the role of ROR2 in the prognosis of gastric cancer. Transwell assay and a BALB/c nude mice pulmonary metastasis model were used to ascertain the role of ROR2 in promoting metastasis in vitro and in vivo. A protein expression array, chromatin immunoprecipitation (ChIP) assay, and luciferase reporter assay were employed to search for the target genes of ROR2. Results: ROR2 was found to be upregulated in gastric cancer tissues, which was correlated with poor disease-free survival (DFS) and overall survival (OS) in gastric cancer patients. Moreover, ROR2 promoted gastric cancer cell migratory and invasive behaviors in vitro and metastasis in vivo. Further research showed that ROR2 promoted gastric cancer metastasis via upregulation of matrix metalloproteinase 3 (MMP3). Analyses of clinical data indicated that high expression of ROR2 was correlated with a high expression of MMP3. Further study showed that ROR2 activated c-JUN by translocating phosphorylated JNK1/2 into the nucleus, and c-JUN interacted directly with the MMP3 promoter, leading to enhanced MMP3 transcription. Conclusions: We report for the first time that ROR2 is upregulated in gastric cancer, promotes metastasis, and is associated with poor prognosis in gastric cancer. The findings suggest that ROR2 may be a promising prognostic predictor for gastric cancer. Silencing the JNK1/2-c-JUN pathway, thereby inhibiting MMP3 expression, may serve as a promising strategy to inhibit gastric cancer progression.

Protective role of host complement system in Aspergillus fumigatus infection.

Invasive aspergillosis (IA) is a life-threatening fungal infection for immunocompromised hosts. It is, therefore, necessary to understand the immune pathways that control this infection. Although the primary infection site is the lungs, aspergillosis can disseminate to other organs through unknown mechanisms. Herein we have examined the in vivo role of various complement pathways as well as the complement receptors C3aR and C5aR1 during experimental systemic infection by Aspergillus fumigatus, the main species responsible for IA. We show that C3 knockout (C3-/-) mice are highly susceptible to systemic infection of A. fumigatus. Intriguingly, C4-/- and factor B (FB)-/- mice showed susceptibility similar to the wild-type mice, suggesting that either the complement pathways display functional redundancy during infection (i.e., one pathway compensates for the loss of the other), or complement is activated non-canonically by A. fumigatus protease. Our in vitro study substantiates the presence of C3 and C5 cleaving proteases in A. fumigatus. Examination of the importance of the terminal complement pathway employing C5-/- and C5aR1-/- mice reveals that it plays a vital role in the conidial clearance. This, in part, is due to the increased conidial uptake by phagocytes. Together, our data suggest that the complement deficiency enhances the susceptibility to systemic infection by A. fumigatus.

Real-World Outcomes in Patients With Brain Metastases Secondary to HER2-Positive Breast Cancer: An Australian Multi-centre Registry-based Study.

BACKGROUND: The development of brain metastases occurs commonly in HER2-positive metastatic breast cancer and is associated with a poorer prognosis. The advent of HER2-targeted therapy has improved overall survival, but the benefit in patients with brain metastases is unclear, as these patients are often excluded from clinical trials. This study aimed to explore real-world outcomes in patients with brain metastases in HER2-positive MBC. MATERIALS & METHODS: Data was extracted from the TABITHA registry, which consists of patient data collected prospectively from 16 Australian sites from 24th February 2015 to 31st October 2021. Data analysed included characteristics of brain metastases, treatment received and survival outcomes. RESULTS: A total of 135 (37%) of 361 patients with HER2-positive MBC were diagnosed with brain metastases during their clinical course, including 45 (12%) with brain metastases at time of MBC diagnosis. 61 (45%) had ≥4 brain lesions. The most common local therapy given was whole brain radiation therapy (WBRT) (36%) followed by multi-modality treatment with both surgery and radiation therapy (27%). The majority of patients received first-line HER2-targeted treatment with trastuzumab and pertuzumab followed by second-line trastuzumab emtansine (T-DM1) but third-line therapy was heterogenous. The median overall survival in patients who developed brain metastases was significantly shorter than those who did not develop brain metastases (58.9 vs. 96.1 months, P = .02). CONCLUSION: Real-world patients diagnosed with brain metastases in HER2-positive MBC have a relatively poor prognosis, despite advances in HER2-targeted treatment. As the range of HER2-targeted treatment expands, it is important to pursue clinical trials that focus on patients with brain metastases.

Exploration of hub genes, lipid metabolism, and the immune microenvironment in stomach carcinoma and cholangiocarcinoma.

