Mechanistic studies of the effects of anti-factor H antibodies on complement-mediated lysis

Dihydrotestosterone Increases Cytotoxic Activity of Macrophages on Prostate Cancer Cells via TRAIL

Although androgen deprivation therapy (ADT) and immunotherapy are potential treatment options in men with metastatic prostate cancer (CaP), androgen has conventionally been proposed to be a suppressor of the immune response. However, we herein report that DHT activates macrophages. When the murine macrophage cell line (RAW 264.7), human monocyte cell line (THP-1), and human peripheral blood monocytes were cultured with androgen-resistant CaP cell lines, DHT increased cytotoxicity of macrophages in a concentration-dependent manner. Further studies revealed that DHT induced M1 polarization and increased the expression levels of TNF-related apoptosis-inducing ligand (TRAIL) in macrophages and that this effect was abrogated when TRAIL was neutralized with a blocking antibody or small interfering RNA. Subsequent experiments demonstrated that induction of TRAIL expression was regulated by direct binding of androgen receptor to the TRAIL promoter region. Finally, an in vivo mouse study demonstrated that castration enhanced the growth of an androgen-resistant murine CaP tumor and that this protumorigenic effect of castration was blocked when macrophages were removed with clodronate liposomes. Collectively, these results demonstrate that DHT activates the cytotoxic activity of macrophages and suggest that immunotherapy may not be optimal when combined with ADT in CaP.

Complement factor H‑related 3 overexpression affects hepatocellular carcinoma proliferation and apoptosis

Complement factor H-related 3 (CFHR3) belongs to the human factor H protein family and is associated with various human diseases, including nephropathy, age-related macular degeneration and atypical hemolytic uremic syndrome. However, to the best of our knowledge, the role of CFHR3 in hepatocellular carcinoma (HCC) remains largely unknown. In the present study, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were performed to determine mRNA and protein expression levels of CFHR3 in HCC and normal adjacent tissue. In addition, CFHR3 was overexpressed in Huh-7 cells and cell counting kit-8 assay was used to determine cell viability. Cell proliferation and apoptosis were assessed using flow cytometry, RT-qPCR and western blotting. The results demonstrated that mRNA (2^−ΔΔCq) and protein expression levels of CFHR3 were significantly lower in tumor tissue compared with in adjacent tissue. Additionally, CFHR3 overexpression decreased cell viability, inhibited cell proliferation and significantly increased apoptosis. It was also identified that CFHR3 could downregulate the expression of Ki67. The results suggested that CFHR3 induced apoptosis by downregulating the expression of survivin and B cell lymphoma 2, upregulating the expression of Bcl-2-associated X and promoting caspase-3 activity. Western blotting revealed that CFHR3 significantly inhibited the protein expression levels of phosphorylated (p)-phosphoinositide 3-kinase (PI3K), p-protein kinase B (Akt) and p-mammalian target of rapamycin (mTOR). Overexpression of CFHR3 suppressed proliferation and promoted apoptosis of HCC cells by inhibiting the PI3K/Akt/mTOR signaling pathway.

Critical role of the C-terminal domains of factor H in regulating complement activation at cell surfaces

The plasma protein factor H primarily controls the activation of the alternative pathway of complement. The C-terminal of factor H is known to be involved in protection of host cells from complement attack. In the present study, we show that domains 19-20 alone are capable of discriminating between host-like and complement-activating cells. Furthermore, although factor H possesses three binding sites for C3b, binding to cell-bound C3b can be almost completely inhibited by the single site located in domains 19-20. All of the regulatory activities of factor H are expressed by the N-terminal four domains, but these activities toward cell-bound C3b are inhibited by isolated recombinant domains 19-20 (rH 19-20). Direct competition with the N-terminal site is unlikely to explain this because regulation of fluid phase C3b is unaffected by domains 19-20. Finally, we show that addition of isolated rH 19-20 to normal human serum leads to aggressive complement-mediated lysis of normally nonactivating sheep erythrocytes and moderate lysis of human erythrocytes, which possess membrane-bound regulators of complement. Taken together, the results highlight the importance of the cell surface protective functions exhibited by factor H compared with other complement regulatory proteins. The results may also explain why atypical hemolytic uremic syndrome patients with mutations affecting domains 19-20 can maintain complement homeostasis in plasma while their complement system attacks erythrocytes, platelets, endothelial cells, and kidney tissue.

