The effect of IgG levels on the number of natural killer cells and their Fc receptors in chronic inflammatory demyelinating polyradiculoneuropathy

Effects of Intravenous Immunoglobulins on Human Innate Immune Cells: Collegium Internationale Allergologicum Update 2024

BACKGROUND

Intravenous immunoglobulin (IVIg) has been used for almost 40 years in the treatment of autoimmune and systemic inflammatory diseases. Numerous cells are involved in the innate immune response, including monocytes/macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils, natural killer cells, and innate lymphoid cells. Many studies have investigated the mechanisms by which IVIg down-modulates inflammatory and autoimmune processes of innate immune cells. However, questions remain regarding the precise mechanism of action in autoimmune or inflammatory conditions. The aim of this work was to review the immunomodulatory effect of IVIg on only human innate immune cells. A narrative review approach was chosen to summarize key evidence on the immunomodulatory effects of commercially available and unmodified IVIg on human innate immune cells.

SUMMARY

Numerous different immunomodulatory effects of IVIg have been reported, with some very different effects depending on the immune cell type and disease. Several limitations of the different studies were identified. Of the 77 studies identified and reviewed, 29 (37.7%) dealt with autoimmune or inflammatory diseases. Otherwise, the immunomodulatory effects of IVIg were studied only in healthy donors using an in vitro experimental approach. Some of the documented effects showed disease-specific effects, such as in Kawasaki disease. Various methodological limitations have also been identified that may reduce the validity of some studies.

KEY MESSAGE

As further insights have been gained into the various inflammatory cascades activated in immunological diseases, interesting insights have also been gained into the mechanism of action of IVIg. We are still far from discovering all the immunomodulatory mechanisms of IVIg.

Therapeutic potential of natural killer cells in neuroimmunological diseases

Natural killer (NK) cells, a major component of the innate immune system, have prominent immunoregulatory, antitumor proliferation, and antiviral activities. NK cells act as a double-edged sword with therapeutic potential in neurological autoimmunity. Emerging evidence has identified NK cells are involved in the development and progression of neuroimmunological diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, autoimmune encephalitis, Guillain-Barré Syndrome, chronic inflammatory demyelinating polyneuropathy, myasthenia gravis, and idiopathic inflammatory myopathy. However, the regulatory mechanisms and functional roles of NK cells are highly variable in different clinical states of neuroimmunological diseases and need to be further determined. In this review, we summarize the evidence for the heterogenic involvement of NK cells in the above conditions. Further, we describe cutting-edge NK-cell-based immunotherapy for neuroimmunological diseases in preclinical and clinical development and highlight challenges that must be overcome to fully realize the therapeutic potential of NK cells.

Anti-Inflammatory and Immunomodulatory Effect of High-Dose Immunoglobulins in Children: From Approved Indications to Off-Label Use

BACKGROUND

The large-scale utilization of immunoglobulins in patients with inborn errors of immunity (IEIs) since 1952 prompted the discovery of their key role at high doses as immunomodulatory and anti-inflammatory therapy, in the treatment of IEI-related immune dysregulation disorders, according to labelled and off-label indications. Recent years have been dominated by a progressive imbalance between the gradual but constant increase in the use of immunoglobulins and their availability, exacerbated by the SARS-CoV-2 pandemic.

OBJECTIVES

To provide pragmatic indications for a need-based application of high-dose immunoglobulins in the pediatric context.

SOURCES

A literature search was performed using PubMed, from inception until 1st August 2023, including the following keywords: anti-inflammatory; children; high dose gammaglobulin; high dose immunoglobulin; immune dysregulation; immunomodulation; immunomodulatory; inflammation; intravenous gammaglobulin; intravenous immunoglobulin; off-label; pediatric; subcutaneous gammaglobulin; subcutaneous immunoglobulin. All article types were considered.

IMPLICATIONS

In the light of the current imbalance between gammaglobulins' demand and availability, this review advocates the urgency of a more conscious utilization of this medical product, giving indications about benefits, risks, cost-effectiveness, and administration routes of high-dose immunoglobulins in children with hematologic, neurologic, and inflammatory immune dysregulation disorders, prompting further research towards a responsible employment of gammaglobulins and improving the therapeutical decisional process.