Background: Gastric cancer (GC) is the 5th most common cause of cancer in the world and the 3rd largest cause of cancer-related death. It is usually associated with a variety of cancers, of which cholangiocarcinoma (CCA) combined with GC accounts for about 1.6%. This study sought to examine the hub genes and role of lipid metabolism in the development and diagnosis of GC and CCA. Methods: To screen potential hub genes, The Cancer Genome Atlas (TCGA) data sets, including the GC (STAD, dataset of GC) and CCA (CHOL, dataset of CCA) data sets, were used to conduct a differentially expressed gene (DEG) analysis and an enrichment analysis of the DEGs. A weighted-gene co-expression network analysis (WGCNA) was conducted to identify the significant gene module and then find the hub genes in the module. To verify the 4 hub genes, we conducted a differentiation analysis of the 4 genes in GC and CCA and found that there were differences. A survival analysis of the hub genes was performed and mutations were mapped. Additionally, tumor immune microenvironment (TIME) and immune analyses were performed to evaluate how lipid metabolism affects the development of GC with CCA. Results: The principal component analysis showed that both GC and CCA had distinct up-regulated and down-regulated genes, which are involved in a variety of metabolic processes. Upon WGCNA, the turquoise and blue modules were meaningful, and the hub genes were identified from these 2 modules. Four hub genes were identified: amyloid beta precursor protein binding family B member 1 (APBB1), Homo sapiens armadillo repeat containing X-linked 1 (ARMCX1), DAZ interacting zinc finger protein 1 (DZIP1), and methionine sulfoxide reductase B3 (MSRB3). In survival analysis, increased expression of the 4 hub genes was associated with inferior survival outcomes, with variations in all 4 genes. Additionally, we demonstrated that genes related to lipid metabolism had an effect on immune function. Conclusions: APBB1, ARMCX1, DZIP1, and MSRB3 affect the development of GC and CCA and can be used as biomarkers. The expression of lipid metabolism genes is related to the TIME of patients with GC and CCA.

The treatment of resectable gastric cancer: a literature review of an evolving landscape.

Background and Objective: Gastric cancer carries a poor prognosis despite advances in treatment. Despite curative-intent surgery, the risk of recurrence is high. Perioperative treatment may improve rates of complete surgical resection and reduce the rate of recurrence. Treatment practices vary worldwide, while perioperative treatment is considered standard-of-care practice in Western countries, upfront surgery followed by adjuvant therapy is preferred in Asian countries. The current literature is complex to navigate with a plethora of studies available for review. The aim of this review is to summarise current evidence regarding the role of perioperative treatment in resectable gastric cancer and to explore future directions in research. Methods: We searched the PubMed database for peer-reviewed original articles from phase III trials, published between 2002 to 2021 with regard to the treatment of resectable gastric cancer. Current active clinical trials regarding the use of targeted therapy and immune checkpoint inhibitors in perioperative and adjuvant therapy were identified using the ClinicalTrials.gov database from the US National Library of Medicine. Key Content and Findings: Compared to surgery alone, the use of perioperative chemotherapy prior to resection of gastric cancer and the use of adjuvant chemotherapy after upfront surgery both improve survival in those with resectable gastric cancer. However, treatment practices vary worldwide. In clinical practice, patient factors such as functional status should be considered when considering treatment approach. Many current clinical trials explore the role of targeted therapy and immune checkpoint inhibitors in the perioperative setting, which appear to be promising. Conclusions: Gastric cancer continues to carry a poor prognosis. The addition of targeted agents and immune checkpoint inhibitors in the perioperative setting appear to be promising although further research is required in this area to assess efficacy. Further clinical research is required to identify new agents and approaches to treatment to improve the survival of these patients.

From discovery to approval: A brief history of the compstatin family of complement C3 inhibitors.

The FDA approval of pegcetacoplan (Empaveli), a PEGylated compstatin-based C3 therapeutic, as a new treatment for paroxysmal nocturnal hemoglobinuria (PNH) marks a milestone in the history of complement drug discovery. Almost 15 years after the approval of the first complement-specific drug for PNH, the anti-C5 antibody eculizumab, a novel class of complement inhibitors with a distinct mechanism of action finally enters the clinic. This landmark decision broadens the spectrum of available complement therapeutics, offering patients with unmet clinical needs or insufficient responses to anti-C5 therapy an alternative treatment option with a broad activity profile. Here we present a brief historical account of this newly approved complement drug, consolidating its approval within the long research record of the compstatin family of peptidic C3 inhibitors.