[Tumor marker tests in bladder cancer]

The gold standard for detecting bladder cancer is cystoscopy which identifies nearly all papillary and sessile lesions. However, it is an invasive procedure causing some discomfort for patients. Urine cytology is the standard non-invasive marker with very high specificity, but unfavourable poor sensitivity for Ta, G1, and T1 bladder tumors. To improve early detection of bladder cancer as well as to monitor treatment response and tumor recurrence, bladder tumor markers are eligible. An ideal bladder cancer test would have the potential to replace or delay cystoscopy in the follow-up of bladder cancer patients. In recent years, the FDA approved non-invasive tumor marker tests ImmunoCyt / uCyt+, BTA TRAK, BTA stat, NMP22, NMP22 BladderChek, and UroVysion have been investigated. The tests demonstrated higher sensitivity for diagnosis of bladder cancer compared to urine cytology. Overall, the mean sensitivity and mean specificity was 64-80% and 71-95% and the mean positive and negative predictive values to detect malignancy were 49-84% and 79-95%, respectively. BTA TRAK, BTA stat, NMP22, and NMP22 BladderChek assays are limited by false-positive results in patients with benign urological diseases such as hematuria, urocystitis, renal calculi or urinary tract infections. Due to low specificity BTA TRAK, BTA stat, NMP22, and NMP22 BladderChek should not be used without first ruling out benign or malignant genitourinary disease other than bladder cancer. With the exception of UroVysion achieving 80% sensitivity and 94% specificity, none of these non-invasive tests revealed a high sensitivity and specificity at the same time, which is a main demand to be made on an ideal tumor marker. Insufficient sensitivity along with limited specificity does not allow replacing cystoscopy in diagnosis of bladder cancer or treatment decisions based on a positive test result.

AFM study of complement system assembly initiated by antigen-antibody complex

The shape and size of complement system C1 components assembled on a SiO2 surface after classical activation by antigen-antibody complex was determined by tapping mode atomic force microscopy (AFM). The SiO2 substrate was silanized and bovine leukemia virus proteins gp51 were covalently bound to the SiO2 substrate. Self-assembly of complement system proteins was investigated by AFM. Uniform coating of silanized surface by gp51 proteins was observed by AFM. After incubation of gp51 coated substrate in anti-gp51 antibody containing solution, Ag-Ab complexes were detected on the substrate surface by AFM. Then after treatment of Ag-Ab complex modified substrate by guinea-pig blood serum containing highly active complement system proteins for 3 minutes and 30 minutes features 2–3 times and 5–8 times higher in diameter and in height if compared with those observed after formation of Ag-Ab complex, were observed respectively on the surface of SiO2. This study revealed that AFM might be applied for the imaging of complement system assembly and provides valuable information that can be used to complement other well-established techniques.

Complement Factor H as a Marker for Detection of Bladder Cancer

Background: The BTA TRAK™ and BTA stat™ tests for bladder cancer use monoclonal antibodies (mAbs) X13.2 and X52.1 to detect factor H (FH)-related material in urine. The exact ligands remain unknown.

Methods: Western blot analyses of purified FH, recombinant factor H-related protein 1 (FHR-1), and serum and urine samples were used to identify the ligands of X13.2 and X52.1. Recombinant FH constructs were used to identify the target sites of X13.2 and X52.1. To analyze whether natural ligands of FH could compete with its recognition by the capture mAb X52.1, we used surface plasmon resonance analysis. The role of the ligands of X52.1 in the BTA TRAK assay was tested with use of purified proteins and FH-depleted samples.

Results: X13.2 bound to domain 3 of FH and FH-like protein 1, whereas X52.1 bound to domain 18 of FH and to FHR-1. Using specific FH depletion from a bladder cancer patient’s urine and purified FH, we demonstrated that FH is the ligand recognized by the BTA TRAK test. By contrast, FHR-1 in urine reduced the FH-dependent test signal.

Conclusions: FH is a tumor marker for bladder cancer. To reveal the presence of bladder cancer, the BTA TRAK assay detects FH, whereas FHR-1 is able to partly inhibit this detection. This indicates a special mechanism for a diagnostic immunoassay based on the combined effect of simultaneous positive and negative signals in a single sample.

Bladder tumor markers for monitoring recurrence and screening comparison of hyaluronic acid-hyaluronidase and BTA-Stat tests

BACKGROUND

One of the goals of a noninvasive test for bladder carcinoma screening would be to reduce surveillance cystoscopies among patients with a history of bladder carcinoma. In addition, an accurate bladder carcinoma marker could be used to screen a high-risk population. The authors examined the efficacy of the hyaluronic acid-hyaluronidase (HA-HAase) and BTA-Stat tests to detect and predict bladder carcinoma recurrence and tested their specificity for bladder carcinoma screening.

