CpG-DNA induces bacteria-reactive IgM enhancing phagocytic activity against Staphylococcus aureus infection

Safety, Tolerability, and Pharmacokinetics of Kukoamine B in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Multiple-Dose Phase I Study

INTRODUCTION

Kukoamine B (KB) is a novel sepsis therapeutic drug targeting lipopolysaccharide and CpG DNA. This study aims to evaluate the safety, tolerability, and pharmacokinetic (PK) profile of multiple doses of KB in healthy volunteers.

METHODS

Healthy volunteers were randomized at a 1:1:1:1 ratio to receive multiple intravenous infusion doses of KB 0.06 mg/kg, 0.12 mg/kg, 0.24 mg/kg or placebo (administered every 8 h per day) for 7 days and subsequently followed up for another 7 days at Peking Union Medical College Hospital. Primary endpoints were adverse events (AEs), and the secondary endpoints were PK parameters of the first administration and the last administration.

RESULTS

Data of the 18 health volunteers in KB groups and 6 in the placebo group were pooled and analyzed. AEs occurred in 12 (66.67%) volunteers in the KB groups and 4 (66.67%) volunteers in the placebo group. Treatment-related adverse events (TRAEs) occurred in 8 (44.44%) volunteers in the KB groups and 2 (33.33%) volunteers in the placebo group. Hypertriglyceridemia (4 [22.22%] vs. 2 [33.33%]) and sinus bradycardia (3 [16.67%] vs. 0) were the most common AEs. The mean elimination half-life, clearance, and distribution volume of KB were 3.40-4.88 h, 9.35-13.49 L/h, and 45.74-101.90 L, respectively. The average accumulation ratios of area under the plasma concentration-time curve and maximum plasma concentration were 1.06 and 1.02, respectively.

CONCLUSION

Single and multiple intravenous infusions of KB at a dose range of 0.06-0.24 mg/kg are safe and tolerable in healthy volunteers.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02690961.

CpG Adjuvant in Allergen-Specific Immunotherapy: Finding the Sweet Spot for the Induction of Immune Tolerance

Prevalence and incidence of IgE-mediated allergic diseases have increased over the past years in developed and developing countries. Allergen-specific immunotherapy (AIT) is currently the only curative treatment available for allergic diseases that has long-term efficacy. Although AIT has been proven successful as an immunomodulatory therapy since its beginnings, it still faces several unmet needs and challenges today. For instance, some patients can experience severe side effects, others are non-responders, and prolonged treatment schedules can lead to lack of patient adherence and therapy discontinuation. A common strategy to improve AIT relies on the use of adjuvants and immune modulators to boost its effects and improve its safety. Among the adjuvants tested for their clinical efficacy, CpG oligodeoxynucleotide (CpG-ODN) was investigated with limited success and without reaching phase III trials for clinical allergy treatment. However, recently discovered immune tolerance-promoting properties of CpG-ODN place this adjuvant again in a prominent position as an immune modulator for the treatment of allergic diseases. Indeed, it has been shown that the CpG-ODN dose and concentration are crucial in promoting immune regulation through the recruitment of pDCs. While low doses induce an inflammatory response, high doses of CpG-ODN trigger a tolerogenic response that can reverse a pre-established allergic milieu. Consistently, CpG-ODN has also been found to stimulate IL-10 producing B cells, so-called B regulatory cells (Bregs). Accordingly, CpG-ODN has shown its capacity to prevent and revert allergic reactions in several animal models showing its potential as both preventive and active treatment for IgE-mediated allergy. In this review, we describe how CpG-ODN-based therapies for allergic diseases, despite having shown limited success in the past, can still be exploited further as an adjuvant or immune modulator in the context of AIT and deserves additional attention. Here, we discuss the past and current knowledge, which highlights CpG-ODN as a potential adjuvant to be reevaluated for the enhancement of AIT when used in appropriate conditions and formulations.

The Central Role and Possible Mechanisms of Bacterial DNAs in Sepsis Development

The pathological roles of bacterial DNA have been documented many decades ago. Bacterial DNAs are different from mammalian DNAs; the latter are heavily methylated. Mammalian cells have sensors such as TLR-9 to sense the DNAs with nonmethylated CpGs and distinguish them from host DNAs with methylated CpGs. Further investigation has identified many other types of DNA sensors distributed in a variety of cellular compartments. These sensors not only sense foreign DNAs, including bacterial and viral DNAs, but also sense damaged DNAs from the host cells. The major downstream signalling pathways includeTLR-9-MyD88-IKKa-IRF-7/NF-κB pathways to increase IFN/proinflammatory cytokine production, STING-TBK1-IRF3 pathway to increase IFN-beta, and AIM2-ASC-caspas-1 pathway to release IL-1beta. The major outcome is to activate host immune response by inducing cytokine production. In this review, we focus on the roles and potential mechanisms of DNA sensors and downstream pathways in sepsis. Although bacterial DNAs play important roles in sepsis development, bacterial DNAs alone are unable to cause severe disease nor lead to death. Priming animals with bacterial DNAs facilitate other pathological factors, such as LPS and other virulent factors, to induce severe disease and lethality. We also discuss compartmental distribution of DNA sensors and pathological significance as well as the transport of extracellular DNAs into cells. Understanding the roles of DNA sensors and signal pathways will pave the way for novel therapeutic strategies in many diseases, particularly in sepsis.

Modulation of the Innate Immune Response by Targeting Toll-like Receptors: A Perspective on Their Agonists and Antagonists

Toll-like receptors (TLRs) are a class of proteins that recognize pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs), and they are involved in the regulation of innate immune system. These transmembrane receptors, localized at the cellular or endosomal membrane, trigger inflammatory processes through either myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling pathways. In the last decades, extensive research has been performed on TLR modulators and their therapeutic implication under several pathological conditions, spanning from infections to cancer, from metabolic disorders to neurodegeneration and autoimmune diseases. This Perspective will highlight the recent discoveries in this field, emphasizing the role of TLRs in different diseases and the therapeutic effect of their natural and synthetic modulators, and it will discuss insights for the future exploitation of TLR modulators in human health.