Biology subjects

Paus, R.

Publications and source records attributed to Paus, R..

5 recordsLinked to original sources

bioRxiv2024

Perceived stress exacerbates psoriasis in human skin in vivo: Insights from a humanized psoriasis mouse model

IntroductionThe widely held belief that psychoemotional stress triggers or exacerbates psoriatic skin lesions lacks sufficient scientific evidence. This study investigated this concept using a psoriasis humanized mouse model. MethodsHealthy human skin was grafted onto SCID/beige mice (n=25), and one month later, psoriatic lesions were induced by intradermal injection of autologous, in vitro IL-2- preactivated PBMCs. Following lesion development, topical dexamethasone (DEX) was applied to induce lesion remission. After lesions disappeared, the mice were exposed to either sonic or sham stress for 24 hours. ResultsSonic stress led to the relapse of psoriatic lesions in all human skin xenografts within 14 days. This relapse was associated with significant changes in psoriasis-related skin characteristics: increased epidermal thickness, K16 expression, keratinocyte proliferation, antimicrobial peptide expression (S100A7, h{beta}2-defensin), and immune activation markers (HLA-DR, ICAM-1, CD1d, MICA-NKG2D). Additionally, epidermal and dermal immune cells (CD3+, CD8+, CD11c+, CD56+, ILC3, c-KIT+ or tryptase+ cells) and psoriasis-associated pro-inflammatory mediators (CXCL10, IL-22, IL-15, IL-17A/F, IFN-{gamma}, and TNF) were found to be increased. Neurogenic inflammation biomarkers (NGF, NK1-R, and substance P) were also significantly upregulated in stressed mice. Treatment with the FDA-approved neurokinin-1 receptor antagonist, aprepitant, prevented stress-induced psoriatic relapses in 4 out of 5 mice and normalized most inflammatory and neurobiological markers. ConclusionsThese findings provide novel, conclusive evidence that perceived stress can trigger psoriatic lesions in human skin xenografts in vivo and highlight the role of substance P-dependent neurogenic inflammation in this process.

immunology↗

bioRxiv2024

Topically applied thyroid hormones stimulate hair growth in organ-cultured human scalp skin

We have previously shown that the thyroid hormones triiodothyronine (T3) and thyroxine (T4) prolong anagen, mitigate stem cell apoptosis, and stimulate mitochondrial functions in microdissected human scalp HFs ex vivo. To circumvent the systemic adverse effects of T3/T4, we have asked in the current pilot study whether topically applied T3/T4 retains hair growth-promoting properties. To prove this, we have topically treated healthy full-thickness human scalp skin with T3 (1, 10nM) and T4 (1, 10M) for six days in serum-free organ culture, using an HF-targeting vehicle that contains only FDA-approved ingredients. This showed that, at distinct doses, topical T3 and T4 significantly increased the percentage of HFs in anagen, decreased the percentage of proliferative (Ki-67+) cells in the hair matrix, did not promote melanogenesis (as measured by quantitative Warthin-Starry histochemistry), and significantly increased keratin 15 expression in the bulge. Finally, T3 and T4, at low concentrations, increase the expression of the hair growth promoters IGF-1 and FGF-7. The lower concentration of T3 and both of T4 also significantly increases the number of CD31+ endothelial cells, suggesting a pro-angiogenic effect, which is also important for hair growth promotion. These preliminary results strongly suggest that topically applied thyroid hormones promote hair growth in intact human scalp on multiple levels ex vivo. This invites the intermittent pulse application of topical T3 and T4 as a novel therapeutic intervention for managing hair loss disorders associated with telogen effluvium, such as androgenetic alopecia.

pharmacology and toxicology↗

bioRxiv2022

Involvement of ILC1-like innate lymphocytes in human autoimmunity, lessons from alopecia areata

Here, we have explored the involvement of innate lymphoid cells-type 1 (ILC1) in the pathogenesis of alopecia areata (AA), because we found them to be significantly increased around lesional and non-lesional HFs of AA patients. To further explore these unexpected findings, we first co-cultured autologous circulating ILC1-like cells (ILC1lc) with healthy, but stressed, organ-cultured human scalp hair follicles (HFs). ILClc induced all hallmarks of AA ex vivo: they significantly promoted premature, apoptosis-driven HF regression (catagen), HF cytotoxicity/dystrophy and most important for AA pathogenesis, collapse of the HFs physiological immune privilege. NKG2D-blocking or IFN{gamma}-neutralizing antibodies antagonized this. In vivo, intradermal injection of autologous activated, NKG2D+/IFN{gamma}-secreting ILC1lc into healthy human scalp skin xenotransplanted onto SCID/beige mice sufficed to rapidly induce characteristic AA lesions. This provides the first evidence that ILC1lc suffice to induce AA in previously healthy human HFs ex vivo and in vivo, and further questions the conventional wisdom that AA is always an autoantigen-dependent, CD8+ T cell-driven autoimmune disease.

immunology↗

bioRxiv2022

AIMP1-derived peptide secreted from hair follicle stem cells activates dermal papilla cells to promote hair growth

Hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) are crucial in the biogenesis and maintenance of hair follicles (HFs). In this study, a fragment derived from aminoacyl-tRNA synthetase-interacting multifunctional protein1 (AIMP1) was secreted from HFSCs to activate DPCs to maintain hair follicle homeostasis. A histological analysis revealed that AIMP1 levels in hair follicles decreased with hair loss. Hair regrowth in AIMP1-induced mice was faster than that in non-induced mice. Deletion mapping revealed 41 amino acids (TN41, aa 6-46) as the active region of AIMP1. The N-terminal peptide fragment of AIMP1 generated by MMP1 was secreted from Wnt-treated HFSCs to activate DPCs via FGFR2. TN41 activated Akt and ERK, increased {beta}-catenin, and enhanced DPCs activation. TN41 also promoted hair shaft elongation in cultured human hair follicles and improved the hair-inducing activity of cultured DPC spheroids. In summation, the AIMP1 fragment secreted from HFSCs appears to stimulate active hair regrowth through activating DPCs.

cell biology↗

bioRxiv2020

Human Hair Graying is Naturally Reversible and Linked to Stress

Hair graying is a universal hallmark of aging believed to be linked to psychological stress. Here we develop a novel approach to quantitatively profile natural graying events along individual human hair shafts, resulting in a quantifiable physical timescale of hair pigmentation patterns (HPPs). Using this approach, we quantify rare events of white/gray hairs that naturally regain pigmentation within days to weeks, thereby quantitatively defining the reversibility of graying in healthy, unmedicated individuals. Proteomic analysis shows that graying is marked by the upregulation of proteins related to energy metabolism, mitochondria, and antioxidant defenses. Combining hair pigmentation profiling and proteomics at the single hair level, we also report hair graying and its reversal occurring in parallel with behavioral and psychological stressors. A computational simulation suggests a threshold-based mechanism for the temporary reversibility of graying. Quantitatively mapping HPPs in humans provides an opportunity to longitudinally examine the influence of life exposures on biological aging.

cell biology↗