The Role of Acupuncture and Its Related Mechanism in Treating Chronic Prostatitis/Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is one of the most common diseases in urology, and its prevalence has been increasing, causing serious urogenital problems in men. Several targeted oral drug therapies exist to treat the pelvic pain experienced in this disease. However, these therapies may have potential adverse effects, and due to the unique location of the prostate, delivery of medications to the target lesion is difficult. Consequently, many patients seek alternative therapies. Acupuncture is a well-established treatment method in traditional Chinese medicine that can improve CP/CPPS symptoms and reduce pain. However, previous systematic reviews overlooked the significance of the characteristics and mechanisms of acupuncture therapy. This study aimed to summarize the characteristics and benefits of acupuncture therapy for CP/CPPS based on relevant literature and predict and analyze its related mechanisms.

The therapeutic potential of natural killer cells in neuropathic pain

Novel disease-modifying treatments for neuropathic pain are urgently required. The cellular immune response to nerve injury represents a promising target for therapeutic development. Recently, the role of natural killer (NK) cells in both CNS and PNS disease has been the subject of growing interest. In this opinion article, we set out the case for NK cell-based intervention as a promising avenue for development in the management of neuropathic pain. We explore the potential cellular and molecular targets of NK cells in the PNS by contrasting with their reported functional roles in CNS diseases, and we suggest strategies for using the beneficial functions of NK cells and immune-based therapeutics in the context of neuropathic pain.

Intravenous Immunoglobulin: Mechanism of Action in Autoimmune and Inflammatory Conditions

Intravenous immunoglobulin (IVIG) is the mainstay of therapy for humoral immune deficiencies and numerous inflammatory disorders. Although the use of IVIG may be supplanted by several targeted therapies to cytokines, the ability of polyclonal normal IgG to act as an effector molecule as well as a regulatory molecule is a clear example of the polyfunctionality of IVIG. This article will address the mechanism of action of IVIG in a number of important conditions that are otherwise resistant to treatment. In this commentary, we will highlight mechanistic studies that shed light on the action of IVIG. This will be approached by identifying effects that are both common and disease-specific, targeting actions that have been demonstrated on cells and processes that represent both innate and adaptive immune responses.

Novel Immunological and Therapeutic Insights in Guillain-Barré Syndrome and CIDP

Inflammatory neuropathies are a heterogeneous group of rare diseases of the peripheral nervous system that include acute and chronic diseases, such as Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The etiology and pathophysiological mechanisms of inflammatory neuropathies are only partly known, but are considered autoimmune disorders in which an aberrant immune response, including cellular and humoral components, is directed towards components of the peripheral nerve causing demyelination and axonal damage. Therapy of these disorders includes broad-spectrum immunomodulatory and immunosuppressive treatments, such as intravenous immunoglobulin, corticosteroids, or plasma exchange. However, a significant proportion of patients do not respond to any of these therapies, and treatment selection is not optimized according to disease pathophysiology. Therefore, research on disease pathophysiology aiming to reveal clinically and functionally relevant disease mechanisms and the development of new treatment approaches are needed to optimize disease outcomes in CIDP and GBS. This topical review describes immunological progress that may help guide therapeutic strategies in the future in these two disorders.

High Dose Intravenous IgG Therapy Modulates Multiple NK Cell and T Cell Functions in Patients With Immune Dysregulation

Intravenous immunoglobulin (IVIG) is an effective immunomodulatory treatment for immune dysregulation diseases. However, the mechanisms by which it reduces systemic inflammation are not well understood. NK cell cytotoxicity is decreased by IVIG in women with reduced fertility, but IVIG effects on NK cells in immune dysregulation are less clear. We hypothesized that IVIG modulation of lymphocyte function, especially in NK cells, is important for resolution of inflammation. Our aim was to identify IVIG-induced changes in a cohort of patients with Kawasaki disease (KD) and those that occur broadly in pediatric patients with various immune dysregulatory diseases. Peripheral blood mononuclear cells (PBMCs) of patients with KD or autoimmune/inflammatory diseases were phenotyped pre and post high dose IVIG treatment by flow cytometry. In KD patients, after IVIG infusion T_reg cell frequency and the proportion of activated CD25⁺ immunoregulatory CD56^bright NK cells was increased, and multiple lymphocyte subsets showed increased expression of the lymphoid tissue homing receptor CD62L. Importantly, IVIG treatment decreased the frequency of cells expressing the degranulation marker CD107a among cytotoxic CD56^dim NK cells, which was reflected in a significant reduction in target cell killing and in decreased production of multiple pro-inflammatory mediators. Interestingly, the activating receptor CD336 was expressed on a higher proportion of CD56^bright NK cells after IVIG in both KD and autoimmune/inflammatory patients while other NK receptors were increased differentially in each cohort. In autoimmune/inflammatory patients IVIG induced the proliferation marker CD71 on a higher percentage of CD56^dim NK cells, and in contrast to KD patients, CD107a⁺ cells were increased in this subset. Furthermore, when PBMCs were stimulated ex vivo with IL-2 or Candida antigen in autologous plasma, more of the CD4⁺ T cells of KD patients expressed CD25 after IVIG therapy but fewer cytotoxic T cells were degranulated based on CD107a expression. In summary, IVIG treatment in patients with immune dysregulation has multiple effects, especially on NK cell subsets and CD4⁺ T cells, which are compatible with promoting resolution of inflammation. These novel findings provide insight into the immunomodulatory actions of IVIG in autoimmune and inflammatory conditions.

