# The skin microbiome in acne

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $524,042

## Abstract

PROJECT SUMMARY/ABSTRACT
Acne is a disease of the pilosebaceous unit (PSebU) that is ranked third among chronic skin diseases for
causing disabilityand is a major cause of psychological impairment and medical expense. The predominant
bacterial species in the microbiome of the PSebU is Propionibacterium acnes (aka Cutibacterium acnes), a
commensal that can trigger inflammation. This proposal seeks to understand why P. acnespromotes
inflammation in only some of the pilosebaceous unit (PSebU) of individuals with acne,yet other individuals do
not have disease. To solve this central question of this major human disease and advance fundamental
understanding of howP. acnesinteracts with the host immune response, we will study disease-associated
phylotypes (PA- acne associated) compared to other strains that do not promote disease (PH- healthy skin
associated).The aims of this proposal are based on several important recent discoveries that have shed new
light on how P. acnesand the PSebU environment can promote inflammation. PAis shown to preferentially
induce pro-inflammatory cytokines IFN-γ and IL-17 whereas PHinduces the anti-inflammatory cytokine IL-10in
peripheral blood mononuclear cells (PBMC).Complementing this, we have also found that thatwhen P. acnesis
placed under anerobic environmental conditions that mimic the plugged PSebU of acne, they then produce
short chain fatty acids (SCFAs) that promote cytokine release from keratinocytes (KC). This occurs due to the
capacity of some P. acnes strains toinduce epigenetic changes that break immune tolerance of KC to TLR
ligands. In this proposal, we will therefore combine our efforts to precisely define mechanisms by which P.
acnesinduces inflammation in the PSebU and promotes disease. Our specific aims are: 1) Determine the
mechanisms by which the acne microbiome can promote pro- vs. anti-inflammatory responses in lymphoid and
myeloid cells, 2) Understand the mechanisms by which metabolites of the acne microbiome induce cytokine
responses in KCs and sebocytes; and 3) Determine how strain-specific members of the skin microbiome
regulate cutaneous inflammation. The proposed studies will provide new insight into how the skin microbiome
shapes cutaneous immune responses leading to inflammation vs. homeostasis, with the potential for
intervention in skin disease.

## Key facts

- **NIH application ID:** 9944455
- **Project number:** 5R01AR074302-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Richard L Gallo
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $524,042
- **Award type:** 5
- **Project period:** 2018-08-13 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9944455

## Citation

> US National Institutes of Health, RePORTER application 9944455, The skin microbiome in acne (5R01AR074302-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9944455. Licensed CC0.

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