FcγRIIIa receptor polymorphism influences NK cell mediated ADCC activity against HIV

Bisecting N-Acetylglucosamine of the N-Glycan of Immunoglobulin G Does Not Affect Binding to Fc Gamma Receptors

Monoclonal antibodies (mAb) produced in 1,4-mannosyl-glycoprotein 4-N-acetylglucosaminyltransferase (MGAT3) overexpressing cell lines have superior in vitro and in vivo activities. The N-glycan of the Fc-region of these mAbs have increased levels of bisecting N-acetylglucosamine (GlcNAc) and reduced core-fucosylation. Although a reduction in core-fucosylation will improve FcγRIIIa binding and antibody-dependent cellular cytotoxicity (ADCC) activity, the influence of bisecting GlcNAc on these activities has been difficult to probe. Here, we describe the preparation of a unique series of homogeneous glycoforms of trastuzumab (Herceptin) with and without core-fucose and with and without bisecting GlcNAc and examine binding to a comprehensive panel of Fcγ receptors. The glycoforms of trastuzumab were prepared by treatment with wild-type Endo-S2 to cleave the chitobiose core of the N-glycan to leave GlcNAc-Fuc that was exposed to an α-fucosidase to provide trastuzumab-GlcNAc. Glycan oxazolines with and without bisecting GlcNAc were prepared by enzymatic remodeling of a sialoglycopeptide isolated from egg yolk powder, which were employed in transglycosylations with trastuzumab-GlcNAc and trastuzumab-GlcNAc-Fuc catalyzed by Endo-S2 D184M resulting in well-defined glycoforms. As expected, core-fucosylation had a major effect on FcγRIIIa binding, which was not influenced by the presence of bisecting GlcNAc. It was found that an A2-glycan (GlcNAc2Man3GlcNAc2) modified by bisecting GlcNAc cannot be core-fucosylated by FUT8. Thus, bisecting GlcNAc has only an indirect influence on FcγRIIIa binding and subsequent ADCC activity by inhibiting core-fucosylation. The results described here provide an understanding of the properties of therapeutic monoclonal antibodies.

From natural defenders to therapeutic warriors: NK cells in HIV immunotherapy

Cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells both play essential roles in controlling viral infections by eliminating virus-infected cells. Unlike CTLs, which require priming and activation by antigen-presenting cells, NK cells possess a remarkable capacity to mount a rapid antiviral immune response immediately after infection. Additionally, they can bolster the adaptive immune system by secreting cytokines and directly interacting with other immune cells. However, during chronic human immunodeficiency virus (HIV) infection, various immune cells, including NK cells, experience functional impairments. This has led to the exploration of NK cell-based immunotherapy as a promising strategy to reverse these dysfunctions and contribute to the pursuit of a functional cure for HIV. Building on the success of NK cell therapies in cancer treatment, these approaches offer significant potential for transforming the HIV cure field. This review provides a comprehensive overview of the latest advances in NK cell-based immunotherapy for HIV, outlining the progress made and the key challenges that must be overcome to achieve a functional cure for people living with HIV.

NK cell subsets and dysfunction during viral infection: a new avenue for therapeutics?

In the setting of viral challenge, natural killer (NK) cells play an important role as an early immune responder against infection. During this response, significant changes in the NK cell population occur, particularly in terms of their frequency, location, and subtype prevalence. In this review, changes in the NK cell repertoire associated with several pathogenic viral infections are summarized, with a particular focus placed on changes that contribute to NK cell dysregulation in these settings. This dysregulation, in turn, can contribute to host pathology either by causing NK cells to be hyperresponsive or hyporesponsive. Hyperresponsive NK cells mediate significant host cell death and contribute to generating a hyperinflammatory environment. Hyporesponsive NK cell populations shift toward exhaustion and often fail to limit viral pathogenesis, possibly enabling viral persistence. Several emerging therapeutic approaches aimed at addressing NK cell dysregulation have arisen in the last three decades in the setting of cancer and may prove to hold promise in treating viral diseases. However, the application of such therapeutics to treat viral infections remains critically underexplored. This review briefly explores several therapeutic approaches, including the administration of TGF-β inhibitors, immune checkpoint inhibitors, adoptive NK cell therapies, CAR NK cells, and NK cell engagers among other therapeutics.

Can Antinuclear Antibodies Have a Pathogenic Role in Systemic Sclerosis?

Systemic sclerosis (SSc) is a connective tissue disease characterized by extensive fibrosis of the skin and internal organs, associated with vasculopathy and autoimmune features. Antinuclear antibodies (ANA) are found in almost all SSc patients and constitute strong diagnosis and prognosis biomarkers. However, it remains unclear whether ANA are simple bystanders or if they can have a role in the pathophysiology of the disease. One might think that the nuclear nature of their targets prevents any accessibility to autoantibodies. Nevertheless, recent data suggest that ANA could be pathogenic or at least contribute to the perennation of the disease. We review here first the indirect clues of the contribution of ANA to SSc: they are associated to the disease subtypes, they may precede disease onset, their titer correlates with disease activity and severity, there is an association between molecular subsets, and some patients can respond to B-cell targeting therapy. Then, we describe in a second part the mechanisms of ANA production in SSc from individual genetic background to post-transcriptional modifications of neoantigens. Finally, we elaborate on the potential mechanisms of pathogenicity: ANA could be pathogenic through immune-complex-mediated mechanisms; other processes potentially involve molecular mimicry and ANA penetration into the target cell, with a focus on anti-topoisomerase-I antibodies, which are the most probable candidate to play a role in the pathophysiology of SSc. Finally, we outline some technical and conceptual ways to improve our understanding in this field.