Immune Checkpoint Inhibitor in First-Line Treatment of Metastatic Renal Cell Carcinoma: A Review of Current Evidence and Future Directions.

The incidence of renal cell carcinoma (RCC) is rising and metastatic RCC carries a very poor prognosis. The treatment paradigm for metastatic RCC has shifted dramatically in the last decade with multi-targeted tyrosine kinase inhibitors (TKI) previously used as first-line treatment but its utility is limited by short-lived efficacy and rapid disease progression. The dysregulation of immune cells in the tumour microenvironment contributes to unregulated growth of RCC. Thus, the use of immune checkpoint inhibitors has become first-line treatment for metastatic RCC and has offered dramatic improvement in clinical benefit and survival. Treatment with immune checkpoint inhibitor in combination with TKI appears to be promising in offering even greater response rates. The treatment for metastatic RCC continues to evolve and ongoing advances with new targeted agents and biomarkers are needed to continue to improve prognosis in the future.

Real-World Data on Outcomes in Metastatic Castrate-Resistant Prostate Cancer Patients Treated With Abiraterone or Enzalutamide: A Regional Experience.

BACKGROUND: Both abiraterone and enzalutamide have shown to improve overall survival (OS), progression-free survival (PFS) and prostate-specific antigen (PSA) response in patients with metastatic castration-resistant prostate cancer (mCRPC) regardless of previous treatment with chemotherapy (COU-AA3011, COU-AA3022, AFFIRM3 and PREVAIL4). The data regarding the impact of these treatments in the real world setting is scarce. This study assessed the real world survival and disease outcomes in mCRPC patients in a regional health service in Victoria with the use of abiraterone and enzalutamide. METHODS: This retrospective clinical audit included 75 patients with diagnosis of mCRPC treated with either abiraterone or enzalutamide between January 1, 2014, and December 31, 2019, at Goulburn Valley Health. Patients were stratified according to the drug received, Eastern Cooperative Oncology Group (ECOG) performance status, Gleason score, burden of disease at diagnosis, presence of visceral metastases and use of previous chemotherapy. The primary end point was PSA response (defined as a reduction in the PSA level from baseline by 50% or more). The secondary outcomes were PSA PFS, radiographic PFS, and OS. RESULTS: Thirty-seven patients received enzalutamide, and the other 38 received abiraterone. Only 20% of patients in either group had visceral metastases. 32% of patients receiving enzalutamide had a high burden of disease, compared to 53% receiving abiraterone. 38% of patients in the enzalutamide group and 53% in the abiraterone group had received prior chemotherapy. PSA response rates were higher in the enzalutamide group than abiraterone group (70.3% vs 37.8%). Both PSA and radiographic PFS were longer in the enzalutamide group than abiraterone group; 7 months vs 5 months for both end points. OS was also found to be longer in patients receiving enzalutamide; 30 months compared to only 13 months in patients receiving abiraterone. CONCLUSION: Both abiraterone and enzalutamide have shown to result in significant PSA response rates, as well as PFS and OS benefit in mCRPC patients in the real world setting. The difference in responses and survival benefit are probably impacted by the unbalanced burden of disease.

Differential expression of complement receptors CR1/2 and CR4 by murine M1 and M2 macrophages.

Macrophages polarize into functionally divergent phenotypes - M1 and M2 - which express distinct receptors. These cells are known to express complement receptors, including CR1, CR3, and CR4. However, whether these complement receptors are differentially expressed on M1 and M2 macrophages is not yet known. Herein, we have examined the expression of CR1 to CR4 on murine bone marrow-derived M1 (stimulated with IFN-γ or LPS) and M2 (stimulated with IL-4 or IL-4 + IL-13) macrophages. We show that M1 cells exhibit increased expression of CR1/2, whereas M2 cells display the higher expression of CR4; CR3 is equally expressed on both the phenotypes. Thus, M1 cells are CR1/2+CR4+, and M2 are CR1/2-CR4+. Functional probing of these cells for their phagocytic ability indicates that M1 cells, which express higher CR1/2, internalize a significantly greater number of C3b-opsonized erythrocytes. Both M1 and M2 cells, on the other hand, internalize iC3b-opsonized erythrocytes to a similar extent. Interestingly, the phagocytic receptor involved in phagocytosis of iC3b-opsonized erythrocytes is only CR3 with no contribution of CR4. We, thus, propose that complement receptor expression can be used in combination with the expression of other known polarization markers to better locate a macrophage along its phenotypic spectrum.

