Healthy individuals genetically at-risk for the development of Pemphigus vulgaris or Alopecia areata share disease-like cytokine dysregulation

Abstract

Autoimmune diseases (AID) are defined by immune dysregulation characterized by specific humoral and/or cell mediated responses directed against the body's own tissues. Cytokines in particular play a pivotal role in the pathogenesis of AID, with proinflammatory cytokines contributing to the initiation and propagation of autoimmune inflammation, whereas anti-inflammatory cytokines facilitate regression of inflammation and recovery from acute phases of the disease. Parallel work by our group evaluating a comprehensive set of pro- and anti-inflammatory serum cytokines in Pemphigus vulgaris (PV) as well as Alopecia areata (AA) uncovered a similar pattern of inheritance specific immune dysregulation in these two distinct autoimmune skin diseases. In AA, we found healthy control subjects who are blood related to AA patients exhibit the same cytokine dysregulation in Th1 and Th17 pathways as do patients with AA. In PV, patients as well as individuals who are healthy but yet carry certain PV-associated HLA alleles (termed here as HLA-matched controls) share a similar, but not fully overlapping pattern of cytokine expression that is distinct from control subjects who do not type for these HLA alleles. Specifically, PV patients as well as HLA-matched controls demonstrate immunological activation of several pro-inflammatory-, Th17-, Th2-pathway associated cytokines, and the chemokine IL-8. Thus, in both AA and PV, we reveal cytokine dysregulations that are linked to genetic background. The presence of disease promoting pathways in not only patients, but also genetically related, but healthy control individuals further evokes the novel hypothesis that there may be co-existing disease counteracting immune protective mechanisms at play in thwarting the threat of disease in genetically predisposed individuals who, despite harboring disease associated immune imbalances, remain healthy. Our data underscore the known tendency of AID to cluster in families and support the notion of the shared genetic/common cause hypothesis across multiple AID.

Keywords: HLA; Th17; Th2; alopecia; autoimmunity; cytokine; pemphigus.

Figure 1

(A) Representative box and whisker plot of TNFα levels among Alopecia areata patients, genetically susceptible healthy controls (first degree relatives of Alopecia areata patients) and not genetically susceptible healthy controls (individuals with no family history of any autoimmune disease). (B) Heatmap of the distribution of four cytokines that were found to be significantly elevated in Alopecia areata patients and genetically susceptible healthy controls (first degree relatives of Alopecia areata patients) when compared to not genetically susceptible healthy controls (individuals with no family history of any autoimmune disease). Heatmap of z-score transformed data was created with Morpheus software. https://software.broadinstitute.org/morpheus.

Figure 2

(A) Representative box and whisker plot of TNFα levels among PV patients, genetically susceptible healthy controls (“HLA-matched”) and not genetically susceptible (“HLA-unmatched”). (B) Heatmap of the distribution of cytokines that were found to be significantly elevated in Pemphigus vulgaris patients and genetically susceptible healthy controls (express Pemphigus vulgaris-associated HLA alleles) when compared to not genetically susceptible healthy controls (do not express Pemphigus vulgaris-associated HLA alleles). Heatmap of z-score transformed data was created with Morpheus software. https://software.broadinstitute.org/morpheus.

Figure 3

Summary schematic outlining cytokine dysregulation among PV and AA patients and control groups.

Figure 4

(A) Cytokine dysregulation shared across related controls/HLA-matched controls and patients with AA/PV: The overlapping portion of the Venn diagram shows cytokine pathways that are shared between both patients with AA and PV, as well as their genetically susceptible counterparts (related controls or HLA-matched controls, respectively). The portion to the right show cytokines that were found to be upregulated in disease alone (note: outside of IL-10 and IL-22, these cytokines were not analyzed for AA patients). (B) Cytokine dysregulation shared across both AA and PV: Both AA and PV share a dysregulation in Th17-pathway associated cytokines as well as TNFα (overlapping area of the Venn diagram). In addition, AA shows dysregulation in Th1-pathway cytokines IFNγ and TNFα (left). PV, on the other hand, shows an additional dysregulation in other pro-inflammatory cytokines (IL-1α, IL-1β, IL-6, IL-8) as well as the Th2 pathway cytokine IL-13 (right).