There are 2 small studies that recently looked at the issue of snot transplants as a treatment for chronic sinusitis. The idea behind snot transplants or sinonasal microbiota transplants is similar to fecal transplants - it's a transplant containing the entire microbial community (fungi, bacteria, viruses) in the form of a sample of snot or nasal mucus from a healthy donor to a recipient with chronic sinusitis (sign of an unhealthy sinus microbiome).
This idea has huge potential as a treatment. The goal in a sinus snot transplant is to have the healthy donor's snot (the mucus) take over and change (engraftment) the recipient's unhealthy sinus microbiome. The hope is that this will restore a healthy sinus microbiome in the person with chronic sinusitis, resulting in sustained improvement in sinus health.
The results from the studies are definitely encouraging, but also a bit mixed. For example, there was sustained improvement (up to 180 days) in 2 out of 3 patients in the 2024 study, but why not the third person? Also, illness may appear in the recipient of the transplant (see patient narratives in the first study). Also, why did some people drop out after the first snot transplant in the 2022 study? In both small studies, most of the the healthy donors were the recipient's spouse or a close friend.
The one concern that everyone has is of the possibility of some unknown disease being transferred from the donor to the recipient. [Note: Post about the Swedish study before it started]
Excerpts from Dec. 2022 Allergy and Rhinology: Upper airway microbiome transplantation for patients with chronic rhinosinusitis
The study, involving patients with CRSsNP, was of an open pre-post interventional design and involved 13 days of antibiotics (amoxicillin/clavulanate 875 mg/125 mg three times daily or, in case of penicillin-allergy, clarithromycin 500 mg two times daily) followed by five daily upper airway microbiome transplants.....All patients had over several years (i.e., far longer than the time span of this study) failed repeatedly on medical therapy and had undergone endoscopic sinus surgery (ESS) with a minimum of bilateral middle meatus antrostomies/ethmoidectomies
3.1 Patient narratives and adverse events Three patients opted not to participate further after visit 1 (V1). The remaining 22 patients completed the trial. Eighteen reported airway symptoms such as cough, sore throat, blocked or runny nose, or common cold-like symptoms during or soon after the transplant procedure. Seven indicated gastrointestinal problems, mainly diarrhea. One patient developed acute purulent rhinosinusitis and pneumonia 34 days after the last transplant. One patient developed a urinary tract infection, and one was diagnosed with diabetes type 2 (2 weeks before V8). One patient developed fever and cough during, and one experienced sinusitis-like symptoms 5 days after the transplant series. The latter two incidents were considered potentially caused by the microbiome transplant series.
3.7 SNOT-22 improvement greater than MCID Sixteen patients reported an improvement in SNOT-22 scores greater than MCID and six did not. Comparing the abundance and diversity of the microbiome of patients, those who featured a lower bacterial abundance and diversity at the start of the study (V1) were more likely to benefit from the treatment, but the difference failed to reach statistical significance (p = 0.23, ANOVA)
4 DISCUSSION In this study, we demonstrate that nasal microbiome transplants obtained from healthy individuals and administered as nasal lavages to patients with CRSsNP are feasible. The patients reported significant long-term symptom reductions, potentially associated with a long-lasting increase in abundance and diversity of the local bacterial flora. The observations, which need to be confirmed by randomized controlled trials, support the view that a disrupted microbiome is a driver of the inflammation seen in CRSsNP, and that restoring its abundance and diversity has therapeutic potential.
Arguably, in this study, the microbiome transplantation series resulted in a change in the nasal microbiome of the CRSsNP patients. This was observed soon after the course of antibiotics, but importantly also after the final observation more than 3 months later (V8). Indeed, such a long-lasting effect might not be expected from antibiotics alone, as indicated, for example, by Sabino et al.14 The “new microbiome” featured an increased abundance and diversity: 17 bacterial species were significantly more abundant at the end of the study (V8). These included three species considered to be human commensals (Prevotella aurantiaca, Clostridium cadaveris, Bacterioides sartori) and one a human pathogen associated with oral/dental infections (Prevotella saccharolyticus). Furthermore, 13 of 17 were nonhuman species (animal, water, soil, etc.), all nonpathogens to humans. We suggest that these effects were produced by the microbiome transplantation intervention.
5 CONCLUSION In conclusion, nasal microbiome transplants to patients with CRSsNP may produce a long-lasting change in abundance and diversity of the nasal microbiome and an associated reduction of symptoms. Although further randomized/sham-controlled studies are warranted, nasal microbiome transplantation, possibly in combination with a preceding course of antibiotics, may emerge as a treatment option for CRSsNP.
Excerpts from April 2024 Allergy and Rhinology: SinoNasal Microbiota Transfer to treat recalcitrant chronic rhinosinusitis: A case series
4 DISCUSSION Collectively, SNMT (sinonasal microbiota transfer) alone led to sustained subjective and objective improvement in two of three recipients, suggesting that SNMT is a safe intervention that may clinically benefit rCRS patients.
Interestingly, aPDT pre-treatment (antimicrobial photodynamic therapy), a process used to sterilize the sinuses did not improve SNMT efficacy and was associated with worse outcomes.
We observed shifts in the microbiota but not donor microbiota engraftment in response to SNMT. As this was a small case series, we have launched a randomized, double-blind, placebo-controlled trial to further test the efficacy of SNMT (vs. a saline placebo) for rCRS (ClinicalTrials.gov identifier: NCT05454072).