METHODS

Over a four year period, the authors prospectively collected 225 urine specimens from 70 bladder carcinoma patients and analyzed them by the HA-HAase test. Tumors were identified during 178 visits, and in 47 specimens there was no evidence of disease (NED). Twenty six of these 70 patients were randomly selected to have the BTA-Stat test (111 surveillance visits). In a separate study, 401 former Department of Energy (DOE) workers, who are likely to be at a higher risk for bladder carcinoma, were screened by the HA-HAase and BTA-Stat urine tests.

RESULTS

The HA-HAase test had an approximately 91.0% sensitivity, 70% specificity, 87% accuracy, 92% positive predictive value (PPV), and 67% negative predictive value (NPV) in the 70 bladder carcinoma patients. There were 14 false-positives; however, 6 of these had recurred in approximately 5 months. Only 4 out of 33 NED cases recurred in that time period (chi-square = 5.43; degrees of freedom [DF] = 1; P = 0.0198). Thus, a false-positive HA-HAase test carried a significant risk of recurrence within five months (relative risk [RR] = 3.5; odds ratio [OR] = 5.44). In a direct comparison, the HA-HAase and BTA-Stat had 94% and 61% sensitivity, 63% and 74% specificity, 87% and 64% accuracy, 89% and 88% PPV, and 77% and 38% NPV, respectively. While 6 of the 10 false-positive on the HA-HAase test recurred in 5 months (chi-square = 9.6; DF = 1; P = 0.004), only 1 of the 7 false-positives on the BTA-Stat test recurred in that time period (chi-square = 0.096; DF = 1; P = 0.756). The RR and OR for the HA-HAase test were 10.2 and 24, and for the BTA-Stat, 1.4 and 1.5, respectively. In the DOE worker screening study, the HA-HAase and BTA-Stat had 14% (56 out of 401) and 16.7% (67 out of 401) positive rates, respectively. Sixty three percent of the positives on the BTA-Stat test, but only 25% of the positives on the HA-HAase test, had benign urologic conditions. None of the biomarker positive cases with clinical follow-up (n = 29) had evidence of bladder carcinoma.

CONCLUSIONS

The HA-HAase test is efficient and superior to the BTA-Stat for detecting and predicting bladder carcinoma recurrence. Noninvasive tests with low false positive rates could be used for bladder carcinoma screening in high-risk populations (e.g., those with occupational exposure to carcinogens or smokers).

Role of innate immunity in cancer

Recently, much progress has been made in the field of tumor immunology. Much of this work has focused on understanding and exploiting the innate immune response to tumor cells. A novel human receptor-ligand system that mediates natural killer (NK) and gammadelta T-cell killing of carcinoma cells has been identified, and the functions of an equivalent system in mice are beginning to be explored. The mechanisms of action of an innate tumoricidal cytokine, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and of tumor cell resistance to it, are emerging, as are the ways in which tumor cells evade the damaging effects of IFN-gamma and of complement. Overcoming tumor cell resistance to innate immune attack could prove to be a fruitful approach to cancer immunotherapy in the clinic.

The BTA stat test: a tumor marker for the detection of upper tract transitional cell carcinoma

OBJECTIVES

To conduct a prospective evaluation to determine the utility of the BTA stat test in the detection of upper tract transitional cell carcinoma (UTTCC). Monitoring for UTTCC currently relies on invasive procedures such as upper tract imaging, ureteral washing cytology (UWC) and/or ureteroscopy, or voided urine cytology (VUC). The BTA stat test is a sensitive qualitative immunoassay that detects human complement factor H-related protein in voided urine.

METHODS

A total of 81 patients participated, 27 with histopathologically confirmed UTTCC, 26 with upper tract calculi, and 28 with microscopic hematuria but no evidence of urologic disease. Voided specimens collected before surgery or treatment were tested with the BTA stat test and VUC. UWC was performed in specimens collected by a ureteral catheter.

RESULTS

The BTA stat test was significantly more sensitive and specific than VUC or UWC. The overall sensitivity for each was 82%, 11%, and 48%; the specificity was 89%, 54%, and 33%. The positive predictive value for the BTA stat test was 79% and the negative predictive value was 91%, both the highest of the three tests.

CONCLUSIONS

The BTA stat test was superior to VUC and UWC in the detection of UTTCC. These results may support the adoption of a less aggressive follow-up policy when monitoring for UTTCC when the BTA stat result is negative. If cystoscopy is negative and the BTA stat test is positive, upper tract investigations should be expedited and, if the bladder is in place, bladder biopsies performed.