Effector mechanisms of anti-CD20 monoclonal antibodies in B cell malignancies.

Activation of the complement system by tumor cells was long believed to only benefit the host. Overexpression of complement inhibitors by many tumor cell types and results obtained in several experimental animal models were all in agreement with this hypothesis. However, recent reports imply that the situation is more complex than initially believed and that under certain circumstances tumor cells may use complement to their own advantage, e.g. by recruitment of suppressor T cells or promoting local angiogenesis. Such a dual role of complement may also be apparent when considering the effect of therapeutic monoclonal antibodies (mAb) used to successfully treat B cell malignancies, such as CD20 mAbs. Some argue that besides direct tumor cell killing by mAbs, two main immune effector mechanisms, complement dependent cytotoxicity (CDC) and antibody dependent cellular cytotoxicity (ADCC), may be competing with each other. Experiments aiming at answering the question whether complement is our friend or foe in mAb therapy ended up with seemingly contradictory conclusions. Herein, we revisit the existing knowledge on this pivotal issue based on rituximab and other anti-CD20 mAb as a model of therapeutic agents

Killing of CLL and NHL cells by rituximab and ofatumumab under limited availability of complement.

Rituximab and ofatumumab are anti-CD20 antibodies applicable to treatment for non-Hodgkin's lymphoma and chronic lymphocytic leukemia (CLL). Effectiveness of both immunotherapeutics may depend on exhaustible complement system. To model the efficacy of complement usage by ofatumumab and rituximab under limited complement availability, we compared complement-dependent cytotoxicity exerted by these antibodies at low (5 and 10 %) and physiological (50 %) serum concentration in twelve CD20-positive cell lines and six freshly isolated CLL cells. Simultaneously, we assessed the expression of CD20 and membrane-bound complement inhibitors. Ratios of CD20 to CD59 and/or CD55 distinguished highly sensitive cells lysed equally efficient by both antibodies from the moderately sensitive cells, which were killed more efficiently by ofatumumab

The complement system is activated in synovial fluid from subjects with knee injury and from patients with osteoarthritis

Concentrations of C4d, C3bBbP and sTCC in synovial fluid. (DOCX 37 kb

Complement inhibitor CSMD1 acts as tumor suppressor in human breast cancer

Human CUB and Sushi multiple domains 1 (CSMD1) is a membrane-bound complement inhibitor suggested to act as a putative tumor suppressor gene, since allelic loss of this region encompassing 8p23 including CSMD1 characterizes various malignancies. Here, we assessed the role of CSMD1 as a tumor suppressor gene in the development of breast cancer in vitro and in vivo. We found that human breast tumor tissues expressed CSMD1 at lower levels compared to that in normal mammary tissues. The decreased expression of CSMD1 was linked to a shorter overall survival of breast cancer patients. We also revealed that expression of CSMD1 in human breast cancer cells BT-20 and MDA-MB-231 significantly inhibited their malignant phenotypes, including migration, adhesion and invasion. Conversely, stable silencing of CSMD1 expression in T47D cells enhanced cancer cell migratory, adherent and clonogenic abilities. Moreover, expression of CSMD1 in the highly invasive MDA-MB-231 cells diminished their signaling potential as well as their stem cell-like properties as assessed by measurement of aldehyde dehydrogenase activity. In a xenograft model, expression of CSMD1 blocked the ability of cancer cells to metastasize to secondary sites in vivo, likely via inhibiting local invasion but not the extravasation into distant tissues. Taken together, these findings demonstrate the role of CSMD1 as a tumor suppressor gene in breast cancer

Correction: Complement inhibitor CSMD1 acts as tumor suppressor in human breast cancer

This article has been corrected: In Figure 4B, the image of MDA-MB-231 cells expressing CSMD1 is an accidental duplicate of the image showing invaded BT-20 cells expressing CSMD1 in Figure 4A. The correct Figure 4, produced using the original data, is shown below. The authors declare that these corrections do not change the results or conclusions of this paper. Original article: Oncotarget. 2016; 7:76920–76933. https://doi.org/10.18632/oncotarget.1272

C4b-Binding Protein Is Present in Affected Areas of Myocardial Infarction during the Acute Inflammatory Phase and Covers a Larger Area than C3

BACKGROUND: During myocardial infarction reduced blood flow in the heart muscle results in cell death. These dying/dead cells have been reported to bind several plasma proteins such as IgM and C-reactive protein (CRP). In the present study we investigated whether fluid-phase complement inhibitor C4b-binding protein (C4BP) would also bind to the infarcted heart tissue. METHODS AND FINDINGS: Initial studies using immunohistochemistry on tissue arrays for several cardiovascular disorders indicated that C4BP can be found in heart tissue in several cardiac diseases but that it is most abundantly found in acute myocardial infarction (AMI). This condition was studied in more detail by analyzing the time window and extent of C4BP positivity. The binding of C4BP correlates to the same locations as C3b, a marker known to correlate to the patterns of IgM and CRP staining. Based on criteria that describe the time after infarction we were able to pinpoint that C4BP binding is a relatively early marker of tissue damage in myocardial infarction with a peak of binding between 12 hours and 5 days subsequent to AMI, the phase in which infiltration of neutrophilic granulocytes in the heart is the most extensive. CONCLUSIONS: C4BP, an important fluid-phase inhibitor of the classical and lectin pathway of complement activation binds to jeopardized cardiomyocytes early after AMI and co-localizes to other well known markers such as C3b

Controversies around the statistical presentation of data on mRNA-COVID 19 vaccine safety in pregnant women

The work entitled "Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons" published on April 21, 2021, in The New England Journal of Medicine, presented data collected from American surveillance systems and registries. However, problems with an unanimous interpretation of those results appeared in the public debate and citing articles. Some stated that the risk of miscarriage in vaccinated women was similar to historical values reported before the vaccines approval. The others stated that risk was highly above-normative in women vaccinated during the first and second trimesters. We found several problems with the statistical treatment/interpretation of the originally presented values: a substantial percentage (up to 95.6%) of missing data, an incorrect denominator used for risk estimation, and too short follow-up that disabled the evaluation of the studys endpoint in numerous participants. Eventually, the Authors published a corrigendum on September 8, 2021, and pointed to updated data. Herein, we explain the statistical controversies raised by the original presentation and stress that analyzing the trade-off between knowledge and confusion brought by the release of incomplete results of such a high social interest, should aid in solving the dilemma of whether to publish preliminary data or none.Funding Agencies|Swedish Research Council (Vetenskapsradet)Swedish Research Council [2017-04951]; ELLIIT Call C grant</p