Can primary immunodeficiencies help to provide insights into infectious risks of therapeutic antibodies?

Immunological Changes in Blood of Newborns Exposed to Anti-TNF-α during Pregnancy

Background

Although anti-TNF-α monoclonal antibodies are considered safe during pregnancy, there are no studies on the development of the exposed-infant immune system. The objective was to study for the first time the impact of throughout pregnancy exposure to anti-TNF-α has an impact in the development of the infant’s immune system, especially B cells and the IL-12/IFN-γ pathway.

Methods

Prospective study of infants born to mothers with inflammatory bowel disease treated throughout pregnancy with anti-TNF-α (adalimumab/infliximab). Infants were monitored both clinically and immunologically at birth and at 3, 6, 12, and 18 months.

Results

We included seven patients and eight healthy controls. Exposed infants had detectable levels of anti-TNF-α until 6 months of age; they presented a more immature B- and helper T-phenotype that normalized within 12 months, with normal immunoglobulin production and vaccine responses. A decreased Treg cell frequency at birth that inversely correlated with mother’s peripartum anti-TNF-α levels was observed. Also, a decreased response after mycobacterial challenge was noted. Clinically, no serious infections occurred during follow-up. Four of seven had atopia.

Conclusion

This study reveals changes in the immune system of infants exposed during pregnancy to anti-TNF-α. We hypothesize that a Treg decrease might facilitate hypersensitivity and that defects in IL-12/IFN-γ pathway might place the infant at risk of intracellular infections. Pediatricians should be aware of these changes. Although new studies are needed to confirm these results, our findings are especially relevant in view of a likely increase in the use of these drugs during pregnancy in the coming years.

To Extinguish the Fire from Outside the Cell or to Shutdown the Gas Valve Inside? Novel Trends in Anti-Inflammatory Therapies

Cytokines are the most important soluble mediators of inflammation. Rare pediatric diseases provided exemplar conditions to study the anti-inflammatory efficacy of new generation therapies (biologics/biopharmaceuticals) selectively targeting single cytokines. Monoclonal antibodies and recombinant proteins have revolutionized anti-inflammatory therapies in the last two decades, allowing the specific targeting of single cytokines. They are very effective in extinguishing inflammation from outside the cell, even with the risk of an excessive and prolonged immunosuppression. Small molecules can enter the cell and shutdown the valve of inflammation by directly targeting signal proteins involved in cytokine release or in response to cytokines. They are orally-administrable drugs whose dosage can be easily adjusted to obtain the desired anti-inflammatory effect. This could make these drugs more suitable for a wide range of diseases as stroke, gout, or neurological impairment, where inflammatory activation plays a pivotal role as trigger. Autoinflammatory diseases, which have previously put anti-cytokine proteins in the limelight, can again provide a valuable model to measure the real potential of small inhibitors as anti-inflammatory agents.

[Medicinal prophylaxis during intensified immunosuppression in children and adolescents : part 2]

The goal of modern antirheumatic therapy is to achieve an optimized disease control. This is individually achieved by an intensified immunosuppression (IS) frequently combining different immunosuppressive agents. Intensified IS should be accompanied by a standardized protocol to monitor immunological changes in the patient. This should include checklists (see Part 1 Screening during intensified IS in children and adolescents). An individual risk stratification according to the planned IS allows a prediction of infectious disease risks for the patient and, thus, individual infection prophylaxis. In addition, standardized management of patients with fever while receiving intensified IS may prevent further complications.

Human TLRs and IL-1Rs in host defense: natural insights from evolutionary, epidemiological, and clinical genetics

Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs) have TIR intracellular domains that engage two main signaling pathways, via the TIR-containing adaptors MyD88 (which is not used by TLR3) and TRIF (which is used only by TLR3 and TLR4). Extensive studies in inbred mice in various experimental settings have attributed key roles in immunity to TLR- and IL-1R-mediated responses, but what contribution do human TLRs and IL-1Rs actually make to host defense in the natural setting? Evolutionary genetic studies have shown that human intracellular TLRs have evolved under stronger purifying selection than surface-expressed TLRs, for which the frequency of missense and nonsense alleles is high in the general population. Epidemiological genetic studies have yet to provide convincing evidence of a major contribution of common variants of human TLRs, IL-1Rs, or their adaptors to host defense. Clinical genetic studies have revealed that rare mutations affecting the TLR3-TRIF pathway underlie herpes simplex virus encephalitis, whereas mutations in the TIR-MyD88 pathway underlie pyogenic bacterial diseases in childhood. A careful reconsideration of the contributions of TLRs and IL-1Rs to host defense in natura is required.

An overview of infectious complications in children on new biologic response-modifying agents

The clinical need for better treatments as well as the significant progress in understanding the pathophysiology of inflammation on one hand, and the progressive development of biotechnology on the other, were the driving force for the emergence of new treatments for autoimmune disorders at the beginning of the 21st century, heralding the ‘age of biologic response modifying agents’ or biologics. This new class of drugs, although in use for just over a decade, has revolutionized the treatment of many inflammatory disorders, such as rheumatic, connective tissue disorders, autoimmune and autoinflammatory diseases. They have already made an immense impact on the quality of life of patients experiencing many years of combined immunosuppressive and anti-inflammatory treatments for chronic and often debilitating diseases. As these drugs were developed with the aim of altering specific components in the immune system function and, in particular, the inflammatory response, it is not surprising that infectious complications, including the severe and unusual, are among the serious side effects alongside other features of dysregulated immune system function, such as autoimmunity, lymphoproliferation and malignancy. The aim of this article is to highlight and anticipate further the infectious risks of the most commonly used biologics in children.