The immune response and aging in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consists of various autoimmune subtypes in which the peripheral nervous system (PNS) is attacked. CIDP can follow a relapsing-remitting or progressive course where the resultant demyelination caused by immune cells (e.g., T cells, macrophages) and antibodies can lead to disability in patients. Importantly, the age of CIDP patients has a role in their symptomology and specific variants have been associated with differing ages of onset. Furthermore, older patients have a decreased frequency of functional recovery after CIDP insult. This may be related to perturbations in immune cell populations that could exacerbate the disease with increasing age. In the present review, the immune profile of typical CIDP will be discussed followed by inferences into the potential role of relevant aging immune cell populations. Atypical variants will also be briefly reviewed followed by an examination of the available studies on the immunology underlying them.

NK cell markers predict the efficacy of IV immunoglobulins in CIDP

Objective

To assess whether IV immunoglobulins (IVIgs) as a first-line treatment for chronic inflammatory demyelinating polyneuropathy (CIDP) have a regulative effect on natural killer (NK) cells that is related to clinical responsiveness to IVIg.

Methods

In a prospective longitudinal study, we collected blood samples of 29 patients with CIDP before and after initiation of IVIg treatment for up to 6 months. We used semiquantitative PCR and flow cytometry in the peripheral blood to analyze the effects of IVIg on the NK cells. The results were correlated with clinical aspects encompassing responsiveness.

Results

We found a reduction in the expression of several typical NK cell genes 1 day after IVIg administration. Flow cytometry furthermore revealed a reduced cytotoxic CD56^dim NK cell population, whereas regulatory CD56^bright NK cells remained mostly unaffected or were even increased after IVIg treatment. Surprisingly, the observed effects on NK cells almost exclusively occurred in IVIg-responsive patients with CIDP.

Conclusions

The correlation between the altered NK cell population and treatment efficiency suggests a crucial role for NK cells in the still speculative mode of action of IVIg treatment. Analyzing NK cell subsets after 24 hours of treatment initiation appeared as a predictive marker for IVIg responsiveness. Further studies are warranted investigating the potential of NK cell status as a routine parameter in patients with CIDP before IVIg therapy.

Classification of evidence

This study provides Class I evidence that NK cell markers predict clinical response to IVIg in patients with CIDP.

Dramatic clinical response to ultra-high dose IVIg in otherwise treatment resistant inflammatory neuropathies

BACKGROUND

Intravenous immunoglobulin (IVIg) has short and long-term efficacy in both chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy with conduction block (MMNCB). There is potential for under and over-treatment if trial regimens are strictly adhered to in clinical practice where titrating dose to clinical response is recommended.

METHODS

We report the response to high-dose IVIg (>2 g/kg/6 weeks) in a subgroup of patients with definite CIDP or MMNCB who were unresponsive to 'usual' dosing. IVIg frequency and dosing was determined for each individual by subjective and objective outcome measures for impairment, grip strength, and activity and participation.

RESULTS

Six patients (three with chronic inflammatory demyelinating polyneuropathy (CIDP), three with MMN) were included. Two patients (one CIDP and one MMNCB) returned to full-time work on fractionated IVIg doses of 5 g/kg/month and 9 g/kg/month. Patient three (CIDP) failed numerous other immunosuppressants but responded to short-term fractionated 4 g/kg/month of IVIg. Patient four has severe, refractory, childhood-onset CIDP, remains stable but dependent currently on 6.9 g/kg/month of IVIg. Patients five and six, both with MMNCB, required short term 4.5-5 g/kg/month to recover significant bilateral hand strength. No IVIg-related adverse events occurred in any individual.