Role of Electrostatic Hotspots in the Selectivity of Complement Control Proteins Toward Human and Bovine Complement Inhibition.

Poxviruses are dangerous pathogens, which can cause fatal infection in unvaccinated individuals. The causative agent of smallpox in humans, variola virus, is closely related to the bovine vaccinia virus, yet the molecular basis of their selectivity is currently incompletely understood. Here, we examine the role of the electrostatics in the selectivity of the smallpox protein SPICE and vaccinia protein VCP toward the human and bovine complement protein C3b, a key component of the complement immune response. Electrostatic calculations, in-silico alanine-scan and electrostatic hotspot analysis, as introduced by Kieslich and Morikis (PLoS Comput. Biol. 2012), are used to assess the electrostatic complementarity and to identify sites resistant to local perturbation where the electrostatic potential is likely to be evolutionary conserved. The calculations suggest that the bovine C3b is electrostatically prone to selectively bind its VCP ligand. On the other hand, the human isoform of C3b exhibits a lower electrostatic complementarity toward its SPICE ligand. Yet, the human C3b displays a highly preserved electrostatic core, which suggests that this isoform could be less selective in binding different ligands like SPICE and the human Factor H. This is supported by experimental cofactor activity assays revealing that the human C3b is prone to bind both SPICE and Factor H, which exhibit diverse electrostatic properties. Additional investigations considering mutants of SPICE and VCP that revert their selectivity reveal an "electrostatic switch" into the central modules of the ligands, supporting the critical role of the electrostatics in the selectivity. Taken together, these evidences provide insights into the selectivity mechanism of the complement regulator proteins encoded by the variola and vaccinia viruses to circumvent the complement immunity and exert their pathogenic action. These fundamental aspects are valuable for the development of novel vaccines and therapeutic strategies.

Virus-Encoded Complement Regulators: Current Status.

Viruses require a host for replication and survival and hence are subjected to host immunological pressures. The complement system, a crucial first response of the host immune system, is effective in targeting viruses and virus-infected cells, and boosting the antiviral innate and acquired immune responses. Thus, the system imposes a strong selection pressure on viruses. Consequently, viruses have evolved multiple countermeasures against host complement. A major mechanism employed by viruses to subvert the complement system is encoding proteins that target complement. Since viruses have limited genome size, most of these proteins are multifunctional in nature. In this review, we provide up to date information on the structure and complement regulatory functions of various viral proteins.

The imitation game: a viral strategy to subvert the complement system.

Viruses are obligate parasites of cellular hosts and therefore are constantly confronted with the host immune system. Evasion of innate immunity mechanisms by viruses is paramount for the establishment of their infection. The complement system can directly neutralize viruses and also augments adaptive immune responses against them. This system, therefore, is central to host innate immune surveillance, and viruses have evolved a multitude of ways to escape its assault. A major strategy employed by viruses is the molecular mimicry of human complement regulators, namely regulators of complement activation (RCA) proteins and CD59. Herein, we outline up-to-date information on the structure, function and role of viral homologs of the human complement regulators in viral pathogenesis.

A Painful Finger: An Unusual Presentation of Von Hippel-Lindau-Associated Advanced Renal Cell Carcinoma.

Bone is reported to be one of the most common sites of metastasis. Acrometastasis is an extremely rare situation and accounts for approximately 0.1% of all metastatic lesions to the skeleton. Here, we present a case of acrometastasis in a 55-year-old woman who presented with a 3-month history of atraumatic right ring fingertip pain and swelling and was subsequently diagnosed with metastatic renal cell carcinoma. This report highlights the importance of clinical suspicion of malignancy at unusual sites in the setting of non-resolving symptoms.

Anticancer therapy within the last 30 days of life: results of an audit and re-audit cycle from an Australian regional cancer centre.

