Concerns over vaccine efficacy after the emergence of the SARS-CoV-2 Delta variant prompted revisiting the vaccine design concepts. Monoclonal antibodies (mAbs) have been developed to identify the neutralizing epitopes on spike protein. It has been confirmed that the key amino acid residues in epitopes that induce the formation of neutralizing antibodies do not have to be on the receptor-binding domain (RBD)- angiotensin-converting enzyme 2 (ACE2) contact surface, and may be conformationally hidden. In addition, this epitope is tolerant to amino acid mutations of the Delta variant. The antibody titers against RBD in health care workers in Thailand receiving two doses of CoronaVac, followed by a booster dose of BNT162b2, were significantly increased. The neutralizing antibodies against the Delta variant suggest that the overall neutralizing antibody level against the Wuhan strain, using the NeutraLISA, was consistent with the levels of anti-RBD antibodies. However, individuals with moderate anti-RBD antibody responses have different levels of a unique antibody population competing with a cross-neutralizing mAb clone, 40591-MM43, determined by in-house competitive ELISA. Since 40591-MM43 mAb indicates cross-neutralizing activity against the Delta variant, this evidence implies that the efficiency of the vaccination regimen should be improved to facilitate cross-protective antibodies against Delta variant infections. The RBD epitope recognized by 40591-MM43 mAb is hidden in the close state.

Background: Triple-negative breast cancer (TNBC) is an aggressive subtype with high metastatic potential, poor prognosis, and the absence of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor 2 (HER2). The lack of these receptors limits the standard treatments, such as hormone therapies and HER2-targeted antibodies like trastuzumab. These challenges highlight the critical need for novel therapeutic strategies. CD147, a transmembrane glycoprotein overexpressed in TNBC, promotes tumor progression, metastasis, and chemoresistance, making it a promising therapeutic target. This study evaluates the antibody-dependent cellular cytotoxicity (ADCC) of HuM6-1B9, a humanized anti-CD147 antibody, against MDA-MB-231 cells, a TNBC model. Methods: CFSE-labelled MDA-MB-231 cells were co-cultured with PBMCs as effector cells (E:T ratio 80:1) in the presence of HuM6-1B9 and incubated for 4 h. Cells were then collected and stained with PI, and CFSE+/PI+ dead target cells were analyzed by flow cytometry. Results: Co-culturing MDA-MB-231 cells with peripheral blood mononuclear cells (PBMCs) in the presence of HuM6-1B9 demonstrated effective ADCC induction without direct cytotoxicity. HuM6-1B9 induced 54.01% cancer cell death via ADCC, significantly outperforming trastuzumab (26.14%) while sparing PBMCs. Conclusion: These findings support HuM6-1B9 as a prospective TNBC therapeutic and warrant further investigation into its clinical potential.

Cluster of Differentiation (CD) 147, a transmembrane glycoprotein, plays a critical role in monocyte function by regulating invasion, migration and cytokine production. This study explored the impact of CD147 on monocyte chemotaxis and inflammatory responses following monocyte chemoattractant protein-1 (MCP-1) modulation using CD147 knockout (CD147^KO) THP-1 monocytes. CD147^KO THP-1 cells exhibited significantly enhanced migration towards MCP-1 and chemoattractants secreted by MDA-MB-231 breast cancer cells compared to wild-type (WT) THP-1 cells, while surface expression of the adhesion molecule CD44 remained unchanged. Despite their increased migration, CD147^KO cells showed no significant differences in CC chemokine receptor type 1 (CC1) or CC chemokine receptor type 2 (CCR2) protein expression. Upon MCP-1 stimulation, CD147^KO THP-1 monocytes exhibited elevated mRNA expression of interleukin (IL)-6 and IL-10, accompanied by a reduction in tumor necrosis factor alpha (TNF-α) at higher MCP-1 concentrations. IL-6 upregulation in CD147^KO THP-1 monocytes appears to be a candidate mediator of their enhanced migratory capacity. In summary, this study highlights the dual role of CD147 as a potential checkpoint in regulating THP-1 monocyte migration, with its function varying depending on the context and microenvironment. Additionally, CD147^KO THP-1 monocytes exhibited a shift in the balance between pro- and anti-inflammatory cytokine responses.