Immunomodulatory Effects of Rhinovirus and Enterovirus Infections During the First Year of Life

Abstract

Early childhood infections have been implicated in the development of immune-mediated diseases, such as allergies, asthma, and type 1 diabetes. We set out to investigate the immunomodulatory effects of early viral infections experienced before the age of one year on the peripheral regulatory T cell population (Treg) and circulating cytokines in a birth-cohort study of Estonian and Finnish infants. We show here a temporal association of virus infection with the expression of FOXP3 in regulatory T cells. Infants with rhinovirus infection during the preceding 30 days had a higher FOXP3 expression in Treg cells and decreased levels of several cytokines related to Th1 and Th2 responses in comparison to the children without infections. In contrast, FOXP3 expression was significantly decreased in highly activated (CD4+CD127-/loCD25+FOXP3high) regulatory T cells (TregFOXP3high) in the infants who had enterovirus infection during the preceding 30 or 60 days. After enterovirus infections, the cytokine profile showed an upregulation of Th1- and Th17-related cytokines and a decreased activation of CCL22, which is a chemokine derived from dendritic cells and associated with Th2 deviation. Our results reveal that immunoregulatory mechanisms are up-regulated after rhinovirus infections, while enterovirus infections are associated with activation of proinflammatory pathways and decreased immune regulation.

Keywords: cytokine; enterovirus; regulatory T cell; rhinovirus; type 1 diabetes.

Figure 1

Proportion (%) of stool samples positive for either enteral or respiratory viruses (433 samples) tested, from all 1,063 stool samples collected during the first 12 months of life. The most frequently detected virus was rhinovirus (Rhino) in 280 of the virus-positive samples, followed by norovirus G1/G2 (Noro) (71), enterovirus (Entero) (59), parechovirus (Par) (46), and rotavirus (Rota) (42 samples), respectively.

Figure 2

Seasonality of virus detection in stool samples. Enterovirus (Entero), parechovirus (Parecho), and rotavirus (Rota) were most frequently detected during autumn months, while norovirus (Noro) was most frequent from February to March. Rhinovirus (Rhino) was most frequent in May-June and September-October.

Figure 3

The intensity of FOXP3 expression, as median fluorescence intensity (MFI), in Treg cells (A, B) and activated Treg cells TregFOXP3high (C, D) during the first year of life according to the detection of viruses in stool samples within three different time windows, 14, 30, and 60 days, before the collection of a blood sample for Treg analyses. Neg, no viruses detected; Pos, at least one virus detected; HRV, human rhinovirus; HEV, human enterovirus. Medians are marked with a horizontal line, and whiskers show 5–95 percentiles. Correction for multiple comparisons (N = 5) retain statistical significance for p values ≤ 0.01.

Figure 4

Rhinovirus infection-related changes in circulating cytokines (pg/ml) in serum in a window of 60, 30, and 14 days after infection. IL-5 (A), IL-13 (B), IFNγ (C), Th17 (D), GM-CSF (E), IL-2 (F), and Th1 cytokines IL-1β and sIL-1R (G, H). Medians are marked with a horizontal line in the boxes, and whiskers show 5–95 percentiles. Correction for multiple comparisons (N = 30) retain statistical significance for p values ≤ 0.0016.

Figure 5

Enterovirus infection-related changes in circulating cytokines. Enterovirus infected infants had a different cytokine profile after the infection showing increased activation of Th1 and Th17, CXCL10 (IP-10) (A), and Il-17 (B) cytokines but reduced activation of CCL4 (MIP-1β, C) and CCL22 (MDC, D). CCL22 is a chemokine derived from dendritic cells and associated with Th2 deviation. Medians are marked with a horizontal line, and whiskers show 5–95 percentiles. Correction for multiple comparisons (N = 30) retain statistical significance for p values ≤ 0.0016.