CONCLUSIONS

These six cases demonstrate the safety and effectiveness of a treatment approach that includes individualised but evidence-based clinical assessment and, when necessary, high-doses of IVIg to restore patients' strength and ability to participate in activities of daily activities. Careful patient selection is important.

High-Dose Intravenous Immunoglobulins in the Treatment of Severe Acute Viral Pneumonia: The Known Mechanisms and Clinical Effects

The current outbreak of viral pneumonia, caused by novel coronavirus SARS-CoV-2, is the focus of worldwide attention. The WHO declared the COVID-19 outbreak a pandemic event on Mar 12, 2020, and the number of confirmed cases is still on the rise worldwide. While most infected individuals only experience mild symptoms or may even be asymptomatic, some patients rapidly progress to severe acute respiratory failure with substantial mortality, making it imperative to develop an efficient treatment for severe SARS-CoV-2 pneumonia alongside supportive care. So far, the optimal treatment strategy for severe COVID-19 remains unknown. Intravenous immunoglobulin (IVIg) is a blood product pooled from healthy donors with high concentrations of immunoglobulin G (IgG) and has been used in patients with autoimmune and inflammatory diseases for more than 30 years. In this review, we aim to highlight the known mechanisms of immunomodulatory effects of high-dose IVIg therapy, the immunopathological hypothesis of viral pneumonia, and the clinical evidence of IVIg therapy in viral pneumonia. We then make cautious therapeutic inferences about high-dose IVIg therapy in treating severe COVID-19. These inferences may provide relevant and useful insights in order to aid treatment for COVID-19.

Recent advances in "universal" influenza virus antibodies: the rise of a hidden trimeric interface in hemagglutinin globular head

Influenza causes seasonal outbreaks yearly and unpredictable pandemics with high morbidity and mortality rates. Despite significant efforts to address influenza, it remains a major threat to human public health. This issue is partially due to the lack of antiviral drugs with potent antiviral activity and broad reactivity against all influenza virus strains and the rapid emergence of drug-resistant variants. Moreover, designing a universal influenza vaccine that is sufficiently immunogenic to induce universal antibodies is difficult. Some novel epitopes hidden in the hemagglutinin (HA) trimeric interface have been discovered recently, and a number of antibodies targeting these epitopes have been found to be capable of neutralizing a broad range of influenza isolates. These findings may have important implications for the development of universal influenza vaccines and antiviral drugs. In this review, we focused on the antibodies targeting these newly discovered epitopes in the HA domain of the influenza virus to promote the development of universal anti-influenza antibodies or vaccines and extend the discovery to other viruses with similar conformational changes in envelope proteins.

The frequencies of Killer immunoglobulin-like receptors and their HLA ligands in chronic inflammatory demyelinating polyradiculoneuropathy are similar to those in Guillian Barre syndrome but differ from those of controls, suggesting a role for NK cells in pathogenesis

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired inflammatory neuropathy, which has similar clinical and pathological features to Guillain-Barré Syndrome (GBS), but differs in time course. We investigated the frequency of genes encoding Killer immunoglobulin-like receptors and their HLA ligands in subjects with CIDP, in subjects with GBS and in healthy controls. There were no differences in KIR gene frequency among the 3 groups. The gene frequencies for HLA-B Bw4-I were significantly greater in CIDP than HC, but did not differ from GBS. The frequency of the combination of 3DL1/HLA-B Bw4I was greater in CIDP than HC, but did not differ from that of GBS. These data raise the possibility of NK cell function being an important factor in the pathogenesis of CIDP.

Pathophysiology and biomarkers in chronic inflammatory demyelinating polyradiculoneuropathies

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired dysimmune disorder characterized by strong heterogeneity in terms of clinical manifestations, prognostic and response to treatment. To date, its pathophysiology and potential target antigens are not totally identified despite substantial progress in the understanding of the involved molecular mechanisms. Recent researches in the field have underlined the importance of cell-mediated immunity (lymphocytesT CD4+, CD8+ and macrophages), the breakdown of blood-nerve barrier, a failure of T-cell regulation, and the disruption of nodal and paranodal organization at the node of Ranvier. This last point is possibly mediated by autoantibodies towards axoglial adhesion molecules which may disrupt sodium and potassium voltage-gated channels clustering leading to a failure of saltatory conduction and the apparition of conduction blocks. The purpose of this article is to overview the main pathophysiologic mechanisms and biomarkers identified in CIDP.