BACKGROUND: The therapeutic landscape in medical oncology continues to expand significantly. Newer therapies, especially immunotherapy, offer the hope of profound and durable responses with more tolerable side effect profiles. Integrating this information into the decision making process is challenging for patients and oncologists. Systemic anticancer treatment within the last thirty days of life is a key quality of care indicator and is one parameter used in the assessment of aggressiveness of care. METHODS: A retrospective review of medical records of all patients previously treated at Goulburn Valley Health oncology department who died between 1 January 2015 and 30 June 2018 was conducted. Information collected related to patient demographics, diagnosis, treatment, and hospital care within the last 30 days of life. These results were presented to the cancer services meeting and a quality improvement intervention program was instituted. A second retrospective review of medical records of all patients who died between 1 July 2018 and 31 December 2018 was conducted in order to measure the effect of this intervention. RESULTS: The initial audit period comprised 440 patients. 120 patients (27%) received treatment within the last 30 days of life. The re-audit period comprised 75 patients. 19 patients (25%) received treatment within the last 30 days of life. Treatment rates of chemotherapy reduced after the intervention in contrast to treatment rates of immunotherapy which increased. A separate analysis calculated the rate of mortality within 30 days of chemotherapy from the total number of patients who received chemotherapy was initially 8% and 2% in the re-audit period. Treatment within the last 30 days of life was associated with higher use of aggressive care such as emergency department presentation, hospitalisation, ICU admission and late hospice referral. Palliative care referral rates improved after the intervention. CONCLUSION: This audit demonstrated that a quality improvement intervention can impact quality of care indicators with reductions in the use of chemotherapy within the last 30 days of life. However, immunotherapy use increased which may be explained by increased access and a better risk benefit balance.

Pembrolizumab Induced Ocular Hypotony With Near Complete Vision Loss, Interstitial Pulmonary Fibrosis and Arthritis.

Clinical outcomes for patients with advanced melanoma have improved significantly with the introduction of immune checkpoint inhibitors. These agents have distinct adverse effects with the potential for heightened host immune responses manifesting as an autoimmune reaction in any organ. We report a unique case who developed pembrolizumab induced arthritis, ocular hypotony with vision loss and pulmonary interstitial fibrosis. A 57-year old gentleman with advanced melanoma was treated with pembrolizumab and attained complete response with no evidence of disease on functional imaging. Treatment was well-tolerated with the only side effect being arthritis controlled with low dose steroids. Following a work related blunt trauma to the right eye, the patient developed bilateral visual impairment secondary to ocular hypotony. The ocular hypotony failed to respond to high-dose glucocorticoid and multiple surgeries. Intraoperatively, ciliary body atrophy was found. Pembrolizumab was ceased after the eye trauma and he remained in complete remission from melanoma. After a further 10 months, the patient developed symptomatic pulmonary fibrosis. There was moderate symptomatic improvement with nintedanib, an antifibrotic agent. This case describes two rare and unique adverse effects. Ocular adverse effects are extremely uncommon and this is the first case to report immune checkpoint inhibitor related ocular hypotony without uveitis to the best of our knowledge. Similarly, the incidence of severe pneumonitis is reported to be low, however limited data is available regarding pulmonary interstitial fibrosis. The occurrence of multiple adverse effects in this case including one occurring several months after cessation of treatment highlights the need for vigilance by clinicians who manage patients treated with immune checkpoint inhibitors. Further research is necessary with regards to rare adverse effects of immune checkpoint inhibitors and the relation of these to treatment administration.

Spatially conserved motifs in complement control protein domains determine functionality in regulators of complement activation-family proteins.

Regulation of complement activation in the host cells is mediated primarily by the regulators of complement activation (RCA) family proteins that are formed by tandemly repeating complement control protein (CCP) domains. Functional annotation of these proteins, however, is challenging as contiguous CCP domains are found in proteins with varied functions. Here, by employing an in silico approach, we identify five motifs which are conserved spatially in a specific order in the regulatory CCP domains of known RCA proteins. We report that the presence of these motifs in a specific pattern is sufficient to annotate regulatory domains in RCA proteins. We show that incorporation of the lost motif in the fourth long-homologous repeat (LHR-D) in complement receptor 1 regains its regulatory activity. Additionally, the motif pattern also helped annotate human polydom as a complement regulator. Thus, we propose that the motifs identified here are the determinants of functionality in RCA proteins.

Current promising treatment strategy for glioblastoma multiform: A review.

Glioblastoma multiform (GBM) is a heterogeneous group of primary neoplasm resistant to conventional therapies. Due to their infiltrative nature it not fully isolated by aggressive surgery, radiation and chemotherapy showing poor prognosis in glioma patients. Unfortunately, diagnosed patients die within 1.5-2 year treatment schedule. Currently temozolomide (TMZ) is the first choice for the prognosis of GBM patients. TMZ metabolites methyl triazen imidazol carboxamide form complex with alkyl guanine alkyl transferase (O6 MGMT- DNA repair protein) induced DNA damage following resistance properties of TMZ and inhibit the overall survival of the patients. Last few decades different TMZ conjugated strategy is developed to overcome the resistance and enhance the chemotherapy efficacy. The main aim of this review is to introduce the new promising pharmaceutical candidates that significantly influence the therapeutic response of the TMZ in context of targeted therapy of glioblastoma patients. It is hoped that this proposed strategy are highly effective to overcome the current resistance limitations of TMZ in GBM patients and enhance the survival rate of the patients.