Targeting NK Cells for HIV-1 Treatment and Reservoir Clearance

Combined antiretroviral therapy (cART) can inhibit the replication of human immunodeficiency virus type 1 (HIV-1) and reduce viral loads in the peripheral blood to undetectable levels. However, the presence of latent HIV-1 reservoirs prevents complete HIV-1 eradication. Several drugs and strategies targeting T cells are now in clinical trials, but their effectiveness in reducing viral reservoirs has been mixed. Interestingly, innate immune natural killer (NK) cells, which are promising targets for cancer therapy, also play an important role in HIV-1 infection. NK cells are a unique innate cell population with features of adaptive immunity that can regulate adaptive and innate immune cell populations; therefore, they can be exploited for HIV-1 immunotherapy and reservoir eradication. In this review, we highlight immunotherapy strategies for HIV infection that utilize the beneficial properties of NK cells.

Different Aspects Concerning Viral Infection and the Role of MHC Molecules in Viral Prevention

Major Histocompatibility Complex (MHC) molecules play a crucial role in inducing an adaptive immune response. T-cell epitopes require compatible MHC molecules to form MHC-peptide Complexes (pMHC) that activate the T-cell Receptors (TCR) of T-lymphocyte clones. MHCs are polymorphic molecules with wide varieties of gene alleles. There are two classes of MHC molecules, class I and II. Both classes have three classical loci HLA-A, -B, and –C are present in class I and HLA-DP, -DQ, and -DR in class II. To induce a compatible T-lymphocyte clone, the T-cell epitope requires the association of the compatible MHC molecule to form pMHC. Each MHC variant possesses a different groove that is capable of binding a different range of antigenic epitopes. Without the compatible MHC molecule, a T cell clone cannot be activated by a particular viral epitope. With the aim of preventing viral transmission, the efficiency of a viral vaccine is related to the existence of specific MHC alleles in the individual. This article proposes the roles of the MHC molecule to prevent viral infection. In addition, the association of the viral receptor molecule with the viral infection will also be discussed.

FUT8 and Protein Core Fucosylation in Tumours: From Diagnosis to Treatment

Glycosylation changes are key molecular events in tumorigenesis, progression and glycosyltransferases play a vital role in the this process. FUT8 belongs to the fucosyltransferase family and is the key enzyme involved in N-glycan core fucosylation. FUT8 and/or core fucosylated proteins are frequently upregulated in liver, lung, colorectal, pancreas, prostate,breast, oral cavity, oesophagus, and thyroid tumours, diffuse large B-cell lymphoma, ependymoma, medulloblastoma and glioblastoma multiforme and downregulated in gastric cancer. They can be used as markers of cancer diagnosis, occurrence, progression and prognosis. Core fucosylated EGFR, TGFBR, E-cadherin, PD1/PD-L1 and α3β1 integrin are potential targets for tumour therapy. In addition, IGg1 antibody defucosylation can improve antibody affinity, which is another aspect of FUT8 that could be applied to tumour therapy.

Are Fc Gamma Receptor Polymorphisms Important in HIV-1 Infection Outcomes and Latent Reservoir Size?

Fc gamma receptors (FcγR) are cell surface glycoproteins which trigger specific effector-cell responses when cross-linked with the Fc portions of immunoglobulin (IgG) antibodies. During HIV-1 infection, the course of disease progression, ART response, and viral reservoir size vary in different individuals. Several factors may account for these differences; however, Fc gamma receptor gene polymorphisms, which influence receptor binding to IgG antibodies, are likely to play a key role. FcγRIIa (CD32) was recently reported as a potential marker for latent HIV reservoir, however, this assertion is still inconclusive. Whether FcγR polymorphisms influence the size of the viral reservoir, remains an important question in HIV cure studies. In addition, potential cure or viral suppression methods such as broadly neutralizing antibody (bNAbs) may depend on FcγRs to control the virus. Here, we discuss the current evidence on the potential role played by FcγR polymorphisms in HIV-1 infection, treatment and vaccine trial outcomes. Importantly, we highlight contrasting findings that may be due to multiple factors and the relatively limited data from African populations. We recommend further studies especially in sub-Saharan Africa to confirm the role of FcγRIIa in the establishment of latent reservoir and to determine their influence in therapies involving bNAbs.

A novel endogenous CD16-Expressing Natural Killer Cell for cancer immunotherapy

Natural killer (NK) cells, as a potential source for off-the-shelf cell therapy, attack tumor cells with low risk of severe cytokine release syndrome (CRS) or graft-versus-host disease (GvHD). Fcγ receptor IIIA, also known as CD16, further confers NK cells with antibody-dependent cell-mediated cytotoxicity (ADCC), one mechanism of action of antibody-based immunotherapy. Here, we establish a novel human NK cell line, oNK-1, endogenously expressing CD16 along with high levels of NK activation markers and low levels of NK inhibitory markers. The long-term expansion and CD16 expression of oNK-1 cells were demonstrated. Furthermore, oNK-1 cells elicit superior cytotoxicity against cancer cells than primary NK cells. In conclusion, this study suggests that endogenous CD16-expressing oNK-1 has the potential to develop an effective NK-based therapy.