<SEC-DOCUMENT>0000899243-23-004798.txt : 20230213
<SEC-HEADER>0000899243-23-004798.hdr.sgml : 20230213
<ACCEPTANCE-DATETIME>20230213173439
ACCESSION NUMBER:		0000899243-23-004798
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20230209
FILED AS OF DATE:		20230213
DATE AS OF CHANGE:		20230213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hayden Michael R
		CENTRAL INDEX KEY:			0001352908

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39122
		FILM NUMBER:		23620290

	MAIL ADDRESS:	
		STREET 1:		C/O ASPREVA PHARMACEUTICALS CORPORATION
		STREET 2:		1203-4464 MARKHAM STREET
		CITY:			VICTORIA
		STATE:			A1
		ZIP:			V8Z 7X8

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			89bio, Inc.
		CENTRAL INDEX KEY:			0001785173
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				831114349
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		142 SANSOME STREET
		STREET 2:		SECOND FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104
		BUSINESS PHONE:		(415) 432-9270

	MAIL ADDRESS:	
		STREET 1:		142 SANSOME STREET
		STREET 2:		SECOND FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-02-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001785173</issuerCik>
        <issuerName>89bio, Inc.</issuerName>
        <issuerTradingSymbol>ETNB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001352908</rptOwnerCik>
            <rptOwnerName>Hayden Michael R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O 89BIO, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>142 SANSOME STREET, 2ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>14.70</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2023-02-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>27400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2033-02-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>27400</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27400</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This option represents a right to purchase a total of 27,400 shares of the Issuer's Common Stock, which will vest in full on February 9, 2024, subject to the Reporting Person's continued service to the Issuer through such date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Ryan A. Murr, as attorney-in-fact for Michael R. Hayden</signatureName>
        <signatureDate>2023-02-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