Clinical and Immunological Profile of Anti-factor H Antibody Associated Atypical Hemolytic Uremic Syndrome: A Nationwide Database.

Background: Atypical hemolytic uremic syndrome (aHUS), an important cause of acute kidney injury (AKI), is characterized by dysregulation of the alternative complement pathway. Autoantibodies to factor H (FH), a chief regulator of this pathway, account for a distinct subgroup. While high anti-FH titers predict relapse, they do not correlate well with disease activity and their functional characterization is required. Methods: Of 781 patients <18-year-old of aHUS in the nationwide database from 2007 to 2018, 436 (55.8%) had anti-FH antibodies. Clinical features and outcome of patients managed in the last 6-year (n = 317) were compared to before (n = 119). In plasma samples of 44 patients, levels of serial circulating FH immune complexes (CIC), free FH, soluble terminal complement complex (sC5b-9), sheep red blood cell (SRBC) lysis and epitope specificity (n = 8) were examined. Functional renal reserve, ambulatory hypertension, left ventricular hypertrophy (LVH), and proteinuria were evaluated in a subset. Results: Patients presented with markedly elevated anti-FH titers (10,633.2 ± 998.5 AU/ml). Management varied by center, comprising plasma exchange (PEX; 77.5%) and immunosuppression (73.9%). Patients managed in the last 6-year showed better renal survival at mean 28.5 ± 27.3 months (log rank P = 0.022). Mean anti-FH titers stayed 700-1,164 AU/ml during prolonged follow-up, correlating with CIC. Patients with relapse had lower free-FH during remission [Generalized estimating equations (GEE), P = 0.001]; anti-FH levels ≥1,330 AU/ml and free FH ≤440 mg/l predicted relapse (hazards ratio, HR 6.3; P = 0.018). Epitope specificity was similar during onset, remission and relapse. Antibody titer ≥8,000 AU/ml (HR 2.23; P = 0.024), time to PEX ≥14 days (HR 2.09; P = 0.071) and PEX for <14 days (HR 2.60; P = 0.017) predicted adverse renal outcomes. Combined PEX and immunosuppression improved long-term outcomes (HR 0.37; P = 0.026); maintenance therapy reduced risk of relapses (HR 0.11; P < 0.001). At 4.4±2.5 year, median renal reserve was 15.9%; severe ambulatory, masked and pre-hypertension were found in 38, 30, and 18%, respectively. Proteinuria and LVH occurred in 58 and 28% patients, respectively. Conclusion: Prompt recognition and therapy with PEX and immunosuppression, is associated with satisfactory outcomes. Free-FH predicts early relapses in patients with high anti-FH titers. A significant proportion of impaired functional reserve, ambulatory hypertension, proteinuria and LVH highlight the need for vigilant long-term follow-up.

Molecular engineering of an efficient four-domain DAF-MCP chimera reveals the presence of functional modularity in RCA proteins.

The complement system is highly efficient in targeting pathogens, but lack of its apposite regulation results in host-cell damage, which is linked to diseases. Thus, complement activation is tightly regulated by a series of proteins, which primarily belong to the regulators of complement activation (RCA) family. Structurally, these proteins are composed of repeating complement control protein (CCP) domains where two to four successive domains contribute to the regulatory functions termed decay-accelerating activity (DAA) and cofactor activity (CFA). However, the precise constitution of the functional units and whether these units can be joined to form a larger composition with dual function have not been demonstrated. Herein, we have parsed the functional units for DAA and CFA by constructing chimeras of the decay-accelerating factor (DAF) that exhibits DAA and membrane cofactor protein (MCP) that exhibits CFA. We show that in a four-CCP framework, a functional unit for each of the regulatory activities is formed by only two successive CCPs wherein each participates in the function, albeit CCP2 has a bipartite function. Additionally, optimal activity requires C-terminal domains that enhance the avidity of the molecule for C3b/C4b. Furthermore, by composing a four-CCP DAF-MCP chimera with robust CFA (for C3b and C4b) and DAA (for classical and alternative pathway C3 convertases), named decay cofactor protein, we show that CCP functional units can be linked to design a dual-activity regulator. These data indicate that the regulatory determinants for these two biological processes are distinct and modular in nature.