Rapid and reversible responses to IVIG in autoimmune neuromuscular diseases suggest mechanisms of action involving competition with functionally important autoantibodies

Intravenous immunoglobulin (IVIG) is widely used in autoimmune neuromuscular diseases whose pathogenesis is undefined. Many different effects of IVIG have been demonstrated in vitro, but few studies actually identify the mechanism(s) most important in vivo. Doses and treatment intervals are generally chosen empirically. Recent studies in Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy show that some effects of IVIG are readily reversible and highly dependent on the serum IgG level. This suggests that in some autoantibody-mediated neuromuscular diseases, IVIG directly competes with autoantibodies that reversibly interfere with nerve conduction. Mechanisms of action of IVIG which most likely involve direct competition with autoantibodies include: neutralization of autoantibodies by anti-idiotypes, inhibition of complement deposition, and increasing catabolism of pathologic antibodies by saturating FcRn. Indirect immunomodulatory effects are not as likely to involve competition and may not have the same reversibility and dose-dependency. Pharmacodynamic analyses should be informative regarding most relevant mechanism(s) of action of IVIG as well as the role of autoantibodies in the immunopathogenesis of each disease. Better understanding of the role of autoantibodies and of the target(s) of IVIG could lead to more efficient use of this therapy and better patient outcomes.

Treatment of chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a sporadically occurring, acquired neuropathic condition of autoimmune origin with chronic progressive or relapsing-remitting disease course. CIDP is a treatable disorder; a variety of immunosuppressive and immunomodulatory agents are available to modify, impede, and even reverse the neurological deficits and sequelae that manifest in the course of the disease. However, in many cases CIDP is not curable. Challenges that remain in the treatment of CIDP patients are well recognized and include a remarkably individual heterogeneity in terms of disease course and treatment response as well as a lack of objective and feasible measures to predict and monitor the responsiveness to the available therapies. In this chapter an overview of the currently used drugs in the treatment of CIDP patients is given and some important and controversial issues that arise in the context of care for CIDP patients are discussed.

Essential role of NK cells in IgG therapy for experimental autoimmune encephalomyelitis

Intravenous immunoglobulin has long been used in treating autoimmune diseases, although mechanisms remain uncertain. Activating Fcγ receptors are receptors of IgG and reported to be essential in intravenous immunoglobulin (IVIG) therapy. Therefore, we hypothesized natural killer (NK) cells, which express abundant activating Fcγ receptors, are the potential cellular target. In experimental autoimmune encephalomyelitis (EAE), we demonstrated that IgG suppressed disease development in intact, but not in NK cell depleted mice. Adoptive transfer of IgG-treated NK cell could protect mice against EAE, and suppressed interferon γ and interleukin 17 production. The percentage of CD4⁺Foxp3⁺ regulatory T cells was significantly increased. The increase of regulatory T cells was also observed in IgG-treated EAE mice but not in NK cell depleted mice. In vitro experiments confirmed that IgG-treated NK cells enhanced regulatory T cell induction from naïve CD4⁺ T cells. Interestingly, cells from draining lymph nodes produced more interleukin 2 after the adoptive transfer of IgG-treated NK cells. We neutralized interleukin 2 and the induction of CD4⁺Foxp3⁺ T cells by IgG-treated NK cells was significantly reduced. To our knowledge, we identified for the first time the critical role of NK cells in the mechanism of IgG-induced induction of Treg cells in treatment of autoimmunity.

Glatiramer acetate in treatment of multiple sclerosis: a toolbox of random co-polymers for targeting inflammatory mechanisms of both the innate and adaptive immune system?

Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of neurons, causing mild to severe symptoms. Several anti-inflammatory treatments now play a significant role in ameliorating the disease. Glatiramer acetate (GA) is a formulation of random polypeptide copolymers for the treatment of relapsing-remitting MS by limiting the frequency of attacks. While evidence suggests the influence of GA on inflammatory responses, the targeted molecular mechanisms remain poorly understood. Here, we review the multiple pharmacological modes-of-actions of glatiramer acetate in treatment of multiple sclerosis. We discuss in particular a newly discovered interaction between the leukocyte-expressed integrin α(M)β(2) (also called Mac-1, complement receptor 3, or CD11b/CD18) and perspectives on the GA co-polymers as an influence on the function of the innate immune system.